Usable energy capacity

Usable energy capacity is the part of a battery's total stored energy that the system can actually draw on. The rest is held back as a reserve. Training material equates usable energy with depth of discharge. A backup reserve and a minimum state of energy set how much charge stays unused in daily cycling. For the SolarEdge Home Battery, the material shows 90% as usable and an example backup reserve of 20%. SolarEdge says the battery offers full depth of discharge, without the 5% manufacturer reserve that other batteries keep. In an SMA planning example, a battery with 10000 Wh total capacity has 50% used by the Sunny Island for storing PV energy, which gives 5000 Wh of usable capacity. A new battery's usable capacity matches its nominal capacity for a ten-hour discharge (C10). It falls as the battery ages, and state of health is reported as the ratio of currently usable capacity to nominal capacity. Usable capacity also depends on temperature: it drops noticeably at 20°C and below, and SMA battery management reduces it by 1% per °C starting at 20°C. Usable energy matters for system design because more of it raises self-consumption. In the SMA example, the self-consumption quota rises from 30% to typically 65%.

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• sentence 2: support check: partial - Usable energy is labeled depth of discharge, and backup reserve and minimum state of energy appear in the diagram, but the claim that they set unused charge is only implied.
• sentence 3: support check: partial - The 90% usable, 20% backup reserve and full-depth-of-discharge/5% reserve note are present, but 'example' is not stated and the 20% is labeled 'actual'. -->