Why install solar panels at your business?

Business solar is worth investigating when your site can use electricity during generation hours and has suitable roof rights. Eligible Great Britain solar installations up to 5 megawatts can investigate export payments [S1]. Compare your own demand, installation costs and operating terms before deciding; the worked example below separates bill reductions from cash income. Checked October 2026.

Last checked 16 October 2026

Why install solar panels at your business?

The commercial question is how much purchased electricity your roof could replace, plus what surplus generation could earn. The government’s Solar Roadmap identifies commercial rooftops as an opportunity and discusses the contract difficulties facing landlords and tenants [S2]. Your decision needs a site calculation.

Start with bills and interval electricity data, then ask for a generation estimate based on your roof. Compare the timing of generation with your actual use. Read commercial solar sizing before approving a system based only on available roof space.

How much solar electricity could your site use?

A kilowatt (kW) measures power; a kilowatt-hour (kWh) measures energy. Ask for annual generation in kWh and an estimate of self-consumption: generation used on site rather than exported. Inspect assumptions for weekends, holidays and seasonal opening before comparing annual totals.

The illustration below keeps generation fixed and changes on-site use. It is an illustration, not a quote. Every cost, tariff, yield and contract term is an assumption, not a market benchmark or partner offer. No grant or tax relief is included. Costs and rates are modelled excluding recoverable VAT; check your position with your accountant.

At mid use, 20,000 × 60% = 12,000 kWh replaces imports, leaving 8,000 kWh exported. Gross value is 12,000 × £0.25 + 8,000 × £0.05 = £3,400. Deduct assumed annual costs of £300 to leave £3,100. Do not add that bill reduction to export income again.

What could solar earn, and how many years until payback?

For self funded solar, annual net benefit equals avoided import cost plus export receipts minus maintenance. For the hypothetical part funded agreement, your retained benefit is 60% of that amount after costs; the funder takes the remainder. This split is a modelling assumption requiring a written commercial agreement.

Net benefit includes bill reductions; it is not all cash income. Simple return on investment (ROI) is annual net benefit ÷ your capital × 100. Simple payback is your capital ÷ annual net benefit. Applying the capital ranges:

For example, mid self funded payback is £20,000–£24,000 ÷ £3,100 = 6.5–7.7 years, rounded. The model excludes finance, tax, degradation, downtime, replacements and tariff changes. Request a fuller appraisal using your own inputs; see business solar payback.

Which funding model fits your business?

With fully funded solar, the funder pays capital, owns the equipment and pays maintenance. In this assumed contract, yearly cash income to you is generation × rent: 20,000 × £0.02 = £400 in each use case. No host capital payback is calculated because the assumed host investment is zero.

Your separate annual electricity bill reduction is on-site use × (£0.25 − £0.18): £560, £840 or £1,120 at low, mid or high use. The funder receives export income. Rent and electricity terms are hypothetical; do not assume an offer includes them. Compare a solar power purchase agreement with buying.

Part funded and self funded arrangements need a clear allocation of ownership, maintenance and revenue rights. Ask your solicitor to review roof access, repairs, assignment and exit provisions. Check how long your business expects to occupy the premises before treating a payback period as acceptable.

Can you sell surplus electricity, and what needs checking first?

The Smart Export Guarantee (SEG) covers qualifying Great Britain solar installations up to 5 megawatts, subject to eligibility and metering [S1]. Obtain a tariff offer for your installation. The assumed export price above is not a published offer.

The Welsh Government technical note explains network compliance and export documentation [S3]. Ask your local distribution network operator (DNO), which manages the electricity network, to confirm the connection route. G99 is the engineering recommendation governing connection approval for relevant generating equipment. Read G98 versus G99 and retain the approval evidence.

What should a roof survey and installer proposal establish?

Request a structural assessment, roof-condition review and layout showing shading, equipment access and expected generation. Ask who pays to remove and refit panels for roof repairs. Include your landlord and insurer in the proposal review where relevant.

England’s permitted-development changes include specific conditions; a national policy announcement is not permission for every roof [S5]. Ask the appropriate council for your site’s route. Use roof suitability and surveys to prepare the survey brief.

HMRC classifies solar panel expenditure as special rate for capital allowances [S4]. Keep tax relief outside the base example until your accountant confirms your treatment. Ask the installer to separate roof repairs, solar equipment, connection and ongoing service costs.

What should you do next?

Use the income and payback calculator to test your own figures, then collect electricity data, roof information and ownership or lease documents. Request comparable proposals with generation, self-consumption, costs and contract assumptions visible. Then get matched with an installer that covers your area.

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