40kW Commercial Solar Panel System UK

The right fit

Why a 40kW system could be the right fit

A 40kW commercial solar system is the entry point of our commercial range. It uses 75 to 90 panels across 180 to 230 square metres of roof and is sized for businesses with annual electricity demand of 30,000 to 45,000 kWh, typically small commercial units, single-tenant offices, light industrial workshops and small hospitality sites. Generation peaks 10am to 4pm, matching daytime operating hours, which means high self-consumption and a faster payback than an equivalent residential system.

The system is eligible for the Annual Investment Allowance, business rates exemption to April 2035 and 20% reclaimable VAT. 75 to 90 panels fit most 200 square metre commercial roofs, including corrugated metal, concrete and slate-tile buildings, and all paperwork and grid approvals are handled end to end by Solar4Good on your behalf.

The datasheet

40kW spec sheet

Indicative figures for a 40kW commercial system on a typical UK site. Your exact output depends on your roof, orientation, shading and usage, confirmed in a site visit.

System size40 kW DC

Solar panels75-90

Roof space180-230 m²

Site demand30,000-45,000 kWh

Annual output34,000 kWh

Self-consumption80-95%

VAT20% reclaimable

Capital allowanceAIA-eligible

Business ratesExempt to 2035

Panel warranty25 yrs

Indicative, not a quote · final figures after a free roof assessment.

What is included

75-90 tier-one panels

High-efficiency panels, sized to deliver 40 kW DC across your commercial roof.

Commercial inverter (three-phase)

A quality inverter, three-phase ready, with capacity for battery and peak-shaving.

Mounting, wiring & connection

All roof mounting, cabling and grid connection, done neatly and safely.

Commercial monitoring dashboard

Live generation and consumption data for your facilities team, set up before we leave.

Full MCS install + AIA guidance

Fitted under our own MCS registration, with AIA capital-allowance guidance for your accountant.

25-year panel warranty

Plus a team you can still call after switch-on. Every job certified under our own MCS registration.

Storage

40kW: self-consumption and battery

Panels only

Good if you use power in the day

The panels power the site during working hours and export the surplus for a payment under SEG. Ideal if your demand is daytime: production, refrigeration, machinery or EV charging while the sun is up.

Panels + battery

The most common upgrade

Battery storage shifts daytime solar into evening, out-of-hours and peak-rate periods, lifting self-consumption further and cutting demand charges. Sized to your load profile during the design stage.

The right size?

Is 40kW enough for your site?

For businesses using 30,000 to 45,000 kWh a year, a 40kW system covers a large share of daytime demand at high self-consumption, and the business-rate and capital-allowance reliefs make the case strong for small commercial sites.

If your demand is higher, a 50kW, 70kW or larger system will suit better; we size precisely from 12 months of your meter data rather than a template. If you also run an EV fleet or want to shift load into the evening, we design in battery storage and commercial EV charging at the site-visit stage.

How it works

Go commercial solar in three steps

STEP 01

Site visit + structural assessment

A local engineer visits, assesses your roof for pitch, orientation and shading, and designs a 40kW system around your actual demand profile. No cost, no obligation.

STEP 02

Fixed-price commercial proposal

A clear, itemised commercial proposal with AIA modelling guidance for your accountant. We handle all paperwork and grid approvals as standard.

STEP 03

Installation & commissioning

Our in-house team completes installation in one to three weeks on site. Tested, MCS-certified and the commercial monitoring dashboard set up before we leave.

Why Solar4Good

Engineer-led, in-house, UK-wide

You work with a UK-wide commercial team based in Harrow, not a remote sales centre. The person who assesses your roof is directly involved in designing the system, and once it is in we handle MCS certification, SEG export-tariff setup and your monitoring app, so you are never left navigating the process alone.

3,000+UK installs

50,000+Panels installed

4.9★from 1,000+ reviews

MCSCertified, in-house

Rated 4.9/5 from 1,000+ verified reviews on Trustpilot, TrustATrader and Google

“George the sales chap was straightforward and honest, and the whole installation team were awesome, courteous and professional throughout.”

Jamie Wilson · Verified Trustpilot review

“From start to finish the whole job has been seamless. The install guys were polite, knowledgeable and efficient.”

Timothy Clarke · Verified Trustpilot review

“I wholeheartedly recommend this company for solar and battery storage installation.”

Soham Acharya · Verified Trustpilot review

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Good to know

The questions businesses actually ask about a 40kW commercial solar system.

Is a 40kW system right for a small commercial site?

A 40kW system is the entry point of our commercial range, sized for annual demand of 30,000 to 45,000 kWh, typically small commercial units, single-tenant offices and light industrial workshops. Generation peaks 10am to 4pm, matching business hours for high self-consumption.

How many panels are needed for 40kW?

75 to 90 panels across roughly 180 to 230 square metres of roof, sized to deliver 40 kW DC. It fits most 200 square metre commercial roofs, including corrugated metal, concrete and slate-tile buildings.

What is the business case for commercial solar?

Commercial solar is eligible for the Annual Investment Allowance, business rates exemption to April 2035, and 20% reclaimable VAT. With high daytime self-consumption, payback is typically faster than an equivalent residential system.

Do you carry out a structural assessment?

Yes. Every commercial project starts with a site visit and structural assessment. A qualified engineer reviews roof type and load capacity and, where available, 12 months of half-hourly meter data to design around your actual demand.

How long does installation take?

Our in-house team typically completes a 40kW installation in 1 to 3 weeks on site. The system is tested, MCS-certified and the commercial monitoring dashboard is set up before we leave.

Who installs it, and do you handle the paperwork?

Most installations are carried out under our own MCS registration. Further afield we use installers working under our MCS registration, and the certificate and workmanship warranty remain ours. We handle all paperwork, grid approvals, MCS certification and AIA modelling guidance for your accountant.