AC Battery System

Adding Storage to Grid Connected PV Systems

A large portion of the energy generated by a typical PV system will be exported to the grid and there is increasing demand for solutions to enable better use of this energy through the use of energy storage.

Adding battery storage enables this excess generation to be stored for use later when consumption is higher than generation. As electricity prices rise this sort of battery storage system will become more and more cost effective. Some systems can also provide backup power in the event of grid failure.

We offer several Energy Storage Solutions to suit different budgets and requirements.

Types of Energy Storage Systems

These can be broadly described as one of three types with the following features:

a) DC Coupled Energy Storage

  • Here the battery is connected on the PV side of the solar inverter
  • A high voltage battery (to match PV voltage) is used to store the energy when it’s generated for when it’s needed
  • There is some (slight) reduction in the PV feed in tariff due to energy used in battery charge/discharge process
  • No requirement to inform the DNO about changes to the system connected to the grid
  • Not possible to charge the battery from cheap rate electricity
  • Usually no operation in the event of a power cut
  • AC Coupled Solar PV Battery Storage System Schematic 02

b) AC Coupled Energy Storage

  • Here the battery is connected on the AC side of the solar inverter
  • An additional battery inverter/charger is required to convert battery power to 230 Vac and vice versa
  • There is no effect on the PV feed in tariff
  • DNO approval needs to be obtained
  • Possible to charge the battery from cheap rate electricity
  • Back-up may be possible with additional switchgear
  • AC Coupled Solar PV Battery Storage System With Back Up Schematic

c) AC Coupled Energy Storage with Back-up

  • Allows operation in event of a power cut
  • Extra protection relays are required to enable AC loads to be run either from grid or from the battery and to provide a new neutral connection
  • These can be included in inverter/charger