Solar & Battery Design Tools for United Kingdom Design Systems, Calculate ROI & Find Installers

Energy Usage

Understanding your household's energy consumption is the foundation of effective solar system design in the UK. The average UK household uses between 10-20 kWh per day, with energy-efficient properties often using significantly less. This relatively modest consumption compared to other countries reflects the UK's temperate climate, smaller average home sizes, and growing awareness of energy efficiency.

Before installing solar, consider reducing your energy consumption through improved insulation and energy-efficient appliances. This can lower the system size you need and improve your investment returns, especially important given the UK's variable solar generation throughout the year.

Note: Actual usage varies depending on property size, building efficiency, climate, and appliances.

Solar System Sizing

You'll need around 3.9kW of solar to match your average UK household consumption. We recommend sizing between 5.9kW and 7.9kW for optimal results, accounting for daily and seasonal variations in solar output. The UK experiences significant seasonal variation, with summer generation typically 3-4 times higher than winter months.

A 6.6 kW system in the UK generates approximately 24.8 kWh daily on average, with seasonal variation from 2.09 kWh/kW/day in December to 4.63 kWh/kW/day in August. This substantial seasonal swing means proper system sizing is crucial for maximising year-round self-sufficiency.

With solar-only (no battery), a 6.6 kW system provides approximately 45% self-usage in the UK, depending on your consumption patterns, drawing 55% from the grid. Adding a 10 kWh battery increases energy independence to approximately 95% annually, reducing grid reliance to 5%. Battery storage is particularly valuable in the UK, allowing you to store excess summer generation for use during darker winter months and maximising the value of your solar investment.

The Smart Export Guarantee (SEG) pays you for excess electricity exported to the grid, with rates varying significantly by supplier. Basic unbundled tariffs average around 4-5p per kWh, whilst bundled tariffs (where you also buy electricity from the supplier) typically offer 13-20p per kWh, with some suppliers like Octopus Energy offering peak rates up to 30p per kWh during high-demand periods. For accurate battery savings and ROI calculations specific to your location and export tariff, use the full Photonik design tool.

Understanding Solar & Battery System Costs

A 6.6 kW solar system in the UK costs approximately £8,752, while adding a 10 kWh battery increases the total to around £13,557. Solar panels and battery storage qualify for 0% VAT (zero-rated) when installed by a VAT-registered installer in residential properties, making solar more affordable than ever. Solar-only systems typically pay for themselves in around 7.6 years, whilst adding battery storage usually extends payback but significantly improves energy independence. The Smart Export Guarantee provides ongoing export payments, improving long-term returns compared to the previous Feed-in Tariff scheme.

The cost breakdown shows estimates for equipment costs and installation labour. Adjust system size and battery storage to see how it affects total investment and payback periods. Note that prices vary by installer and location, with London and the South East typically commanding premium rates. The Smart Export Guarantee (SEG) scheme has no end date and provides ongoing export payments, improving long-term returns.