By the PPA Funding team Last updated
Under a PPA, a generation meter records every kWh your solar system produces. You pay the funder a fixed rate for the solar electricity you use on site, at least 30% below the grid price. Any grid top-up stays on your normal supplier bill, so you receive two separate invoices.
How is the solar electricity you use actually measured?
A dedicated generation meter sits between the solar system and your building's incoming supply. It records the kWh the panels produce, and a second reading captures how much of that output your site consumes rather than exports back to the grid. The funder bills you only for the solar you actually use on site.
Most commercial systems use half-hourly metering, so the data is detailed enough to match your consumption through the day. Your energy manager or accountant can reconcile the meter readings against each invoice line, so the charge is fully transparent.
What does a PPA invoice look like next to a grid bill?
A PPA invoice is simpler than a standard energy bill. It shows the solar kWh you consumed in the period, the fixed rate per kWh, and the total due. There is no volatile wholesale element and no standing charge from the funder for the solar supply itself.
Your usual grid bill continues for the electricity you draw when the panels cannot cover demand, such as overnight or in poor light. Together the two bills normally total less than a grid-only bill, because the solar portion is guaranteed at least 30% below the grid rate.
Who reads the meter, and how often are you invoiced?
The funder or their appointed operator collects the meter data remotely, usually each month, and raises the invoice from those figures. You are not asked to submit readings yourself, though you can view live generation through the system's monitoring portal.
Billing frequency and the exact rate mechanism are set out in your PPA contract, so read those clauses before you sign. Confirm the VAT treatment with your accountant, as that depends on your own circumstances. If you want to see the rate mechanics in full, our guide to PPA contract terms covers the pricing and indexation clauses.
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
Will I still get a bill from my normal electricity supplier?
Yes. The PPA only covers the solar electricity your system generates and you use on site. You keep your existing supplier for grid power drawn at night or when generation is low, so you receive two bills that usually total less than before.
What happens to the solar electricity I generate but do not use?
Surplus generation is exported to the grid. Depending on your agreement, export income may go to the funder, or you may receive a payment through a Smart Export Guarantee tariff. The PPA contract sets out who keeps the export value, so check that clause.
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.