Announcement

Collapse
No announcement yet.

Performance Differences: Black Back Sheet vs White Back Sheet

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Performance Differences: Black Back Sheet vs White Back Sheet

    Is there any significant performance difference between solar panels with a black back sheet and panels with a white colored back sheet?

    The reason I ask is because I'm currently in the process of having a fixed ground mount array installed at my house in Central California. The contract with my contractor calls for Suniva Optimus 270-60-4-100 panels (silver frame, white back), but the contractor wants to switch to Suniva Optimus 270-60-4-1B0 panels (black frame, black back) due to availability. They're telling me that there is no significant performance difference, but I'm not sure if I should believe them. From my perspective, a black back sheet is going to absorb more heat from the sun and reduce power harvest. Since I live in Central CA where summertime temperatures routinely exceed 100 degrees F, I feel that reducing temperatures with a white back sheet would be ideal to maximize performance.

    So, is the color of the back sheet a significant issue? Have there been any studies performed testing the differences in back sheet colors and their effects on power harvest? Appearance of the panels is not an issue whatsoever as they are ground mounted and placed off to the side of my house; performance is most important and I don't want to sacrifice it for aesthetics. Any advice would be appreciated. (And sorry if this has been addressed before; I've been searching online and searching on this forum, but have yet to find anything.)

  • #2
    Originally posted by jbg192 View Post
    Is there any significant performance difference between solar panels with a black back sheet and panels with a white colored back sheet?

    The reason I ask is because I'm currently in the process of having a fixed ground mount array installed at my house in Central California. The contract with my contractor calls for Suniva Optimus 270-60-4-100 panels (silver frame, white back), but the contractor wants to switch to Suniva Optimus 270-60-4-1B0 panels (black frame, black back) due to availability. They're telling me that there is no significant performance difference, but I'm not sure if I should believe them. From my perspective, a black back sheet is going to absorb more heat from the sun and reduce power harvest. Since I live in Central CA where summertime temperatures routinely exceed 100 degrees F, I feel that reducing temperatures with a white back sheet would be ideal to maximize performance.

    So, is the color of the back sheet a significant issue? Have there been any studies performed testing the differences in back sheet colors and their effects on power harvest? Appearance of the panels is not an issue whatsoever as they are ground mounted and placed off to the side of my house; performance is most important and I don't want to sacrifice it for aesthetics. Any advice would be appreciated. (And sorry if this has been addressed before; I've been searching online and searching on this forum, but have yet to find anything.)
    It may very well have some effect on performance, but hard to quantify. The black back sheet will absorb more energy via thermal radiation from the surroundings, but since the backs of the panels won't see much direct solar irradiance and probably not much direct specular or diffuse reflectance, most of what the back of the panel sees will be relatively weak. There may be other factors about the black back panels that have nothing to do w/the backing that would improve performance, but I kinda doubt it.
    Also, in terms of absorbance in the infrared range, which is the bandwidth where most of the thermal radiation from the surroundings originates, the color of the absorbing surface does not matter as much as it does for sunlight.

    Still, given a choice, I'd probably go with the white backing. I bet black backing won't run any cooler. Maybe the reason the black backing is available is because they get hot and nobody wants them. Increased temps. probably won't increase service life either.

    Comment


    • #3
      Originally posted by J.P.M. View Post
      It may very well have some effect on performance, but hard to quantify. The black back sheet will absorb more energy via thermal radiation from the surroundings, but since the backs of the panels won't see much direct solar irradiance and probably not much direct specular or diffuse reflectance, most of what the back of the panel sees will be relatively weak. There may be other factors about the black back panels that have nothing to do w/the backing that would improve performance, but I kinda doubt it.
      Also, in terms of absorbance in the infrared range, which is the bandwidth where most of the thermal radiation from the surroundings originates, the color of the absorbing surface does not matter as much as it does for sunlight.

      Still, given a choice, I'd probably go with the white backing. I bet black backing won't run any cooler. Maybe the reason the black backing is available is because they get hot and nobody wants them. Increased temps. probably won't increase service life either.
      Thank you for the input; everything you said certainly makes sense. I'm surprised there haven't been any official tests done regarding performance of white backed vs. black backed panels.

      Regardless of actual performance differences, you bring up a great point with regards to service life. If black backed panels do reach slightly higher temperatures on a daily basis compared to white backed panels, will it have a notable effect on longevity? Will they break down at a faster rate? Granted, they are still backed by the standard 25 year / 80% warranty, but could black backing account for some additional degradation? Are black backed panels more readily available because nobody wants them in my region?

      Comment


      • #4
        Originally posted by jbg192 View Post
        Thank you for the input; everything you said certainly makes sense. I'm surprised there haven't been any official tests done regarding performance of white backed vs. black backed panels.

