50kW solar system cost: about £63,100, plus 30kW and 100kW systems explained

50kW solar system cost UK: the official figures

The only official national price series for solar is DESNZ's Solar PV cost data, built from the MCS installation database. Its biggest band is 10-50kW, with a median installed cost of £1,262 per kW in 2025/26. Multiply that by system size and you get:

Illustrative figures multiply the DESNZ median cost per kW by system size and are rounded. They include equipment, installation, connection and VAT where it applied, and exclude batteries, extended warranties and other works such as roof repairs. DESNZ measures cost per kW of declared net capacity (DNC). Installers usually quote per kWp of panels, and DESNZ says costs on that basis (total installed capacity) are typically 6-12% lower: the 10-50kW median is £1,204/kWp. Source: DESNZ solar PV cost data, published 28 May 2026.

Two things to know about these numbers. First, they're medians: half of 10-50kW systems cost more, half less. Second, a VAT-registered business can normally reclaim the VAT, so its real cost is lower than a figure that includes VAT. For prices across every size from 10kW up, see commercial solar panel costs. Pricing a home system? Use solar panel costs for homes.

30kW, 50kW and 100kW solar: key facts for 2026

100kW solar system cost: why there's no official figure

We checked. DESNZ describes its release as cost data for small-scale solar PV, and its 2025/26 workbook has three size bands only: 0-4kW, 4-10kW and 10-50kW. There is no official UK figure for a 100kW system, and any page quoting one as "official" is guessing.

What we can say is what moves a 100kW quote, compared with doubling a 50kW one:

• Scale economies. In the DESNZ data, cost per kW falls as systems get bigger: the 10-50kW median of £1,262/kW is well below the £1,780/kW median for 0-4kW home systems. Fixed costs like design, scaffolding, access and commissioning get spread over more panels, so expect a 100kW quote to come in below twice a 50kW one per kW. How far below depends on the site.
• Grid paperwork. Above 50kW, the DNO application moves to the full ENA Standard Application Form with a G5 harmonics assessment. Some DNOs now charge to review the commissioning documents: Electricity North West has done so for schemes over 50kW since 1 January 2026.
• Network works. If the local network can't take the export, you face either an export limit or a connection quote for reinforcement. That can change the economics more than the panels do.
• Inverters and switchgear. Bigger string inverters, a larger AC distribution board and possibly a supply upgrade.
• Structure and roof. 100kW needs roughly twice the roof of 50kW (see below), so more of the building's structure has to be checked.
• Planning. In England, roof solar above 50kW isn't "microgeneration" in law, so the installer has to ask the council whether prior approval on glare is needed.
• Construction management. Bigger jobs take longer with more people on site, and can cross the CDM 2015 threshold for notifying HSE.

The way to get a real 100kW figure is a site survey and a quote broken down per kWp. Our guide to choosing commercial solar installers shows how to compare them.

How much roof does a 50kW solar system need?

It depends on the panel. As an illustration, take a mainstream module: REC's Alpha Pure-R datasheet gives a size of 1,730mm by 1,118mm (1.93m² per panel) and ratings of 400W to 430W. At 430W, that's about 4.5m² of panel per kWp.

Illustration only: our arithmetic from one manufacturer's datasheet (REC Alpha Pure-R, 430W). Panel area only; your installer's design will use the actual module quoted.

Your roof needs more than the panel area, because:

• Edges and access: in England, permitted development needs panels at least 1m from the edge of the roof, and installers leave walkways for maintenance and fire access.
• Flat roofs: tilted rows need gaps between them so one row doesn't shade the next. East-west layouts pack tighter.
• Obstructions: roof lights, plant, vents and parapet shading all take space.
• Structure: a roof with the area but not the load capacity can't take the full system. Ballasted flat-roof systems add weight.

How much electricity does a 50kW solar system generate?

DESNZ publishes the output of tens of thousands of real solar installations through its Feed-in Tariff load factor analysis. The median solar PV load factor (actual output as a share of the maximum possible) was 9.2% in 2024/25, the lowest in the series after a dull year, and 9.6% in 2023/24.

A load factor converts to annual output per kW: 9.2% of the 8,760 hours in a year is about 806kWh per kW, and 9.6% is about 841kWh. As an illustration:

Illustration only: our arithmetic (system size x load factor x 8,760 hours), rounded, from the DESNZ median load factors for Feed-in Tariff solar installations. Most of those are small systems; your site's figure depends on location, orientation, tilt, shading and the weather. DESNZ found the South West, East of England and North East had the highest median load factors in 2024/25, at around 9.5%, and London the lowest.

