Decerna is still fully operational during the COVID-19 pandemic

Photovoltaic array Photovoltaic array

We’d like to let all of our clients know that Decerna is still fully operational during these challenging times.

We are following the advice and guidance from the government, as well as using our own detailed risk assessments and policies, in order to keep ourselves, our clients, and wider society safe from COVID-19.

We are undertaking site visits, following our own strict policies. Staff are using PPE where appropriate, and maintaining social distancing.

Unless it is absolutely necessary to use the office, our staff are all working from home; however, all landlines are redirected to our mobile phones. We are open from 8.30am every weekday, and ready to support your renewable energy, energy storage, energy efficiency and LCA projects.

If you have any enquiries, please call 01670 543 009 or email Or, you can send an enquiry through our contact form on

Hopefully all of this chaos will end soon, and till then, stay safe.

Decerna Team.

EV car blog – 1 year in

It seems like five minutes ago, but it has actually been one year since I bought my first electric vehicle. I only realised this when I had to tax it – for free of course. Technically we had already placed a deposit on a Kia E Niro, but that wasn’t going to turn up until April, so I’m not counting that…

The little Renault ZOE has been great fun to drive, anyone who owns or who has driven an electric car knows how sprightly they can be! Around town, it’s very nippy, responsive & quiet and is a genuine pleasure to drive. To be fair, it’s not so much fun on the open road, especially in ‘Eco’ mode where the top speed is restricted to just 60mph to max out battery life. This can lead to some frustration on faster roads, or I just put it back into ‘Normal’ mode and just go with the flow.

The range is not brilliant, but I knew what I was getting into when I bought it. I have a modest 4.5-mile commute to work, and even in the depths of winter, I only need to charge once a week. A bit of running around and it may need a second charge, no big deal. I can charge at home from surplus solar in the summer or use the numerous free public charging points in Northumberland. There are one or two charge points that charge a set £1 to connect and then free electricity after that. So, bearing all that in mind it has cost me £18 for a year’s motoring, yes just £18! I really don’t know how people can afford to run petrol & diesel cars…

On the thorny subject of cost, EVs are supposed to be expensive right? Well, mine was three years old when I bought it for £8,500, that’s around the same or less than you would pay for an equivalent petrol or diesel car. However, due to the increased interest in electric cars, it’s actually gone up in value by around £1,000 – brilliant! No road tax, and only £18 for fuel it’s the cheapest form of transport I can think of, even walking would cost more in shoe wear!

OK, so it hasn’t all been rosy in the garden; getting on to a public charger can be an issue with taxis realising the benefit and the numerous other EV owners wanting a charge too. The biggest frustration is when you find a hybrid vehicle plugged in, fully charged and just sitting there taking up a space a ‘proper’ EV could be using…

All things considered, I’m still happy with my EV choice and actually having an EV at all. Would I go back to a petrol or diesel? No chance, the cost, noise and servicing costs make it a no-no for me. It will be better when there are more charging points, but I still won’t go back to ICE. Now, an electric motorbike is next up…

This is a Follow on blog from: Living with an Electric Vehicle

Bryan Dixon is the lead for grid related projects at Decerna. He’s currently working on delivering consultancy on large scale energy storage, including preparing four spade ready 49MW/98MWh sites.

A Tale of Two Journeys

The plan was simple, drive from Morpeth, Northumberland to Buckinghamshire. There one day, back the next. 295 miles each way, via the A1, M18, M1, A43 and M40. We had two choices of vehicles, a petrol-fuelled Honda Civic and a Kia eNiro, being the fully-fledged eco-warriors we are, we opted for the brand new eNiro. What could possibly go wrong!

A route was planned, allowing for a lunch and charging stop at Hellaby, on the M18 and a coffee and charging stop at Watford gap services on the M1. We left Morpeth just after 9am on a cool and sunny morning and proceeded without a hitch, enjoying a trouble-free charging stop at Hellaby via a nice shiny Instavolt system with 100 miles added in 35 minutes. Flash your credit/debit card, and away you go. Maccy Ds for lunch and back on the road without a hitch. Mid-afternoon rolls along, time for a break and charge on the Ecotricity network. Not quite as simple, much faffing around with WiFi and apps, and eventually, a slow charge begins. After that, off we go all the way to High Wycombe, not a care in the world. Journey done in 7 hours, terrific.

On the way home the following day we were looking forward to an enjoyable repeat of Monday. How wrong we were, we should have probably guessed we were heading for trouble as went north on the M40 in torrential rain. Being the brave-hearted fellows we are, we headed towards the sanctuary of Watford Gap, with a predicted 50 miles still in the tank, or battery!! Eventually, we spotted the Ecotricity charger on the far side of the building, and so it began as we tried to plug in and start charging, all to no avail. No matter what we tried, nothing worked. Back into the car, as it was wet and freezing cold, checking our phones and looking at the next option, which was Leicester Forest services, almost 40 miles away. It didn’t leave many spare miles, but it was doable. So off we set, driving cautiously but maintaining motorway speeds. After another search, we found the chargers, from the same manufacturer again, we were concerned, and down to 16 miles range. After much messing around with WiFi, apps and 4G we still couldn’t charge. Tried another charging point, not working, oh dear. By the way, it was now very cold and windy. Time to phone the charger vender, after several more minutes of messing about and getting colder we were told the charger would go to free vend and we could help ourselves. How wrong they were, the chargers failed to work. Our last option was the chargers on Leicester Forest, southbound, a quick drive up to the next junction and back down again, we should be all right, but to make sure we cross over the motorway, via the feeding stations over the traffic. One charger had a Model 3 Tesla on it, so they looked like a good bet. So off we set again, crossing the motorway at the next junction when the car dropped into limp mode on the slip road, not ideal, but we made it to the services with 3 miles left. Fortunately, we knew where the chargers were this time. Unfortunately, once again the same charger provider let us down, no end of phones calls later we are left with no choice but to call a recovery truck. For those of you interested, breakdown cover for EVs counts running out of charge the same as running out of fuel and will only take you to the nearest charger, no matter whose it is or what capacity it can charge at. So off we set, on the back of a big yellow break down truck to the Leicester Marriot Hotel and its two 7kW chargers. Luckily for us the staff there were amazing and let us use their charger for free. So, there we sat, with three hours to kill whilst we crammed in enough charge to recommence our journey north.

Obviously, by this time it was dark and raining again. With no faith whatsoever left with the provider of the chargers we kept encountering, we headed to the centre of Derby and an Instavolt charger. Finally, luck was with us, a flash of the card and charging commenced. The only downside was the filthy fast food restaurant that took 12 minutes to make two hot drinks—not going there again. After 45 minutes we decided we couldn’t stand staying there any longer and headed off back to the Instalvolt charger at Hellaby. Apart from the traffic, this leg of the journey went without a hitch. Once at Hellaby, straight onto the Instavolt charger, more coffee and a doughnut and we had enough charge to finally get home. Or so we thought!

Not long after leaving Hellaby, heading north on the A1 the traffic came to a grinding halt, blue lights and no sign of movement, so we nipped off at a conveniently located slip road and navigated around the accident, via yours truly’s map reading capability. Unfortunately, we were suddenly over our mileage estimate to get home. Back to the phone and more searching for chargers, and again for one last time Instavolt saved our bacon, and we actually had the choice of chargers at either Durham or Bowesfield. Twenty minutes charge later and we headed home, with no further incident, arriving in Morpeth at 11pm, 11.5 hours after we set off.

Lessons learned? For me I’ll stick to my Civic, two don’t use an EV south of Sheffield on the M1 and finally, always aim for an Instavolt, although I’m sure there may be other chargers you can rely on.

Bryan Dixon is the lead for grid related projects at Decerna. He’s currently working on technical advice to local businesses through the ERDF funded eGrid project as well as delivering consultancy on large scale energy storage, including an 87MW grid balancing battery.

Matt Cocker is an electrical design engineer at Decerna, and works closely with Bryan on various grid and renewable energy projects. He recently completed work on a project for a local authority including behind the meter batteries with a large photovoltaic array.

Importance of maintenance of solar thermal systems

Recently I was looking at a colleagues’ hot water system and pointed out that his solar thermal system had no pressure in it. He assured me that the local installer had said it didn’t need recharging and that the system was working properly. So, what is the point of having pressure in the system? Well, almost all solar thermal systems are pressurised with anti-freeze based heat transfer fluid and are sealed and pressurised. We’re all used to having to top up the pressure on our boilers from time to time and our boilers usually flash up an error code and stop working if the pressure drops below a certain point. To be fair, some of the latest solar thermal system controllers do this too, but the vast majority will carry on working with virtually no pressure in them.

The main reason that solar thermal systems should be kept pressurised is to raise the boiling point of the heat transfer fluid. Even a basic flat plate solar collector can generate very high temperatures which turn the fluid into high pressure vapour which is forced around the system and into the expansion vessel. This superheated vapour can eventually lead to damage to the system such as perished seals or a leaking expansion vessel diaphragm. Furthermore, each cycle of vapourisation and recondensation degrades the heat transfer fluid slightly. Eventually the heat transfer fluid gathers acidity and the system starts to eat itself from the inside.

Now a well designed solar thermal system will have enough of a “load” to avoid frequent vaporisation of the fluid. In other words, the hot water storage cylinder has to be big enough to ensure there is a volume of water which still needs heating. This is achieved by having a tall thin cylinder where the coldest is at the bottom in the so called dedicated solar zone. On summer days when you’re not using a lot of hot water, your whole cylinder will quickly reach its maximum temperature (usually 60°C to avoid scalding) and then there’s no “load” for the solar thermal system. The solar thermal controller turns off the circulation pump and the fluid in the solar collector quickly reaches its boiling point. This is called stagnation. To protect the system from damage, the solar thermal controller doesn’t allow the pump to switch back on again until the collector has cooled sufficiently. This can often be after sunset so if you do start using hot water in the late afternoon, the solar thermal system can sit there doing nothing until the following day and you miss out on some of the free solar hot water.

The whole point of having your system pressurised is that it stops the system going into stagnation as often so you get a better energy yield and your system lasts longer.

