In grid tie solar photovoltaic system, its actually connected to the grid, and it cannot work without it. When there will be an excess electrical energy generated from grid tie solar system, it will be sold back to the grid, and when there will be lack of electrical energy generation, we mean that electrical output power is not able to handle load demand power, the grid will automatically compensate for power difference, letting the load working efficiently without interruption.
During this process, there will not be an energy storage system to store the excess electrical energy generated on the day time to be used in feeding our home equipment at the night time, instead of injecting it back to the grid.
Adding batteries to solar photovoltaic system
There are two main types of solar batteries in the market; Lead acid and lithium. Although adding such batteries to the solar system will add extra significant expenses on solar system price, but it has much benefits; It will reduce our electricity bill, and we will be independent of the grid keeping our equipment work in case of grid interruption, and this is critical high value benefit in places/areas prone to grid blackout or even has no connectivity with the grid, and specially for some kinds of sensitive equipment like fridges, freezers, and medical equipment.
Solar batteries have a definite life time, so before adding them to our solar photovoltaic system, we need to make economic feasibility study to see whether their financial saving will cover batteries purchasing costs before its failure or not? Generally, the life time for such batteries ranges from 8-15 years, and the longer life time & the higher reliability, the higher batteries costs.
With technology development, we are sure that batteries costs will be reduced and the service life time will be increased, so their economical feasibility will be higher.
For each solar battery brand, there will be a warranty period that will guarantee certain number of years or cycles per its life span. Moreover, and as the batteries degrade naturally, the batteries manufacturer will guarantee to what extent the battery will keep a certain amount of its capacity over the warranty time. Consequently, the brand manufacturer is the only one who knows how long will our solar batteries last and how much power capacity will be loosen over the time.
At the end, we want to re-confirm that batteries are an important part in the solar photovoltaic system, and the crucial factor for purchasing a certain batteries brand is what will be the manufacturer provided warranty period.