What’s the Relation Between The Solar Panel Voltage and Battery Pack Voltage?

There are two different voltage in the solar product,one is for the solar panel and another is for the battery pack. But the voltage for solar panel is always higher than the battery pack voltage. 

I would like to share some experience about the relation between the solar panel voltage and battery pack voltage.

1. The solar panel voltage need to higher than the battery pack voltage because the charging is from solar panel to the battery pack.Just like the watter flow from high to low.

2. The solar panel voltage is about 1.2 to 1.6 times by the battery pack.Too high or too low will also have problem.

High Voltage Condition.

A. Advantage for higher solar panel voltage is it can keep charging when the sun light is not good.Because the solar panel has high voltage itself.This is good for winter or some countries which don’t have good sunlight.

B. The disadvantage for higher solar panel voltage is the charging efficency will be reduced. Because high voltage will lead to low current while the power is fixed(I=W/V).

Low Voltage Condition.

A. Advantage for lower solar panel voltage is to get higher current charging when the sun light is good(I=W/V).

B. Disadvantage for lower solar panel voltage is the solar panel can not charge the battery because the working-voltage of the solar panel may even lower than the battery pack voltage.Just like the water can not flow from low to high.

Base on our experience and test, make the solar panel voltage about 1.2 to 1.6 times by the battery pack voltage is the best match for most countries and weather.