The Asian Development Bank credit facility will fund the growth of the portfolio from around 617MW currently as Mytrah builds its wind and solar capacity.
As part of the expansion it is acquiring 175MW of solar photovoltaic modules from a Chinese firm called Risen Energy.
Mytrah currently has an active development pipeline of about 3,500MW of wind and 500MW of solar.
No details were given about the interest rate that will be paid on the debt.
On the credit facility, chairman Ravi Kailas said: "This is another significant milestone in the development of the company.
“The involvement of the Asian Development Bank is further evidence of the growing maturity and quality of our business, and our contract with Risen is an exciting development in our solar division.
“Together, these underpin our growth plan and we now expect our operating capacity to reach 1,000MW within 12 months."