Status and Technology of Solar Power Generation
“Status and Technology of Solar Power Generation” was the subject of the Hot Topic Hour held on May 26, 2011. Five speakers provided a balanced overview of the subject.
Bart Krishnamoorthy of the Solar Electric Power Association opened the session by explaining efficiency and cost of the different types of PV. While thin film solar is less expensive than conventional solar cells it also less efficient. He divided the PV market applications into three segments; residential, commercial and utility scale. Residential systems are generally less than 10 kW, commercial installations range from 10 kW to 2 MW and utility scale installations are larger than 5 MW.
In 2010 utilities installed 782 MW-ac of solar power, 705 MW of that was PV. This brought the total installed amount of solar energy to 2128 MW-ac, of that 1,627 MW was PV. While Pacific Gas & Electric Co. installed the most MWs in 2009, Southern California Edison has the most total MWs installed. Florida Power & Light installed the largest project in 2010 with the Martin Solar Center at 75 MW. Krishnamoorthy says there were three stages of market development. The first being customer owned, net metered projects. The second being industry driven, net metered projects. The third was utility driven projects at utility scale and utility value.
Two speakers from Burns and McDonnell gave the second presentation. Matthew Brinkman explained that RPS standards enacted by various states are driving utilities toward solar energy. Regulatory uncertainty is another driver. Brinkman said that more PV projects are being installed than solar thermal projects because the financing is better understood for this type of project. Scalability is another reason PV is more popular than CSP. Solar thermal projects require the entire steam cycle, therefore 50 MW is the smallest system that makes economic sense.
Peter Johnston continued the presentation by comparing the project attributes of PV and solar thermal. He did this by using a traffic light system with red, yellow and green lights. PV was a definite winner in this chart in areas of land use, brownfields, water use and cost. Five or 6 acres/MW are required for PV and 7 or 8 acres/MW are required for solar thermal. Costs for PV were given as $3-4/watt for PV and $4-5/watt per solar thermal. The next traffic light chart compared the operational attributes of the two systems. In this area solar thermal was the clear winner in the areas of cloud ride-through and despatchability. Recent loan guarantees have spurred the development of solar thermal plants. The opening of federal lands by the Bureau of Land Management has also been a driver. Another area of interest is the combination of solar thermal plants with fossil-fired power plants.
Paula Mints of Navigant Solar Services described the dramatic growth of the solar industry with a compound annual growth of 65 percent between 2005 and 2010 but pointed out that before 2004 no one made money in the industry. At the present time margins are difficult and competition is fierce. Eighty-nine percent of the present market is in Germany. Since the market for all solar technologies connected into the grid is incentive driven, this means that 97 percent of the market is vulnerable. Mints stressed the main advantage of PV over CPV and CSP is that it’s cheap. Prices have fallen dramatically since 1989. In the CSP area lots of GWs are announced but she predicted approximately 60 percent will not come to pass because of cost and interference from outside parties. In the CPV area announcements total approximately 2 GWp. Her accelerated forecast for 2011 through 2015 for CPV was for 1 GWp. Her conservative forecast for CPV was for 530 MWp.. Mints concluded by saying, “Let’s not count our megawatts before they are connected to the grid because we will have to get used to lower or perhaps no incentives in just a few years.”
Joseph Bessler of Silverwood Energy gave a very detailed explanation of the California Solar Utility Market. On April 12, 2011 Governor Brown signed legislation requiring all Investor Owned Utilities (IOU) to procure renewable energy in the amount of thirty-three percent of retail sales by 2020. In California there are two types of solar utilities – Investor Owned regulated by the California Public Utilities Commission (CPUC) and Public Owned (aka Municipals) with publicly elected boards not regulated by the CPUC. Investor Owned Utilities have two types of programs, one where the project is owned by the utility and RFOs (Request for Offer) where the utility just buys the power. With standard RFO Projects the term is 20 years, a third party is paid the bid price, the energy price is determined by the bid, all bids must be approved by the CPUC and the utility does not have to accept the project. Large scale projects are a separate procurement process.
John King of Combined Power Cooperative provided a perfect end for the session by describing areas for improvement in solar systems. First he also stressed the idea that many of the projects under development will never be built. He reinforced this point by explaining that if all the announced projects were built they would consume about 1.2 percent of total US steel production per year just for CSP in California for the next nine years. For comparison he said US steel consumption for cars is 11 percent.
King provided a capital cost breakdown for CSP plants. The two most expensive items are Solar Field and Thermal Energy Storage. The cost components of the solar field are the reflector system and the receiver system. Polymer reflectors are under development and he said suppliers to watch in this area are Reflectech and 3M. Users of polymer reflectors are CoolEarth and Helioviz AG. In the area of receiver systems SunDrop is working on the direct conversion of biomass to biogas, Arizona State University is studying nanofluids and air was suggested as a working fluid. Interesting things to watch in the area of thermal storage is SandShifter, a cheap and widely available medium. Concrete storage was also suggested. DOE is funding a lot of work in this area.
King concluded with the reminder that water is always an issue especially since the areas with the greatest amount of sunlight tend to be the ones with the least amount of water.
The BIOS, PHOTOS and ABSTRACTS are linked below.
BIOS, PHOTOS and ABSTRACTS – May 26, 2011