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  3. Lots of people talking about buying solar panels.

Lots of people talking about buying solar panels.

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solarpunk
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  • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

    Lots of people talking about buying solar panels. Alas if you look online there's a lot of retailers with all sorts of panels for sale, not all of which are honest. Want an easy way to check if the listed power output is plausible?
    Example using a 50w panel listed on Amazon. It's 370x820mm.
    Step 1 calculate the area in square meters. (0.37*0.82=0.3034)
    Step 2 multiply by 1000w. (0.3034*1000=303.4)
    Step 3 assume 20% efficiency and multiply (303.4x0.2=60.68)

    60.68>50w. It's Plausible.

    #SolarPunk

    disorderlyf@todon.euD This user is from outside of this forum
    disorderlyf@todon.euD This user is from outside of this forum
    disorderlyf@todon.eu
    wrote last edited by
    #4

    @quixoticgeek Are you saying solar panel manufacturers are underreporting the max wattage of their panels? Because when I read the first part of this, I assumed you meant the inverse

    quixoticgeek@social.v.stQ mo@mastodon.mlM 2 Replies Last reply
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    • disorderlyf@todon.euD disorderlyf@todon.eu

      @quixoticgeek Are you saying solar panel manufacturers are underreporting the max wattage of their panels? Because when I read the first part of this, I assumed you meant the inverse

      quixoticgeek@social.v.stQ This user is from outside of this forum
      quixoticgeek@social.v.stQ This user is from outside of this forum
      quixoticgeek@social.v.st
      wrote last edited by
      #5

      @disorderlyf no they under report. The 60 is higher than the 50 rating for the panel, as the panel has a border round it and not 100% of the area is silicon. The 50w panel in the sample has a border of about 20-30mm round the edge that is structural, but not power generating.

      But I've also seen panels the same size listed as 100w. And that's clearly not gonna happen.

      disorderlyf@todon.euD annantidote@chitter.xyzA 2 Replies Last reply
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      • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

        @BoydStephenSmithJr essentially yeah. It varies of course across the planet. But panel rating is based on 1kw/m², and typical efficiency is about 20%.

        oneinterestingfact@mastodon.ieO This user is from outside of this forum
        oneinterestingfact@mastodon.ieO This user is from outside of this forum
        oneinterestingfact@mastodon.ie
        wrote last edited by
        #6

        @quixoticgeek @BoydStephenSmithJr
        And, to return to an earlier theme, slightly more in earth orbit. Going to make cooling those orbiting data centres so much fun.

        quixoticgeek@social.v.stQ 1 Reply Last reply
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        • oneinterestingfact@mastodon.ieO oneinterestingfact@mastodon.ie

          @quixoticgeek @BoydStephenSmithJr
          And, to return to an earlier theme, slightly more in earth orbit. Going to make cooling those orbiting data centres so much fun.

          quixoticgeek@social.v.stQ This user is from outside of this forum
          quixoticgeek@social.v.stQ This user is from outside of this forum
          quixoticgeek@social.v.st
          wrote last edited by
          #7

          @OneInterestingFact @BoydStephenSmithJr exactly. Orbit is a stupid place for a datacentre.

          oneinterestingfact@mastodon.ieO 1 Reply Last reply
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          • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

            @OneInterestingFact @BoydStephenSmithJr exactly. Orbit is a stupid place for a datacentre.

            oneinterestingfact@mastodon.ieO This user is from outside of this forum
            oneinterestingfact@mastodon.ieO This user is from outside of this forum
            oneinterestingfact@mastodon.ie
            wrote last edited by
            #8

            @quixoticgeek @BoydStephenSmithJr
            I suspect Musk knows that. But do the mugs?

            quixoticgeek@social.v.stQ 1 Reply Last reply
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            • oneinterestingfact@mastodon.ieO oneinterestingfact@mastodon.ie

              @quixoticgeek @BoydStephenSmithJr
              I suspect Musk knows that. But do the mugs?

              quixoticgeek@social.v.stQ This user is from outside of this forum
              quixoticgeek@social.v.stQ This user is from outside of this forum
              quixoticgeek@social.v.st
              wrote last edited by
              #9

