A battery storage system can be fitted with a new solar pv system or it can be retro-fitted to an existing system :
Whilst your solar panels are generating energy during the daytime, your home takes priority thereby ensuring that any appliances you use during the day are powered by your solar pv system where possible. Without a battery storage system, the excess energy that you are not using would normally be exported back to the grid but instead it is diverted to the battery storage device and stored for later use. Once the battery is fully charged, only then will the extra energy be fed back into the national grid.
The energy stored in your battery is also available throughout the day so if your panels are producing less energy than the home is demanding, the inverter will check how much energy is stored and if sufficient will release this stored energy from the battery to meet the demand from the house.
A typical home owner can expect to be 80-85% self sufficient from a 5KW battery and an average 4kWp Solar PV System