Microsoft is buying 100 megawatts of solar capacity from Japanese developer Shizen Energy, the latest in a string of renewable energy deals designed to power the tech company’s growing compute needs. 

The agreement, which the companies announced late last week, covers four different solar developments; one is already operating and three are under construction. The deal covers output from the plants for 20 years.

Seattle-based Microsoft already operates two data centers in Japan. Microsoft’s compute capacity is slated to expand as the company invests $2.9 billion in the country over the next year.

Solar has become a favored source of power for tech companies and data center operators in recent years because it is quick and cheap to build. Solar is among the cheapest forms of new generating capacity, and projects are generally completed within 18 months. Plus, users can begin drawing power before the entire project is complete. 

Microsoft has been a big buyer of solar in recent months. Since the year began, the company has contracted more than 1 gigawatt of solar capacity.