The Montalto di Castro photovoltaic power station is a photovoltaic power station at Montalto di Castro in Viterbo, Italy. The project was developed by the independent developer SunRay that was later acquired by SunPower. Construction was completed and the power station was connected to the grid in November 2009. It cost €120 million.

The Montalto di Castro photovoltaic power station has a capacity of 24 MW. It uses 78,720 SunPower solar panels as well as its tracker systems. As planned, the solar panels will be added on until it reaches 100 MW.