A thin film solar cell includes a substrate, a plurality of photovoltaic cells and at least one control unit. The photovoltaic cells generate a photocurrent respectively. Each photovoltaic cell includes a first conductive layer disposed on the substrate, a photovoltaic layer and a second conductive layer. The photovoltaic layer disposed on the first conductive layer has an opening exposing the first conductive layer. The second conductive layer disposed on the photovoltaic layer is connected electrically to the first conductive layer of the adjacent photovoltaic cell through the opening. The control unit is connected to at least one of the photovoltaic cell electrically. When the photocurrent generated by at least one of the photovoltaic cells is different from the photocurrent generated by other photovoltaic cells, the control unit provided a compensable current to the first photovoltaic cell to make the photocurrents provided by the overall photovoltaic cells being matched.