Preventing Derating Losses (example)

Example of preventing derating losses through targeted battery charging when the export limitation is exceeded (Sunny Portal powered by ennexOS, Monitoring > Energy balance).

The energy balance illustrated shows that PV generation is sometimes higher than the sum of self-consumption and permissible feed-in power. To prevent derating losses, the battery system is only charged when the maximum permitted feed-in power would be exceeded. On days with predicted energy surpluses, the Energy Maximizer deliberately plans for free battery capacity in order to store otherwise curtailed energy. This is represented in the figure by the premature termination of the battery charging process shortly before 9:00 a.m.

In this case, the battery system acts as a buffer: As soon as the generated PV power is higher than the permissible kW power fed into the utility grid, the excess energy is automatically used to charge the battery. This prevents PV power from being curtailed and remaining unused due to export limitations.

If the feed-in limit is not reached, the battery is not charged with excess power because utility grid feed-in is prioritized. Only once the export limitation is reached will battery charging begin. This operating strategy ensures that the available PV energy is used efficiently and derating losses are effectively avoided.