        Regardless of actual performance differences, you bring up a great point with regards to service life. If black backed panels do reach slightly higher temperatures on a daily basis compared to white backed panels, will it have a notable effect on longevity? Will they break down at a faster rate? Granted, they are still backed by the standard 25 year / 80% warranty, but could black backing account for some additional degradation? Are black backed panels more readily available because nobody wants them in my region?
        You're Welcome. Opinions vary.
        I doubt it will make a noticeable diff., but as a practical matter, how would such a diff. be measured in the field for warranty purposes - warranties being slippery and full of fine print to begin with.

        Comment


        • #5
          I'm on a SAM kick tonight, so I might as well throw this at it as well.

          Create a system with 12 of the 265-60-4-100 strung into an SMA 3000TL inverter, 20° tilt, 180° azimuth, Mirimar location, some assumed losses. Annual generation is 5621 kWh. Keep everything constant except switch to the black module, generation is 5637 kWh. They both have identical electrical specs according to the data sheets, although the black one has slightly better temp coefficients in SAM which explains the difference in model output. If there is a difference for the reasons you've suggested, SAM doesn't seem to be aware of it. It isn't clear why the temp coefficients are different.

          I couldn't model the 270's, since the black one isn't in SAM. However, a quick look at the data sheets suggests there is a slight difference between them electrically.

          It is possible black backed panels are more readily available because more of them sell for aesthetic reasons, and the warehouses will preferentially stock what sells. I've had more than one installer quote them as a "better looking" panel than the black / whites, although one of them did acknowledge there might be a small performance hit due to temp.
          Last edited by sensij; 10-22-2014, 03:35 AM. Reason: fixed link tags
          CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

          Comment


          • #6
            Originally posted by sensij View Post
            I'm on a SAM kick tonight, so I might as well throw this at it as well.

            Create a system with 12 of the 265-60-4-100 strung into an SMA 3000TL inverter, 20° tilt, 180° azimuth, Mirimar location, some assumed losses. Annual generation is 5621 kWh. Keep everything constant except switch to the black module, generation is 5637 kWh. They both have identical electrical specs according to the data sheets, although the black one has slightly better temp coefficients in SAM which explains the difference in model output. If there is a difference for the reasons you've suggested, SAM doesn't seem to be aware of it. It isn't clear why the temp coefficients are different.

            I couldn't model the 270's, since the black one isn't in SAM. However, a quick look at the data sheets suggests there is a slight difference between them electrically.

            It is possible black backed panels are more readily available because more of them sell for aesthetic reasons, and the warehouses will preferentially stock what sells. I've had more than one installer quote them as a "better looking" panel than the black / whites, although one of them did acknowledge there might be a small performance hit due to temp.
            I'd also think that slight diff. in output is likely due to the temp. coeff. As long as you have all the inputs done for the cases, one other thing might be to add the hourly array ave. mod. temp. to the output, download the outputs to excel and compare the ave. panel operating temp. for each case looking for the black backing to be a higher temp. Could be both temp. coeff. and ave. temp. or more.

            On availability, it may also be that besides aesthetic demand or other demand, or lack of it, one way or the other, vendors favor one panel over the other for profit or higher reliability reasons, or other reasons and push things in that direction.

            Comment


            • #7
              FYI, the black panel has a slightly higher output rating (2W) and also more expensive. Personally I think it also looks better, esp if it's mounted on the roof after comparing my LG300 (black) and my neighbor's SolarWorld 275W (white/silver). Not sure about ground mount though.

              For ref, white panel http://www.civicsolar.com/product/su...ht-solar-panel, black panel http://www.civicsolar.com/product/su...lk-solar-panel

              I don't think thermal issue is not bad, since the black back is facing down. I'd pick the black purely based on spec and price (being the same).
              16xLG300N1C+SE6000[url]http://tiny.cc/ojmxyx[/url]

              Comment


              • #8
                Originally posted by thejq View Post
                FYI, the black panel has a slightly higher output rating (2W) and also more expensive. Personally I think it also looks better, esp if it's mounted on the roof after comparing my LG300 (black) and my neighbor's SolarWorld 275W (white/silver). Not sure about ground mount though.

                For ref, white panel http://www.civicsolar.com/product/su...ht-solar-panel, black panel http://www.civicsolar.com/product/su...lk-solar-panel

                I don't think thermal issue is not bad, since the black back is facing down. I'd pick the black purely based on spec and price (being the same).
                I do agree that they look better and if I was doing a roof mount, I would probably go with the black back for aesthetics. However, with a ground mount system located off to the side of my house, performance is more important. It is interesting that the black panels have a slightly higher PTC watt rating. Since I have a signed contract, there's no price difference (to me) between the black panels and the white panels, but it is interesting to know that there is one.

