30 Detailed Answers
Commercial Solar FAQs for UK Businesses
Honest answers to the questions UK SME owners, finance directors, and operations managers actually ask. Written by the engineers who deliver the installs.
Accredited and certified for UK commercial solar work
These FAQs come from the questions UK SME owners, finance directors, and operations managers ask us most often during initial quoting calls. They cover cost, payback, financing routes, three-phase requirements, AIA tax relief, EPC and MEES implications, employee/customer-facing displays, install timelines, what happens if you move premises, ESG reporting drivers, batteries, and the difference between on-site solar and a green energy tariff. The answers are written by the engineers who actually deliver the installs — not a marketing team. If you have a question we haven't covered, the contact form at the bottom routes straight to our technical team and we usually reply within an hour during UK business hours.
Most-asked questions
How much do solar panels for a business cost in the UK?
A typical SME install ranges from £20,000 (small office, ~25 kW) to £225,000 (light industrial, ~250 kW). Cost per kW is typically £900–£1,300 below 100 kW, falling to £750–£950/kW above 200 kW. After 100% AIA tax relief, effective net cost for limited companies is roughly 75% of headline price.
What's the payback period for SME solar?
5–8 years for most UK SMEs. Daytime-occupied sites with high baseload (manufacturing, retail) hit the lower end. Office-only sites with moderate weekend usage run 7–9 years. Adding battery storage can extend payback by 2–3 years but lifts annual savings 25–40%.
Can a small business afford solar panels?
Yes — most SMEs we work with don't pay any capex up front. Asset finance over 5–7 years is cash-flow positive from month one (the finance payment is less than the bill saving). PPA options have zero capex and start saving from day one. We model both options for every SME quote.
Do we need three-phase electricity for commercial solar?
Not necessarily for installs below 17 kW per phase. For larger systems, three-phase supply is generally required. Many small SMEs have single-phase supplies that limit practical PV to about 13 kW — a three-phase upgrade may be needed for larger systems and we factor this into the feasibility study.
How much does AIA tax relief save us?
100% AIA means the full capex is deducted from taxable profits in year one, up to £1m per year. For a profitable limited company at 25% corporation tax, an £80,000 install delivers £20,000 of tax relief — net cost £60,000. Similar reliefs apply for unincorporated businesses on cash basis.
What about EPC rating and MEES?
Solar improves EPC rating — typically lifts a band C to a B, or a band D to a C. Useful for landlords who must comply with MEES (Minimum Energy Efficiency Standards) — currently requiring band E or above, rising to band C by 2027 and band B by 2030 for non-domestic property. Solar is a recognised contribution.
Can our employees / customers see live generation?
Yes — most SME installs include a touchscreen lobby display showing live generation, lifetime kWh, and CO2 saved. Some clients put the data on their website footer or invoice template as a customer-facing trust signal. Web/app dashboards are standard.
How long does the install take?
From contract to commissioned: 8–16 weeks for sub-100 kW SME installs. Physical install: 1–4 weeks. DNO connection: typically the long pole — 4–8 weeks for G98 (sub-100 kW), 6–18 months for G99 (above 100 kW). We submit DNO application before the survey to compress timelines.
What if we move premises in 3 years?
Three options. (1) Owned system: relocate (15–25% of original cost) or sell with the building (PV adds 5–15% to commercial property value). (2) PPA: contract continues at the original site or transfers with sale. (3) Asset finance: settle the finance balance and sell the system with the building at agreed value.
Are we required to do this for ESG reporting?
Increasingly yes — if you supply FTSE 250 customers, sit in their CDP Supply Chain disclosure, or have a green clause in any contract. SECR (Streamlined Energy and Carbon Reporting) applies to large companies; smaller SMEs aren't directly required but their customers may flow requirements down. Solar is the cleanest Scope 2 reduction available.
Can we add battery storage now or later?
Both work. Adding now: marginal cost is lower because design, switchgear, and installation are bundled. Adding later: you can wait until you have a year of generation data to size the battery accurately. We design every PV system to be battery-retrofittable so the door isn't closed if you choose to wait.