With all of these thoughts still fresh in my mind, I went straight home and had a look at my own solar thermal system. The pressure gauge was also at zero! My system has a datalogger on it so I analysed the historical data and I can see now that sometime in 2017 my system pressure must have dropped because the system started stagnating on a regular basis throughout the summer.

Maximum collector temperature and corresponding energy yield for 2016

The 2016 chart shows that the solar collector never went above 120 degrees C so the system never went into stagnation. The energy yield measured by my system heater meter in 2016 was 1176kWh.

Collector temperature and yield for 2018 (with stagnation)Maximum collector temperature and corresponding energy yield for 2018 (with stagnation)

Compare this with 2018 and the energy yield had dropped by 15% to 992kWh. The red bars shows the average number of hours each month that the system had gone into stagnation. Most of the energy yield loss would be because the system quickly stagnated and was then “locked out” for several hours before cloud cover or darkness allowed the collector to cool again.
So I too need my system recharged. Unfortunately, topping up the pressure on a solar thermal system is a little more involved than it is on a boiler. You have to be able to add fluid without introducing air so it’s usually something best left to an installer who will normally hook the system up to a powerful commissioning pump. Whilst they’re at it they should check the pH of the fluid with litmus paper and that the fluid still has adequate anti-freeze properties with a refractometer. That’s a job for me for the weekend!


It was raining on Sunday so I got busy and serviced the whole system. I started by inspecting the pipework and tightened up a couple of compression fittings where there was evidence of glycol weeping. Next, I checked the heat transfer fluid for pH and refractive index. The pH was around 8.5 which is OK.

pH indicator paperpH indicator paper

The refractometer I used was calibrated for propylene glycol and showed that freezing point of the fluid is -25 degrees C which is more than adequate for the Newcastle area. I released what was left of the pressure in the system and then checked the pre-charge in the expansion vessel.

Refractometer calibrated for propylene glycolRefractometer calibrated for propylene glycol

This was at 1.5 bar which was OK for my system. I then rigged up a commissioning pump using some old home-brew kit and a shower pump.

commissioning pump using some old home-brew kit and a shower pumpCommissioning pump using some old home-brew kit and a shower pump

The pump-station on my solar system comes with a couple of commissioning valves which allow you to push fluid right through the system and circulate it round to eliminate any pockets of air. With my home made setup this only took a few seconds and I was then able to close the return valve and let the pressure build up to 2 bar.

Pressure gaugePressure gauge

After resetting all the valves to their original position and removing my temporary pump, I switched the solar thermal circulation pump on manually to check the flow rate and make sure it was all running silently. Any noise in the system at this point would indicate that there is still air in the system and this can cause damage to the pump through cavitation so it’s quite important to make sure it all runs silently. With the system hydraulics in great shape, the only thing that remains to be done is to give the collector a clean. I might wait until it’s not raining to do that.

Alex Savidis is a renewable energy technical specialist at Decerna. He’s currently working on delivering energy efficiency advice to local businesses through the ERDF funded BEST project as well as delivering consultancy on energy storage and renewables to a variety of private and public sector clients.

Living with an Electric Vehicle

My first 3,500 miles with a Renault Zoe (22kW), it’s certainly been a non-stop roller coaster of mixed emotions !

It’s been an interesting start to EV ownership, firstly with the purchase and then the operation, running & charging. Firstly, the all-important purchase part, this entailed several weeks of eBay, Autotrader and the like with masses of homework on which model to go for. In the end a Renault Zoe with no battery lease was the model of choice, colour was not at the top of the wish list so that made things a bit simpler. As luck would have it exactly the right model with only 8,700 miles on the clock arrived at a dealer very near to me. A deal was quickly done (non-lease Zoe’s don’t turn up that often, you have to move quickly) and I became the proud owner of my first EV.

However, on picking up the Zoe I noticed that it only had 8 miles of range left in the battery, the dealer had yet to have a charger fitted and I live 7 miles away ! A very steady drive home saw me reach ‘limp mode’ for the first and only time and I only just managed to reach a public charger with 1 mile to go…

So, after that incident it was all good, we had our EV charger fitted (a Zappi, heartily recommended) at home to use any surplus solar to keep the Zoe topped up and use when required. A service and MOT came along (very reasonable for both) and a LOT less than a petrol or diesel car. No car tax either, which is nice.

The big bonus from living in Northumberland and having an electric vehicle is the number of free charging points dotted around the county. This has meant that I have only spent £17 to cover 3,500 miles – how cheap is that ! It won’t last I’m sure, but at the moment it’s probably cheaper than running bicycle.

Add in the fact that there has been a significant increase in interest in EVs and the fact that it’s a battery owned model and not a battery lease model means that the little Zoe is actually worth more now than when I bought it ! Quite remarkable and a sign of the times that EVs are starting to take off in the UK.

So it’s worked for me, I have a short commute to work, access to another car (a Kia E Niro EV) if I need to go further afield as the 22kW Zoe only has a short range. It fits my needs perfectly, I have access to numerous free chargers both near where I work and where I live and I can charge of surplus solar at home. I guess it’s not for everyone, I have off-street parking so can charge at home & I can charge for free locally. It’s very frustrating when you get to a car charger to see it occupied, especially if you are down to single figures of range but one thing owning an EV has taught me is to be a little patient.

However, if you are thinking of going for an EV – just do it ! You won’t look back and you’ll wonder how you could afford to keep shovelling all that fuel in to your ‘old school’ car… No messy hands, or smelly diesel fumes, just clean east to use electricity.

Here’s our 2 x EVs –

Two electric vehiclesBryan’s electric vehicles

Bryan Dixon is the lead for grid related projects at Decerna. He’s currently working on technical advice to local businesses through the ERDF funded eGrid project as well as delivering consultancy on large scale energy storage, including an 87MW grid balancing battery.

Are you being LED astray?

LEDs are great aren’t they? Low energy, long lifetime, great colour rendering, instant switch on, compatible with a wide range of controls, low cost…

I remember seeing an LED for the first time when I was about 7 years old. It was a tiny red power indicator for a hi-fi amplifier in my dad’s friend’s house. I was secretly impressed. A few years later I was playing with some LEDs in a Radio Shack electronics kit and learning that you had to control the current to avoid burning them out, but if you got that right they seemed to be practically indestructible. Some 20 years after that I saw my first blue LED on a vacuum system controller that a colleague had built at work. The single blue LED cost £9.95 from RS components and we were all impressed! I knew then that this was the start of something big- we now had red, green, blue and a sort of muddy white when they were combined. Proper white LEDs came along shortly afterwards and I built a dynamo torch using some parts from Maplin. Happy days (and RIP Maplin). Now white LEDs are everywhere. Strictly speaking they’re not actually white, they are blue with yellow phosphors in the lens to give a spectral output that appears white. I digress.

In my job at Decerna I spend quite a bit of time helping local businesses reduce their energy costs through energy efficiency and renewable energy technologies. As you might expect, LED lighting is one of the easiest ways to save energy. Payback times are often just 2 or 3 years and the reductions in greenhouse gas emissions are equally impressive. So you might be thinking “what’s the problem?” Well, quite a lot as it turns out! Read on if you want to know more.

As I found out all those years ago, LEDs need to be driven at a constant current and this is normally done through electronic components built into LED lights. A lot of cheaper LED products use very low quality electronics which fail long before the LEDs themselves. How many home LED lightbulbs have you had to change so far because they started flickering on and off after just a couple of years?  And they’re not exactly cheap to buy compared with the once ubiquitous tungsten filament lamp.

Did you notice I sneaked the f-word in there? That’s right, flicker!  Some of those electronic circuits that drive the LEDs don’t produce a very stable output and they cause the LEDs themselves to flicker. The most obvious type of flicker is the relatively low frequency flicker which many people can actually see. If you buy LED lights that have this behaviour then I’m afraid you’ve wasted your money, but at least you know about it. Unfortunately, there’s a more sinister type of flicker that some LED lights produce and it’s at a higher frequency that we can’t perceive. Research is emerging that it can cause headaches, migraines and even trigger seizures in sufferers of epilepsy. Not good. Worse still, the kit needed to measure the flicker is quite expensive so not many installers or facility managers will have it.

There’s also a growing trend for LEDs to be integrated into the luminaire rather than being supplied as a replaceable lamp in a light fitting. In our offices at we used to have very nice quality T5 fluorescent lighting. The tubes lasted about 20,000 hours and could be easily and cheaply replaced. They’ve all been replaced by the landlord with modular LED units which have no replaceable parts. Sure, the LED luminaires are rated to last 50,000 hours but in a typical office that’s probably only 20 years and then the whole lot has to be replaced: plastic lens, aluminium frame, LED board, electronics driver module, connectors, bracketry, etc. I wonder how much of that lot will actually get recycled? Good thing there’s no mercury in LEDs but we definitely need to take the lifecycle environmental and commercial costs into account before we swap out perfectly serviceable lights with LED alternatives.

We also see a lot of fairly new LEDs in commercial and industrial environments failing. For example we’ve seen high bay LED fittings start to fail after just a couple of years in factory areas where ambient temperatures are high. This high bay LED lamp was actually rated for high temperatures but half of the LEDs on it had died within 2 years.

Failed LED high bayFailed LED high bay

Other types such as fluorescent tubes work better at higher temperatures so there’s still situations where the best course of action would be to hang onto your old lights, particularly if they’re good quality T5s or induction lamps.

So far I’ve criticised low quality LED products for their reliability, tendency to flicker and sustainability credentials, but there’s more. Some of the cheaper products are actually dangerous. This unbranded GU10 LED replacement could have easily caused a fire. And yes, it did have a CE mark!

Unbranded GU10 LED replacement showing internal damage

I’m sure that all of this makes me sound like I don’t like LEDs. That couldn’t be further from the truth. I absolutely love them. It’s the value-engineered rubbish that well-known electrical distributors are peddling that I dislike. If you get the right products in the right place you’ll save a massive amount of electricity and your lifetime costs will be slashed. Getting it wrong is likely to be an expensive or even dangerous exercise.

