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Full time RV'er wants to upgrade solar system -- request review/suggestions

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  • Full time RV'er wants to upgrade solar system -- request review/suggestions

    Hi folks,

    I am new to full-time RV’ing and new to solar power. I have been living in my truck camper for the past six months. The camper came with a 150 watt panel on the roof (of unknown provenance, but probably the Kyocera KD, as it looks very similar) and two (2) 12v Lifeline 150 amp hour AGM batteries. The RV dealership installed an additional 170 watt panel (Zamp) and a 30 amp Zamp charge controller (ZS30A). The camper has a WFCO 8945 converter, and I have a Honda eu2200i generator.

    For the most part, my system works well enough. I live in the camper full-time. I only need to whip out the emergency generator if there have been successive cloudy days and my batteries are starting to get close to 50%. This has worked for the past six months. However, I feel that things are not ideal, and there are two specific issues I have identified.

    The first is that, even with daily full sun (in winter in Southern California), my batteries are never fully charged in the course of the day (although they also never go below 12.5v unless we have two days without sun). I have oriented my rig such that the panels both face south, but they are flat on the roof (not tiltable), and there is a rooftop AC unit between them (so one panel is partially-shaded in the morning, and the other is partially-shaded in the afternoon -- see picture below). I do get 14.4v charging. I am thinking that I should add another solar panel. My charge controller can handle 510 watts, so perhaps I should add an additional 190 watt panel (for 510 watts in total)? This would go in front of the AC unit, so it would not be shaded at any point if I were facing due south (see picture below).

    This is the space where I can install more panels. It’s pretty much the only spot available on the roof. The clear, flat area in front of the AC unit measures 28”x86”. This model of truck camper has a full walk-on roof, so the panels can be installed wherever there is space.


    I have been attempting to learn about this subject matter today, and I concluded that the best thing for me to do would be to add an additional 190 watt panel (for a total of 510 watts, which is the limit of my charge controller) and wire the three panels in parallel, which should work since they are all 12v panels, right? That’s where I got a bit confused because I didn’t understand the VMP aspect. The respective VMP’s of the Kyocera 150 watt, Zamp 170 watt, and Go Power 190 watt are: 18.2v, 18v, and 20.4v. The respective IMP’s are: 8.25A, 9.4A, and 9.3A. If I installed the Go Power 190 watt panel on the roof and wired the three panels in parallel, the voltage of all three panels would drop to 18v (the lowest of the three), which would reduce the output of the 190 watt panel by almost 22%, correct? And if I wired them in series, all three panels would drop to the lowest amperage (8.25A), which would reduce the output of the panels together by 8%, correct?

    So it seems I would be better off installing two Go Power 80 Watt panels, which have a VMP of 18.4v or 17.5v and an IMP of 4.35A or 4.57A (the documentation is different on the Go Power website and in the owner’s manual, which contains the latter set of numbers). If my calculations are correct, installing the four panels in parallel would mean only a 1% - 2% loss of output. That seems much more reasonable to me, even though I would be sacrificing 30 watts on the roof (versus a single 190 watt panel). One significant advantage of two smaller panels is the fact that they would be easier to fit on the very limited real estate on top of my truck camper. Does all that sound correct?

    The second issue is that, on occasions when the sun is absent for long stretches, I whip out the generator to keep my batteries from going below 50% (12.4v), as I mentioned above. But the Zamp charge controller is indicating that my state of charge is 13.3v with the generator plugged in and running. I tried to research this, and it seems the culprit may be the WFCO 8945 converter that came with my camper. Apparently, other people have had the same problem and have replaced their WFCO 8945 units with a drop-in solution from Progressive Dynamics (PD4645), and this solution allowed them to bulk from a generator at 14.4v. Does that sound right? Or could there be some other reason why I can’t bulk from my generator? Also, am I correct in thinking that the charge controller’s display is the right place to look for this information? After all, if the batteries were bulking at 14.4v, this would be reflected on the charge controller display, which displays battery voltage, right?

