• Lorraine
    33
    My brother is looking at installing solar on his 5th wheel before a cross country trip. He is confused about the difference between monocrystaline, polycrystalline and multicrystaline. Can anyone clarify? We have solar panels from back in 2012 but don’t remember which, other than they were recommended by Northern Arizona Wind and Sun. Thanks
  • RVsolar
    179
    You tube is your best friend Ray has lots of real good info .
    I placed solar on my 5th wheel 2880watts video is on YouTube.

    https://m.youtube.com/playlist?list=PLp14lzXh07unQMg1COXX2LOEoLNZoel7z

    https://m.youtube.com/watch?v=zNXW9ceRZ7Q&t=343s
  • Greg F
    159
    Mono panels have a slightly better production vs. size which typically means a smaller panel for the same wattage rating. Poly panels tend to be less expensive but larger for a given wattage rating. Often this makes Poly a good choice for a home where mounting area is plentiful.

    Given roof space constraints on many RV's people tend to go Mono panels but if you have the roof space Poly panels can be a good option if budget is tight.

    Always keep in mind the effects that shading has on panel production. Even a small amount of shade can have a dramatic effect on power production, especially if panels are wired in series. If panels are going to be mounted near things like the roof AC, tv antenna, vents etc. a smaller Mono panel that will be farther away from shade will definitely outperform a poly panel seeing even a small shadow.

    It's easy to identify panels as Mono Crystalline or Poly Crystalline. The Mono panels have the little squares between the cells and the Mono panels don't.

    yis3ir203tqsx05d.jpg
  • Lorraine
    33
    Thanks for that clarification. That’s what he was wondering about.
  • George
    2
    From personal experience I won't wire solar panels in series. I blew out three solar panels because one went into reverse polarity fault . Basically the other three panel tried to feed a dead short in the faulted panel. Just my experience with panels .
    I also worked in industry for over forty years where I;ve seen that happen with commercial grade panels.
  • Bruce
    17
    In addition to what has been said, mono tend to perform slightly better overall and especially in heat. The gap between the two in performance has been closed over the years.
  • Bruce
    17


    While your unfortunate experience is a possibility, such an event is not a likely and a rare occurrence. Should not dissuade anyone from wiring panels in series if that is their choice.
  • George
    2
    Bruce

    For me spending $40 in parts and cable to save time and cost later to replace the panels is worth it. Also it helps to do annual checks on each panel . I tend to error on the side of caution instead of taking the cheapest and easiest installation.
  • Greg F
    159
    That's the first I have heard about blowing out panels in series. Many people run them this way in large mobile installations. This is how home arrays are often run. Groups in series. Nowadays micro inverting panels seem to be a popular method. Micro inverters jump the panel or a small group of panels to 120v where they can be grid tied without being stepped up or down after the panel.

    It seems to be common wisdom that high voltage is the way to go. A claim that on paper makes sense. Mobile applications are not as easily calculable however as a stationary system.

    I run mine in parallel because we like to park in the shade when it's hot. Playing around with series vs. parallel I did find series was slightly better when all the panels had full sun but in the shade production falls off fast compared to parallel, even with small partial shading as you are making one large circuit where panels rely on each other for energy transmission. Despite the bypass diode argument I found that in less than ideal conditions parallel worked better by enough margin to offset the times where sun is unimpeded. In full sun conditions peak efficiency isn't as important to us as we make more than we need unless we want to run the air conditioner. It's those shady conditions where getting every bit matters.

    Of course our biggest lack in efficiency comes from having fixed, non tilting panels which will make much more difference than series vs parallel or PWM vs MPPT. I simply lack the desire to climb up on the roof as I get older so we went over on panels and battery for good conditions and still make what we need when it rains or we are in the woods.

    To compensate for the high amperage parallel wiring creates we upsized our main feeders from the combiner box to the SCC to 2AWG that gives us less than 1.5% voltage drop under max conditions and less than 1% under most conditions. This does add cost and weight but more or less nullifies that main advantage of a series system, cable efficiency.

    One thing I really like about solar and battery systems is that there are so many options and how customizable systems can be to match personal preferences, budgets, roof space and creativity. :)
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