Why not just buy a green energy tariff instead?
You can — but green tariffs are typically 5–15% more expensive than standard, and the 'greenness' is contested (most rely on REGOs which are widely regarded as a weak certification). On-site solar is locked-in cost reduction and indisputable Scope 2 reduction. Many SMEs run a green tariff alongside on-site solar for the residual grid imports.
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30 detailed FAQ pages, each with a 600-1,000 word answer. Click through to the full page for worked examples, comparison tables, and related guidance.
Cost
What does commercial solar cost per kW in the UK?
Commercial solar in the UK costs £900-£1,200 per kW for systems under 100 kW, £750-£950/kW for 100-500 kW systems, and £700-£850/kW above 500 kW. The figure includes panels, inverters, mounting, install, DNO connection, and a 10-year workmanship warranty — but excludes battery storage and any structural or three-phase upgrades.
How much does a 100 kW commercial solar system cost?
A 100 kW commercial solar system in the UK costs £85,000-£110,000 turnkey in 2026, depending on roof type, three-phase status, and whether optimisers are specified. Typical annual generation is 90,000-95,000 kWh, saving £20,000-£25,000/year for a daytime-occupied SME at current grid prices. Simple payback lands at 4-5 years before tax relief, 3-4 years after AIA.
How much do commercial solar panels cost in the UK?
A typical UK SME install ranges from £20,000 (small office, ~25 kW) to £270,000 (light industrial, ~300 kW). Cost per kW is £900-£1,200 below 100 kW, falling to £700-£850/kW above 500 kW. After 100% AIA tax relief, effective net cost for limited companies is roughly 75% of headline price.
What is the cost per kWp for commercial solar in the UK?
Cost per kWp (kilowatt-peak) for UK commercial solar in 2026 ranges from £900-£1,200 below 100 kWp to £700-£850 above 500 kWp. kWp is the rated DC capacity at standard test conditions, not the AC output your meter sees. AC output is typically 5-10% lower than DC capacity due to inverter clipping and system losses.
Savings
How much can my business save with solar panels?
Most UK SMEs save 35-55% on their annual electricity bill with a properly sized solar PV system. For a business spending £30,000/year on electricity, that's £10,500-£16,500 saved every year, rising as grid prices rise. Savings start month one, are non-taxable (they reduce a tax-deductible cost), and continue for 25+ years.
How much can a business save with solar panels?
A typical UK SME with a 100 kW solar system saves £18,000-£25,000 per year at current commercial electricity prices. Savings come from displaced grid imports (largest share, around 60-75% of generation) and SEG export payments (4-15p/kWh) for the rest. Lifetime savings over 25 years usually total £350,000-£550,000 on a £85,000-£100,000 install.
Payback
What's the payback period for commercial solar in the UK?
Commercial solar payback in the UK is 5-8 years for most SMEs in 2026, dropping to 3-5 years after 100% AIA tax relief for profitable limited companies. Payback depends on self-consumption, grid tariff, and system size. Daytime-occupied sites with high baseload (manufacturing, retail) hit the lower end; office-only sites with weekend gaps run 7-9 years.
What is the payback period for commercial solar panels?
Commercial solar panels typically pay back in 5-8 years in the UK in 2026, with the median around 6.5 years. Profitable limited companies using 100% AIA tax relief see payback fall to 3-5 years. The asset then continues generating savings for another 17-22 years before requiring inverter replacement, with panels still producing 87% of original output at year 25.
Grants & Tax
Can I claim tax relief on commercial solar panels?
Yes — UK businesses can claim 100% Annual Investment Allowance (AIA) on commercial solar PV, deducting the full capex from taxable profits in year one (up to £1m/year). For a profitable limited company at 25% corporation tax, that's effectively a 25% discount on the install. Capital allowances rules and timing matter — verify with your accountant before signing.
Are there grants for commercial solar panels in the UK?
