BrightSource Energy is making a big bet on CSP while others switch to PV The third huge US solar project from BrightSource Energy is its largest yet. At a whopping 750 MW it is the size of three or four US coal or gas plants. Its Rio Mesa Solar Electric Generating Facility in California will use the solar tower technology it inherited from Israel's Luz, its parent company (Luz Rises Again as BrightSource for California) in which a field of mirrors on poles reflects sunlight onto a tower to create steam to drive a turbine to make electricity. But it comes at a time when many utility-scale solar companies are switching to PV (photovoltaic) solar - those traditional rooftop solar panels that most people associate with solar - from Concentrated Solar Power (CSP) such as this. Why?