What are some of the technologies used in Distributed Generation (DG) technologies?

DG generally takes place behind the meter of a client and can be renewable or driven by fossil fuels.  The renewables are generally solar but could possibly include wind in some instances. Generally DG includes some combustion generation to ensure reliability and the most environmentally sensitive fuel is natural gas.  Batteries are now beginning to be a part of the behind the meter solution as the prices come down and performance goes up