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Battery charging in the boonies

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    Originally posted by CPG View Post
    I sold and installed solar systems for a lot of years, decades, until it got too regulated. Most of my work was for off grid systems, and then I did grid tied when it was still easy and simple. Being in a very rural area, and having a crane service (my day job) I specialized in large pole mounted arrays that I could fab at home, and deliver and set on site in a couple hours. Point being, on the roof is the last place I would put solar, too damn hot plus a PITA to install. Out of over 50 systems, only 2 were roof mounted. I guess if you have no other choice..... As to their lifespan, I have some panels over 30 years old, still putting out the majority of their rated power, consider them a life time investment.
    It's funny out here - most all solar is residential rooftop (grid-tied) and I understand all your points... I'm not terribly interested in them

    OTOH I have a friend up in the high country , up over 8000' where it's not so bloody hot, and he has a large awesome house but he's off-grid. He's got a very nice solar system that does an awesome job. If it's just one or two people it's more than adequate for seven day weeks and if he has a lot of people up on the weekend there's enough storage to easily cover it and have it fully recover by the next weekend... This makes sense to me...


      Before you buy the 7210a, make sure it is what you need. For most boost applications it is sufficient.

      The other controller i use is a genasun for 52volt li ion, waterproof. It is purpose built with NO user set parameters NO display. Fully potted. Just a single blinking led. With this, all.u need to know, is it working? Total plug and play. USA built. Aerospace quality.
      this is durable all weather shock resistant high efficiency, advanced algorhythms for fast accurate true mppt control. It will set you back a couple of franklins or so. I use it when using the solar electric bike.


        I'd want something completely programmable and from what I can tell that cute little unit is... I think the only limitation is that it isn't terribly high current but likely enough for portable solar and frankly if I ended up with enough panels I could make two of them work very well I think since I want to be able to handle two batteries that have different characteristics - I'd likely go with two from the get go...


          When shading of one panel is possible, or you are using different size (spec) panels you should have a controller for each pamel. They can parallel before battery.
          You can not use two controllers on one panel that i know of.
          Good choice for your use.
          if you are charging your lower voltage battery with the panel, you could be charging higher voltage battery off of the charging battery.

          normally input must be lower than output to work. Otherwise you need a buck not a boost controller
          The 2oo watts of panel is ideally almost 4 amps of 52v. Batteries. That is pretty fast charging.
          real world it almost three.
          if you are worried about low amperage of controller then connect panels in series. With two panels you will now have 37 volts (panel working voltage). Boosting that to 52 will be more efficient and watttage doubled. Do not go over your battery voltage.
          Last edited by Gr8fun; 03-10-2021, 04:14 PM.


          • AZguy
            AZguy commented
            Editing a comment
            Good points

            I wouldn't parallel anything... series the panels is not a bad idea though.. separate cute controllers would be for separate panel sets and a separate battery

          Earlier i mentioned flexible panels as best for portable application. They are far lighter 15 pounds vs 35 pounds for 200 watts with four panels. Much thinner. Bendable (glass does not bend) flexble panels do break with continual flexing.
          But they are more expensive, less durable, and do not shed heat as well as the framed rigid panels. For my use, mounted on bike and trailers, flexible is required. I accept the disadvantages. The price per watt goes down with larger panels . the larger rigid panels would be ideal as an awning for an rv.
          again, depends on your use for choice.