DC coupling means to connect the PV
generator and the battery on the DC side of the inverter instead of on the AC side
and it’s the much better and more preferred solution when it comes to a
co-location of PV generation and battery storage. Generally having a battery
storage in the system enables much more business cases for the independent
power producer, the IPP. Electrical energy for example can be provided during times
of high energy needs and make the IPP more independent from the time when the
sun doesn’t shine. The advantages for the grid operator are that the existing grid can
be utilized much better and without costly grid extensions.
PV generated energy can be stored and fed into the grid when the price for the
kilowatt hour is higher or the sun does not shine. Storage makes the behavior of
the PV plant on the grid very similar to conventional power plants. This is an
important step to an even higher share of renewable energy production. Connecting the battery on the DC side of the inverter instead of the AC side saves
a separate battery inverter and the transformer as well. That means less
investment in equipment, so lower capex and less losses in the system.
The system is available now or in case of the PV plant with future storage
extension. The DC DC combiner as well as the battery can be added later on for
example when battery prices have come down further.