Duel axis tracker foundation

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  • baz0000
    Junior Member
    • Oct 2023
    • 18

    Duel axis tracker foundation

    I have two 4kw (8X500W panels) trackers on order from a Chinese supplier and I'll order in the panels, wire, boxes and breakers if/when they arrive in the Spring of 2024.

    The trackers have a suggested foundation of 2mX2m reinforced concrete pad rising on a plinth to a 400mmX400mm mounting point 600mm above ground. In the USA, you can buy concrete plinths off the shelf but they seem sadly lacking in the UK and pouring such an edifice would require some intricate box work. So, I'm looking at alternative means be that screw piles or even a metal pipe drop into a hole backfilled with concrete. I have the groundwork equipment on hand of a 300mm auger and digger capable of digging 2m depth holes. So I could cut a 2m trench and bottom auger that another 1m dept and then drop a 3.6m pipe with top plate to mount the tracker post onto.

    Does anyone have experience of using screw piles without a toque measuring head? The auger I have is fairly low torque, 2800Nm max, so I'm uncertain that would be grunt enough to drive a pile to a decent depth in clay soil of say 3m. Which is why I'm erring on the 2m deep trench dropped by the auger with a 300mm hole giving another 1m. I would then run a construction tube to the bottom of the trench and backfill the soil and fill the tube with concrete.

    I have calculated the wind loads at 60mph would range from 3kn to 7kn dependent on the season and the tracker weighs in at 350kg including the panels. There is also self levelling wind protection at a pre-set wind speed so these loads are above what would be attained in actual use. The site also has some shelter with surrounding hedges and trees from the prevailing wind direction.

    I was quoted £6k labour and £3k for equipment hire to have piles installed which doesn't make sense seeing I do have groundwork equipment on site. For me the only question is pile or pipe, but only pile if my digger and auger will do the job.

    This will be a strictly DIY project so if anyone is interested in the project progress then I could post a thread on the install as and when it progresses. I'm hoping to start digging in the Spring and have it up and running by late summer of 2024.
  • littleharbor2
    Solar Fanatic
    • Jan 2016
    • 189

    #2
    Welcome to the forum and please post updates of your project. Sounds interesting.
    2 Kw PV Classic 200, Trace SW 4024 460ah,

    Comment

    • Rade
      Member
      • Aug 2023
      • 94

      #3
      Originally posted by baz0000
      The auger I have is fairly low torque, 2800Nm max, so I'm uncertain that would be grunt enough to drive a pile to a decent depth in clay soil of say 3m. Which is why I'm erring on the 2m deep trench dropped by the auger with a 300mm hole giving another 1m. I would then run a construction tube to the bottom of the trench and backfill the soil and fill the tube with concrete.
      I live on a bay in Rhode Island and our building codes require that we accommodate both gale winds and a frost line. I do not know what your local / regional building codes would require, but our States are based on the international building code guidelines, and your footer set to 3m (4ft US) sounds about right. Using a tube should work, so long as it is anchored to the footer. We just went through a great deal of construction on our property that included a lot of foundation build out.

      I found the information for our projects through the UpCode website: https://up.codes/?s=1
      Rade Radosevich-Slay
      Tiverton, RI

      Comment

      • baz0000
        Junior Member
        • Oct 2023
        • 18

        #4
        As a brief project update.

        Trackers have been shipped and expected to arrive in the UK early January 2024. I have no means of tracking the trackers so it'll be wait to see what happens and when.

        I have looked at specs and reviews on inverter and battery storage options and the best combination so far is a Chinese Fox ESS hybrid 8kw single phase inverter and their high voltage 4kw cube battery packs. These are reported to be excellent quality and come with a 10 year warranty. A lot of the lesser known or cheaper alternatives only have 2 or 5 year warranty periods.

        The panels have been specified already with the tracker manufacturer to get the mounts aligned. These will be sixteen JA Solar 500W 2mX1m panels.

        Piles are looking like a forlorn foundation option due to cost. I have received quotes from two companies that are, including sale tax, £7.2k and £12k. I also contacted a bespoke concrete foundations fabricator and was quoted £6k for the two bases. So, I'll just go with a pipe drop to 2m depth and see how that holds up for under £1k outlay.

        For the components I have had initial discussion with an electrical factor company with a branch local to me (CEF) and they have said they will work with me on pricing. I expect the hardware spend to run to £10k before discount (yet to be negotiated).

        Comment

        • BryceFreeman
          Junior Member
          • Nov 2023
          • 16

          #5
          Your project sounds very interesting! Would you mind telling us which company the duel axis tracker is from?

