How long a fully charged solar battery can be used is analysed on a case-by-case basis. For example, the type of battery, the capacity of the battery, the depth of discharge of the battery, the conversion efficiency of the inverter, the amount of power of the load, the environmental conditions of the battery, etc., will affect how long the solar battery can be used, specifically analysed as follows:

1. Battery capacity

Battery capacity refers to the battery can store the amount of electricity, is the main factor that affects how long the solar battery can be used, family use of battery capacity is usually 10 kWh and above, this article to the battery capacity of 10 kWh as an example to illustrate how long the battery can be used with a full charge.

2. The type of battery

Each solar battery has different characteristics, such as lead-acid batteries have a short life, lithium iron phosphate batteries have a long service life, safety and so on, which will affect the battery’s use of time.

3. The depth of discharge of the battery

It refers to how much power the battery can discharge, for example, the depth of discharge of lithium iron phosphate battery is 100%, the depth of discharge of lead-acid batteries is about 50%, the depth of discharge of deep cycle batteries is about 70%, the depth of discharge of lithium-ion batteries is about 80%, the depth of discharge of each type of batteries will be different from the different amount of power provided.

4. The conversion efficiency of the inverter

Because we use AC power in the home, the battery provides DC power, through the inverter will need to convert the battery DC into AC power, which requires an inverter, the inverter in the process of conversion will also have losses, the general conversion efficiency of the inverter is about 90%, which also affects how long the solar battery can be used.

5. The power consumption of the load

Different loads have different power consumption, we need to add the power consumption of the loads together when calculating how long the solar battery can be used, then we can calculate how long the solar battery can be used.

5.1 For example: there is a 10 kWh lithium iron phosphate solar battery, the depth of discharge of the battery is 80%, the conversion efficiency of the inverter is 95%, the daily consumption of the refrigerator is 1.5 kWh, the daily consumption of air conditioners is 2 kWh, the daily consumption of electric water heaters is 2.5 kWh, the daily consumption of lights is 1 kWh, the daily consumption of microwave ovens is 0.5 kWh. How long will a fully charged solar battery last?

The power consumption of the battery is: 10 x 80% (depth of discharge) x 95% (conversion efficiency of the inverter) = 7.6 kWh

The power used by the load: 1.5+2+2.5+1+0.5=7.5 kWh

So a fully charged solar battery will last about a day.