An energy storage device is essentially a device for storing electrical energy. It can come from surplus RE plants, for example, or be taken from the power grid. Thanks to this device, we can not only store energy but, above all, manage resources efficiently to ensure the continuity of electricity supply in the household and reduce electricity purchase costs.
If a consumer has a PV system that is not connected to an energy storage system, the excess production of electricity is fed directly into the grid. The energy suppliers charge a commission for this service, which reduces the amount of energy returned by 20% or 30% (depending on the capacity of the PV system). This is due to the fact that in this case the power grid acts as an energy storage (this phenomenon is called net metering). As a result, the household can only receive 80% or 70% (depending on the capacity of the PV system) of the electricity originally generated for free.
The owners of energy storage systems cumulate the surplus production directly in their systems and reduce the amount of energy fed into the grid. They avoid “storage costs” for the power supplier, as they can use up to 100% of the electricity generated from renewable energy sources.
With this solution, the stored energy can be used, for example, at night when the installed photovoltaic system is not producing electricity. It is also an extremely valuable solution when the power grid fails. When using an inverter with backup function and energy storage, all household appliances can be continuously operated with the stored energy.
