Nameplate capacity

Written and checked by the Energy Merchants desk · Reviewed 3 October 2026

Nameplate capacity is the rating printed on the equipment’s label. For a solar panel it is the watts the panel produces under standard test conditions. For an inverter it is the maximum kilowatts of AC output. For a battery it is the headline kilowatt-hours, which is what the industry also calls nominal capacity. See nominal capacity.

It is a rating, not a promise about output. Real conditions differ from the lab. Heat, shade, dust and angle all pull a panel below its rating, so a 6.6 kW array rarely produces 6.6 kW.

Three different nameplates on one job

In practice

Nameplate figures decide several things on a solar job. The array’s rating in kW is the input for the STC calculation. An array rated 6.6 kW in a zone 3 postcode with a 2026 five-year deeming period gives 6.6 x 1.382 x 5 = 45.6, so 45 STCs. It also decides which category the system falls in: up to 100 kW it is a small generation unit. Above that, up to 1 MW from 1 October 2026, it is mid-scale solar. See mid-scale solar STCs.

The inverter’s nameplate is normally smaller than the array’s, which is allowed, and the network may limit export separately. The array’s kW and the inverter’s kW both matter and should both be on the paperwork.

For batteries, the nameplate is the wrong number for the claim. The program counts usable capacity from the approved listing. See usable capacity.

Common confusion

Nameplate is not measured output, and it is not usable capacity. It is also not the figure on a quote that includes the kWh of a battery with reserve removed. When two numbers disagree, find out which one the scheme uses.

See STC photo requirements, the STC calculator and the glossary.