Researchers at Sandia National Laboratories have developed a new system that will monitor the effect of clouds on large-scale solar photovoltaic power plants.
The system will provide utilities with valuable data to enable them to better predict and prepare for possible fluctuations in power output due to changes in the weather.
The research team is currently focusing on the 1.2-megawatt La Ola solar farm on Lana’I Island in Hawaii. The solar installation is Hawaii’s largest solar energy system and can produce enough power to supply up to 30 percent of the state’s electricity needs.
SunPower Corporation and Castle & Cooke Resorts L.L.C. commissioned the La Ola solar farm in December 2008.
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The high penetration of photovoltaic power on Lana’I Island, combined with the sun and cloud mix at the solar farm, is conducive for prediction and modeling research.
Engineers connected 24 small, nonintrusive sensors to the plant’s photovoltaic panels and used a radio frequency network to transmit data on cloud direction and coverage activity at one-second intervals.
“Our goal is to get to the point where we can predict what’s going to happen at larger scale plants as they go toward hundreds of megawatts. To do that, you need the data, and the opportunity was available at La Ola,” said Scott Kuszmaul, a researcher at Sandia.
While the effects of clouds on small solar arrays are well documented, there are only a few studies on how large-scale arrays interact and function under cloud cover.
Small systems can be completely covered by a cloud, which drastically reduces their power output. However, only a part of a large solar array is covered by a moving cloud, while the rest stays under the sun.
“As solar power continues to develop and take up a larger percentage of grids nationwide, being able to forecast power production is going to become more and more critical,” said Chris Lovvorn, director of alternative energy of Castle & Cooke Resorts, which owns 98 percent of the island.
“Sandia’s involvement and insight has been invaluable in our efforts to meet 100 percent of the island’s energy needs with renewable resources,” he added.
In February, Sandia entered into a cooperative research and development agreement with SunPower to conduct research on integrating large-scale photovoltaic systems into the grid. The United States Department of Energy and SunPower provided a total of $1 million in funding for the research project, which is expected to achieve significant results over the next two years.
