
Sanyo is already among the world's largest manufacturers of solar panels and rechargeable batteries, and is expected to spend US$335m in fiscal 2007.
Japan's solar market is expected to grow at more than 20 percent per year, according to the Nikkei Daily.
Matsushita, the world's third largest rechargeable lithium ion battery maker, is also expanding its output in Japan.
The company plans production increases and a new factory that will raise output by 50 percent to 37 million units a month by April 2010, according to local press.
The burgeoning solar power market has attracted new investment from other Japanese firms, such as Honda which this week announced the opening of a new solar cell manufacturing plant in Japan.
"To reduce its environmental footprint, Honda has been proactively pursuing voluntary targets to make its automobiles, motorcycles and power products cleaner and to reduce CO2 emissions," said the firm in a statement.
"At the same time, Honda has been committed to developing technology for a clean energy source which does not use fossil fuels."