This invention relates to a cheap polysilicon film solar cell, in which, a P-N junction polysilicon upper electrode is prepared on the back electrode/substrate and a SiN anti-reflecting film is set on the incident surface of the cell characterizing that a heavy doped P+ layer and a SiO2 isolation layer blocking the substrate impurity from diffusing to the polysilicon film are set between the substrate and the polysilicon film with the P-N junction, said substrate is a low quality polysilicon plate in the purity less than 4N, which adds a SiO2 isolation layer and a heavy doped P+ layer between the substrate and the polysilicon with the P-N junction, so the low quality polisilocon plates can be used in solar cells effectively so as to reduce the cost of production. |