Choose a battery of the right size.

A solar panel is a device that converts sunlight into direct current. So you have two choices.

1-you can use the power supply immediately with the help of a charging controller and an inverter.

2-you can store energy for later use

The battery is one of the most important but expensive components in offline life.

Therefore, choosing the right solar panel size allows you to store the maximum energy generated by solar panels.

We already know the output power of 400W solar panels, but we will use 3000 watt-hours (this will give you some space to store the extra power in case you didn't use all the power generated by solar panels the day before).

Now calculate the Wh in Ah (because the battery capacity is measured in ampere-hours)

3000Wh / 12V system = 250Ah

3000Wh / 24V system = 125Ah

If you choose a 12v 400W solar system, you need a 5100ah lead acid battery, AGM or gel battery, or 3100ah lithium battery. For a 24v 400W solar system, you need a 150Ah lithium battery or a 250Ah lead acid battery.

With this size battery library and your 400W solar panels, you can store 100% of the electricity generated by solar panels, and you can use your appliances (such as refrigerators, microwaves, lights, televisions, and other heavy appliances) later.

In addition, one more thing you need to remember is the c level of the battery, which is simply the recommended charge and discharge rate, and each battery type has a different c level.

A charging controller or regulator is a device that adjusts the current and voltage from a solar panel to charge the battery pack.

For example, a 12v solar panel will generate a voltage of 18-20V in direct sunlight, but you are using a 12v battery, so the controller here will reduce the voltage to 12v.

This is an interesting part, if you use the PWM charging controller, it will lower the voltage, but will not increase the ampere, resulting in a huge power loss (watts = amperes * volts).

On the other hand, the MPPT charging controller reduces the voltage but increases the ampere, which makes them 30 percent more efficient than the PWM charging controller