Compound Cells Double Solar Electricity Yield
Compound semiconductor cells have helped a solar installation in Seville, Spain, claim a 23 percent sunlight-into-alternating current power conversion record.
In May, German firm Concentrix Solar recorded this figure under normal operating conditions as its 5.6 kW concentrator photovoltaic (CPV) system fed energy into the utility grid.
The record system exploited improved CPV modules, in which the sunlight is focused onto GaAs-based solar cells, to generate direct current power. The system's inverter then changes this output into the AC used by the grid, and Concentrix emphasized the importance of this stage in the overall system efficiency.
“We are overjoyed that we have succeeded in even exceeding the projected values", said Concentrix's CEO Hansjörg Lerchenmueller. He added that the overall system produced “almost exactly double the electricity yield of conventional photovoltaic power systems".
“Most of the time the efficiency is between 21 percent and 23 percent," said the CEO. “Typical daily average AC system efficiency is in the range of 22 percent."
Lerchenmüller said typical silicon photovoltaic modules can deliver 13.5 percent conversion efficiencies: “You lose 4-5 percent in the inverter, and you lose 8-9 percent due to temperature effects, so without even considering other losses you are down to 11.67 percent [with silicon]."
Further improvements to the CPV system efficiency should follow with the introduction of an inverter based on SiC semiconductor components, which the record-breaking system does not yet use.
Lerchenmueller s excitement looks excusable, with a pivotal 100 kW system that uses the record-breaking technology at the ISFOC project in Castilla-La Mancha “ready to be connected to the grid“. Overall Concentrix will contribute 500 kW to this 3 MW CPV project.
The company is also set to begin production at its 25 MW annual capacity system plant in Freiburg later this year. The systems will be sold by Concentrix Iberia, a collaboration between Concentrix and Abengoa Solar. Abengoa operates and builds photovoltaic systems in a portfolio that it says runs to hundreds of megawatts across Europe, Northern Africa and North America.
Although deployments like ISFOC will take up a proportion of its production, Concentrix already seems to be doing brisk business in CPV systems sales. At the CPV Today conference, held in Madrid in early April, Lerchenmueller said that, even with the new plant coming online, Concentrix's capacity for 2008 is already fully booked.
He adds that the company is still receiving lots of requests: “Spain and Italy are in front, but there is a strong interest from the US too," the CEO told compoundsemiconductor.net.