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  1. #1
    Veteran Member hayden's Avatar
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    Default Solar Electric Project

    I've got another project going in parallel with my shop construction. My place is 100% off the grid with power being supplied by solar panels and a backup generator. It works great, but as we use the house more and more we have found the system to be undersized and the generator runs much more than I'd like.

    So, I'm doing a major upgrade of the system. I'll be expanding the solar panels from a little over 600W to over 3100W, and will be replacing the 4KW 120V inverter with a 6KW 240/120 split phase inverter. On the battery front, I'll be changing from a 24V bank to 48V and jacking up the capacity. I haven't nailed down the exact battery sizing, but I'm thinking of something around 1000Ah @ 24V. My current bank is 800Ah @ 24V.

    Since I have a concrete truck coming for my shop foundation, I decided to set the solar panel mounting poles and footings. The first pictures are of the trench I dug for the footings. These babies are 6' deep and will be formed with 36" diameter Sonotubes. There will be two poles spaced 10-11' apart. The poles are aligned E-W so the panels face due south without shading each other.
    Attached Thumbnails Attached Thumbnails -pch_2008-05-29-0028-jpg   -pch_2008-05-29-0029-jpg   -pch_2008-05-29-0030-jpg   -pch_2008-06-02-0043-jpg  

  2. #2
    Veteran Member hayden's Avatar
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    Default Re: Solar Electric Project

    Here are the sonotubes and the poles being prepped. The tube was 12' long and I cut it in half for the two footings. These things are huge, and you can get a sense of it by the way they fill the garage door.

    The poles are 16' long, 6' schedule 40 galvanized pipes. Holly molly steel has gotten expensive. The 21' pipes these were cut from cost almost $600 each! Yikes.

    I put two riser clamps on each pipe offset by 90 deg. On each clamp I replaced one of the bolts with a much longer bolt that I could use to attach prop poles. I also shackled a lifting chain to the other side of one clamp.
    Attached Thumbnails Attached Thumbnails -pch_2008-06-01-0033-jpg   -pch_2008-06-02-0040-jpg   -pch_2008-06-02-0042-jpg  

  3. #3
    Veteran Member hayden's Avatar
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    Default Re: Solar Electric Project

    And here are the poles and sonotubes getting set in position. I put the tubes in the hole first, then worked the pole into the tube, It was a bit tricky doing it. My tractor was about 2' short of being able to lift the poles high enough to just drive them over the tubes and lower them down. As a result, I lifted them as far as I could with the forks, then hefted the end into the tube by hand. I used the forks because the frame has a nice D-ring that I was able to shackle my lifting chain to. The forks also provided side guards just in case the pole got a way somehow, though it would have been difficult because the chain was shacked at both ends.

    Once the pole was down in the hole I could edge the tractor into position to set the pole. I pushed the pole to center the end in the hole, then my wife lowered the pole until the lifting chain went slack. Once the weight of the pole was on the ground, I bolted my braces to those long bolts on the clamps and worked the pole until it was plumb. After the pole was set and braced, I climbed into the hole and leveled the sonotube, then back filled around it with a few inches of crushed stone to keep it from walking around while it's being poured.
    Attached Thumbnails Attached Thumbnails -pch_2008-06-02-0044-jpg   -pch_2008-06-02-0050-jpg   -pch_2008-06-02-0052-jpg   -pch_2008-06-02-0053-jpg   -pch_2008-06-02-0054-jpg  

    -pch_2008-06-02-0055-jpg  

  4. #4
    Super Member 3RRL's Avatar
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    Default Re: Solar Electric Project

    Peter, nice project...I was just reading your updates on your other thread too.
    I guess it's too late now, but I was going to recommend putting those poles farther apart. It's Summer now and the Sun is high, but as Winter comes around and the shadows get low, you might be surprise as to where the shadows are cast. And that's when you need them to work best since there's less daylight. I don't know if you've seen my thread about my solar project, so I went through all that already.
    Will you have the ability to rotate or move the direction your panels are facing? Mine are dual axis but my neighbor sets his manually about 2 or 3 times a year to get the best angles.
    Rob-
    ...The Older I get...the Better I Used to be...
    Member of the Month

  5. #5
    Veteran Member hayden's Avatar
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    Default Re: Solar Electric Project

    I'm not planning to use trackers. Up here at the north pole (Vermont) they don't have the advantage that they do further south. If I was using trackers I'd likely have a problem with shading, but the panels will always be facing due south and the two arrays are in the same plane at all times. Right now I adjust the tilt manually twice a year.

    I checked the site with a solar pathfinder to be sure my exposure was good, so I'm pretty sure I'm OK. The only issue might be that one pole stand a bit higher than the other so late in the day I might get some shading of the eastern array. However, I've got trees that will shade everything later in the day for much of the year. I'm planning to leave the poles at different heights for now. If it's a problem I can always cut the pole down to match the height of the lower pole.

    My fingers are crossed...

