Oil firm Showa Shell Sekiyu said Wednesday it will build one of the world's biggest factories for next generation solar batteries in Japan.

The Japanese firm, part of Royal Dutch Shell group, will spend 15 billion yen (128 million dollars) to build the factory to make thin-film based "CIS solar batteries," the company said.

The factory, which will start operation in 2009, will have an annual production capability of about 60 megawatts, Showa Shell said.