There are no national capital grants for UK commercial solar in 2026. The main support is 100% Annual Investment Allowance (effectively a 25% tax discount) and the Smart Export Guarantee (4-15p/kWh for exports). Mayoral combined authorities (GMCA, WMCA, WYCA, LCRCA) run rotating SME decarbonisation grants worth £5k-£50k. Always check current schemes before applying.
Do commercial solar panels qualify for 0% VAT?
No — commercial solar panels in the UK are charged at standard 20% VAT. The 0% VAT rate introduced in April 2022 applies only to domestic installations on dwellings. Commercial buildings, charities trading commercially, and mixed-use buildings used predominantly for non-residential purposes are all standard-rated. VAT-registered businesses recover the 20% through their normal VAT return.
Finance
How can I finance commercial solar panels?
UK SMEs typically finance commercial solar via four routes: cash purchase (best long-run economics), 5-7 year asset finance (cash-flow positive from month one), operating lease (rental with VAT-recoverable monthly), or PPA (zero capex, discounted electricity rate over 15-20 years). Most SMEs choose asset finance because monthly bill saving exceeds the finance payment from day one.
What is a Power Purchase Agreement (PPA)?
A Power Purchase Agreement (PPA) is a contract where a third party installs and owns solar panels on your roof at zero capex to you, and you buy the electricity they generate at a discounted unit rate (typically 10-25% below grid) over 15-20 years. The provider takes the export income. At end of term you extend, buy out at residual value, or have the system removed.
Planning & Regulation
Can solar panels be installed on listed buildings?
Yes, but only with Listed Building Consent (LBC) and full planning permission. Grade II buildings see roughly 60-70% LBC approval rates with sympathetic design — usually rear-facing roofs, slate-effect or solar tiles, no visible mounting. Grade II* and Grade I see lower approval rates and often need bespoke product specifications. Always engage the council's conservation officer in pre-application discussions.
Do I need planning permission for commercial solar panels?
Most UK commercial solar installs are Permitted Development under Class A Part 14 of the GPDO 2015 — no planning application required. Exceptions: listed buildings, conservation areas, scheduled monuments, World Heritage Sites, ground-mount above 9 m², and panels protruding more than 200 mm above roof plane. Always check before installing — planning enforcement can require removal of non-compliant systems.
When does commercial solar require planning permission?
Commercial solar requires planning permission when Permitted Development rights don't apply: listed buildings, conservation areas (front-facing roofs), scheduled monuments, ground-mount above 9 m², tilted arrays protruding more than 200 mm above roof plane, or where an Article 4 Direction has removed PD rights. The application process takes 8-13 weeks via the Planning Portal.
What building regulations apply to commercial solar installations?
Commercial solar installations must comply with Building Regulations Parts A (structure), B (fire safety), L (energy efficiency), and P (electrical safety). The structural assessment confirms the roof can take added load. BS 7671 (the IET Wiring Regulations) governs the electrical install. CDM 2015 applies to projects over 30 person-days. MCS or NICEIC certification is required to commission, sign off, and unlock SEG.
What is the difference between G98 and G99 applications?
G98 and G99 are the two DNO connection standards for embedded generation in the UK. G98 covers small installs up to 16 A per phase (typically up to 11.04 kW single-phase or 17 kW three-phase) — fast 'connect and inform' process taking 4-8 weeks. G99 covers everything larger — full design and approval process taking 6-18 months. The threshold determines your installation timeline more than any other factor.
Technical
How much roof space do I need for commercial solar?
A commercial solar install needs roughly 6-7 m² of usable roof per kW. A 100 kW system fills 600-650 m². For SMEs, that's typically 50-70% of a light-industrial unit roof, 80-100% of an office roof, or one full bay of a large warehouse. Pitched roofs, shaded roofs, and roofs with skylights or HVAC plant lose effective area — usable area is rarely the full roof footprint.
What size solar system does a business need?
Most UK SMEs need a solar system sized at 60-80% of annual electricity consumption to maximise self-consumption while staying within roof and capex constraints. For a business spending £30,000/year on electricity, that's typically a 60-75 kW system. Sizing should be driven by half-hourly meter data, not roof area or rules of thumb.
