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New Pole Mount PV array

Post in 'The Green Room' started by peakbagger, Jun 11, 2012.

  1. peakbagger

    peakbagger Minister of Fire

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    I got a deal on closeout Evergreen Solar Modules over the winter and finally had time to get them installed on my prior pole mount. The racking is made with Unistrut. Due to the configuration of my inverter I installed 2100 watts (STC) of panels which I feel is "pushing" the capacity of Unistrut. The install went quick but startup got delayed a week due to an unknown prior issue with my existing inverter. My old panels were used monocrystalline while the new ones are amorphous. I havent done a lot of testing but it sure looks like the amorphous panels work better in less than blue sky conditions. On a clear day I am seeing 12 to 14 KWhrs per day, which should get me to the point that I generate more than I need on yearly basis

    The array is adjusted for angle 3 times per year. The brace running down to the concrete post is a new addition to reduce twisting of the array during windy conditions. Do note, the pole is vertical, I must have held the camera crooked.

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  2. Jags

    Jags Moderate Moderator Staff Member

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    Man, that is awesome. Are you grid tied with that system?
  3. begreen

    begreen Mooderator Staff Member

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    Cool. I like the seasonal adjustment. Are these Enphase inverters?
  4. peakbagger

    peakbagger Minister of Fire

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    Its a grid tied system, the pole is 200 feet from the house so a typical off grid unit would require huge wires to get to my basement (unless I went with the new high voltage charge controllers). I have a generator if the power goes out but it rarely does for long. The inverter is a Fronius IG 2000. No real need for microinverters as the panels dont have shading issues and they were brand new to the market and expensive when my Fronius was bought plus they wouldnt have matched my Siemens 65 Watt panels. My old array was only 965 watts but the Fronius was the best fit at the time so it ran underloaded until the upgrade. When I installed it the first time I made sure all the wiring and disconnect switch were sized for the maximum output of the inverter so all I had to do was daisychain the panle wires and terminate them in the old junction box.

    Its a bit hard to see, but the pivot pont for the array is straddled by the two rectangular steel posts (someone gave them to me so thats why I dont have a pipe) with a 3/4" stainless steel pivot rod. The benefit to two tubes is it could make horizontal tracking easy. With the old array I could have put in a linear actuator and tracked it, but with the new wind brace I would have to come up with different approach. Then again at 0.91 cents a watt delivered it made sense to just install the maximum number of panels I could fit.

    The old array would be great for off gird as they are the older type designed to charge batteries plus they are built very heavy duty, the Evergreens are nice but those Siemens Panels were designed for abuse. One of these days I will figure out what I want to do with them.
  5. semipro

    semipro Minister of Fire

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    Looks great. You've inspired me peakbagger. I've been long planning rooftop PV arrays at our place but last week came to the realization that our roof is too shaded for this. I immediately turned my thoughts to a ground-based array like yours. Then I saw your post. I think its an omen.

    I was thinking of placing our array just to the north of our garden knowing that it will always be sunny there. I was also wondering if the light reflected from the array would benefit the garden. Of course, it might also cook my veggies on the plant.
  6. peakbagger

    peakbagger Minister of Fire

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    I have a small array hung off my house that looks like an awning, it requires a hydraulic floor jack to adjust. I will take the pole mount array anytime. Sure it costs a bit more up front but in Northern NH, a roof mount doesnt work well due to snow accumulation. Pole mounts usually get higher overall yearly output as they are easier to adjust and the panel temps are lower. Reflection off the panels may be an issue in VA, but in NH during the spring and fall the panels are angled up at 45 degrees from vertical and during the summer they are 60 degrees so I dont think there would be much reflection issues for the garden. In the winter they are at 30 degrees and I dont see any unusual snow melt in front of them (but my output goes up to above the rated panel load on clear winter days due to reflection off the snow). I do need to run a snowblower in front of them on occasion in the winter after a lot of snow as the snow that slides off them builds up in pile outfront.

    I got the structural tubing for free and used 50 bags of sackcrete to build the base. I had an underground conduit run fairly close by so I didnt have much trenching.

