Battery quote checklist
Twelve things to confirm before you sign — and the three numbers to compare every quote against. Data as of 2026-10-18.
The checklist
| ✓ | Item | Why it moves the number |
|---|---|---|
| ☐ | Usable vs nameplate capacity | Quotes that nameplate the larger figure inflate every downstream calculation by 5–10%. |
| ☐ | Cost per usable kWh | Divide installed cost by usable capacity. Two quotes are only comparable after this normalisation. |
| ☐ | What is included | Panel upgrade, permitting, interconnection application, trenching, bird screen — exclusions are where quotes diverge. |
| ☐ | Warranty term and retention | 10 years at 70% retention is not the same product as 10 years at 100%. |
| ☐ | Round-trip efficiency | AC-to-AC, not DC-to-DC. A tenth of your stored energy is heat. |
| ☐ | Continuous and peak power | Decides which circuits actually run during an outage — a backup question, not a savings question. |
| ☐ | Your export mechanism | Below-retail credit, full retail, or supply-only compensation. Ask your utility, not only the installer. |
| ☐ | Interconnection status and queue | Some utilities are months behind; a signed quote can sit unbuilt. |
| ☐ | Incentive eligibility and deadline | Programs open and close mid-cycle. Get the program name in writing, then verify on the program's own page. |
| ☐ | VPP enrolment terms | Payment per kW-year, dispatch obligations, contract length, exit terms. |
| ☐ | Installer licensing and history | State licence number, years in business, references in your utility's territory. |
| ☐ | Quote validity period | Equipment prices move; a 90-day quote is a different commitment from a 30-day one. |
Email template
Send this to each installer so the replies are comparable:
Subject: Quote clarification — [address]
Thank you for the quote. To compare it fairly with others, please confirm: (1) usable capacity in kWh and continuous power in kW; (2) installed cost broken into hardware, labour, permitting and any panel upgrade; (3) what is explicitly excluded; (4) warranty term and retention percentage; (5) round-trip efficiency, AC-to-AC; (6) which incentive programs you have assumed, with their current status and deadlines; (7) expected interconnection timeline with our utility; (8) how long this quote is valid. Please also state the cost per usable kWh.
Then run the numbers
Enter each quote into the calculator with identical assumptions — same bill, same capacity, same cycles. Compare the payback period, ten-year net and break-even price. If a quote sits above break-even, ask what makes it different: more capacity, an included panel upgrade, a longer warranty — and decide whether that difference is worth the premium.
This page is educational. It is not financial, tax, or installation advice. Data as of 2026-10-18.