              @OneInterestingFact @BoydStephenSmithJr no. It's all greater fool theory.

              oneinterestingfact@mastodon.ieO 1 Reply Last reply
              0
              • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

                @OneInterestingFact @BoydStephenSmithJr no. It's all greater fool theory.

                oneinterestingfact@mastodon.ieO This user is from outside of this forum
                oneinterestingfact@mastodon.ieO This user is from outside of this forum
                oneinterestingfact@mastodon.ie
                wrote last edited by
                #10

                @quixoticgeek @BoydStephenSmithJr
                so like donnie's golden phone they'll pour money in, Musk will pretend to spend it while using it for whatever nazis spend their money on and they'll see no return whatsoever.

                1 Reply Last reply
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                • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

                  @disorderlyf no they under report. The 60 is higher than the 50 rating for the panel, as the panel has a border round it and not 100% of the area is silicon. The 50w panel in the sample has a border of about 20-30mm round the edge that is structural, but not power generating.

                  But I've also seen panels the same size listed as 100w. And that's clearly not gonna happen.

                  disorderlyf@todon.euD This user is from outside of this forum
                  disorderlyf@todon.euD This user is from outside of this forum
                  disorderlyf@todon.eu
                  wrote last edited by
                  #11

                  @quixoticgeek Yeah, I'd been waiting for efficiency to get to the point where we actually could get 100w out of a panel that size, but it's looking like I might just want to shell out for a bigger battery and (relative to its capacity) drip feed it solar. I want a panel I could fit inset into a window since I'll likely be living in a rental for at least another year.

                  quixoticgeek@social.v.stQ 1 Reply Last reply
                  0
                  • boydstephensmithjr@hachyderm.ioB boydstephensmithjr@hachyderm.io

                    @quixoticgeek So, solar flux at the surface (of Earth) is approximately 1kW/m^2?

                    ariaflame@masto.aiA This user is from outside of this forum
                    ariaflame@masto.aiA This user is from outside of this forum
                    ariaflame@masto.ai
                    wrote last edited by
                    #12

                    @BoydStephenSmithJr @quixoticgeek That's the approximate peak illumination at the peak of the day. 9am-3pm have reasonable illumination but most commercial panels have efficiencies in the low 20 percent it's a reasonable way of telling if they're bullshitting. You probably won't get that much because of the effect of heat on efficiency mind you.

                    raymaccarthy@mastodon.ieR 1 Reply Last reply
                    0
                    • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

                      @disorderlyf no they under report. The 60 is higher than the 50 rating for the panel, as the panel has a border round it and not 100% of the area is silicon. The 50w panel in the sample has a border of about 20-30mm round the edge that is structural, but not power generating.

                      But I've also seen panels the same size listed as 100w. And that's clearly not gonna happen.

                      annantidote@chitter.xyzA This user is from outside of this forum
                      annantidote@chitter.xyzA This user is from outside of this forum
                      annantidote@chitter.xyz
                      wrote last edited by
                      #13

                      @quixoticgeek @disorderlyf ...and probably they are counting on different weathers, latitudes and angles, as in not promising close to the optimum case.

                      disorderlyf@todon.euD edavies@functional.cafeE 2 Replies Last reply
                      0
                      • annantidote@chitter.xyzA annantidote@chitter.xyz

                        @quixoticgeek @disorderlyf ...and probably they are counting on different weathers, latitudes and angles, as in not promising close to the optimum case.

                        disorderlyf@todon.euD This user is from outside of this forum
                        disorderlyf@todon.euD This user is from outside of this forum
                        disorderlyf@todon.eu
                        wrote last edited by
                        #14

                        @annantidote @quixoticgeek I'm in BC, so I'm already expecting things to not be optimal, but I also might have a place to put it where it'll get as much sun as it possibly can.

