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Any benefit flatter angle, tracking mount, for summer ?

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  • Any benefit flatter angle, tracking mount, for summer ?

    With an easy to change horizontal angle on tracking mount, is it worth it for the summer months considering the rise and set lower angle? Is there some chart, or app that I can find for my position whether it's worth it?

  • #2
    Originally posted by Brian53713 View Post
    With an easy to change horizontal angle on tracking mount, is it worth it for the summer months considering the rise and set lower angle? Is there some chart, or app that I can find for my position whether it's worth it?
    There are a few websites that can be used to give you the proper angle for positioning photovoltaic panels during each annual season for your location.

    It is well worth the effort to do so.
    4400w, Midnite Classic 150 charge-controller.

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    • #3
      1.) For most locations, tracking is probably not cost effective in terms of cost or maint. That is, the net present value (NPV) of adding single axis tracking will be more than the NPV of the additional energy produced. It'll also take more maint. KISS applies.
      humb: Best summer orientation, equator facing at latitude -15 deg. tilt. Best winter orientation, equator facing at latitude + 15 deg. Best spring/fall orientation, equator facing with tilt = latitude.
      3.) Some variation for local conditions may be needed. For example, locations w/early morning fog/clouds will shift ideal azimuth west maybe 5-10 deg. or so. Or, lots of snow cover may increase optimum winter tilt 5-10 deg. or so.
      4.) Run PVWatts and use seasonal (3 month or so) totals to optimize at various tilts and settle on what will perhaps be a compromise azimuth. You might be surprised to learn how effective 3 tilts es done 4 times/yr. by hand can be.

      Most of this is not rocket science.

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      • #4
        Maybe, Do you run out of power in the summer, that changing angles will solve ? I just set my arrays for winter angle, and the longer hours in summer makes up for not having to re-tilt the panels and I still hit float
        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

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        • #5
          Forgot to mention ground-mounted, human-powered moving of the array two or three times. Changed to a flatter angle for the summer wondering if it's worth it considering the sunrise and sunset lower angle than the midday overhead angle. How many hours in the morning and evening is the Sun at a lower angle than the midday summer overhead angle?

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          • #6
            As J.P.M. suggested, just run the orientations you are considering in PVwatts to see the effect. For even more powerful modeling, install System Advisor Model (SAM).
            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

            Comment


            • #7
              Originally posted by Brian53713 View Post
              Forgot to mention ground-mounted, human-powered moving of the array two or three times. Changed to a flatter angle for the summer wondering if it's worth it considering the sunrise and sunset lower angle than the midday overhead angle. How many hours in the morning and evening is the Sun at a lower angle than the midday summer overhead angle?
              We have a Summer angle, a Spring/Autumn angle and a Winter angle.

              The sun's daily path seems to linger in the Summer arch for a long time, while the transition from Summer to Autumn happens quickly.

              Our PV array is only setup to have those 3 angles.

              We only mess with it four times a year. It takes us about 20 minutes each time, to change from one angle to the next.

              4400w, Midnite Classic 150 charge-controller.

              Comment


              • #8
                Originally posted by Brian53713 View Post
                Forgot to mention ground-mounted, human-powered moving of the array two or three times. Changed to a flatter angle for the summer wondering if it's worth it considering the sunrise and sunset lower angle than the midday overhead angle. How many hours in the morning and evening is the Sun at a lower angle than the midday summer overhead angle?
                Tilt angle adjustments for a period, be it a season, month, day or minute work (if done correctly) by increasing time integrated sum of the product of (cosine of the solar angle of incidence on a collection device X normal (perpendicular) beam radiation) for that period. Maximizing that sum will maximize the P.O.A. irradiance for that period.

                In the bigger scheme of things and as a practical matter, more attention is usually paid to the period +/- ~ 3 to 4 hrs. on either side of solar noon, with the sum of those values maximized over the period in question - say, a season.

                Beyond those times, that is, relatively early and late in the day, decreased P.O.A irradiance, combined with the increased reflection losses from glazing as the angle of incidence increases, multiply together to reduce production to usually something less than 5-10 % of the daily total, +/- some. Often, morning or late day weather conditions such as fog etc., reduce those totals further.

                Bottom line: For seasonal adjustments in particular, concentrate on what's happening +/- 4 hrs. around solar noon and less about the tails (early and late) parts of the day.

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                • #9
                  I have pole mount and a wall mount array that both can be adjusted for seasonal angle. Long ago I figured I gain about 10% by changing angles seasonally. Realistically I live in a snow zone and the bigger benefit is I adjust them at 30 degrees off vertical in winter so snow doesn't build up as much and they tend to self clear quicker. The PV models don't deal well with snow covered ground which when the panels are adjusted at a winter angle reflect extra light on the panels. in combination with cold weather and clear winter skies I can exceed the rated capacity of my panels

                  I designed both array systems. The pole mount takes less than 5 minutes to switch as its a center pivot that is pretty well balanced. The wall mount requires a floor jack to move. It takes me about 15 minutes to switch.

