Pros & Cons: Distributed Rooftop Solar vs. Desert Solar Thermal

Utilities plan to use solar power from both the massive solar plants that are being built in the California Mojave desert, as well as large scale distributed rooftop solar projects, like the one Southern California Edison is planning. So which technology is better? Centralized solar systems that use the sun’s heat to generate electricity, or hundreds of rooftops covered in solar panels strung together to generate power?

Roy Kuga, the vice president of the Energy Supply Division at California utility PG&E, had some interesting ideas about the pros and cons of each technology at the Berkeley, Stanford CleanTech Conference Series on Wednesday. Basically, while solar thermal plants provide lower solar prices, higher efficiencies and better energy storage, distributed solar rooftop programs are quick to deploy, and less costly when it comes to transmission lines and water needs. Check out the detailed list below:

Distributed Photovoltaic Solar Rooftop Projects:


  • These projects can get up and running fast. Around 8 months, Kuga says, noting that the solar industry is also trying to bring down this time dramatically.
  • Distributed projects are not dependent on building long transmission lines to remote locations (such as the desert).
  • Distributed projects are also not dependent on the high water needs that solar thermal plants require for cooling.


  • Distributed systems have high costs of deployment. Because each system is a separate project, each rooftop installment requires a lot of labor, transaction and implementation costs.
  • They scale more slowly because it takes time to get all the rooftops up and running.

Solar Thermal Plants:


  • Solar thermal plants benefit from the economies of scale that can deliver lower solar power prices.
  • Solar thermal plant efficiencies are commonly higher than rooftop systems.
  • Solar thermal systems have pretty good energy storage technologies, so they are compatible with the intermittencies of solar. Solar thermal plants can store energy for when the sun goes down better than rooftop systems.

Cons: (Also check out our 8 Offbeat Hurdles for Solar Power Plants)

  • Solar thermal plants in the middle of the desert are transmission line dependent. Transmission lines are costly and difficult to get built.
  • Solar thermal plants need a lot of water, which is costly and delays permitting.
  • Solar thermal plants need a lot of land and require extensive permitting processes to get approved.