                        quixoticgeek@social.v.stQ 1 Reply Last reply
                        0
                        • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

                          Lots of people talking about buying solar panels. Alas if you look online there's a lot of retailers with all sorts of panels for sale, not all of which are honest. Want an easy way to check if the listed power output is plausible?
                          Example using a 50w panel listed on Amazon. It's 370x820mm.
                          Step 1 calculate the area in square meters. (0.37*0.82=0.3034)
                          Step 2 multiply by 1000w. (0.3034*1000=303.4)
                          Step 3 assume 20% efficiency and multiply (303.4x0.2=60.68)

                          60.68>50w. It's Plausible.

                          #SolarPunk

                          terrybtwo@ohai.socialT This user is from outside of this forum
                          terrybtwo@ohai.socialT This user is from outside of this forum
                          terrybtwo@ohai.social
                          wrote last edited by
                          #15

                          @quixoticgeek The UK has lots of information in data sheets. What there isn’t is anything useful Like how long to repay the cost. Getting a straight answer from installers is tougher than getting a politician to say yes. Getting advice on if they’ll repay the cost within your lifetime is close to impossible. Then there’s the battery.
                          We got ours from Costco because they were the only ones not trying to sell panels + battery as a package. We got a battery later - I’m not sure it was a good idea.

                          quixoticgeek@social.v.stQ 1 Reply Last reply
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                          • disorderlyf@todon.euD disorderlyf@todon.eu

                            @annantidote @quixoticgeek I'm in BC, so I'm already expecting things to not be optimal, but I also might have a place to put it where it'll get as much sun as it possibly can.

                            quixoticgeek@social.v.stQ This user is from outside of this forum
                            quixoticgeek@social.v.stQ This user is from outside of this forum
                            quixoticgeek@social.v.st
                            wrote last edited by
                            #16

                            @disorderlyf @annantidote note that the angle that gets best yield in summer, Vs best yield in winter is very different. Also where in BC matters a lot.

                            Btw. Happy to offer advice, and sanity check designs for anyone doing a solar build.

                            1 Reply Last reply
                            0
                            • disorderlyf@todon.euD disorderlyf@todon.eu

                              @quixoticgeek Yeah, I'd been waiting for efficiency to get to the point where we actually could get 100w out of a panel that size, but it's looking like I might just want to shell out for a bigger battery and (relative to its capacity) drip feed it solar. I want a panel I could fit inset into a window since I'll likely be living in a rental for at least another year.

                              quixoticgeek@social.v.stQ This user is from outside of this forum
                              quixoticgeek@social.v.stQ This user is from outside of this forum
                              quixoticgeek@social.v.st
                              wrote last edited by
                              #17

                              @disorderlyf if you're putting a panel behind a glass window. Assume about 50% less power from it. I have a 100w panel behind a double glazed window and get about 50w from it peak.

                              1 Reply Last reply
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                              • annantidote@chitter.xyzA annantidote@chitter.xyz

                                @quixoticgeek @disorderlyf ...and probably they are counting on different weathers, latitudes and angles, as in not promising close to the optimum case.

                                edavies@functional.cafeE This user is from outside of this forum
                                edavies@functional.cafeE This user is from outside of this forum
                                edavies@functional.cafe
                                wrote last edited by
                                #18

                                @annantidote @disorderlyf No, there are standard test conditions for which panels are rated. As @quixoticgeek says it assumes insolation of 1 kW/m², also a specific spectrum of light (corresponding to a panel standing on flat dusty red ground in Texas with the sun at a particular elevation IIRC) and particular temperatures for the ambient air.

                                But, yes, panels can produce more than the “peak” output quoted. E.g., when a cloud has just blown away so the panel is cooler and therefore operating more efficiently and there's also more sunlight because of the reflections from the cloud just out of the line of sight. So “peak” would be better called ”nominal” output.

                                annantidote@chitter.xyzA 1 Reply Last reply
                                0
                                • terrybtwo@ohai.socialT terrybtwo@ohai.social

                                  @quixoticgeek The UK has lots of information in data sheets. What there isn’t is anything useful Like how long to repay the cost. Getting a straight answer from installers is tougher than getting a politician to say yes. Getting advice on if they’ll repay the cost within your lifetime is close to impossible. Then there’s the battery.
                                  We got ours from Costco because they were the only ones not trying to sell panels + battery as a package. We got a battery later - I’m not sure it was a good idea.

