What is the cheapest route for electricity generation, solar pv or solar thermal?

Solar photovoltaics (PV) and solar thermal power are both viable routes for creating solar electricity. PV converts sunlight directly to electric current using solar cells made with semiconductors. Solar thermal power systems use heat from the sun to boil water, or a handful of other fluids, to create steam to power an electric generator.

Solar power's history is relatively short, and in that time, solar thermal has maintained a sizable lead over solar PV in terms of cost per kilowatt-hour. That is due primarily to scaleability. Solar thermal power is best suited to large solar farms consisting of thousands of mirrors reflecting sunlight onto rows of fluid-filled black pipes or central receiver towers filled with water or molten salts. Recently, however, solar PV costs have been dropping, thanks to less demand and ramped-up supply of solar-grade silicon.

According to recent figures from the Energy Information Administration, the cost of solar PV (assuming a minimum system size of 25 megawatts) is 26.22 cents per kWh. Parabolic trough solar thermal systems run for an average of 22.47 cents per kilowatt-hour. Both numbers are base figures that ignore rebates and incentives. Comparatively, coal-fired electricity often retails for less than 10 cents per kWh. So both solar PV and solar thermal, although the latter is significantly cheaper, have a long way to go to reach grid parity, or equal footing, with fossil fuels.