Directory:Sol Solution

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Sol Solution Has developed a photovoltaic system that takes advantage of chromatic aberration called a 'Rainbow Concentrator' to separate and concentrate the solar spectrum with a single inexpensive Fresnel lens. This allows higher efficiencies for solar cells that can optimize the antireflective coating, the material to adjust the bandgap and the front and backside texturing to maximize the optical length.


Official Website


There was an error working with the wiki: Code[1] Refractive spectrum splitting concentrator system 2007

Inventor: Don Wagner

NEC Member Dr. Richard George Commented:

I would not vote for your Rainbow Concentrator as a top 100 technology for the following reasons:

1) This patent is for what is a marginal improvement on fresnel lens but for which there is no compelling market requirement as no commercially available PV chips can leverage its benefit at this time. Furthermore, as the market has effectively chosen triple junction technology, it is not clear that there is any need for this rainbow concentrator lens.

2) Viable solar concentrator systems require a lot more than a method of concentration. Other core components include the concentrating PV chips, the method of cooling the chips, the method to seal and protect the chips, the tracking system, and the core assembly.

3) No evidence of a working prototype or any certifications (UL or IEC) completed or under testing. It typically takes 18-24+ months of pilot installation testing to get to the point where one can raise the capital to mass produce the product and then start the certification process. Certifications alone take 9-18+ months and require that the product be in production.

4) No evidence of being able to deliver a CPV product at customer prices that are economic and in megawatt volumes.

5) The article from renewable energy access is irrelevant and is not your technology. Even if they achieve 42% efficiency in a lab, there is a huge chasm between one test chip in a lab and a commercially viable operation with sufficient funding (hundreds of millions of dollars) capable of manufacturing 100s of megawatts of these chips each year. There are multiple non-trivial milestones this group would have to achieve before this research would result in a commercially viable product. Furthermore, such a venture would be years behind Emcore, Boeing Spectralabs, Azure Space, and other existing 3J CPV chip vendors who have product available today. This would be a very hard sell to investors given the risk. Any patented concentration method that is dependent on their research being commercialized would have to wait until the underlying chip is commercially available (2-3 years at best) to even build a prototype. This would put commercialization 5+ years away and be even risker.

6) Although higher efficiency is good, the ability to deliver product in quantity at customer prices that allow grid-parity, is more important than achieving efficiency records. Furthermore, there are often tradeoffs between cost of manufacturing and maximum efficiency.

Response from Don Wagner

1) While no commercially available chips are currently available,

Emcore, NREL and UD have ALREADY made these solar cells. "The record-

breaking system features three types of solar cells-one made by

industry (Emcore), one by the National Renewable Energy Laboratory and

one by UD." ( Dr. Richard George mentions that "the market has effectively chosen triple junction technology". With

all due respect, currently the bulk of the sales are for non-

concentrating flat panels. Spectrolab's future road map plans to use

more than three junctions. Look at and you will currently see 17 different companies with at least 10

different approaches. This is like the car market before the model T.

Solar is in it's infancy and I for one have no crystal ball of where

it will be in five years. While this may be a "marginal improvement"

in the Fresnel lens, the way it is used is very different. The current commercial state of the art is using three junction horizontally stacked cells. By not having the cells stacked. You can use the same technology but with an increase in efficiency due to anti-reflective

coatings and texturing tuned for a subset of the spectrum. This also means that there will be less waste heat which will also let the cells be more efficient. This is how the 42.8% efficiency record was set. but the big

improvement will hopefully be in cost.

2) I agree with you 100%. This is only one component of a system.

3) I have a working prototype ( and (MATLAB) models with 80x to 400x concentration

4) That is true of any new technology.

5) This technology is not competing with Emcore or Spectrolabs, but will be use their (or other manufacturers) technology. The cells needed have already been developed although at this point not in production quantities.

The article is relevant since this technology can use the exact same solar cells that they are using. The main difference is that the project mentioned in the article uses very expensive dichroic filters instead of an inexpensive fresnel lens.

6) Again I agree with you. Realistically the only important metric is

dollars per watt.