So where can we go to get further advice? Well, experts in 9 European countries have collaborated to produce some excellent guidance through a Horizon2020 funded project called PremiumLight Pro. In the UK, this is delivered by the Energy Saving Trust. It’s definitely worth checking this free resource out before you’re LED astray!

Alex Savidis is a renewable energy technical specialist at Decerna. He’s currently working on delivering energy efficiency advice to local businesses through the ERDF funded BEST project as well as delivering consultancy on energy storage and renewables to a variety of private and public sector clients.

Heat pumps vs gas boilers (Part II)

This is an update on a previous blog from the 24th of June 2013, updated to take account of developments with Air Source Heat Pumps and the decarbonsing of the UK electricity grid.

Air Source Heat Pumps

Air source heat pumps use electricity to generate heat much more efficiently than normal electric heaters. They operate like refrigerators in reverse and normally have a fan to blow outside air over an evaporator heat exchanger. An electrically powered compressor raises the temperature of the refrigerant and this heat is given up to a condenser inside the property. Heat pumps can deliver several units of heat for every unit of electricity. This ratio is often called the co-efficient of performance (COP) which tells us how well a heat pump performs under set conditions. Over a longer period (e.g. a heating season), a measure of performance called the SPF (Seasonal Performance Factor) is often used. This blog looks at how high the SPF needs to be for the heat pump to outperform a condensing gas boiler in terms of greenhouse gas emissions as well as running costs.

Greenhouse Gas Emissions

Air source heat pumps run on electricity. When this blog was originally written, according to the UK Government’s “2012 Guidelines to Defra / DECC’s GHG Conversion Factors for Company Reporting” the average value for greenhouse gasses emitted per kWh of electricity was 0.54702 kgCO2eq(GWP100)/kWh. Since then it has dropped significantly.

If we look at the “Greenhouse gas reporting: conversion factors 2019” we have a value of  kgCO2eq(GWP100)/kWh for Scope 2 emissions.

However, this is purely the electricity grid’s average value. Let’s think about this in more detail. In the UK grid, there is a mixture of gas (via Combined Cycle Gas Turbines), nuclear, wind and solar, with some biomass and imported electricity from interconnectors. Within the UK electricity grid, coal is effectively now gone. Most renewables depend on the weather so are quite variable in their output, and nuclear remains at full output constantly, therefore if there is additional demand, it will lead to more electricity generation from CCGT.

Ecoinvent is a not-for-profit organisation which provides an industry standard a database for Life Cycle Assessment purposes. Using their Ecoinvent 3.5 database, we find the (high voltage) emissions from a UK based CCGT to be 0.3514 kgCO2eq(GWP100)/kWh. We then take a reasonable assumption on the loss via the electricity network of 7%. This gives us a climate change impact of 0.3760 kgCO2eq(GWP100)/kWh. It is important to remember the Ecoinvent database includes everything, including the infrastructure of the CCGT.

The UK Government figures give  0.18385 kgCO2eq(GWP100)/kWh for the impact of gas. If we assume that the alternative to a heat pump would be a new gas boiler at 90% efficiency this will give an impact of 0.2043 kgCO2eq(GWP100)/kWh. This means, for a heat pump to have a lower level of greenhouse gas emissions, it would need to have a SPF of over 1.72 in the UK. In our 2012 blog we calculated a SPF of 2.41 to break even in terms of greenhouse gas emissions


Installation costs vary considerably but in general a domestic air source heat pump based central heating system will cost at least twice as much to install as an equivalent gas central heating system. Given that we’ve already established Since the electricity industry was privatised, there has been a bewildering array of utility tariffs so it can be difficult to work out the relative running costs of gas boilers and heat pumps However, using figures from the UK Government we find an average direct debit electricity bill is based on £0.181/kWh whilst gas was  £0.044. This includes the standing charge spread on average across 3,800kWh/year of electricity and 15,000 kWh of gas.

As before it can be assumed a gas boiler will run at 90% efficiency, so the cost per kWh of heating would be 0.0489 £/kWh. This would suggest that in order for the heat pump heating cost to be the same or better than gas, the SFP would be need to be 3.70. Interestingly, this is higher than the value of 3.45 found based on 2012 prices.  But that’s something of an oversimplification because air source heat pumps currently benefit from Renewable Heat Incentive (RHI) payments of 10.71p per kWh. So a typical domestic property requiring 15,000kWh of heat per year would attract payments of £1,606.50, equivalent to £11,245.50 over the 7 year payment term. In most cases this would exceed the installation cost of the heat pump system including the oversized radiators that are needed to achieve high SPFs.

Real World SPF values

The Energy Saving Trust carried out on site testing of 83 heat pumps, published in the report “Getting warmer: a field trial of heat pumps”. This showed for air source heat pumps the ‘mid-range’ of measured SPFs was near 2.2 and the highest figures in excess of 3.0. The test also included ground source heat pumps, which has slightly higher measured system efficiencies than the air source heat pumps. The ‘mid-range’ ground source system efficiencies were between 2.3 and 2.5, with the highest figures above 3.0.

Further analysis of the EST trial by DECC in March 2012 (Detailed analysis from the first phase of the Energy Saving Trust’s heat pump field trial) examined a number of these heat pump installations in more detail, paying particular attention to the factors that influence system performance. It appears some sites had anomalies in the data, for example boost heater energy consumption not measured, the contribution of an oil boiler being included in system heat and some data provided from a manufacturer rather than the EST monitoring system. Consequently, some of the EST report data has been revised and Table 1 of the DECC report shows the mean system efficiency to be 1.82 for ASHP and 2.39 for Ground Source Heat Pumps (GSHP). The ‘good performance’ GSHPs achieved 2.98 and 3.04 system efficiencies.

Decerna has carried out detailed monitoring of numerous air source heat pumps, and our results tally with those of the Energy Savings Trust, with values between 2.0 and 3.0, although the upper end is rare.

It is important to note that both the Energy Savings Trust report and Decerna’s own work has shown that heat pumps tend not to as well as manufacturer’s literature would suggest. This is due to a variety of reasons, including incorrect system sizing, inadequate radiator sizing, poor installation and commissioning and a lack of end user information on how to get the best from the system.

Further research is needed on the SPF of heat pumps, in order to advise government policy.


This blog shows a different situation to that of our previous heat pump blog. Now, for the UK, as long as there is an SPF of more than 1.7, then it will have a low climate change impact than a gas boiler. As 2.5 is a reasonable value for an SPF, then heat pumps can now be considered a better environmental choice than gas boilers.

As long as a heat pump has a SPF greater than 1 then it should be cheaper than direct electric heating

Without considering income from the RHI, a heat pump will be marginally more expensive to run than a condensing gas boiler. However, a properly specified and carefully installed air source heat pump which attracts RHI payments is a sound financial investment.


Further reading:

For a detailed look at the performance of solar thermal, thermodynamic panels and Air Source Heat Pumps in relation to domestic hot water, please see  our discussion paper “COP Water Heating Technologies”

If you are interested in lab or in-situ monitoring of the COP of heat pumps, please email or call 01670 543 009


Alex Savidis is a renewable energy technical specialist at Decerna. He’s currently working on delivering energy efficiency advice to local businesses through the ERDF funded BEST project as well as delivering consultancy on energy storage and renewables to a variety of private and public sector clients.

Tom Bradley is a Life Cycle Assessment expert at Decerna. He’s currently working on various projects related to analysing the environmental impacts of new and existing technologies, including undertaking the Life Cycle Assessment on the MAGNIFICENT algae bioproduct project.


Tea boiler energy use

Everyone is a creature of habit. One of my habits is to go round switching off lights. Sometimes I can be a bit over zealous about this and hear an angry voice from the office toilets as I “do my rounds”. The Decerna offices have the latest energy efficient LED lights but the controls haven’t yet been upgraded by our landlord so if I’m the last one out of the office I pick up my cycle helmet from the kitchen area, switch off the lights and any other appliances and head for home. Recently though, something’s been bothering me : the tea boiler.

With a 2.8kW heating element and 10 litres of stored hot water, this is perhaps our most heavily used piece of equipment in Decerna. It really does get some hammer! But it’s left on all night and this got me wondering how much energy could be saved if I were to turn it off at night. And how long would it take to reheat when the first of my caffeine addicted colleagues arrives the next morning?

Checking the datasheet I found no mention of energy consumption so I hooked up our spare Loxone energy monitoring kit. This neat smart home system is quick to set up and can be used to control appliances plugged into it and remotely access the data. A couple of days later I was studying the graphs and had to come clean to my colleagues about why morning coffee had been somewhat tepid the day before!

So what did I learn? Left to its own devices, the boiler used approximately 1027Wh overnight just to keep the water hot. And by turning it off at 5.30pm and back on the following morning. it took 16 minutes to warm up and consumed 747Wh electricity in the process, a waste of 280Wh per day. That works out to about 100kWh per year. Doesn’t sound like much but you try generating 100kWh of electricity – it’s much harder than you think!

About 10 years ago I read the book Sustainable Energy Without The Hot Air by the late great David MacKay. One of the chapters in this excellent free book is entitled “Every BIG helps”.  I remember reading that If you leave your mobile phone charger plugged in, it uses one quarter of one percent of your home’s electricity. You could say that switching off the tea boiler is just like “fiddling while Rome burns” but I reject that argument – we all need to be more energy conscious in our lives. Fly less, eat less meat, cycle to work, walk to the shops. And switch off the lights.


Alex Savidis is a renewable energy technical specialist at Decerna. He’s currently working on delivering energy efficiency advice to local businesses through the ERDF funded BEST project as well as delivering consultancy on energy storage and renewables to a variety of private and public sector clients.

What is the Export Tariff?

Is the Export Tariff the same as the Feed in Tariff?


In the Export Tariff funded by taxes?

No, it is included with people’s bills

So, is the Export Tariff a subsidy?

No, it is a method for people with solar to sell electricity to the grid at market rates (when you include the losses in transmission)

So, what does the government want to do?

The Export tariff will end on the 29th March 2019. This means that any electricity exported from a new domestic solar PV array will be given to the grid for free, and then the energy companies sell this electricity back at a profit

I need a metaphor to understand this

Imagine you grow your own food, and grow too much for yourself. You are banned from selling it, but someone from Sainsbury’s comes in to your garden, steals your food and sells it to your neighbours. Unfair, right? Well that’s what the government is doing to solar

Is that legal?

