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Solar for my Momentum 397TH

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  • Solar for my Momentum 397TH

    Starting this thread to document the process of designing and building my solar system. My scheduled off-line date, now that the line is running again, is July 13. I expect most of my solar work to be done in August and/or September. I plan to do as much as possible myself. I've been researching for about 4-5 months and am nearing completion of my design. Many times in life, I've been tempted, and sometimes failed to resist said temptation, to "cheap out". That will not happen with this project. While I am able to afford to pay cash for this project, it is important to complete this year, while the solar rebate is still 26%. When you see the picture, you'll understand.

    I initially decided to build around Battle Born 24V 50Ah batteries because of their performance record and long warranty. But, 8 batteries takes up a lot of space and requires a lot of heavy, expensive battery cable. This week someone asked why I wasn't considering Victron batteries. I looked into the solution (25.6V, 200Ah per battery). The cost of the batteries themselves is basically the same for 8 Battle Born or 2 Victron. Obviously with only 2, I save the cost and weight of 6 sets of cables, 6 battery disconnect switches and 6 fuses. The Victron batteries are a little heavier than the Battle Born batteries, but take up much less precious floor space...almost half. Between the cost, weight and floor space savings, the decision was easy. My near-final drawing is in the first comment below. At this point, the only thing missing is the communication and monitoring connections between all the components.

    If you have any questions about the configuration, I'd be happy to answer them. Note, however, I'm really not interested in any debate or discussion of "why didn't you use brand x which is so much cheaper".

    The approximate MSRP of components (not including cables or labor) is $16K. Since I intend to do it myself, it'll be mostly slave labor. I may pay my son to help some.
    Last edited by Sckarolek; 05-07-2020, 09:14 PM.
    My trailer: Grand Design Momentum 397TH with many small modifications and a fairly large (1700W panels, 10KW batteries) DIY solar install.

    My truck: 2020 RAM 3500 Laramie Longhorn 4x4 DRW, 6.7L Cummins HO Turbo Diesel, Aisin 6-speed, 4.10 axle, Patriot Blue Pearlcoat, Longhorn L1, Towing Tech, Max tow, Towing prep, 30K 5th wheel, Cold Weather pkg, Safety group, Body color bumpers, Tow hooks, Auto level, 50 gal fuel, Bed step, Side steps, Sunroof, Aux switches, Air Horn, TruXedo Sentry bed cover

  • #2
    Attached Files
    Last edited by howson; 05-08-2020, 06:08 AM. Reason: Photo was super small, so took diagram from "Document Your Solar..." thread and pasted here. Hope you don't mind! -Howard
    My trailer: Grand Design Momentum 397TH with many small modifications and a fairly large (1700W panels, 10KW batteries) DIY solar install.

    My truck: 2020 RAM 3500 Laramie Longhorn 4x4 DRW, 6.7L Cummins HO Turbo Diesel, Aisin 6-speed, 4.10 axle, Patriot Blue Pearlcoat, Longhorn L1, Towing Tech, Max tow, Towing prep, 30K 5th wheel, Cold Weather pkg, Safety group, Body color bumpers, Tow hooks, Auto level, 50 gal fuel, Bed step, Side steps, Sunroof, Aux switches, Air Horn, TruXedo Sentry bed cover

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    • #3
      Sckarolek ,

      My intent and purpose with the text below is to share lessons-learned. I know from my own experience it's what I didn't know that bit me. With all the research and planning you may have already accounted for all of the questions and possible "got yas" below. Bottom line--I hope you receive this input with the good intentions used when it was written.

      Consider investigating colan's experience with Victron batteries as documented in this thread: https://gdrvowners.com/forum/operati...s-in-a-315rlts In post #2 he laments not being able to adjust the shore power capability (30A vs 50A campsite) via the CCGX. Further posts in that thread have more detail as he had to purchase the MultiControl in addition to the CCGX in order to adjust it. He would be better able to explain. Victron is always improving and updating their devices, so possibly this limitation no longer exists.

      Does Victron now have an internal BMS in their battery or are the BMS' not shown in the diagram?

      Does the CCGX have enough connections (some require VE.Bus, some VE.CAN, VE.Direct, etc) for all of the devices in your configuration? The new Cerbo GX is effectively a CCGX with more connections and with the screen separate. I know the Cerbo has three VE.Direct connections (vs two on the CCGX). I believe the two SmartSolar MPPTs will each require a VE.Direct port. I am not familiar with how the Shunt or some of the other components in the configuration will interconnect. Another nice feature of the Cerbo is having the screen separate means it can be far from the other devices without having to run all the cables that distance, too. Just something to consider.

      How are the 12v systems that do NOT run through the RV electrical panel going to be tied in? (Emergency brake actuation at minimum. Not sure of what else on a Momentum is powered prior to electrical panel. On my 315RLTS the front nose jack and scissor stabilization jacks are all powered prior to the electrical panel.)

      Your system is quite robust--the possibility of overloading the inverters and/or draining the batteries is more remote than in my configuration. But if you haven't read my experience, please take a moment and review this thread: https://gdrvowners.com/forum/operati...er-overloading

      A 24V system is definitely beneficial for all the reasons documented in your OP, but one consideration related to solar is when the MPPTs will turn on (pass solar to the batteries). I know the Victron MPPTs will not start charging until PV (solar voltage from the panels) is 5v higher than the battery's standing voltage. In other words, if the battery is at 23v the MPPT won't start passing power until the PV is at 28v. That's a relatively high voltage for PV. Easily overcome by wiring panels in series, but too many in series has it's own potential problems. Again, I documented my learning curve and you can find it here: https://gdrvowners.com/forum/solar/1...n-2019-315rlts

      One item I am not very familiar with is the Autotransformer. I read the description and part of the component's manual, but I'm still a little fuzzy on the need for the component. If you don't mind, can you elaborate on how it will operate in your proposed system and why it is needed?

      I truly hope something here is helpful. I am looking forward to reading about your install!

      Howard
      Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

      2017 Ford F-350 DRW, '19 315RLTSPlus

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