A credible UK battery quote separates usable capacity, inverter output, installation scope and VAT treatment, then models savings from your own import and export rates—not a generic household.
The six numbers the quote must expose
Start with final installed price, usable kWh, continuous inverter output, warranted energy throughput, expected annual cycles and the export rate used in the savings forecast.
- Usable rather than nominal capacity
- Final installed price after 0% VAT treatment
- Import and Smart Export Guarantee rates
- Backup circuits and changeover equipment
- DNO application and metering work
- Product and workmanship warranties
Challenge the installer’s payback
A stored solar unit is not free: it gives up the export payment you would otherwise receive. Savings therefore come from avoided imports minus sacrificed exports, after round-trip losses.
If a quote assumes daily full cycles, ask to see the household interval data supporting that assumption. A large battery that is not filled and emptied regularly cannot earn the forecast return.
What 0% VAT does—and does not—mean
Qualifying electrical storage batteries are zero-rated until 31 March 2027. That tax treatment lowers the customer price but does not prove the underlying hardware or installation price is competitive.