Seasonal storage for photovoltaic systems
Stand-alone power applications are a significant market sector for PV power systems today and into the near future. An important technical constraint for wider use of PV power systems in stand-alone applications in cold climates is the difficulty of storing summertime energy for wintertime use. At higher latitudes, a solar system has surplus production during the summer and an energy deficit during the winter. At very high latitudes, there is practically no solar energy available during the wintertime and therefore some kind of seasonal storage is needed for applications which operate year-round. The winter energy demand of a solar-based system can be met by either a back-up primary battery or genset (see Chapter 9), or the system can be designed to be completely self-sufficient, i.e. able to store excess summer PV production for the wintertime.