Case study

Techno-economic energy study on a local authority depot

solar pv panelsSolar PV modules

A large county council requested a feasibility study to assess the value of installing various renewable technologies at one of their largest depots.

The main priority of this work was to assess and review the viability for their own proposal for a ‘zero carbon depot’, which aimed to reduce the site’s carbon footprint to zero or less, with the possibility of exporting surplus electricity back to the grid.

The project was to utilize the following technologies:

  • Solar PV;
  • Energy Storage;
  • Smart Grid with Private Wire;
  • Future proofed Electric Vehicle (EV) charging infrastructure;
  • Air Source Heat Pumps and Infrared Heating Solutions;
  • Point of Use Hot Water Systems;
  • Building Energy Efficiency Works.

Outline & objectives

To undertake this work we assessed:

  • Current carbon footprint;
  • CO2eq savings;
  • Size of PV installation required to support the site;
  • Size, type and number of heat pumps required;
  • EV charging load required to electrify the existing fleet;
  • Optimum battery size.


The project resulted in the following:

  • A report based on two PVSyst studies providing monthly and annual predicted outputs;
  • Full analysis of current electricity and gas usage and calculation of their carbon impact;
  • Calculation of the 25-year CO2eq savings based on multiple PV installations and the comparison of this against the current CO2eq emissions of the site;
  • Overview of the requirements required to replace the existing gas boilers with air source heat pumps;
  • Full analysis of the current vehicles fleet (153 vehicles), research of suitable replacement EVs, with calculations of the charging requirements of this new fleet, based on different charger types and vehicle usage profiles;
  • Matching predicted energy generation and consumption with a proposed battery system, capable of fully supporting the site;
  • Overview of PPAs and sleeving arrangements which may be a valuable source of income to the council;
  • Production of a breakdown of predicted costs of element of the site development;
  • Final summary of further issues which the council had yet to consider which would impact their outline plan and future development of the site.

This ensured the local authority had all the information required in order to make decisions on the future energy strategy for the depot, and also to inform future funding bids.