"There are still too many system design options for HCPV which will delay its market acceptance"
Concentrator cells have been reaching increasingly impressive efficiencies, inspiring new interest in the high-efficiency, high-concentration approach. Currently, the record efficiency is 40.7 percent for a three-junction GaInP/GaInAs/Ge cell.
From JX Crystals' perspective, its president Dr. Lewis M. Fraas sees the LCPV approach as fast to market with minimal risk.
"It is a simpler approach to understnd in terms of relaibility and O&M because it is evolutionary from the traditional planar silicon module. Because of its simplicity, LCPV may be more suited to commercial building flat rooftops," he recently told CPVToday.com in an interview.
"For the longer term, JX Crystals is also involved in HCPV. We have a dual focus Casegrain approach where the combined cell efficiencies can easily hit 44 percent. Our view is that while the 35 percent monolithic cell is attactive, because of the penalty of DNI vs global (78 percent) and the optical losses (85 percent), a 23 percent silicon planar cell competes (0.78x0.85x35 percent=23 percent). However, in the longer term, 44 percent provides a real significant advantage," said Dr. Fraas, who is scheduled to speak during CPV Summit USA 2009 (scheduled to take place on February 3-4 in San Diego).
Dr. Fraas also spoke about the potential of LCPV and HCPV, why HCPV has received more funding and much more. Excerpts:
CPVToday.com: When compared with solar thermal approaches, CPV provides a qualitatively different approach, typically with lower water usage, greater flexibility in size of installation, and the ability to respond more quickly when the sun returns on a cloudy day. The tracking used for CPV also implies relatively higher electricity production per installed kilowatt, compared with fixed flat plate. What's your viewpoint regarding the CSP vs CPV growth or technology superiority?
Dr. Lewis M. Fraas: LCPV can be useful for 3 kW to 500 kW applications. HCPV in fields can be appropriate from 100 kW to 10 MW fields. CSP is for very big central power systems. These partitions are very approximate but demonstrate the probable market segmentation.
CPVToday.com: Considering LCPV and HCPV debate (where proponents of LCPV say that the HCPV hypothesis is a flawed one. Not only does it not yet deliver commercially - a product of high cell costs and high system costs to achieve required accuracies - but it creates a range of technical problems that are both difficult (and expensive) to solve), how do you assess this battle?
Dr. Lewis M. Fraas: Based on technology, LCPV is nearer to market given investment. HCPV is still under development and will be for at least three more years and will need much more money to build the component supply infrastructure. I see LCPV as potentially providing credibility for HCPV.
I do not see a conflict between them as they will address different market sectors. The real tragedy has been lack of government funding for CPV development at the system level. HCPV has received more funding because of the spectacular cell efficiency. LCPV has been overlooked. Both are very promising and there should not be a conflict except for the lack of funding for CPV in general vs thin film PV. CPV needs to demonstrate lower cost and this can be most rapidly demonstrated with less funding via LCPV.
CPVToday.com: It is being said that medium concentration (around 40x) currently offers the most reliable and cost-effective solution. What's your viewpoint regarding the same?
Dr. Lewis M. Fraas: No. This is superficial and overlooks cell packaging issues for long term durability. For LCPV, packaging for durability has already been demonstrated riding the coat tails of planar.
MidCPV pacaging runs into thermal and durability vs cost problems as well as cell supply problems. The same DNI vs global and optical losses hit MidCPV without the high >35 percent cell option.
CPVToday.com: The recently formed CPV Consortium says CPV "is on the cusp of delivering" on its promise of low‐cost, reliable solar‐generated electricity that will be cost competitive with traditional energy sources. And the challenge now is to assure that a proper foundation and infrastructure is in place to support CPV. How do you think the industry is placed to cope up with such challenge?
Dr. Lewis M. Fraas: There are still too many system design options for HCPV which will delay its market acceptance. LCPV can demonstrate the lower cost faster but is presently under funded relative to HCPV. Low cost will require investment in high volume manufacturing for LCPV. There is also the certification and qualification bottle neck for CPV at least in the US.
Spain is addressing this qualification issue with the ISFOC fields for HCPV but the US government is still sleeping on this. Early CPV manufacturing requires government buys for parallel demonstration and certification efforts lasting for a couple of years. This was done for planar Si in the late 70's with JPL block buys. ISFOC is doing it now for HCPV. There is no such opportunity now for LCPV.
CPVToday.com: CPV start-ups are planning extensive field testing to validate the reliability and energy production modelling and are also working with project developers and third party engineering firms to mitigate any perceived risk of deploying their respective technologies. What's your viewpoint regarding the same?
Dr. Lewis M. Fraas: This activity in the US is lacking for LCPV companies. JX Crystals has done this with our 100 kW 3-sun system operating in China now for over two years. We also have small three-sun rooftop systems operating now for over one year in the US at ORNL and at UNLV. This activity was made possible via $2 million from the Chinese government and $10 thousand from the US government.
CPV Summit 2009, San Diego
CPV Summit 2009 is scheduled to take place in San Diego (February 3-4, 2009). For more information, click here:
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