Commercial Solar PV, FAQs
Honest answers to the questions our customers actually ask. Last updated for 2026.
Common questions about commercial solar PV
These are the questions UK businesses actually put to us before they sign off six figures of capex, and the answers are grounded in real numbers rather than sales copy. You will find straight guidance on what a commercial system costs per kWp, why the typical payback runs 5 to 8 years, how 100% Annual Investment Allowance and reclaimable VAT change the net figure, and which funding routes apply to your sector. We cover the practical hurdles too: how a G99 grid connection works and why DNO timescales can stretch from 4 weeks to 18 months, when Permitted Development covers your roof and when you need planning, and what happens to the asset if you sell or relocate before payback.
If your question is not answered below, the honest starting point is a free desk feasibility. We model each system from your half-hourly meter data, so the fastest way to a specific answer is to request a quote. You can also read the detailed cost and payback guide, review the grants and funding routes that apply to your building type, or browse real projects in our case studies.
How much does a commercial solar PV system cost in the UK?
Commercial solar PV typically costs £900-£1,300 per kWp for systems under 100 kW, falling to £750-£950 per kWp between 100 and 250 kW and £600-£800 per kWp above 500 kW. In real terms a 50 kW office system is roughly £45,000-£60,000, a 250 kW warehouse system £190,000-£240,000, and a 1 MW factory system around £600,000-£750,000. After 100% Annual Investment Allowance, the effective net cost for a profitable company is roughly three-quarters of the headline price.
What is the payback period for commercial solar panels?
Most UK commercial solar installations pay back in 5 to 8 years. Buildings with high, steady daytime demand, such as factories, warehouses with refrigeration, and manufacturing, reach the lower end at 4-6 years because they consume most of what they generate. Office and retail sites with lighter weekend use run 6-8 years. The panels carry a 25-year performance warranty, so the system delivers 15-20 years of near-free power after payback.
How much can commercial solar cut our electricity bills?
A well-sized commercial PV system commonly cuts total grid electricity costs by 30-60%. The exact figure depends on how much of the generation is used on site: a daytime-occupied building consumes 55-75% of its solar directly without a battery, and adding storage pushes self-consumption to 80-95%. The saving is a permanent hedge, it grows in value every time grid prices rise.
How big a commercial solar system do we need, and how much roof does it take?
As a rule of thumb, 1 kWp of PV needs about 5-6 sqm of unshaded roof and generates roughly 900-1,000 kWh a year in the UK. We size from your half-hourly meter data rather than roof area alone, aiming for annual generation equal to 60-85% of your consumption. A 1,000 sqm warehouse roof typically supports 150-180 kWp; a 250 sqm office roof around 30-40 kWp.
Do commercial solar panels work in the UK climate?
Yes. UK commercial arrays reliably produce 900-1,050 kWh per kWp per year, and modern panels generate usefully in diffuse and overcast light, not just direct sun. Output is naturally higher April-September, which suits most commercial demand profiles. Correct panel selection, orientation and inverter sizing matter far more than raw sunshine hours.
Should we add battery storage to a commercial solar PV system?
Battery storage makes sense when a meaningful share of demand falls outside generation hours, evenings, weekends or overnight, or where you want resilience and grid-service revenue. It typically lifts self-consumption from 55-75% to 80-95% and adds 25-40% to annual savings, at the cost of a longer payback. We model PV-only and PV-plus-battery so you can compare, and design every system to be battery-ready even if you add storage later.
What grants and tax relief are available for commercial solar?
The main lever is 100% Annual Investment Allowance, which lets a company deduct the full capex from taxable profit in year one. VAT is reclaimable for VAT-registered businesses, and the Smart Export Guarantee pays for surplus export. Energy-intensive manufacturers may access the Industrial Energy Transformation Fund, public bodies use Salix and the Public Sector Decarbonisation Scheme, and some combined authorities run regional SME grants.
How does grid connection (the DNO) work for a commercial installation?
Small commercial systems can use the G98/G99 fast-track, but most need a full G99 application to your Distribution Network Operator. For larger systems, export limitation (G100) is often used to secure a connection quickly and avoid costly network reinforcement. Timescales range from 4-12 weeks for small connections to 6-18 months for larger ones, so we submit the DNO application early, usually before the site survey.
Can we fund commercial solar without paying upfront?
Yes. Asset finance spreads the cost over 5-7 years and is usually cash-flow positive from month one, as the finance payment is less than the bill saving. A Power Purchase Agreement needs zero capex, a funder installs and owns the system and you buy the power at a fixed rate below grid. We present cash purchase, asset finance and PPA side by side with the IRR for each.
Will solar affect our roof warranty or need structural work?
We assess roof condition, remaining warranty life and structural loading before design. Non-penetrative clip-fix mounting suits most metal warehouse and industrial roofs and preserves the roof warranty; pitched and flat roofs use appropriate ballasted or fixed systems. Roofs over about 1,000 sqm usually get a structural survey for the additional dead load and wind uplift, and pre-2000 roofs get an asbestos check.
Do we need planning permission for commercial solar panels?
Most commercial rooftop PV falls under Permitted Development (Class A Part 14), so no planning application is needed. Exceptions are listed buildings (which need Listed Building Consent), conservation areas and street-facing arrays, and ground-mounted systems above permitted-development thresholds. We confirm the planning route as part of the feasibility study and handle any application required.
How long does a commercial solar installation take?
From signed contract to a commissioned system is typically 8-20 weeks. The physical install is 1-6 weeks depending on size, but the critical path is usually the DNO connection, 4-12 weeks for smaller systems and up to 18 months for large ones. Submitting the grid application early is the single biggest lever on the overall timeline.
What happens if we move premises or sell the building?
You have three routes. An owned system can be sold with the building (PV typically adds 5-15% to commercial value) or relocated for roughly 15-25% of the original cost. A PPA transfers with the sale or continues at the original site. An asset-financed system can be settled and sold with the building at an agreed value. The right approach is modelled around your expected tenure.
Why use a specialist commercial installer rather than a general electrical contractor?
Commercial PV is an engineering and finance exercise, not just a wiring job. A specialist models from half-hourly data, holds MCS commercial certification, understands G99 connections and permitted development, arranges asset finance and PPAs, and backs the workmanship with an insurance-backed warranty. Generalists can fit panels, but rarely design for optimal self-consumption or navigate DNO and grant processes, which is where most of the value is won or lost.