Under EU rules, probably not, so it depends on the Brexit deal as to if the government is allowed to do this.

But doesn’t this only effect rich homeowners? I heard on BBC File on Four people get a 12% rate of return on solar installation investments.

That’s not true, the highest rate of return was 11% in 2011. Since then, the rate of return has substantially decreased. Also, that’s talking about the Feed in Tariff, not the Export Tariff

But still, it only effects rich homeowners with cash to spare right?

No, the solar industry in 2015 employed 36,000 hard working people. Since various anti-solar policies came in, this has dropped to maybe 15,000 people. These are direct jobs, there are additional jobs supported, such as scaffolds. The loss of the Export Tariff will result in thousands more job losses.

Also, as well as supporting many small British companies, solar is used by social housing landlords, hospitals, schools, community energy projects and a range of other organisations.

But the government is supporting solar in other ways?

No, from the “solar tax” element of business rates, making the grid connection process more complex, reducing the Feed in Tariff by random large amounts (sometimes illegally), and also removing rules to have renewables on new build, the solar industry has not had a positive experience of government policy.

But the UK is really dark anyway, surely solar doesn’t make much electricity?

In 2018, on a sunny summer day at midday solar generated up to 27% of UK electricity. The UK has 12GW of solar.

Why is the Export Tariff removal happening?

We don’t know

Can I do anything about this?


  1. First, sign this petition:
  2. If you run a company, sign this letter:
  3. Then, write to your MP through this link: (or write independently)
  4. Next, go and see your MP, find their details from:

More info at:

New build estates may not be able to cope with renewables

With the increasing penetration of new renewable technologies (generation, heat pumps & electric vehicles) within housing estates it is worth noting that not all estates are created equally. In fact many modern housing estates with have their electrical network built and controlled by an Independent Distribution Network Operator (IDNO). IDNOs build electrical networks to different requirements to traditional Distribution Network Operators (DNOs). This has a major impact on what additional technologies a housing estate can cope with.

In some areas ≥50% of new connections to the electricity distribution system are being undertaken by IDNOs. The majority of these works take the form of new housing developments, ranging from 25 to >450 dwellings. The design of the IDNO network is typically based on a diversified load (ADMD) of 1.2-2kW per dwelling for a typical non-electrically heated dwelling.

To reduce the costs of installing a new IDNO network, the transformer size within a substation is based on the maximum capacity of the site (ADMD x no. of Dwellings), with each feeder designed using the smallest usable cable size for this load. This differs significantly from the methodology used by DNOs. DNOs must consider losses (wasted electricity) when designing their substations, often installing larger transformers to reduce losses whilst also facilitating future development of the network. Secondly, DNOs will install large cables from the substations and only install smaller size cables into cul-de-sacs, which, by their nature, will be lightly loaded with no possibility of additional buildings being constructed.

The problem of the IDNO design is that there is very little capacity within the local network for the addition of multiple installations of embedded generation, heat pumps or multiple EV chargers.

In conclusion, it may well be the case that older estates will be able to handled the increased penetration of new technologies far more effectively and cheaply than a new build estate, where significant reinforcement work may be required for a very small number of dwellings whose energy profiles change. In short, new build estates are not designed to allow renewable energy systems on houses.

Article by: Matt Cocker – Electrical Design Engineer – Decerna

What is G98?

Photovoltaic canopyPhotovoltaic canopy

Why the new standard? Well, the Energy Networks Association has revised G83 to both modernise the standard and to take into account newer technologies which are now commercially available. The new standard also falls in line with the current European standard EN 50438. The new standard applies to micro-generation up to 16A per phase (3.68kW for single phase or 11.04kW for three phase) based on a 230 volt or 230/400 volt supply respectively. The main changes are that battery storage is considered and that all equipment must be type tested and approved.

G98 is published by the Energy Networks Association (ENA) and comes into effect on 17 May 2019 for Micro-generators commissioned on or after that date. The definition of Micro-generators includes electricity storage devices and hence the new standard also applies to electricity storage devices (batteries). Micro-generators that conform to G98 may be connected in advance of the 17 May 2019 as they will also conform to the existing G83 requirements.

G98 has been written to take account of the EU Network Code on Requirements for Grid Connection of Generators 14 April 2016. All the micro-generators must meet all of the requirements set out in G98. They must have achieved full conformance of fully type tested and have provided proof that the requirements have been met. In order to conform to G98 the customer installation shall conform to the requirements of EN 50438 together with additional requirements also detailed in this document as well as the IEE wiring regulations, BS7671:2018. The purpose of G98 is to explain the technical requirements for connection of Micro-generators for operation in parallel with a public Low Voltage Distribution Network, by addressing all technical aspects of the connection process, from standards of functionality to on-site commissioning.

In accordance with the Electricity Safety, Quality and Continuity Regulations (ESQCR) the Installer is required to ensure that the DNO is made aware of the Micro-generator installation before the time of commissioning or no later than 28 days (inclusive of the day of commissioning) after commissioning. The new standard also comprehensively lists all the testing and commissioning requirements that must be adhered to along with the minimum test results required to provide a satisfactory test result. Onus is now put on the customer to ensure that all safety information is kept up to date. As previously under G83 it is the installers responsibility to notify the local DNO and ensure all paperwork is fully completed and compliant to the new standard.

Full details can be found at the website below –

If you need any help with grid connections for renewable energy or battery storage, we provide support from initial budget enquiries all the way to full turnkey of connections. We also run a bespoke grid connection training course. For information on this and other services, please just get in touch with us on 01670 543 009 or email

A successful NE Expo for Decerna!

Decerna have had a successful NE Expo this year as their fabulous ‘Desk Gardens’ went down a storm!

Decerna (NDE), a Blyth based organisation that carries out a wide range of work within the renewable and low carbon sectors brought a new, 100% renewable marketing tool to the NE Expo on Wednesday 2nd May!

People visiting the exhibition were intrigued by the little logo’d aluminium pots on the Decerna stand and played a guessing game as to what they actually contained.

Guesses from visitors were amusing and brought about some interesting conversations at the stand.

The 100% renewable pots were in fact little ‘desk gardens’ containing soil and mint seeds which, over the period of 21-28 days will grow and bring happiness as well as mint for tea for people working at their desks (either at home or at work).

Most people at the NE Expo took away their little desk garden with a skip and a smile on their face along with the promise to upload their very own photos when the seeds start to grow.

Hayley Corney, from NDE said;

We were over the moon that the little desk gardens were a success! They fitted in nicely with our ethos of renewables and gave a great talking point for all the visitors to the Expo.

NDE are now looking forward to exhibiting at the Federation of Master Builders on 29th June.

For more information about the FMB event visit HERE

Follow Decerna on Social Media via:

Decerna LinkedIn
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Decerna Twitter

What is SolarCoin and does it matter to the UK Solar Industry?

Photovoltaic array on our training centre, now registered for SolarCoinPhotovoltaic array on our training centre, now registered for SolarCoin

You may have recently heard about SolarCoin (§), although it has been around since 2014, the currency started to hit the energy headlines with ACWA Power becoming the first utility PV developer to begin to use SolarCoin[1]. At NDE we heard about the currency a few days ago, discussed at a Solar Trade Association meeting. So, what is it? What is it for? Is it any use?

What is SolarCoin?

SolarCoin is essentially another cryptocurrency, the most famous cryptocurrency is the one which started it all, Bitcoin. Without going into too much detail, a cryptocurrency is a type of electronic currency which uses cryptography to secure its transactions. All transactions are recorded via a distributed ledger, the blockchain, a VERY big tamper proof database decentralised over many computers across the world. In order to receive SolarCoins, like any other cryptocurrency, you use a wallet, this is a secure personal database where you keep the address of your coins on the currency’s blockchain, and your personal keys to these coins. You can either download a program to keep a wallet on your computer, or use an online service. After this you can then register your photovoltaic system with, who validate applications at the beginning of each month. You receive SolarCoins for every MWh of electricity generated. In terms of systems smaller than 100kW, this is a deemed production (365 days * 24 hrs * 15% * Your kWp Nameplate Capacity/1000). This works out to 1.314 * your installed kWp nameplate capacity = §1. Larger systems require a form of metering that can be validated. The initial SolarCoin grant is retroactive to the install date of your facility or Jan 1, 2010; whichever is more recent. Whilst there have been concerns over the use of energy by Bitcoin, SolarCoin uses a much lower amount of energy as it is based on a proof-of-stake system as opposed to a proof-of-work system. SolarCoin began in 2014[2], based on an idea first presented in 2011 for an Electricity-Backed Currency[3].

Is SolarCoin any use?

If you are already involved in renewable energy, instead of thinking of SolarCoin as a variant of the technology behind Bitcoin, it is better to think of it as a global equivalent of the Renewables Obligation Certificate (ROC). Within the UK, these were gifted to accredited renewable generators per MWh of green electricity produced, and then traded on a market. This is a useful analogy, because it gives us an idea of the necessary value for a Solar Coin to make a difference, and also shows a model that SolarCoin could replicate globally. Sadly, ROCs are now closed to new entrants.

In terms of ROCs, energy suppliers were mandated by government to produce a certain level of green electricity, if they failed, then they would be fined. However, if a generator did not have enough renewable generation, they could instead buy ROCs from green generators. Two important factors here, first, the value of a ROC varied between around £36.99 in 2010/2011 to £45.58 in 2017/2018[4]. The amount given to technologies varied from 2009 onwards, with ground mounted PV receiving 1.7 ROCs/MWh in 2013/2014, and 0.8 in 2016/2017 (a variation from £71.43/MWh of solar in 2013/2014 to £36.46/MWh of solar in 2017/2018). This value was enough to support the UK electricity market, and make wind farms and solar farms financially viable, and create enough interest from investors to support UK renewables. This is not about just making renewables competitive, as they often already are, it is about making them of interest enough so investors who otherwise would not care about renewables move into this market, and lead to more renewables being constructed. It is important to note that this doesn’t involve a large percentage increase in Solar Coin, currently it is trading at £0.5/§, so it would require a roughly 100 fold increase, which in the world of digital currencies is not impossible. Remember, from 2010 to today Bitcoin varied from $0.003/BTC to $13,800/BTC in 2018, with much volatility in between. However, for SolarCoin to be truly useful it needs to be far more stable than Bitcoin.