Ask every installer for a site-specific generation estimate in kWh a year, with its assumptions, and an estimate of how much of it the site will use on the spot. That second number drives the savings, because power you use yourself replaces grid electricity at your full unit rate, while exported power earns an SEG rate that is usually lower.

G98 or G99? A 50kW solar system needs G99

Small generators up to 16 amps per phase (about 3.68kW single-phase or 11.04kW three-phase) connect under the ENA's G98 process. Anything bigger, which means every 30kW, 50kW and 100kW system, needs approval from your distribution network operator under G99 before it's switched on.

Export limits. If the local network can't take your full export, the DNO may offer a connection with an export cap. The inverters are then set to hold export at the agreed level, under the ENA's G100 arrangements. That's often fine for a site that uses most of its solar. If you export a lot, a battery can soak up the surplus: see commercial battery storage.

Export meter. Electricity North West says exports above 30kW need their own export MPAN. Your installer should confirm your DNO's rule. The full process is in our G99 application guide.

MCS, the Smart Export Guarantee and the 50kW line

50kW isn't a random number. Several rules change there:

The Smart Export Guarantee covers solar up to 5MW of total installed capacity. To get paid, exports must be metered by a half-hourly meter with an export MPAN. The Smart Export Guarantee pays for solar you export, on systems up to 5MW in Great Britain. Suppliers set their own rates; the law only says the rate must be above zero, so shop around.

Planning in general: Most roof-mounted commercial solar in England is permitted development (the old 1MW cap was removed in December 2023), but bigger non-microgeneration systems need prior approval on glare, and listed buildings always need consent.

30kW, 50kW or 100kW: which size suits your site?

The right size isn't the biggest system the roof can hold. It's the one that matches how the site uses electricity in daylight:

• Start with half-hourly data. Many business sites with a larger supply have half-hourly metering. Twelve months of it shows your daytime base load in summer and winter, and how much a given system would export.
• 30kW suits sites with a steady weekday load: offices, small manufacturing units, shops with refrigeration, school blocks and farm buildings.
• 50kW suits sites with bigger daytime loads or long hours: workshops with compressors, cold stores, care homes, hotels, dairies.
• 100kW and up suits warehouses, factories and multi-building sites, or sites adding fleet EV charging or heat pumps that will raise daytime demand.
• Plan for tomorrow's load. EV chargers, heat pumps and electrified processes all add demand that solar can cover.
• Weekend and holiday gaps. If the site is quiet at weekends or in August, size to the working-day load, or add a battery.

Sector guides: warehouses, factories, farms, offices and small businesses.

Tax, business rates and VAT on a 50kW system

HMRC's manual is explicit: "all capital expenditure on the provision of solar panels is specifically designated as special rate" (CA22335). So the AIA is the big lever. A company spending £150,000 on a rooftop system can usually deduct the whole lot from that year's profits, as long as the AIA hasn't been used up on other kit.

Business rates: In England, plant and machinery used to generate or store power from on-site renewables (solar included, and batteries where the power stored is mainly or exclusively renewable) is excluded from rateable value until 1 April 2035. Wales (from 1 April 2024) and Scotland (from 1 April 2023) have equivalent exemptions running to 2035. Adding panels to your roof shouldn't raise your rates bill.

VAT: Ordinary business premises pay 20% VAT on solar, batteries and heat pumps, which VAT-registered businesses can normally reclaim. The 0% rate is only for homes and buildings used solely for a relevant charitable purpose, and it runs to 31 March 2027.

More detail in solar panel capital allowances and commercial solar grants.

How to get a 30kW, 50kW or 100kW system quoted

What to have ready

• Twelve months of electricity bills, or half-hourly data from your supplier.
• Your supply capacity (kVA) and whether the site is single or three-phase.
• Roof type, rough age and any known structural limits or asbestos.
• Plans that will change your load: EV charging, heat pumps, new machinery.

What every quote should show

• System size in kWp and price per kWp, with panel and inverter models.
• Generation estimate in kWh a year, and how much the site will use itself.
• Who handles G99, and what happens if export is limited.
• MCS certification (up to 50kW), warranties, monitoring and O&M.
• What's excluded: roof repairs, structural works, DNO charges, batteries.

Next steps

1. Tell us about the site using the form. It takes two minutes.
2. One suitable installer contacts you to arrange a survey. Not a ring-round.
3. Survey and quote, sized to your load, with the grid and tax position set out.
4. G99 application, then installation, commissioning and SEG registration.