Solar Panels: PV vs. CPV vs. ???

[I promise to post – sometime in the near future – my old notes on how PV and CPV solar panels work.  Hopefully this post won’t require much in the way of prerequisites.  -gayn]

While the history lesson of the Betamax has not escaped me, I continue to believe that Concentrating PV’s (CPVs) will win out over PV’s where, of course, PV = photo-voltaic solar cell.

The basic issue is that PV’s are simpler, cost-less (per square foot), and yet have lower efficiency and hence for a given panel size, produce less electricity.  In contrast CPV’s are way more complex, cost more (per square foot of panel), and have almost triple the efficiency producing far more electricity for a given panel size.  The additional complexity also adds more maintenance for a CPV panel.  Finally, the PV team shouts, “We’re cheaper now!”

OK, so why am I so optimistic about CPV?  Let’s consider the three parts to a CPV panel.  First the optics – either parabolic mirrors or Fresnel focusing lenses – are made of cheap glass.  With volumes, this piece will become extremely cheap.

Second, the high tech metal alchemy that produces the stack of three solar diodes that capture three different wavelength ranges of light from the (concentrated) sunlight is going to plummet in cost.  While there is still a race to find the right semi-conductor metals and the right doping combinations for maximum efficiency, there is a theoretical limit on efficiency for such cells.  Soon enough the competitors will converge, if not on one solution, then on similar enough solutions that the manufacturing folks can optimize the process of creating them and benefit from the increasing volumes.

Semiconductor process technology will also make these chips smaller, which is greatly to the advantage of the folks with the concentrating optics.  Currently there is around a 600 to one focusing of sunlight cross-sectional area to the area of a solar cell, and this will surely go to 1000 to one, with the obvious economic benefit.

Third, the original clunky dual axis solar trackers necessary to keep the CPV panels orthogonal to the sun’s rays are already getting lighter, cheaper, and more reliable.  Another economic benefit.

The CPV vendors, due to the cost and complexity of their initial products seem to have been going after the big utility installations. As the above economic benefits materialize, smaller installations will be more reasonable, e.g. commercial and residential rooftops.  This will drive the volumes up and the prices down.  It may also permit the CPV vendors to do what the PV vendors are doing now by financing an installation.

So what could make all this crystal ball gazing go wrong?  Well there are signs of unbelievably cheap PV materials – not based on Silicon dioxide chips.  I could imagine it so cheap that every building would just drape this material around on every surface that faces the sun.  (I just don’t see this happening very soon, if at all.)

Another possibility would be that another form of Green Energy comes along that is an order of magnitude more cost effective than solar.  There are lots of candidates, from making energy from ocean waves, to making it from trash.  Again, I don’t see any of these hitting the shores like a tsunami.

Thus, my money is on CPV technology – at least for the foreseeable future.

 

-gayn

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2 Responses to “Solar Panels: PV vs. CPV vs. ???”

  1. bitcoin raspberry pi miner Says:

    Hey! I’m at work surfing around your blog from my new apple iphone!

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  2. Nanda Says:

    Hi,

    Thanks for your post. Very clear and concise overview if the PV and CPV and CSP updates. Got a lot of information from one single source. I am an individual trying to get into manufacturing of one of the components required for green technologies. I am actually quite soaked at the lack of mad production and deployment of the above solutions in door of the worry of global warming, acute power shortages in major economies like India and unavailability of power solutions in remote areas of countries like Nigeria and many African nations. I feel there is a lot of market potential in such places to push in green power and also save the earth in a small way and provide good good quality of life for a lot of people.

    Would love to have some pointers towards manufactures of solar trackers, CPV system producers, Fresnel lens manufacturers, solar collectors manufacturers and emerging technologies in the solar diodes.

    Keep up the good work!

    Thank you!

    Nanda.

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