Whilst a value of between £36 and £71 per Solar Coin would give a financial case for solar farms, what about domestic renewables? We will demonstrate this with a model based on Newcastle upon Tyne, as this is the nearest city to our offices.

In 2016 there was a major crash in the solar PV industry, which it has never recovered from. This was caused by a reduction in the Feed in Tariff from £0.1233/kWh to £0.045/kWh[5], and resulted in approximately 18,000 redundancies across the industry[6]. The purpose of this was to reduce electricity bills, and was estimated to reduce the estimated electricity bill in the UK by £0.50 a year[7]. In addition, there is an export tariff, which is £0.0503/kWh against a deemed export of 50%. If we take the 2015 Feed in Tariff as the value which sustained a strong industry, then equating the Feed in Tariff and deemed Export Tariff gives us £148/§ as a target value.

For our model, we make the following assumptions:

  • SolarCoin Vale = £148/§
  • SolarCoin yearly value increase = 2%
  • Electricity cost = £0.16/kWh
  • Exported electricity = 50%
  • Electricity prince increase per year = 5%
  • Cost per kWp = £1,500
  • Size of array = 4kWp
  • Degradation of panels per year = 2% of year one
  • Roof orientation = 0° (South)
  • Roof pitch = 35°
  • Irradiance = 916kWh/kWp (PVGIS data based on CMSAF)
  • Feed in Tariff and Export Tariff = £0

This gives the following results:

  • Payback = between five and six years
  • Profit over 20 years = £22,593

This depends on many factors. If the use of the PV was 100% with no export, even without SolarCoin the payback would be just over 8 years, with SolarCoin at £148/§ the payback would be just over 4 years. Other options, such as domestic batteries, will obviously change the economic models.

Clearly, for the UK, a modest increase in SolarCoin could help the solar industry. The problem is, whilst previous policies have shown these values to work, SolarCoin requires stability, something which cryptocurrencies do not display, partially as they all follow Bitcoin values, which as the current fashionable cryptocurrency is currently in the state of being an investment option rather than a form of currency. However, the values which SolarCoin needs to achieve to make a significant difference in the global solar industry is not that much of a jump.

In terms of simplicity, cryptocurrency is far more complex to deal with than a simple Feed in Tariff submitted four times a year, and if as an industry this was to be taken seriously, possibly an organisation such as MCS could receive and distributed SolarCoin to domestic customers, this would have the added advantage that as all domestic PV should be installed by MCS accredited installers, then there would be a verifiable record of PV installations from MCS which SolarCoin could use to know who should receive coins.

In short, we feel SolarCoin is something worth watching, and if there is increased stability and a modest increase in value, then it could have a major impact on renewable developments in the UK, and logically have similar impacts globally, and thus help society move towards the levels of renewables necessary to make the reductions in greenhouse gases mandated by climate science.

At Decerna, we get very excited about new things which can help renewables, and we just registered our renewable energy training centre in Blyth to get SolarCoins. We train electricians how to install solar, design solar farms and sort out grid connections for solar/wind/battery farms.

Thanks to the STA for checking the solar facts within this blog.









The Paris Agreement

We live in a different world. For the first time in history, all countries have agreed to take action on climate change.

The Paris Agreement, agreed on the 12th December 2015, finally gives targets and a framework for reducing greenhouse gas emissions by all countries. This has not been an easy task, it has taken 23 years of various negotiations, to the point where some would argue it is too late. But the agreement means it now may be possible to avoid dangerous climate change.

What does the agreement give? There is a target to keep global temperatures well below an increase of 2°C against pre-industrial temperatures by the year 2100, with an intention to increase less than 1.5°C. In 2015 the global average temperature reach 1°C higher than pre-industrial, so this is a hard target. However, any more and there is a significant threat of dangerous climate change.

The agreement also puts in place a transparent system to monitor countries’ plans and progression on reducing greenhouse gas emissions. Interestingly, the agreement also urges those countries who did not agree to the Kyoto Protocol and/or Doha Amendment to sign up now to those previous treaties, giving targets to all countries prior to 2020, although it does not force them to sign. Various measures are in place for technology transfer, financial support and adaption. It also requests the United Nations’ Intergovernmental Panel on Climate Change to produce a detailed scientific report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways.

However, there are problems, several of which were brought up by Paul Oquist, from the Nicaraguan Government. As acknowledged in the document, each country before the meeting submitted an Intended Nationally Determined Contributions (INDC), which is essentially a plan on how to make their contribution to reducing greenhouse gas emissions. The plans that were submitted will however lead to a 3°C rise in global temperatures, far too much compared with the 1.5°C which is needed to avoid dangerous climate change. A further issue which we note is that some countries, such as the UK, currently have energy policies which are damaging to renewable energy, and thus do not fit with the Paris Agreement.

Paul Oquist also highlighted his concern that with regard to financial compensation for loss and damage caused by climate change, paragraph 52 of the Paris Agreement effectively prevents countries from receiving financial compensation from larger polluters for the consequences of climate change. According to an interview on BBC News 24, this was apparently something the US, Europe and many other rich nations required.

“52. Agrees that Article 8 of the Agreement does not involve or provide a basis for any liability or compensation”

Despite all of this, the agreement finally makes a global commitment to fight climate change. In the words of Paul Bledsoe,  former climate adviser to President Bill Clinton:

“The agreement provides a road map, now we need to build the road”.

Together, as a global community, we now need to build a low carbon society. The most important thing that the Paris Agreement does is finally give investors confidence in renewable energy, and in global government support, this opens the door to major investments in low carbon technology energy. In turn the agreement may also significantly increase the disinvestments in fossil fuels. The technologies to fight climate change exist; solar thermal, photovoltaics, concentrating solar power, hydro wind, CHP, biomass etc all work well, and they all are part of the large integrated solution that can remove fossil fuels from the energy sector. Already in the UK renewable electricity contributed 25% of electricity in the most recent quarter of 2015, we can go much further. Buildings waste too much energy, but buildings already exist that take in more CO2 than they emit though their lifetimes, this approach needs to become the norm not the exception. There are technology areas where we need more research, energy storage (be it batteries, hydrogen, algae biofuels etc) needs more work to ensure that we can have a 100% renewable energy grid. Whilst transport will also be able to hit zero emissions through future high energy density storage technologies, other industries will need carbon capture in order to continue. On a policy side, governments need to finally stop subsidising the fossil fuel industry, and at the very least provide renewable energy with the same level of subsidies as fossil fuels currently receive.

We believe that whilst the Paris Agreement does not go far enough, it will push the technologies far enough so that eventually we will no longer need a global agreement or targets, as energy efficiency and renewable energy makes far more sense than fossil fuels, both environmentally and economically.

Now the hard work begins.

The full English text of the agreement is at:

Save UK Solar #keepfits

Photovoltaic system in BlythPhotovoltaic system in Blyth

The UK solar industry in the UK is facing significant challenges, with a range of proposals in the government Feed in Tariff consultation which ends on Friday. These include an 87% reduction in the Feed in Tariff, changes to the export tariff, limits on Feed in Tariff installations per quarter and changing the tariff increases from RPI to CPI. These are considered by many to pose a very serious threat to the continuation of the solar industry in the UK. So far this month as a result of these proposed cuts Mark Group, Southern Solar, and Climate Energy have collapsed, with over 1,000 jobs lost. The Solar Trade Association estimate there are a further 26,000 jobs at risk across the UK due to the Feed in Tariff changes, whilst the whole industry employs 35,000 people. The Feed in Tariff consultation claims that all of this is necessary to reduce bills, in reality bills will only be reduced by fifty pence a year.

To help prevent these changes, and save UK jobs, as many people as possible must respond to the government consultation.

A simplified version, which can take a few minutes to fill in, is available at:

Please pass this on to your employees, friends and family to fill in before Friday 23rd October.

Also, if you have time, you could instead fill in the full consultation, which is at and finally, if you have chance, please also sign this petition:

More Information

Closure of Southern Solar
Closure of Mark Group
Community Energy England report on the FiT changes
Solar Trade Association £1 solar rescue plan

Energy Policy in the UK

There is a great deal in the press and social media about changes in UK renewable and low carbon energy policy. It is very hard to keep up with current policy; therefore, we have written this blog to explain what is happening, and what avenues there are for the renewable and low carbon industry to support itself. This is not a political blog, and only seeks to provide information.


1.1    Climate Change Levy

This policy was a simple carbon tax paid by businesses who were in either the industrial, commercial, agricultural or public services sector. A business would not pay the tax on any energy from certified renewable energy sources. The idea of this was to encourage businesses to use renewable energy.

In the Budget 2015 it was announced that renewable energy would also be charged this carbon tax, and will be taxed for the greenhouse gases they have not emitted.

1.2    Onshore wind planning

Major changes have been made to planning laws within England which effectively make it impossible for Local Authorities to approve any onshore wind projects unless they lie within areas allocated for such development in Development Plans. A very small number of Local Authorities currently have such allocations and it is likely to take several years for the planning system to ‘catch up’. In addition, the right to appeal projects refused locally to the national Planning Inspectorate has been removed – this policy just applies to onshore wind proposals.

1.3    Onshore Wind

The subsidy available for onshore wind farms in the UK was scheduled to be phased out in 2016, and allowed developers to plan ahead accordingly (the average site taking five years to develop). However this has been removed completely with no notice, impacting the economics of most projects and companies facing huge financial losses for development costs, as well as denting investor confidence.

1.4    Photovoltaics (Solar PV)

A number of changes are to be implemented on photovoltaics. The Renewables Obligation, which currently supports larger rooftop and solar farm projects between 50kWp and 5MWp in size, is to be closed from 1 April 2016, as well as a planned reduction in levels of support for projects currently in the pipeline.  Critically, DECC is also proposing to end ‘grandfathering’ within the scheme from now on, the guarantee that a certain level of subsidy will be provided throughout the lifetime of a solar project once built.