                Comment


                • #9
                  Originally posted by sensij View Post
                  I'm on a SAM kick tonight, so I might as well throw this at it as well.

                  Create a system with 12 of the 265-60-4-100 strung into an SMA 3000TL inverter, 20° tilt, 180° azimuth, Mirimar location, some assumed losses. Annual generation is 5621 kWh. Keep everything constant except switch to the black module, generation is 5637 kWh. They both have identical electrical specs according to the data sheets, although the black one has slightly better temp coefficients in SAM which explains the difference in model output. If there is a difference for the reasons you've suggested, SAM doesn't seem to be aware of it. It isn't clear why the temp coefficients are different.

                  I couldn't model the 270's, since the black one isn't in SAM. However, a quick look at the data sheets suggests there is a slight difference between them electrically.

                  It is possible black backed panels are more readily available because more of them sell for aesthetic reasons, and the warehouses will preferentially stock what sells. I've had more than one installer quote them as a "better looking" panel than the black / whites, although one of them did acknowledge there might be a small performance hit due to temp.
                  I just tried downloading SAM, but it looks likes the website is under maintenance right now as I couldn't create an account. I've never used the program (I'm new to this site) so I don't know much about it.

                  Anyway, interesting about the power output differences between the two. However, I wonder if the Miramar location (which is San Diego I believe) in the program affects those numbers differently than if my location were used in Central California, more specifically Fresno, CA. San Diego is 70-80 degrees in the summertime whereas Fresno is 90-100 degrees and perhaps SAM is accounting for lower average panels temps in SD. I wonder if the more extreme summer temps in my area would skew those numbers differently.

                  Comment


                  • #10
                    I just sent an e-mail to Suniva to ask their opinion and I'm interested to see what they have to say. Not sure if I'll get an honest answer out of a manufacturer (or an answer at all), but I'll post back if and when I hear anything.

                    I did find this webpage earlier and the comments here do make sense. http://www.c-changes.com/types-of-solar-panel

                    "Black framed panels and even the latest “All Black” panels with black frames and black backing definitely have a better appearance than standard aluminium framed panels. They look particularly good on slate or dark colour plain tile roofs, but don’t make much difference on red or modern roofs. BUT.... black backed panels, in particular, will get a lot hotter, which will cause the solar cells to work less efficiently and you will generate less electricity. You will be paying more for the panels and generating less. So it is only worth fitting black backed panels if you are really concerned about the appearance of the panels and are prepared to accept that they won’t work as well as standard panels, eg if in you live in a conservation area."


                    "For some reason in our crazy UK market, many people are now offering completely black panels, not only with black frames, but also with a black backing behind the cells instead of the traditional white. It is true that these do give a much better appearance, particularly on slate roofs or old traditional cottages with dark coloured plain tiles.

                    However, the problem with having a black backing, is that black absorbs light and heat from the sun. this means that you do not get the extra benefit of some of the sunlight being reflected back onto the cells by the backing material. Also, the panels get hotter. Solar cells, like most electrical equipment, are more efficient when they are cooler, so that panels with black backs are always going to perform less effectively than ones with standard white backing.

                    If you are concerned about the appearance on your property, then we would recommend having a halfway house of using a panel with black anodised outer frame, instead of standard aluminium, but still have a white backing material. REC, as an example, have told us that they are not even going to produce a black backed module, because their main concern is always to try to improve the electricity that their PV panels generate and black backing is a retrograde step."

                    Comment


                    • #11
                      Originally posted by jbg192 View Post
                      I just tried downloading SAM, but it looks likes the website is under maintenance right now as I couldn't create an account. I've never used the program (I'm new to this site) so I don't know much about it.

                      Anyway, interesting about the power output differences between the two. However, I wonder if the Miramar location (which is San Diego I believe) in the program affects those numbers differently than if my location were used in Central California, more specifically Fresno, CA. San Diego is 70-80 degrees in the summertime whereas Fresno is 90-100 degrees and perhaps SAM is accounting for lower average panels temps in SD. I wonder if the more extreme summer temps in my area would skew those numbers differently.
                      SAM, PVWatts and a lot of other stuff used to estimate average long term output provides output that is site specific. Both of those tools and many others use something called a TMY file. There are other weather resources but the TMY stuff is probably still the most common. The TMY files are NOT average weather. They are more "typical" weather with 12 "typical" months chosen using selection criteria that hopefully is representative of what a typical year would be if all 12 of the "most typical" months were strung together.

