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Increase photovotaic output

  1. Jan 23, 2010 #1
    Could placing a photovotaic inside of focus of a concave mirror amplify the effiecentcy X times?would commercial panels take the extra lumens?
  2. jcsd
  3. Jan 23, 2010 #2


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    Last edited by a moderator: Sep 25, 2014
  4. Jan 23, 2010 #3
    Two things:
    1) the solar conversion efficiency (electricity watts out per unit area/solar insolation per unit area) decreases for high power in because the solar photovoltaic cells get too hot. They need to be cooled.

    2) Regardless of how much solar reflector magnification is used, the land area required per electrical watt out is still limited by the solar insolation per square meter, ~ 800-1000 watts peak per square meter at sea level at noon.

    Bob S
  5. Jan 23, 2010 #4
    Yeah, and just to add to this, putting a solar panel at the foci of a concave mirror is a bad idea. Incredibly high temperatures can be reached, basically detroying all or part of the panel.
    I have seen angled flat mirrors(or aluminum foil) used. This provideds for more light hitting the panel, but evenly distributed(as opposed to concentrated like with concave)
    This can be extremely effective.

    Still, there is much to consider. Decent solar cell panels are expensive. Modifying how its designed to be used can destroy it if understanding and precautions are not taken.
    And sometimes it's pointless, as there is a maximum energy output regardless of input.

    For example, if you bought a good quality 100-watt solar cell and at high noon in Florida in June it produces nearly 100-watts you are doing well! I would NOT attempt to increase incident light under that circumstance.
    Depending on manufacturer, there are immutable upper limits. A 100 watt solar cell might be able to peak at 125-135 watts(not sure the actual ratings)
    Thus increased incident light will increase output up to its peak rating, then no further.
    And, above its peak, the solar cell will start to be destroyed.

    The point here is this: doubling the incident light for that above arrangement(by even using just one large mirror) will potentialize a 140-165 watt output, which is above it's peak rating and will start to destroy the panel. Bye-bye 300-500 dollars.

    So, don't do that.

    Now, let's say you have that same panel but live in a different climate such that in June on a clear, sunny day at noon that same panel only produces 50 or 60 watts, even pointed directly at the sun.

    Under those conditions, it can be a good thing to artifically increased incident light, again remembering not to do it so much that it goes at and beyond peak rating.
    Indeed, with enough mirrors one can produce 100 watts from moonlight alone.

    But the bottom line is cost. My personal experience is that it is better to just buy another panel and/or a solar tracking mechanism.
    I live in Montana and installed solar panels on both my house and 5th wheel.
    I found it better to just "stick to the basics" Extreme reliabilty that way.
  6. Jan 23, 2010 #5


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    That sounds like some kind of multijunction high efficiency PV cell, like the ones from Spectrolab, and are intended to be used in concentrators.

    Is that what Framen has produced here? He claims he can get a GW(e) from 12 km^2. Well 12 km^2 receives ~10 GW of solar radiation in Israel at noon, so 1 GW(e) is a 10% overall efficiency claim for such a plant, nothing spectacular. The cost per Watt would be the interesting figure.
    Last edited by a moderator: Sep 25, 2014
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