You want to use more of your generated solar power yourself: This is only possible with an PV power storage system. But how big does this system need to be? What usable storage capacity should the battery have? Is it 5.7 kWh, 9.6 kWh or even more? Several factors need to be considered when calculating the size of the electricity storage unit for your photovoltaic system.

7 Factors you should consider when calculating
the size of your electricity storage system:

1. Your annual electricity consumption

The first factor to consider when sizing your PV power storage system is your current annual electricity consumption. It is best to check your electricity bill for your consumption over the last five years and calculate a yearly average. If you are moving into a new house, you can use a benchmark. For example, the average consumption of a family of 4 is around 4,000 kWh/year.

2. Your projected future electricity consumption

A power storage system is always an investment in the future. Therefore, you should think carefully about which electricity consumers you will add in the future. Keywords: e-scooters or heating via a heat pump.

3. Size of the PV-system

What is the ratio of generated electricity to self-consumed electricity? Do you generate a lot of electricity with low consumption? Do you feed large amounts of not required electricity into the public grid during the day? A larger storage battery can reduce this. You increase your self-consumption.

4. The desired degree of self-sufficiency

The more independent you want to be from energy suppliers, the more self-generated electricity you should use. It is only possible with a PV power storage system. The degree of self-sufficiency shows you the percentage of your annual electricity consumption you can cover with your self-generated solar power.

5. Self-consumption share

The degree of self-sufficiency and self-consumption are interrelated. The self-consumption share indicates how much of the generated solar electricity you consume directly in your household. The electricity stored temporarily in the solar storage unit is also taken into account. The higher the self-consumption, the less solar electricity is fed into the public grid.

6. Consumption times

Another factor often not considered when calculating the electricity storage capacity is your consumption times. If you consume electricity mostly in the evening or at night, then you need a larger electricity storage unit as your PV system does not produce any electricity at this time. Whereas you use most of your electricity during the day, the electricity storage unit can be sized smaller.

7. PV system orientation

Consumption times and PV module orientation are also correlated. If your PV system faces south, you will generate the most electricity at midday. If your system is oriented east/west, you will generate the most electricity in the morning or afternoon. If you usually consume electricity in the evening and your modules face south, a larger PV power storage unit is recommended to store the generated energy for self-consumption.

Calculating usable storage capacity

The optimal size of the PV power storage unit is based on the following considerations: How much self-generated solar power do you want to use and when? Our specialist partners will be happy to advise you in detail.