                      By your comments and questions, I'd respectfully suggest your level of knowledge with solar energy is not yet well developed. Educate yourself a bit on solar energy and then start with PVWatts before you tackle SAM. Sort of like getting a learner's permit and a driver's license before you climb into a formula one car and head to Lemans. SAM is quite powerful, but it will let you do things that won't work too well and never tell you. Or, the warning messages won't do you much good if you don't know what they mean. Meant as a friendly comment only. But, the mantra of the day seem to be it's a free country, so enjoy.

                      Comment


                      • #12
                        Originally posted by jbg192 View Post
                        I do agree that they look better and if I was doing a roof mount, I would probably go with the black back for aesthetics. However, with a ground mount system located off to the side of my house, performance is more important. It is interesting that the black panels have a slightly higher PTC watt rating. Since I have a signed contract, there's no price difference (to me) between the black panels and the white panels, but it is interesting to know that there is one.
                        If it was me, I'd get the white ones. After a few days/weeks you and everyone else will stop noticing them anyway.

                        Comment


                        • #13
                          Originally posted by J.P.M. View Post
                          SAM, PVWatts and a lot of other stuff used to estimate average long term output provides output that is site specific. Both of those tools and many others use something called a TMY file. There are other weather resources but the TMY stuff is probably still the most common. The TMY files are NOT average weather. They are more "typical" weather with 12 "typical" months chosen using selection criteria that hopefully is representative of what a typical year would be if all 12 of the "most typical" months were strung together.

                          By your comments and questions, I'd respectfully suggest your level of knowledge with solar energy is not yet well developed. Educate yourself a bit on solar energy and then start with PVWatts before you tackle SAM. Sort of like getting a learner's permit and a driver's license before you climb into a formula one car and head to Lemans. SAM is quite powerful, but it will let you do things that won't work too well and never tell you. Or, the warning messages won't do you much good if you don't know what they mean. Meant as a friendly comment only. But, the mantra of the day seem to be it's a free country, so enjoy.
                          No offense taken. I'm certainly no expert on solar technology, especially considering all this was foreign to me only a few months ago. My knowledge is nowhere near as advanced as those on this forum, but I also don't think my last post was written clearly either. I do understand how PV Watts works with regards to providing site-specific data, as I've used it in the past to determine the effects of different system configurations and calculate various performances figures. While I've never used SAM, I assume it would work similar to PV Watts, but is simply a far more powerful tool capable of more advanced configuration options & scenarios. All I meant in my previous post was that perhaps the 16kwh annual production difference noted in SAM between black & white backed 265W panels in SD would be more pronounced in Central CA since summertime heat would be a more significant factor in the weather calculations that are used by the program to estimate annual production figures.

                          Comment


                          • #14
                            Originally posted by jbg192 View Post
                            All I meant in my previous post was that perhaps the 16kwh annual production difference noted in SAM between black & white backed 265W panels in SD would be more pronounced in Central CA since summertime heat would be a more significant factor in the weather calculations that are used by the program to estimate annual production figures.
                            I'm not comfortable enough in these results to feel good about running the follow up simulation. For some reason SAM is showing a slight difference in the temperature coefficients of the 265 W modules that does not agree with the data sheets. If that difference is really true, then the black ones will *slightly* outperform the white ones as the temp gets hotter. 16 kWh is much less than the margin of error for this kind of thing, especially when you have a factor like panel color that is not accounted for in SAM (based on what is in the documentation, and based on other tests I've run).

                            How many panels are being put up? If possible, my vote would be to install one string of black, and a string of silver / white, in way that will allow both strings to see the same amount of sun. If using microinverters, even easier. Publish the results here after a few months of running!
                            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                            Comment


                            • #15
                              Originally posted by sensij View Post
                              I'm not comfortable enough in these results to feel good about running the follow up simulation. For some reason SAM is showing a slight difference in the temperature coefficients of the 265 W modules that does not agree with the data sheets. If that difference is really true, then the black ones will *slightly* outperform the white ones as the temp gets hotter. 16 kWh is much less than the margin of error for this kind of thing, especially when you have a factor like panel color that is not accounted for in SAM (based on what is in the documentation, and based on other tests I've run).

                              How many panels are being put up? If possible, my vote would be to install one string of black, and a string of silver / white, in way that will allow both strings to see the same amount of sun. If using microinverters, even easier. Publish the results here after a few months of running!
                              That would definitely be an interesting test doing one string black and the other white! I'm honestly surprised it hasn't been done before to see if there is a difference. However, for my installation, it'll have to be one or the other as they'll all be mounted together on a single rack mount with two string inverters; while I'm not too concerned about aesthetics, it would look a little funny having my array split in half with two different panel types. Thank you though for offering to run another simulation, much appreciated, but it doesn't sound like it would be beneficial.

                              Comment

                              Working...
                              X