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  • Trying to complete a previous owners solar project

    Hello all, have recently bought a 1988 houseboat whose owner had passed. Appears the po was gathering components to install a solar system and need a little help in trying to figure out his intentions so I might finish the install. Have been around the construction industry for 30yrs, I am just familiar enough with electrical configurations to be dangerous.

    Live in southern Florida, plenty sunshine. Not much as far as power consumption per day - small fan, led tv, small fridge, occasional microwave or coffee pot and battery charger to keep the starter batteries topped of while docked away from shorepower. Most days its on shorepower, longest trip out of dock anticipated at 3 days. Night time power is the most desirable. Small tv, anchor light and a fan. Fridge is on a timer and doesn't run at night . There is a 5000 watt generator on board, just didn't want to run it at night for the small load that the pv might provide while on the river.

    There are:
    5 BP panels - SX3175N, 175w, 36.1v, 4.5a each.
    4-12v 190ah agm sealed batteries
    Tripp-Lite inverter MV2012UL - 2000 watt (12v input, 120v out)

    I know I will need a mppt charge controller. I am not married to the inverter, would like to work with 24v or 48v, but that is a nice inverter to just toss aside.

    Regarding the PV setup...series or parallel? Have read opinions for both. My impression is that the correct mppt controller would work either way, but opinions are all over the place.

    If I series the batteries 2 banks of 2 or 1 bank of 4....are there charge controllers with inverter modules or must the inverter be a separate unit?

    If these components don't work with each other, looks like craigslist or ebay may be getting some business....

    Thanks so much...

  • #2
    Welcome Mike.

    You will get a lot of good advice here, but you can also jump start your knowledge of off grid systems by reading all of the sticky threads in the Off Grid section.
    That will allow you to better understand the recommendations that you get.

    For any substantial loads, a 12V system simply cannot cut it and you would be better off changing your inverter before you start.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

    Comment


    • #3
      AGM batteries do have a pretty long shelf life but you might want to get them topped off ASAP. How long have they been sitting? They sound like some substantial batteries. I have some 12 volt 145 Ah batts. and they are over 100 lbs. apiece.
      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

      Comment


      • #4
        With those solar panels, you don't have much choice. No series arrangements are possible with 5, voltage would be too high for any charge controller appropriate for your usage. All 5 in parallel would support a 24 V battery, or 12 V too if the charge controller is mppt.
        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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        • #5
          Originally posted by Mike Wells View Post
          Most days its on shorepower, longest trip out of dock anticipated at 3 days:

          There are:
          5 BP panels - SX3175N, 175w, 36.1v, 4.5a each.
          4-12v 190ah agm sealed batteries
          Tripp-Lite inverter MV2012UL - 2000 watt (12v input, 120v out)

          I know I will need a mppt charge controller. I am not married to the inverter, would like to work with 24v or 48v, but that is a nice inverter to just toss aside.
          First with 5 panels you have shot yourself in the foot. 5 is a Prime Number and that only leaves you with 1 option of all in Parallel and a 12 volt system. Neither of which you want any part of. You need to loose a panel or gain a panel. Take your pick.

          As for an MPPT controller, size depends on what battery voltage you choose, and panel wattage. I am going to assume you will NOT use 12 VOLTS. So at 24 volts, which is perfect for your size if you loose a panel will require a minimum 30 amp controller. If you gain a panel will require a minimum 45 amp controller.

          If you use 4 panels and use a controler with an Input Voc of 150 volts, you wire all 4 in series. If you use 6 panels 3S2P. Be aware if you have any shadows, you are screwed.

          Personally with the batteries you have assuming they are still good, I don't think you have any need for solar if your longest trip is 3 days. The batteries have 9 Kwh capacity and that means you have 2 Kwh per day usage for 3 days without a recharge. From what you have stated will not use anywhere near 2 Kwh per day. Besides you will not have enough panel power to generate 2 Kwh per day. If I were you just buy a good 24 volt charger and recharge while docked. If needed out at sea recharge with the genny and call it done. Sell the panels to pay for a good charger and hardware.
          Last edited by Sunking; 04-30-2017, 06:45 PM.
          MSEE, PE

          Comment


          • #6
            Originally posted by Sunking View Post

            First with 5 panels you have shot yourself in the foot. 5 is a Prime Number and that only leaves you with 1 option of all in Parallel and a 12 volt system. Neither of which you want any part of. You need to loose a panel or gain a panel. Take your pick.

            As for an MPPT controller, size depends on what battery voltage you choose, and panel wattage. I am going to assume you will NOT use 12 VOLTS. So at 24 volts, which is perfect for your size if you loose a panel will require a minimum 30 amp controller. If you gain a panel will require a minimum 45 amp controller.

            If you use 4 panels and use a controler with an Input Voc of 150 volts, you wire all 4 in series. If you use 6 panels 3S2P. Be aware if you have any shadows, you are screwed.
            These are 72 cell panels. They are high voltage to support a 24 V battery, all in parallel. No need to drop a panel.
            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

            Comment


            • #7
              Originally posted by sensij View Post
              These are 72 cell panels. They are high voltage to support a 24 V battery, all in parallel. No need to drop a panel.
              OK my bad. I only picked on 175 watt and assumed they were 36 cell. But I would still loose or gain a panel. All 5 in series now requires an expensive Combiner and Fuses. 2S2P of 3S2P no fuses or Combiner needed. Will save on much much smaller wire$.

              MSEE, PE

              Comment


              • #8
                Hello again. All excellent advice and thanks to all. Had some damage from hurricane Irma so we have been making repairs. I have since added a panel, (6 now), was gifted a 48v pure sine wave inverter and a 60a mppt controller from a family member.
                Question is, if I set my batteries up in a 48v bank, will the panels wired 3s2p work? That will give me 108v@9a to the controller...yes/no?

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                • #9
                  Or maybe a safer setup would be 2s3p? Would give me more room for high voltage on cooler days...

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                  • #10
                    3S2P will work great and safer than 2S3P. With 3 in parallel you would be required to use expensive fuses and combiner. As long as Voc is less than 120 volts, you are good to go.
                    Last edited by Sunking; 05-11-2018, 05:49 PM.
                    MSEE, PE

                    Comment


                    • #11
                      Those BP solar panels are about 45 Voc. On a nice cold morning you risk running over 150 volts. One thing that would help would be a Midnite Classic 150 charge controller. You'll have a bonus 48 volt buffer to protect you from frying your controller.
                      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                      Comment


                      • #12
                        2 in series might be marginal for managing an EQ charge on a warm day, but is also pretty high Voc on cold mornings - plug the numbers into a string calculator for your site, put in your low temp for the last 100 year, and see if anything will fry.
                        http://www.midnitesolar.com/sizingTo...playSizing.php
                        put numbers in, see it your controller frys. This sizer will give volts/amps/watts and you will manually have to decide if it's a fit.
                        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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