Solar PV

Please note: This article is for educational purposes only. Always consult a qualified solar PV installer before making any decisions about installing solar panels at your business premises.

Solar PV systems generate electricity whenever light shines on them, reducing the amount of electricity a business needs to buy from the grid. For commercial buildings with suitable roofs, solar PV is one of the most established and cost-effective renewable energy investments available, with payback periods typically ranging from 8 to 12 years.

Contents

1. What is Solar PV?
2. Potential Impacts
3. Important Considerations
   1. System Size and Efficiency
   2. Feasibility of PV Installation
   3. Roof Types
   4. Direction of the Arrays
   5. Sizing the Solar PV System
   6. Cost and Payback Periods
   7. Maintenance

What is Solar PV?

Solar PV systems generate electricity whenever there is light shining on them — the sunnier it is, the more they generate. The electricity produced reduces the amount you need to purchase from the grid. With a larger system, there will be periods when generation exceeds consumption, and surplus electricity is exported to the grid for use by other nearby buildings. Solar PV works well alongside battery storage systems, which can capture that surplus for use during evenings or cloudy periods.

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Potential Impacts

• Environmental Benefits: Solar PV systems reduce reliance on fossil fuels, cutting greenhouse gas emissions and air pollution, and directly supporting a business’s Carbon Reduction Plan targets.
• Energy Independence: Generating electricity on-site reduces dependence on imported fossil fuels and provides greater resilience against energy price volatility.
• Financial Savings: Solar PV offers long-term savings by cutting electricity bills, with potential additional income from electricity exports.
• Intermittency: Solar PV generation depends on weather conditions and sunlight availability. Integrating battery energy storage can enhance reliability during low sunlight or high demand periods.

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Important Considerations

System Size and Efficiency

Solar module output is rated in Watts under Standard Test Conditions (STC) — a specific intensity and quality of light. A module rated at 450W produces that output under STC. Combining ten such modules gives an array output of approximately 4,500Wp, where “p” denotes peak performance under STC.

Solar module efficiency measures how effectively a module converts sunlight into electricity. A 20% efficient module generates around 200W per m² under STC. While this figure may seem low, solar energy itself is free and limitless, making even modest efficiency commercially viable. Efficiency varies depending on sunlight intensity, temperature, and module quality.

Feasibility of PV Installation

Most buildings with suitable unshaded roofs can accommodate solar PV. Key considerations include planning permission, structural capacity of the roof, and future access for maintenance. Safety measures such as handrails may be required. Larger systems may also require DNO permission to connect to the local power grid.

Roof Types

For buildings with southerly-facing sloping roofs, various fixing systems can accommodate solar PV across slate, tiled, steel, and aluminium roof types. On flat roofs, panels are angled to capture more energy and prevent dust buildup. Common flat roof mounting methods use A-frames secured with ballast weights, which require a structural engineering assessment to ensure stability during adverse weather.

Direction of the Arrays

For optimal energy production, solar PV modules should face south and be tilted at an angle. The recommended tilt in the Northeast of England is around 40°. Software models using historical weather data estimate approximately 900kWh per year for every kWp of installed capacity — meaning a 3kWp system would produce around 2,700kWh of electricity annually in this region.

Sizing the Solar PV System

Solar PV is most beneficial for businesses that consume electricity primarily during daylight hours and operate throughout the week. Oversizing the system may not be cost-effective, as excess electricity exported to the grid generates less value than electricity consumed on-site. Accurate estimation of self-consumption is crucial and requires expert advice alongside analysis of historical consumption data.

Cost and Payback Periods

The cost of solar PV installations has reduced significantly in recent years, with typical prices around £1,000 per kWp. Payback periods for commercial installations generally range from 8 to 12 years, depending on self-consumption levels, system orientation, shading, and energy tariffs. Strategies such as diverting surplus electricity to heating or installing battery storage can further enhance the financial return.

Maintenance

Solar PV systems are highly reliable, with modules often backed by warranties of 25 years or more. Power output decreases slightly over time due to natural degradation, but this decline is minimal. Regular maintenance includes cleaning panels in dusty locations, inspecting fixings, and conducting periodic electrical inspections. Fire safety considerations should also be assessed, with specialist advice recommended to ensure ongoing compliance with safety standards.

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