Commercial solar panel costs

What you are actually paying for

The panels are the visible part and often not the largest line. A commercial installation also covers the mounting system that fixes to your roof structure, the inverters, all the cabling and containment back to your distribution board, the electrical works at the board itself, scaffolding or other access equipment, the application to your district network operator, and the commissioning and certification at the end.

There’s usually design work in there too, and there should be. A system laid out from your actual consumption pattern is a different thing from one laid out to fill the available roof.

What moves the price up or down

Roof complexity leads. A single-pitch steel roof with clear access is about as straightforward as it gets. Multiple roof levels, fragile or ageing coverings, restricted access for scaffolding, or anything requiring an asbestos survey will all add labour and time.

Electrical distance matters more than people expect. If the array sits a long way from the intake position, the cabling and containment run grows and so does the cost.

Then there’s the network connection. Larger systems go through a fuller application process with the district network operator, and where the local network needs reinforcement to accept your export, those costs land on the project. It’s one reason two identical buildings in different areas can price differently through no fault of the installer.

Why bigger systems cost less per unit

Several elements of a project cost roughly the same regardless of scale. Someone still has to survey the roof, produce a design, submit the network application, mobilise a team and commission the finished system. Spread those across a small array and they weigh heavily on each unit of capacity. Spread them across a large one and they almost disappear.

The practical implication is that trimming a system down to reduce the headline price often raises what you pay per unit of capacity installed. Whether that’s the right call depends on your consumption, not on the roof.

How the payback actually works

Two streams repay a commercial system. The larger one is electricity you no longer buy, valued at whatever your import costs you, including the network charges and levies that sit on every unit. The smaller one is export income on generation the building doesn’t use.

Because those two are valued differently, the single most important number in any financial case is the share of generation expected to be used on site. A design assuming most of it gets used will show a much shorter payback than one assuming most gets exported, and the difference between those assumptions is worth more than any discount on the panels. Ask what the assumption is and what it’s based on.

There’s a second effect that rarely appears in a proposal. Electricity you generate yourself can’t be repriced at your next renewal. A business covering part of its own demand has reduced its exposure to the market, which has a value that doesn’t show up in a simple payback calculation.

Where batteries fit

Storage adds cost and changes the shape of the case rather than simply improving it. A battery lets generation produced at midday be used in the evening, so it earns its keep on sites with meaningful demand outside daylight hours. Hotels, care homes, leisure centres and anywhere running late shifts are the obvious candidates.

For a business that empties out at five, a battery is often solving a problem the site doesn’t have. Model it separately from the panels so you can see what each part contributes.

What it costs to keep running

Not a great deal, which is one of the quieter attractions. There are no moving parts in a panel. Budget for periodic inspection and occasional cleaning, more often on dusty or agricultural sites, and expect to replace inverters once during the system’s life since they work harder than anything else in the array.

Monitoring comes with the installation and it’s worth actually looking at. Underperformance tends to be gradual, and a system quietly producing less than it should can go unnoticed for a season if nobody checks.

How tax changes the real cost

Solar equipment is plant and machinery for capital allowances purposes, and for most commercial installations the Annual Investment Allowance relieves the full cost in the year of purchase. Because solar falls into the special rate pool it sits outside full expensing, though in practice the Annual Investment Allowance covers typical projects anyway.

VAT applies to commercial installations and VAT-registered businesses recover it as normal, with allowances then claimed on the net cost. The detail, along with the funding routes where somebody else finances the system, is in our grants and funding guide. Capital allowances only have value where there are profits to set them against, so your accountant should confirm the position for your business.

Comparing quotes like for like

Put the quotes side by side and check the same handful of things on each. What capacity is actually being installed, and which panels and inverters. Whether scaffolding and access are included or excluded. Whether the network operator application is the installer’s job. Whether commissioning and certification are in the price. What the workmanship warranty covers, and for how long, as distinct from the manufacturer warranties on the equipment.

Then look at the generation estimate and ask what data produced it. When a cheaper quote turns out to have equivalent scope and a realistic estimate, it’s a better quote. Most of the time something has simply been left out, and it reappears as a variation once the scaffolding is up.