Mitsubishi UFJ Financial Group Inc. and Mizuho Financial Group Inc. are in a neck-and-neck race to be the biggest lead arrangers of lending to the renewable energy industry in the first half of the year, highlighting the more active financing role for Japanese banks in clean energy.

MUFG has the edge over Mizuho in writing project finance loans to clean-energy developers for the period, according to data compiled by Bloomberg New Energy Finance. As of Thursday, MUFG was credited with $1.697 billion (about ¥190 billion) of asset financing, compared with $1.662 billion for Mizuho, the BNEF data show.

Support for renewables since the Fukushima disaster in 2011 and the search for steady yields outside the country have helped push the nation's lenders into the top tiers among their global rivals. In 2011, only MUFG was in the top five lenders exposed to asset finance deals in clean energy, according to BNEF. Last year, three of the five biggest lenders were Japanese.