  Decentralized renewable energy systems can be low-carbon power sources, and
promoters of local economies. It is often argued that decentralized generation
also helps reducing transmission costs, as generation is closer to the load,
thus utilizing the transmission system less. The research presented here
addresses the question whether or not, or under what circumstances this effect
of avoided transmission can actually be seen for a community-operated cluster
of photovoltaic (PV) power plants in two sample locations, one in Germany and
one in Japan. For the analysis, the newly developed instrument of MPI-MPE
diagrams is used, which plot the maximum power import (MPI) and maximum power
export (MPE) in relation to the reference case of no local generation. Results
reveal that for moderately sized PV systems without battery storage, avoided
transmission can be seen in the Japanese model location, but not in Germany. It
was also found that an additional battery storage can lead to avoided
transmission in both locations, even for large sizes of installed PV capacity.
