in addition in the course of the energy sector reform which began in some electricity facilities of the rural grids have been corroded damaged or generally could not meet the demand and thus needed either replacement or modification again incurring large expenses the improvement of living standards and the economic development of rural areas a consequence of electrification stimulate electricity demand and put power supply companies under permanent financial strain rural grids need constant renovation and maintenance a survey conducted by the institute of electrical engineering jkd in inner mongolia in late chinese academy of science revealed that out of pvwindbattery hybrid systems for which statistics were available a total of systems were malfunctioning