This component of the photovoltaic system is used to store the solar electricity. Without the storage, the solar power produced must be consumed directly or fed into the public grid – otherwise it is lost. Direct use is often not or only partially possible because PV produces most of the electricity during the day. However, experience shows that demand typically increases towards evening times. The feed-in tariff for solar electricity is much lower than the purchase price, however. Economically speaking, it doesn’t make sense to feed electricity into the grid during the day and draw it from the grid in the evening. A storage solution therefore considerably increases the economic efficiency of the photovoltaic system.
The following classifications are available for storage devices:
Most storage systems can be easily integrated into existing PV systems. It may be necessary to replace the inverter. It should be kept in mind, however, that most storage systems are relatively large.
To determine the appropriate storage capacity, daily power consumption has to be calculated. You can calculate the annual power consumption as an average of the last five years.
For example, if it amounts to 6,000 kWh, continue to calculate:
6,000 kWh / 365 days = 16.44 kWh/day.
If we assume that about 2/3 of this consumption should come from the storage, the result is:
16.44 kWh * 0.66 = 10.8 kWh
In this case, a storage with the capacity of 10 kWh should be sufficient.