pgtruspace's blog

about things that interest me.

Solar power project

40 Solar Photo Voltaic panels, over 8 thousand watts, 8Kw of panels mounted for maximum winter power production. The winter angle, 42 degrees, also aids with snow shedding, half hour of sun will clear the panels.

40 – 200 watt Sanyo/Panasonic panels mounted like shingles to create a water shedding roof over the wood frame structure and cover the electrical system and batteries. The next step is to upgrade the battery system to provide up to 35 – 48Kwh of batteries to supply 5 days of power to the farm grid. Then Inverters to turn the 48vdc from the battery bank into 240/120 split phase power needed to run the water pump and other 240/120 loads. Presently the panels are directly connected to a 36vdc bussed battery and grid-tie system that pumps 2Kw back into the local grid. While better then nothing this is very a inefficient coupling that wastes over half of the power harvested and will produce nothing if the grid is down.

Back of rack shingled with copper clad thin FRP

only 30 minuets of sunlight cleared the snow from the rack.

8 Kw of Photovoltaic: this link should load a new window with more construction details

5 responses to “Solar power project

  1. The True Nolan January 18, 2022 at 6:33 pm

    Very nicely done! The truck peeking out of the back shows the scale of it. I like the shingling of the panels; good idea! I may be doing something similar at my off-grid place. So far, I have just done a small roof mounted set of panels (400 watts — makes me feel, uh, inadequate when I see your 8000W!) but need to clear more trees and brush before I decide where to put a bigger system.

  2. p.g.sharrow January 19, 2022 at 12:32 pm

    @The True Nolan, I hope your array is usable for you. Mine is mostly just show for now. building out of your pocket is slow an painful. I need lots of batteries next as well as a power management system, Expensive! stuff. Right now a bunch of the panels are tied directly to the buss with enough batteries to drag the panel 58 vdc down to 36-40vdc that is required to drive a handful of old grid-tie inverters that are also tied to the buss. About 2Kw to the grid is the best we can do right now.
    We had an opportunity to buy 50 panels at a total cost of $2,500 but they sat in a pile for 2 years before we acquired enough materials to build the rack to mount them on. Every time Public Graft and Extortion, slams us with an increased bill we cringe, How do you pay for the power AND build a system to reduce that bill? Only rich people with large incomes can afford the givernment programs that we all pay
    for.

  3. p.g.sharrow June 27, 2022 at 7:22 am

    As you can see the shingling effect allows the use of a ladder on the face for maintenance. the frames keep the ladder clear of the panel glass.
    The good shingle effect with joint covers and the back covering protects the wooden rack very well from the effects of heavy rains and snow that we get.
    The angle of the rack is excessive. I should have used the angle of the Latitude. I was aiming for maximum winter production ( latitude plus 15 degrees ), most people go for maximum summer production ( which is latitude minus 15 degrees.). For my general purpose needs a neutral angle would have been best.

  4. The True Nolan July 3, 2022 at 3:29 pm

    Neutral angle sounds good. Probably not worth the effort and expense of a tilting array. As you say, batteries are problematic, and in the long run the most difficult part to deal with. I keep wondering how difficult it would be to adapt some used electric or hybrid car batteries. There should be a lot of those coming available now, and an EV uses roughly the same amount of power as a house, so one good battery pack should just about do it.

  5. p.g.sharrow July 4, 2022 at 6:43 am

    @the True Nolan; Yes there are lots of used car batteries in the secondary market, Not cheap yet, but coming down. When I got the solar panels, they were cheap used from Solar field PV upgrade. They had been donated to a none-profit and I got a bulk deal for my cash “Donation”. Nice panels 10years old All “B” grade but still most of them produce at spec. I bought extras so I could swap out any defective ones. I bought a dozen used Grid tie Emphase inverters that were also pull outs and cheap.But that proved a miss-match, ( part of my learning curve). took me over a year to figure out why they wouldn’t work. I thought they were defective. They have built-in safety features built into them that prevented them from working with the output of my panels. Once I figured that out, I could jury-rig the buss to force the panels to work in the range of the inverters. I also found a deal for used LiFePo4 BMS controlled batteries, Trouble was those deals were “one of” and the after market prices jumped as DIY people discovered those markets, and resalers got involved to make money from the spread.
    We have about $4,000 in money into this project and about $5,000 to go, Far cry from the $125,000 that professionals would charge us.

    If you have the space and a good Solar window you can adjust the panel rack a bit to produce power at the best advantageous time of day. My rack is just sitting on the ground so I can move it around a bit as I experiment with it. The rack was built with used wood lumber, Screwed together so I could rebuild it if require, a full adjustable Steel rack would be Ideal, but expensive. Most of the adjustable racks of panels that I have seen wind up having the tracker systems disabled once there is a failure of it ( often) and the optimum is discovered. So not really worth the cost and trouble to increase power production, Just install more panels.

    The installation of a solar rack on a roof is an engineering night mare. Most roofs are wood construction so the roof panel interface causes a self-destruct situation. The glass and metal panel system expands and contracts with heat, Wood expands and contracts with humidity. That contrary movement damages the panel-roof interface and your roof soon leaks. So plan on a 10% summer / winter movement to preserve your roof. and most roofs are composite covered with only a 25-30 year life, some poor bastard will have to deal with re-roofing to preserve the building as the roof membrane fails. In the case of my rack the panels are the roof watershed membrane and the expansion / contraction is isolated to each panel.

    The price and improved features of the Power Point Tracker / inverters have come down to the point that they are a good deal. New batteries are also coming down. All I need is money,now, Ha Ha Ha !At least now the system is producing 2 Kw for a few hours and reducing our power bill a bit and any addition in the future will improve that. And I have a toy to tinker with if I get bored…pg

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