General buying guidance only. It is not an engineering design, compliance determination or product specification.
Put the system boundary on one page
Compare the battery, PCS, controls, switchgear, software, cabling and site works that are included—not just a headline capacity or equipment price.
Separate confirmed facts from assumptions
Each proposal should say which load, tariff, operating schedule, grid condition and site layout it uses. If the inputs differ, the results are not directly comparable.
Read exclusions and responsibilities first
Installation, permits, commissioning, freight, taxes, spare parts and local service can sit outside the equipment price. Identify who owns each task and when the warranty starts.
Ask for a revision path
When the site data changes, know which parts of the design and price will be reviewed again. Keep versions and dates with the project record.