What size solar system does my business need? (sizing methodology)
To size a commercial solar system, start with your annual kWh consumption from your bills, target 60-80% of that as annual generation, then check against roof area (6-7 m²/kW), electrical capacity (G98 vs G99 threshold), and budget. The right size is the smallest of these four ceilings. Insist on PVSyst modelling from half-hourly meter data, not generic estimates.
Performance
Do solar panels work on cloudy days?
Yes — solar panels generate electricity from diffuse light on cloudy days, typically producing 10-25% of their peak output. UK weather averages 60-70% cloudy days per year, but cloudy generation accumulates substantially: a 100 kW system in the UK generates 85,000-105,000 kWh/year despite cloud cover. Panels actually perform marginally better in cool cloudy conditions than in hot direct sun above 30°C.
How efficient are commercial solar panels?
Commercial solar panels in 2026 typically achieve 20-23% efficiency at Standard Test Conditions, with leading Tier 1 modules (Trina Vertex S+, JA Solar Deep Blue, Longi Hi-MO 7) reaching 22.5-23%. Higher efficiency means more kW from less roof area, useful where space is tight. The system as a whole loses 8-15% to inverter, cabling, soiling, shading, and temperature — real-world AC output is typically 85-92% of DC nameplate.
How much energy does a commercial solar panel produce?
A typical 540 W commercial solar panel in the UK produces 480-580 kWh per year, with the variation driven by location (south coast vs Scottish highlands), orientation, pitch, and shading. South-facing 35-40 degree pitch in the Midlands is the benchmark — about 530 kWh/panel/year. The whole system produces 850-1,050 kWh per kW of nameplate annually.
How does UK cloudy weather affect commercial solar performance?
UK cloudy weather is fully accounted for in commercial solar yield calculations — the long-run average is 850-1,050 kWh/kW/year across the UK, with year-to-year variation typically ±5-8%. Cloudy days reduce instantaneous output but accumulate over the year. UK silicon PV achieves 80-85% of Mediterranean yields per kW because cooler panel temperatures partly offset higher cloud cover.
Maintenance
What does commercial solar panel maintenance involve?
Commercial solar maintenance is light: annual visual inspection (£200-£500), cleaning every 2-5 years (£400-£1,500 per clean), monthly remote monitoring review, inverter replacement at year 11-13 (£6k-£15k for 100 kW system), and warranty claim management when needed. Total annual maintenance budget for a 100 kW system: £400-£1,000/year on average. Most issues are caught through monitoring.
How can I make commercial solar panels last as long as possible?
Commercial solar panels last 30-40 years with proper maintenance: annual inspection, cleaning every 2-5 years, prompt resolution of any monitoring alerts, and inverter replacement at year 11-13. Avoiding microcrack damage during install and using Tier 1 panels with PID resistance are the biggest factors in long-term performance. Most UK commercial systems operate well beyond their 25-year warranty.
What maintenance do commercial solar panels require?
Commercial solar panels require annual visual inspection, periodic cleaning (every 2-5 years), continuous remote monitoring, and one mid-life inverter replacement at year 11-13. There are no daily, weekly, or monthly physical maintenance tasks. Total maintenance time: roughly 4-8 hours per year for a 100 kW system, mostly handled by contracted O&M services.
End-of-Life
How long do commercial solar panels last?
Commercial solar panels last 30-40 years physically with Tier 1 manufacturers offering 25-year linear performance warranties at 87% of nameplate. Inverters typically need replacement once around year 11. Real-world UK installs from 1995-2000 are still operating at 80-85% of original output. Asset life is typically constrained by inverter and switchgear, not the panels themselves.
What happens to solar panels at the end of their life?
End-of-life solar panels in the UK are recycled under WEEE Regulations 2013 — the panel manufacturer or installer is legally required to take them back at no cost to the owner. Modern recycling recovers 95%+ of materials (glass, aluminium, silicon, copper, silver). Most UK solar from 1995-2010 is still operational. Genuine end-of-life recycling won't be at scale until 2035-2050.