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Home > How to calculate the capacity of the batteries in each solar home power system?

How to calculate the capacity of the batteries in each solar home power system?

Before selecting the power inverter, we have to calculate the load and the backup time. To select the battery the following formula can be used.

First calculate the total watts of the load. For example, Fan (80 Watts), Tube light (40 Watts) TV (150 Watts) etc. Then fix the backup time required. After getting both these, use the formula

Total load in watts / Voltage of the battery x Backup hours required.

For example if the load is 400 watts and we require 3 hours backup time ,so the capacity of the battery should be 400 watts / 12 volt x 3 hours =100 Ah.

But a 100 Ah battery will not usually give a calculated backup time, since there will be some power loss due to heating as well as in the supply lines. So the backup time may be 2-2.5 hours depending on the condition of the battery. So it is better to use next ranges such as 150 Ah or reduce the load.

Before selecting the power inverter, we have to calculate the load and the backup time. To select the battery the following formula can be used.

First calculate the total watts of the load. For example, Fan (80 Watts), Tube light (40 Watts) TV (150 Watts) etc. Then fix the backup time required. After getting both these, use the formula

Total load in watts / Voltage of the battery x Backup hours required.

For example if the load is 400 watts and we require 3 hours backup time ,so the capacity of the battery should be 400 watts / 12 volt x 3 hours =100 Ah.

But a 100 Ah battery will not usually give a calculated backup time, since there will be some power loss due to heating as well as in the supply lines. So the backup time may be 2-2.5 hours depending on the condition of the battery. So it is better to use next ranges such as 150 Ah or reduce the load.

Proper maintenance of the battery is necessary to increase its life. Always keep the battery and the Inverter in a dust free ventilated area. The terminals of the Inverter should be firmly connected to the battery. Loose connection may reduce current flow and may also cause sparking. The Tubular battery usually has water level indicators. Check the water level periodically. If required, top up with mineral free battery water. Do not add tap water. Tubular battery requires water top up only once in 6 months. If the water level is going down frequently, it indicates evaporation of water due to heating. It indicates the damaged condition of the battery.