An Arizona-based maker solar panels has really taken off, as it has signed a long-term agreement to provide solar panels and its profits have doubled.

This story from Forbes says First Solar Inc. has seen its stocks surge as its solar business takes off:

First Solar also said Wednesday it is entering the U.S. residential market through a five-year contract with SolarCity Corp.

First Solar, which produces cadmium telluride-based solar panels, will supply 100 megawatts of modules to SolarCity, a Foster City, Calif.-based residential solar installer, beginning in the first quarter of 2009. First Solar will also make a $25 million equity investment in SolarCity, which is part of a $30 million round of financing that will fund SolarCity’s continued U.S. expansion.

Analysts say that First Solar is on track in its strategy to expand its U.S. utility presence.