Xu Pengfei (L), China's first individual user of grid-connected photovoltaic (PV) power, introduces PV solar batteries to his friend on the top of his flat building in Qingdao, East China's Shandong province, Jan 13, 2013. As Xu's "personal power plant", the eight pieces of PV solar batteries have a total installed capacity of 2 kW, with a grid-connected voltage of 220 V. It not only provides electricity for Xu's family, but also sells surplus electricity to the state grid, which has been the first successful case ever in China. [Photo/Xinhua]