Commercial Solar for Hampshire Organisations

Every commercial roof I survey asks a different engineering question. The sector matters less for the sales pitch and more for the design: roof construction, weight margins, load profile and supply type all change what I specify. Here is what your building type typically means in practice.

Warehouses & industrial units

Steel portal-frame buildings with trapezoidal metal sheeting are the easiest large roofs to work with — short-rail fixings clamp straight to the crowns, keeping added weight low. Daytime loads from refrigeration, compressors and conveyors soak up generation as it happens, which is where the payback lives. Distribution units around Southampton and the M27 corridor are the classic case: 100 kWp+ of unshaded south-facing steel doing nothing.

Offices

An office's 8am–6pm, five-day load profile is the best natural match to solar output of any building type. The catch is usually the roof: flat membrane roofs need a ballasted, wind-sheltered layout and an honest assessment of the deck's remaining life before anything goes on it — re-roofing under an array is expensive. Business-park offices around Basingstoke are a good fit when the roof checks out.

Retail & hospitality

Seven-day trading means higher self-consumption than almost any other sector — there is rarely a quiet Sunday when generation goes to waste. Retail premises are also the most likely to be leasehold, so landlord consent comes first (see the FAQ below). I cover high-street and retail-park units across Portsmouth and Christchurch.

Farms & rural businesses

Barn roofs offer serious area, but purlin condition and fixing type vary more than any other building I survey, and rural sites are the most likely to be on a single-phase or constrained supply — which can cap system size or need a DNO conversation before design starts. Test Valley and the Andover area are where I see this most.

Schools, halls and places of worship

These bring their own funding routes, governance and (for churches) faculty consent, so they have their own pages: schools & colleges, community centres and churches & places of worship.

A commercial job is not a big domestic job. Wherever you are across Hampshire, five things change, and they are worth understanding before you get quotes.

Three-phase supply. Most commercial premises have a three-phase supply, which means three-phase inverters, balanced loading across phases, and a meaningfully higher ceiling on system size than any house.

Grid permission comes first, not last. Anything above 3.68 kW per phase (about 11 kW total on three-phase — i.e. virtually every commercial system) needs G99 approval from the DNO before installation, not a notification afterwards. Most of our 30-mile radius sits in SSEN's Southern licence area, and I handle the application, single-line diagrams and protection settings myself. DNOs must acknowledge within about 5 working days and issue a connection offer within up to 65 working days on a standard application — in practice I tell clients to allow two to three months in the project plan and to never order kit before the offer lands.

Export limits are common — and manageable. On constrained parts of the network the DNO may cap how much you can export. A G100 export-limitation scheme usually solves it, and a battery turns the capped surplus into evening consumption instead of a lost asset — see our guide to commercial battery storage costs.

Structural sign-off. A pitched metal-roof array adds roughly 12–16 kg/m²; a ballasted flat-roof system adds several times that. I check purlin spacing, sheet gauge and deck condition on every survey, and where the margins are tight a structural engineer signs the roof off before I fix anything to it. No exceptions.

Half-hourly data makes the design honest. Larger sites are settled half-hourly, and Britain's move to market-wide half-hourly settlement is extending that to smaller meters. If you can get half-hourly import data from your supplier before the survey, I design against your actual consumption profile rather than an estimate — it is the single most useful document you can hand me.

As a sizing reference, here is what commercial systems typically look like on the south coast, based on the 950–1,050 kWh per kWp yield well-oriented roofs achieve here:

These are honest planning figures as of mid-2026, not quotes — shading, roof condition, access and the DNO position move every one of them, which is why I survey personally before putting a number in writing. Most rooftop schemes on non-domestic buildings in England fall under permitted development, though listed buildings and conservation areas need checking. Once running, a commercial system should be inspected annually — details on our maintenance page.

Commercial solar is taxed differently from domestic, and the differences mostly work in your favour — provided you claim the right relief. Two things catch people out. First, VAT: the 0% rate that applies to domestic solar until 31 March 2027 does not apply to businesses — commercial installs are standard-rated at 20%, but a VAT-registered business recovers that in full, so the ex-VAT figures above are your real cost. Second, capital allowances: solar PV sits in the special-rate pool, so it does not qualify for full expensing (and the old super-deduction ended in 2023) — the routes that actually apply are these:

Worked through: a £50,000 system claimed under AIA takes the full £50,000 off taxable profits in year one — worth £12,500 to a company paying corporation tax at the 25% main rate. Combined with the electricity it stops you buying, that is how commercial payback lands in the 4–6 year range. I am an installer, not a tax adviser — have your accountant confirm the treatment for your circumstances before you commit.

Buying vs a PPA. Outright purchase keeps every kWh and every allowance, and suits any organisation with capital or asset finance available — it is what most of my clients do. A power purchase agreement (a third party funds and owns the roof array, you buy the power at an agreed rate) trades most of the upside for zero capital outlay, and generally only stacks up on larger roofs with long lease certainty. If your site is around the port and industrial estates, the Southampton commercial page covers local specifics, and pairing the array with storage — see commercial battery storage in Southampton — is often what pushes self-consumption above 80%.

How much disruption will a commercial solar installation cause?

We lease our premises — can we still install solar?

Do you offer maintenance contracts for commercial systems?