                                  quixoticgeek@social.v.stQ This user is from outside of this forum
                                  quixoticgeek@social.v.stQ This user is from outside of this forum
                                  quixoticgeek@social.v.st
                                  wrote last edited by
                                  #19

                                  @TerryBTwo it depends a lot on what your usage is like, how big a battery you can afford, do you want to charge an EV? Power a heat pump? Etc... There's a lot of variables. I think with a modern solar install, the average household is likely to pay back a suitable solar install in 3-5 years. But it does depend a lot. Gone are the days where ROI was double digits years.

                                  terrybtwo@ohai.socialT 1 Reply Last reply
                                  0
                                  • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

                                    Lots of people talking about buying solar panels. Alas if you look online there's a lot of retailers with all sorts of panels for sale, not all of which are honest. Want an easy way to check if the listed power output is plausible?
                                    Example using a 50w panel listed on Amazon. It's 370x820mm.
                                    Step 1 calculate the area in square meters. (0.37*0.82=0.3034)
                                    Step 2 multiply by 1000w. (0.3034*1000=303.4)
                                    Step 3 assume 20% efficiency and multiply (303.4x0.2=60.68)

                                    60.68>50w. It's Plausible.

                                    #SolarPunk

                                    vgarzareyna@mstdn.mxV This user is from outside of this forum
                                    vgarzareyna@mstdn.mxV This user is from outside of this forum
                                    vgarzareyna@mstdn.mx
                                    wrote last edited by
                                    #20

                                    @quixoticgeek why only 20%?:0

                                    quixoticgeek@social.v.stQ drj@typo.socialD 2 Replies Last reply
                                    0
                                    • vgarzareyna@mstdn.mxV vgarzareyna@mstdn.mx

                                      @quixoticgeek why only 20%?:0

                                      quixoticgeek@social.v.stQ This user is from outside of this forum
                                      quixoticgeek@social.v.stQ This user is from outside of this forum
                                      quixoticgeek@social.v.st
                                      wrote last edited by
                                      #21

                                      @vgarzareyna cos commercial solar panel efficiency is about 20%. Some manufacturers claim closer to 25%, but they typically lose some of that efficiency in the first few weeks of operation. As a ballpark for judging if a panel is too good to be true. 20% works and makes for easy maths.

                                      vgarzareyna@mstdn.mxV raymaccarthy@mastodon.ieR 2 Replies Last reply
                                      0
                                      • quixoticgeek@social.v.stQ quixoticgeek@social.v.st

                                        @vgarzareyna cos commercial solar panel efficiency is about 20%. Some manufacturers claim closer to 25%, but they typically lose some of that efficiency in the first few weeks of operation. As a ballpark for judging if a panel is too good to be true. 20% works and makes for easy maths.

                                        vgarzareyna@mstdn.mxV This user is from outside of this forum
                                        vgarzareyna@mstdn.mxV This user is from outside of this forum
                                        vgarzareyna@mstdn.mx
                                        wrote last edited by
                                        #22

                                        @quixoticgeek that's really cool! thanks for the info. as I mentioned in a different response, i thought efficiency was way higher, but the cool part is we have a lot of margin for improvement

                                        quixoticgeek@social.v.stQ billiglarper@rollenspiel.socialB 2 Replies Last reply
                                        0
                                        • vgarzareyna@mstdn.mxV vgarzareyna@mstdn.mx

                                          @quixoticgeek that's really cool! thanks for the info. as I mentioned in a different response, i thought efficiency was way higher, but the cool part is we have a lot of margin for improvement

                                          quixoticgeek@social.v.stQ This user is from outside of this forum
                                          quixoticgeek@social.v.stQ This user is from outside of this forum
                                          quixoticgeek@social.v.st
                                          wrote last edited by
                                          #23

                                          @vgarzareyna we're doing better than photosynthesis. That's about 1% efficient...

                                          1 Reply Last reply
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