A common myth about solar energy is that it can only be relied on when the sun is shining. You need the sun to generate electricity from solar energy, but what about the times when the sun isn't shining? In such cases, a solar battery can be an important addition to your solar power system. It helps you store excess electricity that you can use when your solar panels aren't generating energy and gives you more options for how to power your home.
Residential and commercial solar energy systems paired with battery storage—generally called solar-plus-storage systems—provide power regardless of the weather or time of day without relying on backup power. PV stand alone or hybrid power generation systems has to store the electrical energy in batteries during sunshine hours for providing continuous power to the load under varying environmental conditions.
Solar batteries can only store DC electricity, so there are different ways of connecting a solar battery to your solar power system. When it comes to solar battery types, there are two common options: Lithium-ion and Lead-acid.
Mostly Lithium-ion battery technology for its higher DoD, reliable lifespan, ability to hold more energy for longer, and a more compact size.
DC-Coupled Storage: With DC-coupled storage, the DC energy generated by the solar panels flows through the charge controller and then directly into the solar battery. A DC-coupled battery is more efficient because the current only has to switch from DC to AC once.
The performance of the PV system with battery storage depends on the battery design and operating parameters of the system.
Functions of storage batteries in a PV system:
Energy storage and autonomy: To store the electrical energy produced by the PV array and to supply energy to electrical loads as and when needed (during nighttime and non sunshine days in winter)
Stabilization of voltage: To supply power to electrical loads at stable voltages by suppressing voltage fluctuations in PV systems and protecting loads from damage.