    Basically, as you can probably tell, I know just enough about solar energy to be dangerous to myself and my system. It seems to me, based on my limited knowledge and experience, that the best move for me right now is to add more solar wattage on the roof and replace the WFCO converter. Then, if I wanted to get my batteries to a complete, full charge every once in a while (which I read is important for the batteries), I could bulk with the generator early in the morning (before the sun comes out), and then let the panels do the best they can for the rest of the daylight hours. And the extra panels would help to get to a full charge on a daily basis, too. That’s my thinking, anyway. I should note that I boondock 100% of the time these days.

    In summary: my plan is to install two Go Power 80 watt panels in addition to my existing one (1) Kyocera 150 Watt panel and one (1) Zamp 170 Watt panel. I also will replace the WFCO converter with the PD upgrade.

    FYI, I plan to hire someone to do the installation work, but I first want to better understand the problem and what is being done and why before I spend my money. Thank you in advance for any replies and information or suggestions.

    Here is a marking on the unknown 150 Watt panel. I tried googling the code, but it didn’t give me any results.


  • #2
    When mixing solar panels your system will be as strong as your weakest link i.e. the 150 watt panel. In my "opinion" save those two dissimilar for something else and calculate what you need in panels and buy as needed since you are limited in real estate you want to do it right. Though I suggest learning more before taking the plunge and to save yourself money by doing it yourself. Less than year ago I had no solar panels then started off with 400 watts and only 230AH @12v now I'm up to 1200 watts 440AH @24v. all self learned, you can do it too with patience and clean slate.

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    • #3
      You heard right about the WFCO, they are notorious for not actually ever doing a bulk charge up to 14.4V. Mine behaves this way as well, 13.6V is the highest I'll ever see from shore power. So as a full timer, you'll definitely want to replace the WFCO as better backup charging source. I have heard good things about PD converters, are they the ones with the Wizard Pendant that allows you to manually enter the bulk charge phase? There are Boondocker models as well, the RV internet forums love to suggest chatting with Randy at bestconverters dot com about replacing the WFCO with something that does a better job of bulk charging. Even with a proper-performing converter, it still takes 12+ hours to get to a full charge from shore/generator power. But having a proper bulk charge voltage will get you to the 90%-ish state more quickly which is usually enough to get by.
      I'm an RV camper, mine has 280 watts of solar

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      • #4
        Regarding the solar, I believe it is best to have matching panels rather than mix-and-match. If you're investing on full time, may as well do it right from scratch.
        I'm an RV camper, mine has 280 watts of solar

        Comment


        • #5
          Hi @weldman! I just wanted to say hi from Helena, fellow Montanan here.
          Sorry to threadjack MG1965
          I'm an RV camper, mine has 280 watts of solar

          Comment


          • #6
            Originally posted by ewarnerusa View Post
            Hi @weldman! I just wanted to say hi from Helena, fellow Montanan here.
            Sorry to threadjack MG1965
            I'm on the other side of the state in Miles City, or I should say about 35 miles off grid and that's the city on my address. Been through Helena few times, not bad place but too many regulations.
            I'm a full time RV camper too at the current statistics of power I put in previous posts, currently in Texas snow birding.

            Comment


            • #7
              Originally posted by MG1965 View Post
              Hi folks,

              The first is that, even with daily full sun (in winter in Southern California), my batteries are never fully charged in the course of the day (although they also never go below 12.5v unless we have two days without sun). I have oriented my rig such that the panels both face south, but they are flat on the roof (not tiltable), and there is a rooftop AC unit between them (so one panel is partially-shaded in the morning, and the other is partially-shaded in the afternoon -- see picture below). I do get 14.4v charging. I am thinking that I should add another solar panel. My charge controller can handle 510 watts, so perhaps I should add an additional 190 watt panel (for 510 watts in total)?
              It may be more cost effective to upgrade your charge controller from PWM to MPPT. Do you know what the voltage output of your panels is? Depending on the voltage upgrading to MPPT can yield a significant increase in output. PWM cannot increase current. If you have 20v & 6A from the panels your battery gets 6A @ 12v or (6A)(12v) = 72w. MPPT is able to buck the voltage and increase current so the input can be 20v instead of 12v. So 20v and 6A in would be bucked to 12v & 10A out for ~120w. A 66% increase.

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