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Area required for 1 kW

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  • Area required for 1 kW

    Some where i read for 1 KW system area required is about 16 Sq m.
    Please give comments on this and if it is true explain the method of calculation.

    Second question : i have are of 800 sq m which is shadow free. i have calculated per day generation possible in this area by considering the insolation data of the location and efficiency of solar panel as.
    Area = 800 sq m
    average insolation = 5.73 kwh/sq m
    So 800*5.73=4584 kwh
    fficiency of panel is about 12%
    per day generation = 4584 * 12%= 550 KWh
    have i done right calculation?
    From this point 550 KWh generation per day.... How i calculate PV size required?

    Thanks

  • #2

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    • #3
      Mike, Sunking or Rich - please check to verify or correct. Pretty sure I made my one mistake for the year already but who knows for sure!

      Better to work from daily insolation. For 5000 watts/m3/day - average annual insolation for my area. A number can be obtained from the NASA site for many places in the world.

      For 1 meter square

      1) 5000 watts/m2/day
      2) Of the 5000 watts per day probably something like 85% is within usable hours (from my solar thermal system) similar to the 5 hour number
      3) 16% panel efficiency
      4) 80% system efficiency for grid tied - for off grid 50% is closer

      5000 * 85% * 16% * 80% = 544 watts/m2/day useful electrical energy generated

      Russ
      Last edited by russ; 04-06-2011, 06:04 AM.
      [SIGPIC][/SIGPIC]

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      • #4
        Originally posted by vikas maurya View Post
        average insolation = 5.73 kwh/sq m

        kW/m2/day - not kWh
        Thanks
        My message was too short to be accepted so I am typing this to lengthen it.

        Russ
        [SIGPIC][/SIGPIC]

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        • #5
          Close enough Russ for a guestimate
          MSEE, PE

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          • #6
            Thanks Sunking - The PV Watts site points out there can be up to 30% variance in results over time.

            I enjoy reading where someone says 'my system performs exactly as PV Watts says it should'. PV Watts is an average over time - the only way it can be done.

            Russ
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            • #7
              Originally posted by russ View Post
              The PV Watts site points out there can be up to 30% variance in results over time.
              That would be downward over time.
              MSEE, PE

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              • #8
                That is one and also the variance from year to year.

                Russ
                [SIGPIC][/SIGPIC]

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                • #9
                  Originally posted by russ View Post
                  Mike, Sunking or Rich - please check to verify or correct. . . . . .

                  For 1 meter square

                  1) 5000 watts/m2/day
                  2) Of the 5000 watts per day probably something like 85% is within usable hours (from my solar thermal system) similar to the 5 hour number
                  3) 16% panel efficiency
                  4) 80% system efficiency for grid tied - for off grid 50% is closer

                  5000 * 85% * 16% * 80% = 544 watts/m2/day useful electrical energy generated

                  Russ

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                  • #10
                    The 1000 watts per m2 has no meaning in calculating what a system will do.

                    That is a number for a standard test only and not normally seen in most of the world.

                    Russ
                    [SIGPIC][/SIGPIC]

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                    • #11
                      Right - Do you have any idea where the 5 hours comes from?

                      Do you have any idea how often per year a site receive 1000 watts/m2

                      Do you have any idea what daily insolation is or where to learn what that number is.

                      Taking a number from here and there and multiplying them together to come out with 13 kW rather than 9 kW (which is still a rough number) wasn't to sharp.

                      The 1000 watts/m2 * 5 hours is like multiplying goats and pigs to come up with chickens.

                      Russ
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                      • #12
                        Originally posted by russ View Post

                        5000 * 85% * 16% * 80% = 544 watts/m2/day useful electrical energy generated

                        Russ
                        now to obtain 544 w/m2/day............wat will be the panel size

                        i think for this 80 wp panel is enough......pls correct me if wrong

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                        • #13
                          Originally posted by vikas maurya View Post
                          now to obtain 544 w/m2/day............wat will be the panel size

                          i think for this 80 wp panel is enough......pls correct me if wrong
                          You are way off. The number is make believe assuming a 20% efficient panel of 1/mt2. But to answer your question a 200 watt panel that occupies 1/mt2. Realistically all you can buy in your country is around 10 to 12%, so cut the production in half.
                          MSEE, PE

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