How does solar thermal energy differ from photovoltaics?

• A. Solar thermal uses photovoltaic cells to generate electricity; PV uses concentrated sunlight to heat fluid
• B. Solar thermal uses concentrated sunlight to heat a working fluid to drive a turbine; PV converts light directly to electricity; solar thermal can include storage for dispatchability
• C. Solar thermal and PV operate identically
• D. Solar thermal cannot be used for storage

Answer: (B)

Solar thermal energy uses concentrated sunlight to heat a working fluid to a temperature high enough to generate steam and drive a turbine, whereas photovoltaics convert light directly into electricity inside semiconductor cells. Because the system creates heat, that heat can be stored (for example in molten salt) and later converted to electricity, giving dispatchable power even after the sun sets. In contrast, PV systems produce electricity immediately when illuminated, and storage must be added separately (batteries or other technologies) to provide power when sunlight isn’t available. That combination—heating a fluid to drive a turbine plus potential heat storage—distinguishes solar thermal from PV.