Parallel systems Solar energy systems in parallel is the current pattern of the mainstream system, if set enough quantity, will be able to effectively reduce the traditional peak electricity supply,reach the goals to use natural energy instead of fossil energy , Japan, Germany and United States and other advanced country is making every effort to promote this type system. This system apart from supply the production of electricity power set point, also can send the surplus electricity to the public power lines , power companies buy back (currently the advanced countries have preferential rates back to the sale).can provide the public during the daytime peak demand,so that can reduce the republic power’burden .This system mainly as energy-saving purposes, must be set at region which the common power line may arrive . Such a system does not configure the batteries, set up and maintenance costs low, but only achieve energy saving effects during the day when there is sunlight , still required to use of electricity from power companies when at night and lack of sunshine hours.