    Two things to consider is that the pole needs to a get a lot bigger diameter as the height increases and the wiring must be "inaccessable" without using tools. Many panel mounts are surrounded with a chain link fence around them which makes them pretty ugly and "threatening" to some folks. If there were a lot of kids around or there was a high crime rate, a fence may be preferable but in my case neither was an issue. I also went with "black frames" they are a bit less noticable than the older style alumimum frames.
  7. semipro

    semipro Minister of Fire

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    Where is your inverter located? Is there any reason you can't locate it in a weathertight enclosure near the collectors? Heat could be an obvious issue.

    I've got quite a bit of spare tubing and can weld so I may be able to build the support system inexpensively.
    I really like the idea of manual angle adjustment by season, ground-level access for installation and maintenance, and not having to put holes in my roof.
    The reason my roof is now sunny is because deciduous trees have grown to shade it. They didn't used to.
    It seems their shading benefit is worth more to me than being able to mount PV panels on my roof.
    Thanks for the info.
  8. peakbagger

    peakbagger Minister of Fire

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    The inverter is in the basement, it could just as well be at the pole and many inverters are in rain tight enclosures so they could be pole mounted. They do need cooling so they shouldnt be installed in an enclosure The maximum amperage is around 9 amps @240volts AC so the wiring size isnt an issue.
  9. Jags

    Jags Moderate Moderator Staff Member

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    In short words (if possible) what are the advantages/disadvantages of mono/poly/amorphous? I have been trying to keep an eye out for good deals, but have not recently kept up with the tech like I should.
  10. Jags

    Jags Moderate Moderator Staff Member

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    Belay my last. I actually went and did the homework. Interesting. What is a good price per watt these days? Fleebay is all over the place.
  11. peakbagger

    peakbagger Minister of Fire

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    Sunelec.com (Sun Electronics) in Miami are the close out kings for PV overstocks. They are not a full service house but usually set the bar on lowest price. I see several name brand panels for 1.25 dollars per watt. You also need to add in delivery, I paid $500 to get 23 panels delivered from Miami to Northern NH and could have saved at least a third by picking them up at a local freight terminal. They have other panels listed at 99 cents per watt but they are for a shipping container full. The big ticket item is the inverter (or inverters if you go with microinverters). Remember there still is a federal tax credit for 30% of the total installed system cost, plus most state have incentives.

    Flebay has a lot of non UL rated panels and some that may have forged listings. Stick to known brand unless you want to use them for off grid and dont care how long they last. The harbor freight panels typically are pretty poor quality.

    If you do deal with Sunelectronics , keep detailed notes and dont assume they know what they are doing. They did a big Evergreen close out last fall and it just about drove them out of business as they didnt have the resources to handle the volume. I think they have learned some lessons but managed to piss off a lot of folks along the way..

    By the way Evergreens are sort of half moncrystaline and half amorphous due to the way they were manufactured.
  12. Jags

    Jags Moderate Moderator Staff Member

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    Good info. Thanks.
  13. velvetfoot

    velvetfoot Minister of Fire

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    I've just started scratching the surface, but did you get a certified outfit to install your original system to qualify for any kind of rebate? I think that's the case here, but I'm not sure.
  14. peakbagger

    peakbagger Minister of Fire

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    I did my own design based on a lot of study over the years. In NH, you can DIY but need a sign off for electrical unless the town doesnt elect to inspect residential (like mine). I did get a state rebate and the 30% fed rebate. My system was grandfathered so I didnt need a site survey, but I had already done one using a transit so I knew I was in good shape. You rebates stated int he other post were a lot more attractive than mine.

    Worse case is I have a PE stamp, so if there was an issue I was comfortable enough with the design that I would be willing to stamp it. For most folks I would recommend going with a commerical racking system to avoid the stamping issue.
  15. peakbagger

    peakbagger Minister of Fire

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    The new array generated about 280 kWhrs for the month of July. I wish that would be the case for the rest of the year! I do not keep extensive records on what I send into the grid (no need for a separate meter in NH), so I am not sure how much I have "banked" for winter. I will when I get my electric bill this month. I do know that my meter is definitely counting down, the next goal is to watch what happens when it goes below zero.

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