seasonal adjustments

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fatheadl
fatheadl Solar Expert Posts: 31 ✭✭
Hi all,

1) Is there any benefit to seasonal adjustment's? If yes, how much.
2) For 2 sets of series panels in parallel, if one string is shaded, does it affect the output of the unshaded string?

Thanks

Comments

  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
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    Re: seasonal adjustments

    Fatheadl,
    1) Is there any benefit to seasonal adjustment's? If yes, how much.

    You can visit RReDC to compare data for a location in your area. For example, you might to compare the annual total of monthly averages for a south-facing array tilted up at latitude vs the totals for April through September for Lat + 15 degrees and October through March for Lat - 15 degrees. I think the difference for fixed at latitude vs summer- and winter settings in my area is <4%.

    See: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/sum2/state.html
    2) For 2 sets of series panels in parallel, if one string is shaded, does it affect the output of the unshaded string?

    It depends. If a string is significantly shaded and its voltage is reduced, that would probably lower the other string's output voltage as well. However, if the shading only reduces current but not voltage, then the other string won't be significantly affected.

    HTH,
    Jim / crewzer



  • BB.
    BB. Super Moderators, Administrators Posts: 33,476 admin
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    Re: seasonal adjustments

    To clarify Jim's comment... I believe that if you have two strings, and shade one panel in one string, your total output will be reduced by 1/2 (i.e., the one string is no longer able to supply any current since its output has been reduced below that of the other string connected in parallel).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SolarJohn
    SolarJohn Solar Expert Posts: 202 ✭✭
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    Re: seasonal adjustments

    I recently wrote about this topic on my blog.  I included a few links that should be helpful.

    http://solarjohn.blogspot.com

    John
  • fatheadl
    fatheadl Solar Expert Posts: 31 ✭✭
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    Re: seasonal adjustments

    Hi Jim
    You can visit RReDC to compare data for a location in your area. For example, you might to compare the annual total of monthly averages for a south-facing array tilted up at latitude vs the totals for April through September for Lat + 15 degrees and October through March for Lat - 15 degrees. I think the difference for fixed at latitude vs summer- and winter settings in my area is <4%.

    See: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/sum2/state.html

    I live in Jamaica, the nearest place to me is San Juan, Puerto Rico. So without specific data, I was asking generally.

    Thanks

  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
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    Re: seasonal adjustments
    "I live in Jamaica..."

    OK... the following map may be helpful. You'll have to search around the Internet for more specific data.

    See: http://www.mrsolar.com/Merchant2/merchant.mvc?Store_Code=MSOS&Screen=faq23c

    HTH,
    Jim / crewzer