In a written solar-plus-storage backup proposal, what do energy capacity and power capacity describe, and which units does DOE give as typical?
Energy and power
The U.S. Department of Energy (DOE) defines energy capacity as total energy stored (usually kilowatt-hours, kWh, or megawatt-hours, MWh); power capacity is the amount released at a given time (usually kilowatts, kW, or megawatts, MW).
DOE says solar-plus-storage can provide backup during electrical disruptions and benefit residential and commercial solar customers. This establishes no model-specific loads, runtime, outage performance or home fit.
How can a homeowner identify which exact battery/inverter model and current product document each quoted rating belongs to?
Compare the actual proposals
For each quote, copy its date/revision, exact battery/inverter/system model, quoted rating and unit, and cited product document/version. Record only stated backup loads/circuits, configuration, assumptions, limits and exclusions; mark missing or conflicting details unknown.
Keep energy capacity (kWh or MWh) separate from power capacity (kW or MW). A rating alone does not establish which loads a system would serve, runtime or home-specific backup performance.
Ask the proposal writer to identify the current product document behind each rating and state included backup loads, configuration and assumptions. Ask the qualified project professional to clarify unresolved design questions in writing.
U.S. Department of Energy: storage basics