SINGAPORE/HONG KONG, May 20 (Reuters) - Asia-Pacific investment firm PAG said on Monday it had raised $550 million for its first renewable energy fund, which focuses on investments in physical assets in Asia and includes solar power in Japan as its primary target.

PAG, which manages more than $55 billion of capital ranging from private equity to credit, said in a statement that investors in the PAG REN I fund include pensions, sovereign wealth funds and fund-of-funds investors in North America, Europe and the Middle East.

In a separate statement on Monday, Abu Dhabi sovereign investor Mubadala Investment Company said it had made a cornerstone investment in PAG REN I, marking its first investment in Japan's clean energy sector.

Mubadala did not provide details on the size of its investment.

"The strong response to this fund demonstrates investor confidence in the need and opportunity to enable the transition from fossil fuels to clean, domestically produced sources of energy generation in Asia," PAG Renewables President and CEO James Buford said in a statement.

PAG's first renewable fund adds to fundraising activities in the energy market in the Asia-Pacific region. PAG said it is the largest and fastest-growing region globally and requires more than $2 trillion of investment in renewable power generation and energy storage over the next decade.

Japan is the second-largest energy market in Asia and needs annual renewables investment to grow more than five-fold between 2023 and 2030 to hit its targets of doubling renewable generation between 2020 and 2030 and achieving net zero emissions in 2050, PAG added.

Mubadala's investment added to a recent partnership where it was part of a group of investors led by PAG that in March acquired a 60% stake in Chinese property giant Dalian Wanda's mall unit for $8.3 billion. (Reporting by Yantoultra Ngui in Singapore and Kane Wu in Hong Kong; Editing by Jamie Freed)