With regards to the Feed-in Tariff, which supports small-scale rooftop and solar farms, the government has removed ‘pre-accreditation’ to a fixed tariff level, meaning that complex community and commercial projects that can take longer to complete could have to deal with reducing tariff levels between the start and finish of the project [[1]]. It is important to note however that these changes do not affect domestic solar.

The government has halted the Feed in Tariff from January 14th to February 8th 2016. From February 2016 the Feed in Tariff will be reduced to 4.39p/kWh for domestic systems, 4.39p/kWh for 10-50kWp installation, decreasing to 0.87p/kWp for >5MW installations. This represents a 65% cut for domestic installations. There will be three monthly decreases (degressions) in the tariffs available for new entrants to the scheme, so it is better to install now rather than later. The largest issue is the “cap” system, which limits the number of PV new PV installations which can receive the Feed in Tariff from February 2016 to the first quarter of 2019. The limit is approximately 60% of the installations in 2014, thus is can reasonably assumed that the Feed in Tariff will be closed by the end of 2016 for PV.

1.5    Zero Carbon Homes

The polices for Zero Carbon Homes were announced in 2006. All new domestic buildings would be zero carbon if they were built in 2016 or after. The same applied to commercial buildings from 2019 onwards. With the deadline less than six months away, and after massive investment by many companies to prepare for this target, it was scrapped in June 2015.

1.6    Green Deal

The Green Deal was a policy to help insulate homes through a loan scheme paid back in bills. A further part of this was the Green Deal Home Improvement Scheme. The government removed financial support for these in July 2015, with no replacement policy suggested. [[2]]

1.7    Green Investment Bank

The Green Investment Bank was created to lend money to renewable energy projects at a reasonable interest rate. The money for the organisation was gathered from dormant bank accounts, those of people who had either died, or long forgotten about their bank account. The government is now seeking to sell the Green Investment Bank.

1.8    Renewable Heat Incentive

The renewable heat incentive was created to support heating technologies, such as solar thermal, heat pumps and biomass. It has been announced this will be reformed to reduce the cost by £700m.[3]

1.9    Delay of Contracts for Difference

The Department of Energy and Climate Change has postponed the next Contracts for Difference auction for renewable energy projects. Contracts for Difference are a complex new scheme to support energy projects (not just renewable), however, currently there is no date given as to when the renewable energy Contracts for Difference auction will happen.[[4]] There will be further announcements in the autumn.

1.10   Cuts to the Department of Energy and Climate Change of 90%

Recent research by the politically-neutral environmental thinktank the Green Alliance has shown that the Department of Energy and Climate Change is facing a 90% cuts in staff budget over the next three years. The net result of this will be loss of almost all expertise and capability within the department.[[5]]

1.11   Energy Company Obligation

The government have announced that after the current round of Energy Company Obligation (the main source of funded insulation in the UK) there will be a one year pause. Many in the insulation industry warn that this could lead to the industry’s collapse.[[6]]

1.12   VAT on Solar

Photovoltaics and solar thermal will be charged 20% VAT from the 1 August 2016, up from 5%.


According to the UK Government’s Department of Energy and Climate Change’s figures, the savings from removing financial support for the photovoltaic industry in the ways suggested in the Energy Bill will be 50 pence a year.[[7]] The wind changes will achieve a similar saving.

Furthermore, the UK spends £26 billion [[8]] a year on subsiding fossil fuels, compared with the 3.5 billion [9]on renewable energy.


3.1    Scrapped renewable energy projects

So far, 270MW of wind farm projects have been scrapped because of the changes.[[10]] It is expected that 2,500 turbines will be ultimately cancelled , with a total energy output of that of one large coal fired or nuclear power station.[[11]] Similar issues are hitting the photovoltaic industry. Ultimately it can be expected in 2016 the UK photovoltaic industry is unlikely to survive, and the wind industry will be significantly reduced. No technology should receive subsidy for a moment longer than is necessary, but removing it prematurely undermines investor confidence in UK infrastructure projects.

3.2    Foreign investment

With regard to internal investment in the UK, we know of one major company and at least four European wind developers who have decided to cease or significantly reduce plans to develop in the UK (fortunately for us, not clients of ours). Another firm we were in talks with from mainland Europe have decided to avoid the UK. According to the news website, industry insiders suggest the recent reduction in the offshore wind farm plans for Dogger Bank were in part due to uncertainty over UK energy policy.[[12]]

3.3    Jobs

The renewables industry supports 112,026 jobs within the UK, and the energy efficiency industry provides several thousand more.[[13]] The photovoltaic industry employs 38,200 people whilst the wind industry directly employs 19,000 (30,000 if we include associated jobs [[14]]). A significant level of redundancies due to these changes have already begun, with the closure of both Southern Solar and Climate Energy, many redundancies at Mark Group and numerous small companies. The Solar Trade Association estimated in December 2015 that the current job loses caused by government policy were 1800, with 1600 extra on notice of redundancy, and many more to follow. [[15]]

3.4    Increasing energy bills

As shown in the past, the increases in energy bills in the UK are driven by the wholesale price of fuel, not renewable energy technologies. To reiterate research by the Government’s Committee on Climate Change, not implementing renewable energy policies will add £600 to household energy bills by 2050.[[16]]

3.5    Fuel poverty

By removing the zero carbon homes policy, there is no longer an incentive to make future highly efficient buildings, meaning that fuel poverty will continue to be a problem in the UK. Over the past 12 months the fuel poverty gap in the UK (the level of how deep into fuel poverty people are) is estimated to have increased by 3%. [[17]] Zero Carbon homes were meant to help stop this trend. Additionally, the one year pause in ECO will mean mass insulation of fuel poor homes will stop in the UK for at least a year.

3.6    Energy security

Renewable energy is a major part of the UK’s energy mix. There are now so many solar photovoltaic panels across the UK that they have the same output over a year as a coal fired power station[*]. Additionally, renewables are supporting the UK grid, for example in October 2015, wind power kept the grid running at a time when eight nuclear reactors were down and the Didcot B gas power station was offline.[[18]]  It is not possible to build fossil fuel or nuclear power stations as fast as we can build renewables. Halting the UK’s renewable energy development will leave the UK more reliant on imported energy.

3.7    International agreements

The UK will fail on its agreements on renewable energy and climate change due to these policy changes. Within the European Union there is a target of 20% of all energy from renewables by 2020. The UK was given a lower target of 15%. However, with the new energy policy changes, the UK may not be able to hit this target.

3.8    Climate Change and the Paris Climate Change talks

These changes will obviously affect the UK’s ability to hit its climate targets, both the UK’s own targets and those mandated by the Paris agreement in order to prevent a global 2°C rise in temperatures and thus dangerous climate change. According to the Climate Change Committee, new energy policies are required to reduce the UK’s greenhouse gas emissions. [[19]]


No, but as an industry we must be more cautious of government policies and incentives which can change at any moment.


Here are some things you can do:

5.1    Petitions

There is a petition on the Government website for a review of these changes, if it hits 100,000 people it will force a debate in parliament.

There are two petitions on 38 Degrees as well, please sign them.

5.2    Talk to your MP

All the MPs in parliament need to understand the threats the current energy policy changes pose to jobs, fuel poverty and energy security. Please do write to and/or meet with your MP (find them and use the materials in this blog. Or if you don’t have much time then use twitter to tweet to your MP.

5.3    Respond to consultations

The government is putting out a number of consultations on these changes. Friends of the Earth are currently challenging the government on the very fast timescales of these consultations. We will keep this updated as they come out.

5.4    Support lobby bodies

The Solar Trade Association and Renewables UK are both fighting these changes, if you are in a company that is a member of these organisations, please get as involved as you have time for.

5.5    Spread the word

The changes to energy policy are harmful to the UK, and are being driven under the banner of reducing bills. This does not fit with the financial data from government, please spread accurate information to the media and general public. Writing to your local paper (or national papers), using blogs, talking to people you know about all of this, it all helps.

Many thanks to Dan Grierson from The Energy Workshop, Sonia Dunlop from the Solar Trade Association and Alison Hood from Fact Check the Energy Bill for additional information


[*] According to DECC, there was 7,750 MW of solar at the end of June 2015. A reasonable approximation based on this would suggest this would produce 6.6TWh a year. If we assumed a coal power station running 8760 hours a year, then this is the equivalent of a 751MW station, such as Keadby Power Station

[1] Solar Trade Asssociation, “Investor confidence to take blow with proposal to end guaranteed level of support through lifetime of large-scale projects,” 22 07 2015. [Online]. Available:

[2] The Carbon Brief, “Explainer: Amber Rudd ends Green Deal energy efficiency scheme,” 24 07 2015. [Online]. Available:

[3] Energy efficiency scheme cut as Osborne announces next phase of green policy shake-up, Business Green, 2015 (

[4], “DECC postpones next Contracts for Difference auction,” 22 07 2015. [Online]. Available:

[5] Green Alliance, “What new spending reductions could mean for DECC,” 2015. [Online]. Available:

[6] Green building firms facing ‘depressing’ wait for new energy efficiency plan, Business Green, 2016 (

[7] The Guardian, “Solar power subsidies cut might save just 50p on average electricity bill,” 22 July 2015. [Online]. Available:

[8] International Monetary Fund, “See spreadsheet in Country Database “By Product 2015” for UK statistics,” [Online]. Available:

[9] HM Government, “Cost of renewables: DECC states that this is £3.5bn in 2014/15,” [Online]. Available:

[10] A. Hood, “Fact Check the Energy Bill,” 17 08 2015. [Online]. Available:

[11] BBC, “Onshore wind farms cancelled as subsidies cut,” 22 07 2015. [Online]. Available:

[12], “Dogger Bank: Plans for 2.4GW of offshore wind capacity scrapped,” 07 08 2015. [Online]. Available:–Plans-for-2-4GW-of-offshore-wind-capacity-scrapped/.

[13] [Online]. Available:

[14] 38 Degrees, “Save onshore wind,” 2015. [Online]. Available:

[15] STA Briefing: STA and RUK Jobs Survey Nov 15 [online], 2015 (

[16] Decerna, “Does renewable energy cause fuel poverty?” 12 03 2013. [Online]. Available:

[17]HM Government, “Annual Fuel Poverty Statistics Report 2015,” Department of Energy and Climate Change, 2015.

