MNES : Large-scale use of solar water beating systems (SWHS) can help in improving the overall conventional power supply by reducing demand, according to a senior official of the ministry of non-conventional energy sources (MNES). "The use of SWHS by one lakh households each replacing two kw electric geyser can save 100 mw of power demand during morning hours," K C Khandelwal, advisor, MNES said.