The solar panel role in the solar photovoltaic system, is just to convert sun-light to DC electricity, it cannot store energy, so we use batteries to store electrical energy at the time of excess solar light to be used at the times of no solar light.
Mainly in most of places, there are 2 types of solar photovoltaic systems to be used. The first is the grid tie solar system, in which extra generated electricity will be sent back to the electrical grid, and then the solar system owner takes credits from the electric grid to be used in his future bill, and saving his money. The second is the off grid solar system, in which you totally depend on your solar system to power your home, as the power grid is no longer works as a backup.
It is clear that off grid solar system is a way of reducing greenhouse gas emissions and to be used in remote areas in which no power grid is available, while in grid tie system, you will not be worried of not getting sufficient solar power to run your home.
The question is, for off grid solar system, where will the extra energy go, and how we can increase our batteries lifespan?
There are 2 conditions affecting solar batteries badly, its over-charging an under-charging. The overcharging will overheat batteries and reduce its lifespan, also undercharging will affect batteries performance and reduce the lifespan. To avoid such 2 conditions, we use the solar charge controller.
The charge controller will help regulating storage energy, as it charges batteries, and when it is full, it shuts the electrical charging current flow, but when it is undercharging, it switches on charging current to batteries. It’s an important part of the solar system, because it fully controls batteries, and once it is full, it diverts extra energy to other parts which is in need of it, based on your setup.
Solar batteries are an essential part of the off grid solar system, and maintaining its charging level is acceptable condition is so important as well, so we have to think where we should send the generated energy after batteries is fully charged, because this helps in saving our money.