Japan designated 7.368-megawatt of power generation capacity from renewable energy sources as eligible to the country's feed-in tariff system in the seven months ending in January, the Ministry of Economy, Trade and Industry said Tuesday.

Of the 7.368 MW, more than 90% was from solar power and only 19% of the capacity has started operations, data from METI show.

Japan has seen an investment boom in solar power since July when the country's new feed-in tariff law took effect. Under the law, all 10 regional power utilities must buy electricity generated from renewable energy sources at specified prices for specified time periods. Solar power projects have attracted many investors because they typically don't require environmental assessments and take a shorter time to build.