Photo credit: All Seasons Roofing

At first everything was peachy-keen for Concentrated Solar Power (CSP) plants. Everyone from the president to the average eco-friendly observer was (many still are) excited at the prospect of solar power plants easily and Green-ly taking over for the dirty smokestacks of fossil fueled energy. Then, as the first few plants went online around the world, and the massive land rush took off here in the States, many onetime proponents started having second thoughts — and the debate is on.

As we rush to utilize renewable energy ASAP, some environmental groups and consumers are growing concerned that we’re moving too fast. In an effort to spur on this debate, below are 20 points of comparison between rooftop solar and utility-scale solar power plants (typically CSP). But first, a personal disclaimer:

Throughout the course of my writings here at CalFinder Solar, I’ve made it no real secret that I’ve grown to support rooftop solar, or more formally, distributed generation over concentrated solar power. I assert, however, that my preference is not because I work for a solar installer, nor due to the fact that CalFinder is a “residential” solar website. It is simply that I believe the benefits of rooftop solar outweigh those offered by CSP.

With that out in front, and to spell it all out (however briefly), here are 20 points of comparison between rooftop and concentrated solar. Please note that I resist my bias: CSP does have its unique benefits which I do not deny and by which strong arguments are made.

The Rooftop vs. the Power Plant

1. Transmission. A big one: Rooftop puts solar power directly into the home and existing grid. CSP would require massive upgrades to an already suffering national grid.
2. Land. Solar plants require massive amounts of land for the large collector arrays. Rooftop solar requires none that hasn’t already been developed.
3. Water. A very hot aspect of the debate at present: CSP thermal plants require a lot of water for cooling. Unfortunately they are to be located in desert regions already suffering from water shortages.
4. Flora. A big complaint from environmental groups regarding solar plants is that it would ravage desert ecosystems by “scraping” the land clean.
5. Fauna. At the same time environmentalists argue that rarely-visible-but-nevertheless-existent desert wildlife would be transplanted (i.e., the desert tortoise).
6. Speed. A big plus for CSP. Proponents say that large-scale solar plants are the only way to increase national usage of renewable energy at the rates proposed by states and the federal government. (See renewable portfolio standards)
7. Jobs. An arguable point. All agree that the solar industry creates high quality jobs. Yet solar plants require very little maintenance and relatively small crews. Rooftop installations would employ thousands of installers, electricians (plumbers for residential thermal applications) and laborers to install systems, as well as eventually maintain or replace them down the line.
8. Savings. Rooftop immediately starts saving on electric bills and payback periods continually grow smaller. Where are the individual savings from solar plants? Most predict higher energy costs in the near term at least.
9. Power over Power. Somewhat related to #8, rooftop puts power in the hands of the homeowner or family; they purchase only the power they need or sell back what they don’t; partially eliminating the power company from the equation. CSP promises clean energy, not necessarily cheaper electric bills. Fair regulation could overcome this.
10. Energy Conservation. A family with a solar system on their roof is much more likely to keep track of and conserve their power usage in order to get the most bang for their buck.
11. Up-Front Costs. Although decreasing at this time, up-front costs remain the biggest hurdle to widespread rooftop solar installations. With solar plants, that is taken care of by big companies who can afford it.
12. Tax Credits. Now both are relatively even on this account, at least federally — homeowners, utilities, and Big Solar can enjoy 30% credits for the next eight years.
13. Distribution. Rooftop is applicable anywhere in the country, while CSP is primarily relegated to spacious and sunny deserts.
14. Property Value. Rooftop solar greatly increases home property value and many states have made them exempt from property taxes … one more benefit for lucky solar homeowners.
15. Innovation. All of the solar industry is seeing technology innovations, but primarily in the photovoltaic (PV) sector: i.e., rooftop and building integrated technology.
16. Storage. Rooftop solar energy can be sent back to the grid or stored in batteries for use at night. Long-term storage remains a struggle for CSP, although innovations are there.
17. Siting. The potential of a home PV system can be limited by site issue for homes not built with solar power in mind (the majority to this point). Not much of an issue for solar plants who use wide open and very sunny deserts — not counting the problems with land lease approval, etc.
18. Local Economy. Arguably, widespread rooftop solar better benefits the local economy by spreading extra money (in utility savings and jobs) across the population. Concentrated solar may also concentrate wealth.
19. Scalability. Large-scale rooftop systems are possible in open urban spaces such as parking lots and commercial rooftops. Utilities too can benefit from rooftop solar.
20. Renewable Sprawl? The million dollar question: Why eat up thousands of acres of natural landscape when millions of acres of already developed land, retaining many of the benefits described above, is currently available?

Feedback: I would love to hear any and all opinions on this matter or reactions to this post. Regardless of what this writer believes, the debate does not stop here, nor anywhere, anytime soon in all likelihood. In fact, it is this very debate that may come to define our national history in the decades to come. Care to join in?

Photo credit: NREL

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Posted on May 26th in Solar Politics by Dan.