Back-up function of the inverter

The GoodWe inverters are only design to be connected to the grid and are not suitable for pure off grid operations. However, the storage inverters are equipped with a back-up function that allows the inverter to keep supplying power to a small number of appliances during a shorter period. This can for example be useful in places with unstable grid than suffers from frequent power outages.

In case the inverter loses connection to the grid (for example during a power outage) the inverter will shut down for a very short time (only 0,01seconds!) and restart in backup mode that keep powering the backup loads as long as the installed PV and battery can manage to generate enough energy to cover the loads.

The picture below shows the flow diagram of the power when connected to the grid as well as when the connection is lost (green square).

As seen in the picture, the backup loads are connected separately to the inverter and are the supplied with power both when connected to the grid as well as without.

The maximum load that can be connected as backup loads are limited and depends on the inverter model. The total load connected as backup loads can not exceed the rated capacity of the inverter and is also limited to be distributed equally over each phase. Therefore, it is necessary during installation to choose what appliances that should be connected as backup loads. Often, appliances that uses little power are chosen (e.g., router/modem, lights, television, computers, and fridge/freezer). More power demanding appliances (e.g., washing machine, stove, oven, and electrical heating) will often exceed the maximum capacity that can be connected as backup loads and are therefore not recommended to connect as backup loads. 

The number of appliances connected as backup loads will also limit the time they can be sustained during a disconnection from the grid. For example: If there is a power outage during night-time, the PV won’t supply any power and all power will be extracted from the battery. If more loads are connected and used, the battery will of course be drained much faster and thereby reducing the time the backup loads can be powered.