          Comment

          • baz0000
            Junior Member
            • Oct 2023
            • 18

            #6
            The trackers are from this company, ordered via Alibaba.

            Shandong Zhaori New Energy Tech. Co. is a high-tech company with independent intellectual property rights. We offer quality R&D, production, and engineering services for new energy solutions.


            Tracker model ZRT-08 (X2)

            I asked for DDP freight to be included in their price so there should not be any additional import or forward freight charges to pay. US1,600 each.

            They are definitely budget 2 axis trackers with extending/retracting power arms, as opposed to the more expensive slew drive option. They do have a limited axis movement of + or - 50 degrees, some slew trackers I looked at stated a 120 degree of rotation.

            I'll post up some pictures of what turns up and if any costs do get added.

            Comment

            • baz0000
              Junior Member
              • Oct 2023
              • 18

              #7
              A third screw pile quote has come in from another company, mid range at £9k. So it's £7.2k to £12k for a screw pile foundation or £1k for a steel pipe into a dug and augured hole. I'll be getting my 2.5T digger out to do the groundwork.

              Comment

              • bcroe
                Solar Fanatic
                • Jan 2012
                • 5199

                #8
                Cement is not very expensive, most of the cost is labor in making
                the hole. With all our rock and the cold, it is pretty much necessary
                here to dig holes for any foundation. I bought new a bottom of the
                line mini backhoe to do it myself, for under US $4000 delivered.
                No appointments or worrying about the weather.

                48 in down rebar is joining front and back columns. First dig took me
                3 days, with a little practice digging this hole was down to 1/2 day.

                I also bought new a bottom of the line trencher for US $3000
                delivered to allow burying cables. A couple big rocks had to be dug
                out along the way. It was not self propelled, but that boat winch
                worked even better. good luck, Bruce Roe

                7FtHoe.JPG
                24FouPosts.JPG
                Trencher1.JPG

                Comment

                • BryceFreeman
                  Junior Member
                  • Nov 2023
                  • 16

                  #9
                  Originally posted by baz0000
                  The trackers are from this company, ordered via Alibaba.

                  Shandong Zhaori New Energy Tech. Co. is a high-tech company with independent intellectual property rights. We offer quality R&D, production, and engineering services for new energy solutions.


                  Tracker model ZRT-08 (X2)

                  I asked for DDP freight to be included in their price so there should not be any additional import or forward freight charges to pay. US1,600 each.

                  They are definitely budget 2 axis trackers with extending/retracting power arms, as opposed to the more expensive slew drive option. They do have a limited axis movement of + or - 50 degrees, some slew trackers I looked at stated a 120 degree of rotation.

                  I'll post up some pictures of what turns up and if any costs do get added.
                  Thank you for the sharing. Glad to find something new.

                  Comment

                  • baz0000
                    Junior Member
                    • Oct 2023
                    • 18

                    #10
                    Update - December 2023

                    I had a long phone conversation with a Scottish based pile supplier/installer in November and they happen to have a branch operation close to where I live. Their pricing isn't anywhere near as scary as the other pile options for two pile installation at £1k. It's not the final install offer as a capping plate needs to be designed and manufactured to attach to the screw pile top and also form a base to mount (via 8 bolts) the tracker pole onto. They are proposing that a tripod pile arrangement is more suited to our ground conditions (clay) to maximise stability. That will undoubtedly raise the costs but I do quite like the idea of a tripod foundation to the trackers.

                    The trackers haven't arrived yet from China so there is still time to evolve and develop foundation plans.

                    I have stumbled upon a contact in my local pub that I've talked to for years but only just found out he can make to size and deliver prefab concrete slabs so it looks like the base for the battery shed could be sorted on mates rates for a 6' X 6' base to a metal high security shed to house the expensive 20kW Lipo battery packs and 8kW hybrid inverter. So all suppliers are in place whichever way the foundations go, ready for if/when the trackers do turn up and the ground dries out a little from the current very wet state. Anyone living on clay knows ground work in the Winter is never ideal, things can get very sticky very quickly.

                    Comment

                    • baz0000
                      Junior Member
                      • Oct 2023
                      • 18

                      #11
                      The trackers were dropped off today. The 5m bars and slats have to be the 16m2 of solar panel mount and I'd assume the crate contains the 2m mounting poles, controllers, hardware and the motorised arms. It looks like checking the contents will be my weekend job. Once successfully checked off then I'll let the foundation company and the solar parts supplier know its a green light to start up.

                      I will order in the PV panels straight away seeing they were part of the spec when the trackers were ordered as the mounting hole locations are drilled according to the specific panel mount holes. Then it'll be see how soon something can be organised around the foundations; be that screw pile of the cheaper pipe drop.

