How important is cell efficiency

How important is the efficiency of a solar panel when selecting a panel. I'm looking at installing a grid tied system in phoenix and my contractor is recommending the Sanyo HIT Power N 210 panel over the Sharp 224 U1F because it is more efficient and will produce more power on hot days. And of course the Sanyo system is more expensive.

How important is efficiency in hot weather?

Can someone shed some light on this.

Comments

  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: How important is cell efficiency

    Unless you have severe space limitations, the effect is pretty much zero. The only thing that higher efficiency gives you is a few more watts in the same panel area/space.
  • System2System2 Posts: 6,290 admin
    Re: How important is cell efficiency

    Thanks, that is what I thought.

    I know heat affects the output of a panel, how can I tell by looking the specification of a panel that ambient temperature will affect one panel more or less than another panel.
  • nigtomdawnigtomdaw Solar Expert Posts: 705 ✭✭
    Re: How important is cell efficiency

    The differences between panels made of the same material poly crystalline silicon or mono crystalline will be slight.

    More important and will have a larger affect of power yield will be how the panels are installed. Panels on a single pole mount or ground mount with lots of free air circulation will fair better than roof mounted panels. The better the air circulation the better the cooling properties the higher power harvest.

    Whilst Manufacturers claim efficiency ratings of XYZ, your biggest performance gain will be looking at $ per watt and on Branded Products who have a good history in the PV Panel market and excellent warranties

    Nigel
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: How important is cell efficiency

    also note that you are paying an extra high premium for the high efficiency. unless it is that vital to fit so many watts of pv in a given area then go by the price per watt. this may reduce the system output somewhat given the same number of pvs used, but it may be a big $ savings.
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: How important is cell efficiency
    solar4mae wrote: »
    Thanks, that is what I thought.

    I know heat affects the output of a panel, how can I tell by looking the specification of a panel that ambient temperature will affect one panel more or less than another panel.

    The panel's datasheet should give a Temperature Coefficient rating for Pmax which will tell you how much power is lost for every degree C above 25 degrees C. This value is dependent on the type of panel and doesn't have anything directly to do with the efficiency. Poly and mono panels are more affected by high temperatures than amorphous silicon panels. For example:
    • The Sharps you mention are pure poly and have a temperature coefficient of -0.48%/C
    • Kaneka K60 is pure amorphous and has temp coef. of -0.23%/C
    • The Sanyo HIT's are hybrid panels (so a bit of both) and have temp. coef. of -0.34%/C

    Out of the lot, the Kaneka's tolerate high heat the best, but they're also the least efficient, so would require more space, and more mounting structure, cables etc.

    What it comes down to is how important the various factors are to you and your particular requirements.
    - If space is short then go for the hybrid sanyo's
    - If high temp performance is of the utmost importance, then consider amorphous or hybrid panels
    - If money is tight, then consider the sharps
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: How important is cell efficiency

    To compare real world output of various panels and panel types, try: http://www.sonnenertrag.eu/suche.php
    it's a huge database of grid connected PV systems with real statistics. Recommend you choose to search for German plants as they have the largest number of PV systems by far. If performance in high temperature conditions is a concern, then Spain is your best bet.
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