[18] Ecotricity, “Why Nothing Happened,” 07 11 2014. [Online]. Available:

[19] The Fifth Carbon Budget The next step towards a low-carbon economy, Committee on Climate Change November 2015 (

The end of Community Energy?

wind turbine in Blyth

12th August 2015 –  Please note, since this blog was published, there have been further announcements regarding Community Energy and renewable energy in general, and therefore this blog is no longer accurate. We will update this page as soon as time allows

2014 was a positive year, the Department of Energy and Climate Change began to support Community Energy, and there was the launch of Community Energy England (which we were one of the first commercial companies to join). Germany had shown with the numerous examples how it could work, and it seemed the UK government was supportive of similar measures over here. Community Energy could play a part in reducing fuel poverty, lowering greenhouse gas emissions, and improving energy security.

What a difference a few months makes. Now the Community Energy sector in the UK is under serious threat due to two major policy changes.

The Financial Conduct Authority (FCA) have changed the rules under which Energy Co-operatives can be established, and their controversial interpretation of the Co-operative and Community Benefit Societies Act essentially means the successful model of Community Energy demonstrated in Germany is now ineligible in the UK. The FCA also wish Community Energy organisations to be restricted financially to ‘philanthropic levels’. To explain this in more detail, the Co-operative and Community Benefit Societies Act was an attempt to consolidate existing legislation. However, the issue is with the FCA’s recent policy choices in interpreting what is meant by ‘co-op’, and ‘community benefit’. Rather than keeping to the flexibility provided by the UN-recognised definition of co-ops, or to modern conceptions of social enterprise, the FCA has defined co-ops narrowly to the exclusion of Community Energy generators. It is also seeking to implement a policy that in practice makes mutuality, commerciality, and social value, incompatible.

Secondly, the tax rules were changed. Unlike small companies, Community Energy schemes are now unable to benefit from two major schemes, the Enterprise Investment Scheme and Seed Enterprise Investment Scheme tax relief. According to Community Energy England, the change has successfully already placed 20 Community Energy projects in danger of collapse.

These two changes together are believed by many involved in the sector to be a successful attempt to remove Community Energy from the UK, and ensure it will never be possible to replicate the German success in the UK.

At Decerna, we work with communities on energy projects, helping communities generate energy and save energy, lowering levels of fuel poverty. This is something we wish to continue doing, and hope that the recent changes can be reversed.

Community Energy England are working hard to get an amendment into the upcoming Finance Bill to give Community Energy projects a two year transition period with regard to tax relief. The FCA changes are currently under consultation and are also being challenged.

For more details on this, and how you can help, contact Community Energy England on: and check their briefing document at

For more on our Community Energy work, contact

Many thanks to Co-operatives UK for additional information contained within this blog

Urban Community Energy Fund (UCEF)

Sunrise over the original wind turbines in BlythSunrise over the original wind turbines in Blyth

Decerna have been working with local community charities and trusts on energy efficiency /  renewable energy projects for some time. There are a range of funds out there to help organisations access the technical expertise required to assess the potential for renewables, of which the Rural Community Energy Fund (RCEF) and Urban Community Energy Fund (UCEF) are the latest. From information we have from the providers, we have out together some information and links to help you and your group find out more.

As always, any help or guidance needed, please let us know  Contact our community energy lead on 07572 531716 or email us on

What are the funds about?

Launched in November 2014, the Urban Community Energy Fund (UCEF) has been set up to complement the Rural Community Energy Fund (RCEF) – ensuring that every community in England can access funding support for renewable energy projects.
The two funds were established separately and on different timescales because they are funded differently:

  • UCEF was launched in November 2014 with government funding through the Department of Energy and Climate Change, and is administered by the Centre for Sustainable Energy (CSE) and Pure Leapfrog
  • RCEF was launched in June 2013 with funding through the Department for Environment, Food and Rural Affairs (Defra), and the Department of Energy and Climate Change and is administered by WRAP.

Are we urban or rural?

Simply put, the rules are that:

  • Urban areas are defined as settlements with more than 10,000 people which do not lie within a predominantly rural local authority area.
  • Rural areas are defined as situated in a predominantly rural local authority area and within a settlement of less than 10,000 people.
  • Urban areas that may be eligible for the RCEF scheme are defined as settlements with more than 10,000 people that lie within a predominantly rural local authority.

What help is available with the UCEF?

The Urban Community Energy Fund (UCEF) is a £10m fund to kick-start renewable energy generation projects in urban communities across England. Community groups will be able to access grants and loans to support renewable energy developments.

Grants of up to £20,000 are available for the more speculative, early stages of your project’s development, such as public consultation and preliminary viability studies.

UCEF will also provide loans of up to £130,000 to develop planning applications and a robust business case to attract further investment. This will help your project become ‘investment ready’, that is, at the right stage to secure a bank loan or another form of investment.

Who can apply?

Any of the following groups are eligible to apply for the fund:

  • Registered Company (including CICs)
  • Charitable Incorporated Organisation
  • Registered Societies (formerly known as IPS)
  • Parish and Town Councils

Your community group will need to be incorporated to apply to UCEF. This helps to protect both your group as individuals and your group’s project (and therefore UCEF’s investment). Incorporation is relatively simple, and can be quick and inexpensive.

What technologies are eligible?

The technologies that will be considered under UCEF include the following:

  • wind turbines
  • hydropower
  • photovoltaics
  • solar thermal
  • ground, water and air source heat pumps
  • anaerobic digestion
  • biomass
  • low carbon/renewable heat networks
  • gas combined heat and power (CHP) units

If you would like to find out more about the schemes and how Decerna can help with your application and project, contact our community energy lead on 07572 531716 or email us on

NDE discussion paper – COP of water heating technologies

1. Introduction

It is generally understood COP falls off with increasing temperature difference; hence it follows the COP when producing hot water is expected to be lower than that for space heating. However, the COP quoted in sales literature is often that measured for space heating performance and few, if any, studies have made a direct comparison of the COP when heating domestic hot water only.

Comparing like-for like performance requires a standard test method. EN13203 tapping cycle no. 2, reflects typical DHW energy use of 5.845 kWh/ day, around 120 litres, in line with the SAP predicted consumption for a 3 bedroom property. This article summarises the test results for a number of water heating technologies, enabling some comparisons to be made.

2. Test method

2.1. NDE tapping cycle tests

Decerna (NDE) conducted tap cycle no. 2 tests on the following technologies:

Ongoing trial of a packaged thermodynamic solar water heater with public results

  • Ongoing trial of a thermodynamic solar system with heat exchange to a high performance cylinder
  • 2m2 conventional solar thermal system, with 300 litre total storage and immersion-only back up
  • One month trial of MCS installed ASHP with 210 litre cylinder in the training centre

2.2.Tap cycle control

To ensure straightforward comparative testing, the test rig subjects each DHW unit to EN13203-2, tapping cycle no.2. The same tap cycle is also used in EN16147:2011, known as tapping cycle M.

The tapping cycle has 23 draw-offs during the day, from 07:00 through to 21:30. Each draw-off starts at a fixed time of day (as Table 1), and ends when the appropriate quantity of hot water heat energy has been delivered. Hence, fixed quantities of energy are drawn-off, not specific volumes of water (e.g. if the water temperature is cooler, the valve is open longer until the required heat is measured). The total daily draw is 5,845Wh per day.

2.3. Test rig Instrumentation

Quantity Measuring device
Electricity Elster A100C tariff grade electricity meter
Temperature Fine tip PT100 immersed in fluid pipe for heat calculation & control
Solar irradiance Kipp and Zonen SP-lite pyranometer in plane with collector
Water consumption Titan OG4
Heat Energy of DHW Calculated from temp and flow (mcdT) by controller in real time
Heat output of heat pump Sontex Supercal 531 with 440 flowmeter (RHI & MID compliant)
Table 1: test rig instrumentation

3. Results

Results are presented for:

  • Thermodynamic panel, from February to August, in lab
  • Conventional solar water heater with immersion back up, for June to September, in lab
  • ASHP unvented cylinder system for part August and September, in training centre

The COP values in the tables include the tank heat loss as part of the hot water load in order to give a realistic comparison with what would be achieved in service, whereby the system would have to produce energy to overcome the tank losses.

3.1 Thermodynamic panel

The thermodynamic system is a single panel, 210 litre unit with compressor and ancillary equipment housed in the top of the tank casing. The unit was fitted with a timeswitch to ensure it only operated between 6:30 and 21:00 hrs. In general, the unit would heat the cylinder and switch off on its thermostat by around 3 or 4pm, the setpoint being 55°C. Table 2 shows the monthly average data for the unit.

Month External ambient temperature °C In-plane solar irradiance Wh Electricity consumption(Ehp) Coefficient of Performance COP (COPhp)
January 7.0 307 5735 1.43
February 8.7 1789 5514 1.50
March 10.1 2743 4491 1.87
April 12.2 2206 4258 1.91
May 15.0 2733 3839 2.10
June 17.9 2667 3655 2.19
July 18.8 2758 3784 2.23
August 16.3 2689 3603 2.27
Table 2; performance test data for thermodynamic unit

The data presented online ( shows the total daily COP and irradiance plotted as a bar chart. Fig. 1 shows the results for June.

Decerna - daily thermodynamic system results for JuneFig.1 Daily thermodynamic system results for June

The COP (including the tank loses) is very close to 2.5 on several occasions, surpassing that required to qualify as renewable under the European Commission Renewable Energy Directive. On 12th June it is 2.50.

3.2. Conventional solar thermal

Two flat plate collectors are mounted on the building roof at 30° tilt angle, with total aperture area of 4.2m2 feeding a storage volume of 300 litres comprising 150 litres dedicated solar volume, 150 litre with back up via a immersion heater timed for 5pm to 8pm, setpoint 55°C. The solar controller was set similar to industry good practice settings of 65  maximum tank temperature, dT on of 6° and dT off of 4°C. The test commenced on June 6th, with solar contribution from June 10th (due to a sensor fault).

