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PV vs. Solar Thermal

Distributed solar modules are gaining ground on concentrated solar thermal plants.

Fortnightly Magazine - July 2008

between 1985 and 1991, the loss of heat transfer oil through leaks was a significant problem. 14 Although much has been learned through the operation and maintenance of existing parabolic-trough plants, it is unlikely that technological improvements will eliminate the risks of leaks or the associated impact on performance and cost.

By comparison, the technological and operating risks of utility-scale PV are small compared to those of CSP plants. PV facilities face far fewer challenges for siting and permitting—largely because they are modular and don’t need to be installed in several hundred megawatt increments to achieve economies of scale. Moreover, that modularity allows DCS to be installed in dispersed locations, and this can improve availability by reducing the impact of a site-specific weather patterns. Additionally, DCS has little or no need for water, no air- or water-borne pollutant emissions, and uses no environmentally hazardous working fluids such as oil and molten salt.

O&M costs likewise are much smaller for state-of-the-art PV arrays than they are for parabolic trough fields. Non-tracking, ground-mounted PV arrays have no moving parts, and today’s thin film Cd-Te modules exhibit both low failure and low performance degradation rates. 15

Finally, the manufacturing supply chain for thin film Cd-Te equipment is well established and is growing quickly. First Solar, which today has a manufacturing capacity of 300 MW a year, plans to more than triple its capacity by the end of 2009. Other thin-film manufacturers also are increasing their production capacity, and this is resulting in significant reductions in equipment prices.

A recent presentation by Lazard projects a levelized cost of energy of $90/MWh for First Solar thin-film technology, based on total project capital costs of $2,750/kW and fixed O&M costs of $25.00/kW-yr. 16 If those cost estimates hold true, or are even close, then Cd-Te DCS represents a significant advance over the projected costs of CSP and of competing PV technologies. And, given the modular nature of DCS installations, those installations can more closely track load growth and can even be developed in conjunction with planned residential, commercial, and industrial growth centers.

Given today’s relatively limited PV manufacturing capacity and the momentum of CSP development, the industry likely will continue to invest in parabolic trough CSP plants. However, thin-film PV technology already is knocking at the generation developer’s door. In the long run, DCS plants likely will gain a strong foothold in the market as economic forces drive the industry toward the most efficient, cost-effective, and environmentally benign solar electric technologies.

 

Endnotes:

1. Burr, Michael, “ Taming the Wind ,” Public Utilities Fortnightly , February 2008, Still another issue is the tendency for wind resources to not be available at peak times, such as on the hottest days.

2. Integration of Renewable Resources: Transmission and operating issues and recommendations for integrating renewable resources on the California ISO-controlled grid, CAISO, November 2007. Available at: http://www.caiso.com/1ca5/1ca5a7a026270.pdf.

3. Analysis of Wind Generation Impact on ERCOT Ancillary Services Requirements – Draft Final Report, ERCOT , March 2008. Also: Moland, Gary, “ Windpower’s Warning ,” Public Utilities Fortnightly , May 2008.