What Goes Into Commercial Solar Installation Costs

Commercial Solar Installation Costs by System Size — 2026

Installation cost per kWp falls as system size increases due to economies of scale in panels, inverters, and installation labour. The table below shows realistic 2026 all-in costs — including everything from panels and mounting to G99 application and monitoring setup.

System Size	Total Cost	Cost/kWp	Annual Generation	Annual Saving*	Payback
10kWp	£8,000–£11,000	£800–£1,100	~8,500 kWh	~£2,550	3–4yr
30kWp	£22,000–£30,000	£730–£1,000	~25,500 kWh	~£7,650	3–4yr
50kWp	£37,000–£50,000	£740–£1,000	~43,000 kWh	~£12,900	3–4yr
100kWp	£72,000–£95,000	£720–£950	~87,000 kWh	~£26,100	3–4yr
150kWp	£104,000–£135,000	£690–£900	~130,000 kWh	~£39,000	3–4yr
200kWp	£134,000–£175,000	£670–£875	~174,000 kWh	~£52,200	3–4yr
350kWp	£224,000–£290,000	£640–£830	~305,000 kWh	~£91,500	3–4yr
500kWp	£310,000–£400,000	£620–£800	~435,000 kWh	~£130,500	3–4yr

* Annual saving calculated at 30p/kWh with 90% self-consumption. Actual figures vary by tariff, location and consumption profile.

What's Included in Commercial Solar Installation Cost

A comprehensive commercial solar installation quote should include the following components. Ensure any quote you receive specifies each item — vague "supply and install" quotes often exclude significant costs that appear as variations later.

Solar Panels (35–45% of total cost)

Panel cost depends on wattage rating, brand, and efficiency tier. In 2026, mainstream commercial solar panels range from 420W to 580W per panel. Tier 1 manufacturers (JA Solar, LONGi, Trina, Canadian Solar) command a small premium over lower-tier alternatives but offer greater confidence in 25-year performance guarantees. Bifacial panels add approximately 8–12% to panel cost but generate 5–15% more electricity from reflected ground light — ROI-positive on most commercial ground mounts.

Inverters (12–18% of total cost)

For systems up to 100kWp, string inverters (Huawei, SolarEdge, Fronius, SMA) are the standard choice, typically costing £4,000–£15,000. For systems 100–500kWp, central inverters or multiple large string inverters reduce cabling costs. Microinverters (Enphase) are rarely cost-effective on commercial systems above 30kWp but are used in shading-affected installations where per-panel optimisation justifies the premium.

Mounting System (8–15% of total cost)

Mounting system cost depends primarily on roof type. Metal roof clamp systems are cheapest (£8–£12/m²); pitched tile systems require additional flashing and fixings (£10–£18/m²); ballasted flat-roof systems require structural assessment and additional material (£12–£20/m²). Ground-mounted structures range from £15–£35/m² depending on terrain and wind zone.

Electrical Installation (15–25% of total cost)

Electrical work includes DC cabling from panels to inverter, AC cabling from inverter to distribution board, generation meter installation, and earthing. For systems requiring G99 grid connection, additional DNO-compliant protection relays and metering add £2,000–£8,000 depending on DNO requirements and system size.

G99 Grid Connection Application (£1,500–£8,000)

Systems over 50kWp require a G99 application to the local Distribution Network Operator. The application fee varies by DNO and system size: typical charges are £800–£2,500 for the application itself, with potential additional costs for feasibility studies (£1,500–£5,000 for complex sites). Timeline: 14–20 weeks from submission to formal approval. We submit G99 applications on your behalf as part of our standard service.

Scaffolding & Access (5–12% of total cost)

Scaffolding is required for virtually all commercial roof installations. Cost depends on building height, perimeter, and access complexity. A standard single-storey factory roof costs £3,000–£8,000 for scaffolding; multi-storey or complex access adds significantly. Some flat-roof installations use MEWP (cherry pickers) rather than scaffolding, which can reduce this cost on accessible sites.

Monitoring System (£500–£3,000)

Modern commercial solar inverters include built-in monitoring accessible via web portal or app. We configure monitoring to display live generation, export, and consumption data. Advanced monitoring with half-hourly export reporting (required by some DNOs for G99 export) and integration with building management systems adds £1,500–£3,000.

What Drives Cost Variation

Roof Type

Metal (standing seam or trapezoidal) roofs are 10–20% cheaper to install than tile or flat felt roofs. Asbestos cement (AC) roofing requires specialist handling, surveys, and often overcladding — adding £8–£18/m² before solar panels can be installed.

Building Height and Access

Every additional storey adds 15–25% to scaffolding costs. Sites requiring road closures for scaffold access may need additional permits and traffic management (£500–£2,000).

Export vs. Zero-Export

DNOs increasingly restrict new commercial connections to zero-export configurations, especially in grid-constrained areas. Zero-export systems require a generation limitation unit (£800–£2,000) which caps system output to match site consumption. Export-enabled systems require smart meters and may face delays of 6–12 months in heavily-constrained areas.

Battery Storage Addition

Adding commercial battery storage (typically 50–200kWh for a 100–300kWp solar system) adds £25,000–£95,000 to project cost but increases self-consumption from 65–75% to 80–92%, significantly improving financial returns. Battery cost has fallen 35% since 2022 and continues to decline.

How Tax Incentives Reduce Your Effective Installation Cost

Incentive	Type	Value	On £150k Project
Annual Investment Allowance (AIA)	Tax relief (CT)	100% of cost, Year 1	£28,500–£37,500 saved
VAT Relief	0% VAT	Saves 20% vs standard	£30,000 saved vs gross
Business Rates Exemption	Rates relief	No rateable value increase	£2,000–£8,000/yr saved
Smart Export Guarantee (SEG)	Revenue	4–20p/kWh exported	£500–£3,000/yr income

Regional Cost Variations

Commercial solar installation costs vary by approximately 8–15% across UK regions, driven by labour rates, supply chain logistics, and local contractor availability. London and South East installations typically cost 10–15% more than the national average; Northern England and Scotland are broadly in line with the national average. The good news: higher solar irradiance in the South (1,050–1,150 kWh/m²/yr vs 900–980 kWh/m²/yr in Scotland) partially offsets the London cost premium.

Financing Options: Purchase vs. Lease vs. PPA

You don't have to fund commercial solar from capital reserves. Three financing routes are available:

• Outright purchase: Best financial return (3–6yr payback), full AIA tax relief, you own the system. Best for businesses with available capital or strong balance sheet.
• Solar lease: Fixed monthly payment, no capital outlay. You own the system after the lease term (typically 5–10 years). Monthly payment is typically 60–80% of your projected energy saving, so cash-flow positive from day one.
• Power Purchase Agreement (PPA): No capital outlay, no ownership — you simply pay a fixed rate per kWh for all solar electricity generated on your roof. Rate is typically 15–22p/kWh vs your current 27–35p/kWh tariff. PPA terms are typically 15–25 years.

Hidden Costs to Watch For

When comparing quotes, watch for these commonly excluded costs that can add 15–25% to the headline price:

• G99 application fee (sometimes quoted as "additional to system cost")
• DNO protection relay and metering upgrades
• Structural engineer survey (required on flat roofs and for >25-year-old buildings)
• Asbestos survey (required if original construction pre-dates 1999)
• Electrical distribution board upgrade (if existing DB has insufficient capacity)
• Scaffolding and traffic management
• Building insurance notification (required by most insurers for commercial properties)

Our fixed-price quotes include all of the above where applicable. We identify potential hidden costs during our free feasibility survey and include them in the project cost before you commit.