The case for commercial solar is generally stronger than the domestic one, and it rests on a single point: most businesses use electricity when the sun is up.
Here is how to build a case you can defend to a board.
Last reviewed 4 Nov 2026.
Start with your half-hourly data
If your supply is half-hourly metered, and most commercial supplies are, you can get detailed consumption data from your supplier. Ask for at least twelve months.
This is the single most valuable thing you can do before speaking to an installer. It tells you:
- What you use, hour by hour, through the year
- How much of a given system’s generation you would actually use on site
- How much you would export
- Whether a battery would add anything
A quote built against your real profile is worth far more than one built against an annual total. An installer who does not ask for the data is not building you a proper case.
The value of a generated unit
Two different numbers, and the gap between them is the whole case:
- A unit used on site saves you the full price you pay for commercial electricity, including the non-commodity charges that come with it
- A unit exported earns you an export rate, which is materially lower
So the case rests on self-consumption. A business operating five days a week during daylight has a strong case. A business operating at night or at weekends has a weaker one, and should look at the shape of its demand carefully before committing.
Building the case
- Establish your actual consumption profile from half-hourly data
- Establish your real cost per unit, including all the charges on the bill, not just the commodity rate
- Get generation modelled against that profile, showing used and exported separately
- Value used units at your real cost, exported units at the export rate
- Include the connection cost and timescale, which can be significant. See grid connection
- Include the roof. If the covering needs replacing in ten years, that cost belongs in the case
- Take advice on the tax position. Capital allowances and VAT treatment depend on your circumstances and your accountant should tell you, not us
Assumptions that usually turn out to be wrong
- Self-consumption assumed rather than modelled. The most common error and the one that most distorts the answer
- Electricity priced at the commodity rate rather than the full delivered cost
- Roof condition and remaining life ignored
- Connection timescale and cost assumed to be trivial
- Growth or contraction in the business not considered. A system sized for today’s operation may be wrong if you are expanding or moving
- Lease length ignored. If you rent the building, how long do you have, and what does the lease say about alterations and about what happens to the system at the end?
That last one stops more commercial projects than any technical issue. Sort it before you spend money on design.
Where a battery fits
Commercial batteries make sense for different reasons from domestic ones:
- Peak shaving, reducing demand charges where your tariff has them
- Storing generation where your demand and your generation do not line up
- Resilience, where an outage costs you real money
The case depends on the shape of your tariff as much as on your consumption. It needs modelling against the half-hourly data, not a rule of thumb.