                  Comment


                  • #10
                    Originally posted by peakbagger View Post
                    I have pole mount and a wall mount array that both can be adjusted for seasonal angle. Long ago I figured I gain about 10% by changing angles seasonally. Realistically I live in a snow zone and the bigger benefit is I adjust them at 30 degrees off vertical in winter so snow doesn't build up as much and they tend to self clear quicker. The PV models don't deal well with snow covered ground which when the panels are adjusted at a winter angle reflect extra light on the panels. in combination with cold weather and clear winter skies I can exceed the rated capacity of my panels

                    I designed both array systems. The pole mount takes less than 5 minutes to switch as its a center pivot that is pretty well balanced. The wall mount requires a floor jack to move. It takes me about 15 minutes to switch.
                    When you write pole mount, is that one support in the ground or several ? Or a structure with elevation but no azimuthal adjustment ?

                    Yea, most models don't handle snow well in terms of either albedo enhancement or penalties from covering array area. Lots of variation in snow makes it hard to quantify .

                    My numbers for % instantaneous enhancement from ground snow cover over no snow cover from measurements taken over many years in Buffalo suggest about 10% or so gain in efficiency for thermal applications from albedo enhancement. Ideal winter tilt for my location there with snow cover present was ~ 70-72 deg. with respect to horizontal and ~ 60-62 deg. for bare ground. Interestingly perhaps, a vertical orientation was within a few % or so of the ~ 70 deg. tilt with snow on the ground and a whole lot easier to keep snow free. If I was still living there, and using active solar thermal (but not to suggest active solar thermal heating is easy or even possible to make cost effective in that location), I'd go vertical, add ~ 5% surface area and stay inside more. Better yet, go passive solar with nite insulation. Still not cost effective for heating only, but I got to sit inside the collector on sunny days and enjoy some warmth. Priceless.

                    Comment


                    • #11
                      Originally posted by peakbagger View Post
                      I have pole mount and a wall mount array that both can be adjusted for seasonal angle. Long ago I figured I gain about 10% by changing angles seasonally. Realistically I live in a snow zone and the bigger benefit is I adjust them at 30 degrees off vertical in winter so snow doesn't build up as much and they tend to self clear quicker. The PV models don't deal well with snow covered ground which when the panels are adjusted at a winter angle reflect extra light on the panels. in combination with cold weather and clear winter skies I can exceed the rated capacity of my panels

                      I designed both array systems. The pole mount takes less than 5 minutes to switch as its a center pivot that is pretty well balanced. The wall mount requires a floor jack to move. It takes me about 15 minutes to switch.
                      That sounds excellent. So far things aren't adjustable here, but that should change. It would take some electric motors
                      to get down to 20 minutes. Bruce Roe

                      Comment


                      • #12
                        Actually twin rectangular tubes standing side by side the width of a unistrut apart poured in a large concrete post. There is a 3/4" stainless shaft that runs through the two rectangular tubes. There are three unistruts that pivot off the shaft, one between the two posts and one on either side. This allows the entire array to pivot in one direction for elevation while being held from rotating. The movable part of the array is centered on the pivot so its very well balanced. I built the array from scratch and assembled it by hand by myself from the ground. In order to install the panels I would rotate the frame around the axis and install one at a time then rotate the rack back the other way, that way the array was pretty pretty close to balanced and I was always working on the lower edge. I do have two wind braces that run from the lower edge of the frame back to the center post to cut down on rotational "whipping" that can occur in high winds. I usually only leave one on in in the spring and summer. I am in high wind zone and haven't had any issues. The array used to have different panels and was modified for my current setup. I did it with mostly single unistrut which was readily available, If I were to build it from scratch I would use the double and triple unistrut sections to stiffen things up. I have PE stamp if I need it but our local town inspector didn't require a professionally designed mount.

                        Comment


                        • #13
                          Originally posted by peakbagger View Post
                          Actually twin rectangular tubes standing side by side the width of a unistrut apart poured in a large concrete post. There is a 3/4" stainless shaft that runs through the two rectangular tubes. There are three unistruts that pivot off the shaft, one between the two posts and one on either side. This allows the entire array to pivot in one direction for elevation while being held from rotating. The movable part of the array is centered on the pivot so its very well balanced. I built the array from scratch and assembled it by hand by myself from the ground. In order to install the panels I would rotate the frame around the axis and install one at a time then rotate the rack back the other way, that way the array was pretty pretty close to balanced and I was always working on the lower edge. I do have two wind braces that run from the lower edge of the frame back to the center post to cut down on rotational "whipping" that can occur in high winds. I usually only leave one on in in the spring and summer. I am in high wind zone and haven't had any issues. The array used to have different panels and was modified for my current setup. I did it with mostly single unistrut which was readily available, If I were to build it from scratch I would use the double and triple unistrut sections to stiffen things up. I have PE stamp if I need it but our local town inspector didn't require a professionally designed mount.
                          I think I understand. Sounds like you had fun designing it. Thank you for the info..

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