Decerna - June COP and irradiance data for solar thermal systemsFig.2 June COP and irradiance data for solar thermal systems

Fig.2 shows the results for June.

The daily variation is strongly related to the solar irradiance, with a peak COP of 48 achieved on June 12th when total in-plane irradiance was 6550 Wh/m2. Conversely, it falls to 1.98 on 15th June when solar irradiance was only 2735 Wh/m2. As the test did not commence until June 6th, data is not available for earlier months. The monthly averages are presented in Table 3.

Month External ambient temperature °C In-plane solar irradiance Wh Electricity consumption Coefficient of Performance COP
June 17.9 4741 1801 13.0
July 18.8 4449 3861 8.0
August 16.3 4068 2787 5.0
September 15.8 2890 4085 2.38

Table 3; performance test data for solar thermal + immersion unit

3.3          Air source heat pump and 250 litre cylinder

The NDE training centre has heating and hot water provided by a Mitsubishi EcoDan 8.5kW air source heat pump fitted by MCS contractors along with an OSO 250 litre twin coil mains pressure cylinder. The cylinder also has solar thermal, but to ensure this test was air-source only, the solar circuit was drained and valved off. The building space heating remained switched off throughout the test to ensure all electricity consumed is for DHW preparation only.

A duplicate control system ensures the same tapping cycle is drawn as per the other tests in the Brunel building. Limited results are available; from 21st to 26th August and from 8th September onwards due to staff holidays. The September data is presented in Fig. 3.

Decerna - Spetember COP and outdoor temperature data for ASHP systemFig.3  – September COP and outdoor temperature data for ASHP system

Fig.3 shows the available data for September. Daily COP for the DHW system including tank loss is reasonably consistent within the range 1.44 to 1.88, with average for the month of 1.59.

The COP is shown in Fig.3 in three ways:

  1. COP heat pump is the ratio of heat energy delivered to tank (measured by the heat meter) divided by the electricity consumed and is the closest comparison to the heat pump lab test EN 14511:2011, (albeit at the higher flow temperature than that usually reported at A7W35)
  2. COP domestic hot water system is the daily total domestic hot water energy draw off (5845Wh) divided by the total electricity consumed by the heat pump in that day. Hence, it takes no account of tank losses.
  3. COP domestic hot water system inc tank loss includes the tank losses as part of the hot water load on the system, as per the thermodynamic test. The standing loss is that declared by the manufacturer at 1.95 kWh/day (

The COPs are represented in Fig 4. COPdhwsl includes tank losses and can be compared with the other two technologies.

Decerna - Showing boundaries assumed for the COP values for ASHPFig.4 Showing boundaries assumed for the COP values for ASHP

 4. Conclusions

NDE tested three hot water heating technologies using EN13203 tapping cycle no. 2, a standard load profile to compare energy efficiency of different water heaters. Tapping cycle no.2 provides a typical DHW energy use of 5.845 kWh/ day, around 120 litres, in line with the SAP method predicted consumption for a 3 bedroom property.

The water heaters tested were:

  • a packaged solar thermodynamic unit
  • a conventional solar thermal system with immersion back up
  • a conventional cylinder heated by an MCS compliant air source heat pump

Monthly average COP values are presented based on the monitored data. The COP is calculated as the ratio of hot water load + tank losses divided by the electricity consumed in each 24hr period within the month.

The results show a range of COP values for the thermodynamic system, from 1.43 in January to 2.27 in August. The daily value exceeds 2.5 on several occasions, surpassing that required to qualify as renewable under the European Commission Renewable Energy Directive. It appears the COP varies more with ambient temperature than the daily solar gain.

The conventional solar thermal system COP is strongly related to the solar irradiance, with a peak COP of 48 achieved on June 12th when total in-plane irradiance was 6550 Wh/m2. Conversely, it falls to 1.98 on 15th June when solar irradiance was only 2735 Wh/m2. The monthly average is 13.0 for June, falling to 2.38 for September.

The ASHP system daily COP for the month of September is reasonably consistent within the range 1.44 to 1.88, with average for the month of 1.59; due to the standing losses from the system when considered as a hot water only package (as would typically be the case in summer).

As with any monitoring trial, a longer monitoring period would enable greater confidence in the conclusions drawn, but the results do show the difference between technologies when considered as units solely for the production of domestic hot water.

Appendix: Seasonal Performance Factor SPF

Ofgem definition: (from

  • SPF is a measure of the operating performance of an electric heat pump heating system over a year. It is the ratio of the heat delivered to the total electrical energy supplied over the year.
  • SPF = Total heat energy output per annum (kWh) ÷ Total input electricity per annum (kWh)
  • For example, a heat pump with an SPF of 2.5 will on average deliver 2.5kWh of heat for every 1kWh of electricity it uses.

The SEPEMO report ( describes SPF as evaluation of field measurement data according to the defined system boundaries, and notes (p.17): There are different existing standards and regulations for calculating the SPF. These calculation methodologies are mainly based on input from the testing standard EN 14511. The system boundaries of testing standards are however focused on the heating or cooling unit itself. In comparing test results, the system integration is not taken into account. Therefore these standards do not include the entire energy consumption of the auxiliary drives on the heat sink and heat source side.

Four SPF methodologies are used in SEPEMO, which include an increasing amount of auxiliary devices in the system e.g. circulator pumps, air source fans etc.

SPFH1 contains only the heat pump unit and evaluates the performance of the refrigeration cycle. The system boundaries are similar to COP defined in EN 14511. It is therefore effectively a lab test, but may exclude the energy consumption of any air fan or ground pump.

SPFH2 contains the heat pump unit and the equipment to make the source energy available (e.g. ground pump, air fan) for the heat pump. SPFH2 evaluates the performance of the HP operation, and this level of system boundary responds to SCOPNET in prEN 14825 and the RES-Directive requirements. It is therefore effectively a lab test, but includes the energy consumption of any air fan or ground pump.

SPFH3 contains the heat pump unit, the equipment to make the source energy available (e.g. ground pump, air fan) and the back up heater. SPFH3 represents the heat pump system and thereby it can be used for comparison to conventional heating systems (e.g. oil, gas boilers etc). The back-up heater consumption to ‘make-up’ temperature for high load conditions e.g winter and DHW production may have a critical impact on the SPF, especially in a poorly designed or operated system where electric boost heating is often used.

SPFH4 contains the heat pump unit, the equipment to make the source energy available, the back up heater and all auxiliary drives including the auxiliary of the heat sink system. SPFH4 represents the heat pump heating system including all auxiliary drives which are installed in the heating system. It is therefore similar to SPFH3 but with the addition of pump energy in the heat distribution system.

All the above SPFs are aimed at reporting performance of systems predominantly for space heating. Although hot water service can also be measured using SPFH3 and SPFH4, in order to compare hot water performance of different water heaters the product COP should be determined using tapping cycles to give fair comparison, as the tank losses need to be included.

EN16147:2011 provides a test method to achieve this and determine the COPdhw – defined as ‘coefficient of performance which is determined by the use of EU reference tapping cycles and which includes the heat losses of the storage tank

>>>Download the pdf of the COP of water heating technologies report here<<<

NDE updates off grid PV system

Whiteburnshanks cottageFigure 1: Whiteburnshanks cottage

Three years ago, The Whiteburnshank Trust approached Decerna to investigate high running costs for their outdoor education centre; an old shepherd’s cottage located in the heart of Kidland Forest. This centre has an off-grid electricity system with 24V battery bank, a 2.5kW wind turbine, 6 x 150W PV modules and a 10kW diesel generator for back up.  Our recommendations at the time included more regular maintenance of the battery cells and generator, more efficient use of electricity (including better user awareness) and potentially charging per-unit to reflect the very expensive costs of diesel genset charging. Additional PV was an option, but at the time considerably expensive.

Three years on, with the development of the PV market, PV module costs have fallen dramatically to the region of £0.50/Wp and The Trust reconsidered extra PV. The original PV system uses modules designed for battery charging which are now increasingly difficult to source and very expensive compared to those designed for grid connected systems.

Decerna recommended fitting around 2kWp of ‘grid market’ PV modules connected to the existing battery system using a max power point solar charger to regulate the output to the batteries. We worked with a steel fabrication company (Life Engineering in Washington) to design tilted racks to mount the array. Due to the sloping site, the modules are arranged in groups of three rather like a stepped terrace of housing. Each unit is wired as a series string, with the resulting approx. 100 volts DC fed to the battery room via armoured cable.

The tilted racks are anchored to ground using stakes and ballasted with tree trunks (the plan is is to build a ‘ballast garden’ of small shrubs to blend with surroundings)

Soon after connection, in a clear sunny cloud break, the system delivered impressive results, with a charging current of 70 amps delivered to the batteries and an indicated power of 1850 Watts. This is double the current delivered to the batteries by the generator so should help improve the battery state of charge considerably.

Nick Davies of NDE & Adrian Copley of Whiteburnshank Trust celebrate completionFigure 2: Nick Davies of NDE & Adrian Copley of Whiteburnshank Trust celebrate completion

Background on Whiteburnshanks

Whiteburnshank has been lived in for many years and is one of only three farms that remain in use in the Kidland forest today. In 1993 the Whiteburnshank Trust was set up to provide a centre for young people in the county. The trust is responsible for developing and maintaining the centre and is made up of a small committee of volunteers who manage, maintain and try to develop and improve the centre. It is non profit making and has only a small working income which just covers costs and routine maintenance. Further information, and booking enquiries, can be found at Available 365 days a year, the cottage is ideal for groups and is used Scouts, guides, D of E, school groups, bona fide organisations etc.

Upper Coquetdale electricity supply

Many properties in the Upper Coquet valley and other remote rural areas of Northumberland do not have access to grid electricity. This can present real problems for residents in terms of the extra cost of alternative power sources which is invariably diesel generators for electricity, and in the more remote areas this presents additional problems of cost, noise and delivery access for bulk diesel delivery. The problem is quite widespread and a recent petition to Northumberland County Council to invest resources in studying the issue attracted over 450 signatures [1].

[1]  Northumberland County Council Petitions Committee