                      20240104_133722.jpg
                      20240104_133732.jpg

                      Comment

                      • BryceFreeman
                        Junior Member
                        • Nov 2023
                        • 16

                        #12
                        Can't wait to see how the tracker will look like finally. Keep updating!

                        Comment

                        • baz0000
                          Junior Member
                          • Oct 2023
                          • 18

                          #13
                          Items checked and all seems to be as ordered.

                          On the construction material, its all steelwork. No lightweight aluminium panel support bars here, its all cold steel, and with that heavy. At least being all steel I won't need to worry about earthing the individual panels. There will be one main 70mm2 earth lead run from the centre bar to a ground 4 foot 5/8" spike.

                          I have been musing about how to go about assembling the panel support frame 8 foot off the ground using ladders but with the weight of the 5m centre box section that isn't going to be possible without access to a strong three man crew on hand. So, I'll prefab the panel frame alongside the final location with the four end panels fitted and then mechanically lift the frame onto the tracker support pole. That'll then just leave the 4 centre panels to fit once the lifting straps are out of the way.

                          The lift weight of frame and 4 panels will be around 200kg so not something that can be easily manoeuvred manually. Not that manual assembly wouldn't be possible if installed a piece at a time and with a minimum of 3 people muscling in. It'd be manageable but working around positioning and bolting down 4m or 5m pieces of metal 8 foot off the ground would never be easy away from a hard standing location.

                          In real life up close and personal, I have to say it looks a lot bigger than it did in the browser pictures.

                          20240106_153645.jpg

                          20240106_153607.jpg
                          Last edited by baz0000; 01-06-2024, 12:53 PM.

                          Comment

                          • baz0000
                            Junior Member
                            • Oct 2023
                            • 18

                            #14
                            There was a quick hardware supplier change last week. CEF were proving difficult to gain answers to simple questions and I invariably ended up chasing up emails with phone calls so I put the shopping list out to a couple of alternative suppliers. One never responded to the website shopping list which is surprising seeing they sell everything from terminals and connectors and this was a North of £10k list. Fortunately the one I was hoping to reply did which wasn't a surprise as they have a ton of reviews praising their customer service. Any email enquiry was responded to quickly, they are somewhat less contactable by phone. The business address is a private home so they are clearly a order processing outfit rather than a wholesale stockist. The best thing was the free advice, they recommended I change the battery storage model as the one I specified is still available but is discontinued. The company is the Eco Supermarket where Ollie assists you with your enquiry.

                            The initial hardware order was for the panels, ordered on Thursday and delivered the following Monday. So, I now have everything I need to get started once the foundations are sorted.

                            20240117_112930[1].jpg

                            Solar Panels are JA solar JAM66S30-505/MR, 505W 46V.

                            Comment

                            • baz0000
                              Junior Member
                              • Oct 2023
                              • 18

                              #15
                              I have to make a choice for the foundations to the tracker post next week, to have a chance to break ground in March, with the choice of either:

                              1. A supporting pipe
                              A 2.6m 220mm mild steel pipe with capping plates either end. The 400mm top plate will have the tracker post mounting holes plasma cut and supporting ribs off the pipe. There will be lifting handles (using straps) welded to the pipe 600mm from the top (soil level). The lifting straps will allow the pipe to be lowered into a hole (rather than dropped) and supported if need be at the desired height before pouring concrete. The pipes will each weigh in around 100kg of steel.

                              Cost £700 for the two pipes
                              Paint and primer £100
                              Est. £600 for the concrete - approx 4m3 to 5m3

                              Total cost est. £1,400

                              2. Ground Screws
                              The proposal from the ground screw company is to drive 3 screws to 1.4m depth and add 500mm or 1m extensions to go deeper if required. To use 4 screws per tracker with three in a triangle around the post and a 4th directly under the tracker post. The mounting plate for the tracker post to be attached to each screw top and be a figit spinner shape to allow close up access to the tracker post.

                              I have an outline quote of £2,100


                              The ground screw option is an easier job as it would be installed for me ready to bolt on the tracker post. The pipe option would be neater with a much lower above ground footprint topped with a 400mm round mounting plate rather than a 1500mm triangular mounting plate.

                              The pipe drop requires a fair bit of ground work. The fabricated pipe would need priming and enamel painting. A trench would need to be dug to 6' depth but I do own a digger so no equipment hire is required. I'd have to then mix the concrete. I do own my own mixer but its probably going to be 50 loads in the mixer to back fill the trenches. There is no site access available for a concrete delivery.

                              A pipe is likely to be more enduring being 5mm wall steel as opposed to 2mm on a ground screw.

                              Any words of support or wisdom in making the choice will be happily considered.

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