By the PPA Funding team Last updated
A commercial solar system is sized around how much electricity you use and when, not just your available roof. The aim is to maximise self-consumption — using as much of the generation on site as possible — because that is where the savings come from. Bigger isn’t automatically better.
Sized to your demand, not just your roof
The best system matches your usage pattern so most of the generation is consumed on site. An oversized array that exports a lot of cheap surplus earns far less than one tuned to your actual daytime demand.
Roof and site set the ceiling
Available area, orientation, shading and roof condition cap how much you can install. A good design balances those constraints against your load to find the sweet spot.
Battery storage changes the maths
Adding a battery lets you use more of a larger system by storing daytime surplus for the evening — so storage can justify a bigger array than solar alone.
This guide is general information, not financial or tax advice. Your circumstances determine what applies — please confirm with your accountant or advisor. Get a tailored proposal →
Frequently asked questions
Should we fill the whole roof with panels?
Not necessarily. The most cost-effective system is sized to your demand so you use most of the generation. If you add battery storage, a larger array can make sense. We model this for your site.
How do you work out the right size?
From your consumption data, tariff, roof and goals. That lets us design a system that maximises self-consumption and return, which we set out in a free proposal.
Related guides
- Solar for leasehold and tenanted commercial property
- Protecting your business from rising energy costs
- Grants and funding for commercial solar in the UK
See our funding options, commercial solar and solar by industry pages.