  6. #6
    Veteran Member hayden's Avatar
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    Default Re: Solar Electric Project

    In between rain showers I managed to get all the electrical conduit in place where it will be embedded in the concrete footings. This approach will take some of the strength away from the concrete, but I think there will still be plenty to hold the main pole.

    As you can see from the pictures, there are quite a few pipes. Some of it is for the solar arrays, and some is in anticipation of a hydro shed another 150' down the hill. I figured I'd use the conduit run from the panels to the house for both devices, even though I'm only putting in the solar now. I also have two conduits running in parallel. One for high voltage DC from the panels and ultimately the hydro generator. Code requires that these be in their own conduit and not be shared with other cables. The second parallel pipe is for low voltage control wires. Right now I don't need any for the panels, but some day I might put in a tracker or other monitoring device. I'm also considering relocating my TV dish to the side of the pole so I might need to run coax. Both the high and low voltage conduits then continue on to the eventual hydro shed. For now they will be capped off and burried.

    There is also one pipe that runs between the solar mount poles to consolidate the power at one pole before running up to the house.

    The pipes running to the house are capped off too for now. Later I'll trench and extend them into the house, but for now I wanted to jump on the poles (actually the concrete footings) while I have concrete tucks coming through.

    Finally, I'm ready to pour and hope to tag onto a footing pour tomorrow.
    Attached Thumbnails Attached Thumbnails -pch_2008-06-03-0063-jpg   -pch_2008-06-03-0067-jpg   -pch_2008-06-03-0066-jpg  

  7. #7
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    Default Re: Solar Electric Project

    Great job. Does your state of NH/VT have any rebates or other incentives on PV systems? And if so, does the PV system need to be grid tied?
    A 600 watt system will not make much power but a 3100 watt system will do much better. Is this your year round house? Hunting cabin? Or?
    What about the rest of your energy needs like water heating and space heating?

  8. #8
    Veteran Member hayden's Avatar
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    Default Re: Solar Electric Project

    I need to check and see if anything has changed, but last I looked VT (where the property is located) only offered incentives for grid-tied systems. Oh well.

    The house is 200 years old but was never electrified and sits about 3/4 mile from the last pole. About 10 years ago I built a trial system to see how inverter technology worked, etc. The first system was a 1 KW 12V inverter/charger, 4 deep cycle marine batteries, and a generator. It was a great success, so I added about 150W of solar panels. We were only using the house on occational weekends so the panels were mainly to keep the system charged up while we were away.

    A couple of years later we started using the place more frequently, though still on weekends, and we added a bunch of creature comforts like dishwasher, microwave, washer/dryer, TV, etc. To support that I upgraded to a 4KW 24V inverter/charger, upped the panels to the current 600W+, added a quality built-in 4KW generator, and switched to good quality batteries more suitable to the purpose. It's powering the TV I'm watching now, plus the laptop and satellite internet I'm typing this on.

    Now I'm retired (though still pretty young) and we are spending about half our time here. I'm also building a shop that needs to be powered. When we are here the generator runs anywhere from 30 minutes to several hours each day even if the sun is shining. The inverter size of 4KW may seem small, but it has never been a limiting factor, including while we have had construction underway with multiple compressors and other power tools running. However, I use more KWh per day than the panels support - by a lot. The other issue is that my existing system is 120V only and I have the two legs of the 240V split-phase panel tied together. I'd rather be running true 240/120, especially out to the shop. All this has led me to this next upgrade.

    One thing we did when we modernized the house was to pay special attention to electric usage knowing that it would be a limited resource. It's amazing what you can do if you pay just a little attention to conservation. At any point during the day or evening we typically are drawing between 10 and 20A from the batteries. That's 250-500W to run the entire house. About half of that is the TV/Sat TV. To get that, we started by pushing everything we could to propane. The heat, hot water, dryer, stove, generator, and even the fridges are propane. Heat is circulating hot water so the only power consumption is a 75W circulator pump. Forced hot air, in contrast, consumes a bunch more than that for the air blowers. Lights are all CF, and I select appliances very carefully. Most are needlessly wasteful. Our dishwasher, for example, had a water boost heater element and an air dry heater. I disconnected both of them and have never missed either.

    The best part of the whole thing is that you can live off the grid but still live a normal life. I have all sorts of power tools, compressors, welders, etc. and use them as I would anywhere else. It just takes a little effort and ingenuity.

    Peter

  9. #9
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    Default Re: Solar Electric Project

    For those who lust after being able to do similar or simply have an interest in renewable energy, have a look at Home Power Magazine: Solar | Wind | Water | Design | Build. they have a magazine available as download or hardcopy that has been of great interest to me over the years.

    The magazine covers solar, wind and water power as well as how to reduce the energy you consume.

    Cityfarma
    Kubota L4400 & FEL, 9 point spring tyne harrow, 33 acres of sanity.

  10. #10
    Veteran Member hayden's Avatar
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    Default Re: Solar Electric Project

    Agreed - Home Power is a great magazine (probably the only) on the subject.

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