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  • Gr8fun
    replied
    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.

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  • AZguy
    commented on 's reply
    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

  • Gr8fun
    replied
    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 will.be 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.

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  • AZguy
    replied
    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...

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  • Gr8fun
    replied
    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.

    Leave a comment:


  • AZguy
    replied
    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...

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  • CPG
    replied
    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.

    Leave a comment:


  • calfee20
    replied
    I have been thinking of getting a portable for my RV. That charge controller is quite interesting. One more reason for the portable.

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  • AZguy
    replied
    I get it with panels - I may not have a lot of hands on but I understand AZ is far from the ideal environment... We got tons of sun but.... more than is good and not only is the heat really high, months of 40-50C ambient, let alone the surfaces in the sun get far hotter... 160F (~70C) ain't nothin..... heck, the interior of my car gets that... and the UV load is crazy too... most anything left in the outdoors will perish within a season or two

    I made a thread here sort of poking fun at folks that thought their BBSHD's got hot... mine gets too hot to touch before I even turn it on just from sitting out in the sun...

    Folks think this is a good place for rooftop solar but we'll see... I suspect most will be hurting within ten years and that's the expected ROI - heck, most business propositions won't consider an ROI of more than 18-24mo... but don't get me going on that ;-}

    A lot of what makes me think that portable is the best thing for many applications out here

    OTOH rode all day in 25C until just got home this evening when it was lusciously cool at 18C... but the hot stuff isn't far away...

    Leave a comment:


  • Gr8fun
    replied
    The panels get very hot. I have measure 160 degrees. Your temperatures will be higher.. Panel efficiency drops dramatically with heat. Providing adequate space for air circulation is necessary for output. Cool mornings clear skies are best.

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  • AZguy
    commented on 's reply
    Not the least bit interested in mounting panels to my roof - just thinking of portable panels that I can toss in the back of the truck

    This is what my RV friends do although finding any appreciable shade in the desert is a very odd commodity and there's an argument for the panels providing shade for the RV

  • Gr8fun
    replied
    The problem with rv solar panels on the roof is that most people prefer to park in the shade. Duh. Not good for solar.
    this is good case for portable solar. Suitcase. Possible Multiple 50 watt panels stored in hard case.

    Leave a comment:


  • AZguy
    replied
    I have about half a dozen electric bike batteries and just got a hold of a monster 14s8p unit and it's got me thinking of it as a portable energy source beyond just the bikes - it's an overkill for most of my bike use... and since I have so many other batteries, might as well keep them in the mix... charging from 110V (whether my gas generator or the wall) is a no-brainer... I have a 300W 12V inverter which is good enough for most vehicle use although it would be nice to bump that up to 400W for the big battery...

    That little controller got me thinking more but I've always thought solar panels packed in the back of the 4x4 pickup or even the car trunk might be good for off-grid...

    I'm starting to think what I ought to do is build my own battery controller... something that can handle anything from 12V lead-acid to 72V Li-ion (best to be able to do two simultaneously I think) that integrates charging from wind/solar, DC 12V-? or AC 110/240 and then I'd have it all.... something that will put out 12VDC too...

    Then I get realistic and ask myself what I need... likely only an inverter for the big battery for now... If I only had endless time/money Click image for larger version

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  • CPG
    replied
    I charge my bikes 100% of the time from some combination of grid tied solar, wind, or hydro, as I have all three plus the grid. On a trip I use a 400 watt inverter, and with a Prius you can be charging with the engine off, and have no fear of running the car battery down as it will monitor it and start the engine if required, all automatically. I have never actually used my 1 KW Yamaha for charging my bikes, as the car is actually a more fuel efficient way to do it. I go out for a few hours not days, so recharging in the boonies is not an issue, solar is one way for sure, just a lot of crap to haul around and it may be cloudy.

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  • AZguy
    commented on 's reply
    I've got no interest in a solar powered bike per se, but I am starting to think about solar powered charging, particularly for when spending time in the backcountry. I recently got a very large Li-ion battery and this piques my interest even more and I think I'd like to setup a portable solar system, likely scalable with 200-1KW (rated, not necessarily the output) of portable panels. Not even sure where to begin with the panels to be honest but I do have friends that have solar systems on their RV's so I'll likely be picking their brains a bit...
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