By the PPA Funding team Last updated
The cost of a commercial solar system depends mainly on its size, your roof and how much electrical work is involved. Buying outright means a capital cost per kilowatt installed; under a PPA there is no upfront cost at all — you simply pay for the power the system generates at a rate below the grid.
What drives the price
The biggest factor is system size (kWp), followed by roof type and condition, access, and any electrical or grid-connection works. Larger systems generally cost less per kilowatt because fixed costs are spread across more capacity.
Buying versus a PPA
If you buy outright, you pay a capital sum and own the system. Under a PPA there is no capital cost — the provider funds, installs and maintains everything, and you pay only for the energy used. That removes the price barrier entirely and shifts the cost to a predictable per-unit rate.
Getting an accurate figure
Because every roof and load profile is different, the only reliable cost is a tailored one. A free assessment gives you real numbers for your site — whether you want a purchase price or a PPA rate.
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
Is there really no upfront cost with a PPA?
Correct. Under a PPA the provider covers the full cost of design, funding, installation and maintenance. You pay only for the clean power you use, at a fixed rate below the grid.
Is buying cheaper over the long run?
Owning the system can give the strongest long-term return because you keep all the savings, but it needs capital upfront and you take on the asset. A PPA trades some long-term value for zero cost and zero risk. We compare both for you.
Sources & further reading
Related guides
- Capital allowances on commercial solar: full expensing & AIA explained
- How solar improves your commercial EPC (and helps with MEES)
- How much can your business save with commercial solar?
See our funding options, commercial solar and solar by industry pages.