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Most wattage I can fit on a high roof sprinter (~128" x ~58")

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  • Most wattage I can fit on a high roof sprinter (~128" x ~58")

    Hey folks, looking for opinions on the most juice I can pull from my roof space. I don't mind a little overhang on the sides and back. So far, the best I've found would be 3 x 345w Sunpower x21 t modules at 61.4" x 41.2". This would overhang the sides a bit isn't stealth, but I can mitigate that. Unfortunately, I can't find a source for Sunpower, except the company itself, and they won't sell me 3 panels.

    Anyone have any better ideas? I'd love to have at least 750w.

    Cheers
    Alex

  • #2
    1.) Part of my ignorance: What is a roof sprinter ?
    2.) Do you have local codes or an HOA to deal with ? There may be permitting, setback or other use restrictions/requirements. Suggest you look before you leap.
    3.) As an end user, Sunpower will not sell to you directly. Look for dealers on the net. They are mostly installers who may/may not sell equipment only.
    4.) Sunpower will have close to the greatest STC power density (STC W/m^2), but you'll pay ~ 20% or more for Sunpower than for other equipment with close to the same STC power density for what may be a relatively small increase in bottom line annual output.
    5.) If you are considering DIY, and still want Sunpower panels, you'll probably be looking at used equipment.
    6.) Have you used PVWatts to estimate annual output and also how much that output will produce in terms of reducing an electric bill ?

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    • #3
      Hi JPM. No HOA to worry about. This will be going on a Mercedes Benz Sprinter van (of which I own the high roof version). My usage varies. But I'll always have a 12V fridge and freezer running. But I'd like to run an assort of fans when it's hot, a thirsty gaming laptop, charge accessories, and maybe, maybe, a window AC unit during peak output.

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      • #4
        Originally posted by Withalligators View Post
        Hi JPM. No HOA to worry about. This will be going on a Mercedes Benz Sprinter van (of which I own the high roof version). My usage varies. But I'll always have a 12V fridge and freezer running. But I'd like to run an assort of fans when it's hot, a thirsty gaming laptop, charge accessories, and maybe, maybe, a window AC unit during peak output.
        Thank you. Still run PVWatts for what I assume will be a horizontal orientation for a SWAG of daily output at a location. Also, as SWAG, you might get ~700 - 800 W max out of 3 ea., 300 STC W panels in high summer for an hour or two on either side of solar noon under clear skies in high summer. About half that or less in fall/winter, and down to ~ 10 % or so any season under cloudy skies.

        Nice hobby and I'm a big R.E. fan, but if $$, aesthetics and hassle (including not getting blown away by wind loadings) are considerations, I'd simply run off batteries and leave the engine running when A/C was necessary.

        Solar is nice and fun, but it has limitations that peddlers don't talk about and the popular press is ignorant of.

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        • #5
          Haha, yes. I understand AC is practically impossible. I'll have a generator for when I need it at night (if I do)

          This is my second rig with a solar system. The first was a 310w module, with 200ah of batteries and a single freezer.

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          • #6
            Alex, i think you've already got your answer on the panels, just a comment about being "stealth"...i'd focus on making your rig do what you want and "stealth" be damned. You're not fooling anybody. Every cop, security officer, and towtruck driver knows what a sprinter in the back of a parking lot is doing. If they didn't before, they certainly do now, since every Instagrammer and her boyfriend in the world are doing the van thing. Hell, i already live in an RV and i'm thinking about the van thing (just test drove some a few days ago). So i get it...but it ain't a secret.

            Far more important than trying to look like some abandoned work van is remaining below the annoyance threshold of those around you. We stay in all sorts of parking lots in our 25' long shiny silver box. NOT stealth. Permission, politeness, and just not hanging around too long seem to be far more important than whether your rig looks like it 'ought' to be there.

            - Jerud
            ------------------------------------------------------------
            1220W array / 1000Ah LFP house bank
            MidniteSolar Classic, Magnum MS2812
            ME-RC, Trimetric, and JLD404
            2001 Fleetwood Prowler 5th wheel 25 foot, self-rebuilt
            Full-time 100% electric boondocking (no propane, no genny) since 2015
            www.livesmallridefree.com

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            • #7
              Yeah, I've never had a problem as long as I'm careful where I park. I'm usually in the field anyway. I've been van and truck camping for the better part of a decade. What I meant in the OP was that I don't care if the panels are overhanging and giving away my stealth abilities, cause it's not that important.

              Also, no one has made any suggestions as the best panels to make use of my space, so I'm just going to go with whatever I can find to be the best space use on my own.

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              • #8
                If you can find some good used Sunpower panels , and they fit well, they would be the best , power output wise.
                2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                • #9
                  I gotcha, glad to hear you've already got that figured out. There are so many people going nuts about vans now, with lots of crazy expectations. I am guilty of being unreasonably grouchy about it.

                  My takeaway from the above posts was that Sunpower panels will get you the max power density per area, but you'll pay a premium and sourcing will be a hassle. Aside from them...Watts per square inch probably won't vary much and it'll be mostly about finding a panel with the right dims that let you tessellate efficiently for your roof, and a supplier with good shipping : ) Are you using the factory rack system or making your own? What else do you have on the roof, any vents/antennas?

                  The last time i checked out Sprinters was 2016 and the old spec sheet i have lists ~70" inside cargo width. 58" seems really narrow, does the Sprinter taper a lot up to the roof?

                  Congrats on scoring a 4x4 btw. At 128", it sounds like you got the short wheelbase for good departure angle...awesome! Make sure you put good tires on.

                  -Jerud

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                  • #10
                    Oh, i meant to add -- but i also kinda hate to bring it up...have you considered ground-deploy panels? You could put two panels lengthwise down the center of your roof, and have 2 more which you store on top of them while driving (obviously care must be taken to secure them and protect from damage). Take 2 down and set up on the ground, can even get a decent tilt - this would get you up to 4 panels instead of 3 and not take up any space inside the van. A bit more wiring though...i believe you'd want to have 2 separate charge controllers in that situation but they could each be smaller...?

                    If you drive, deploy, and stay put for more than a few days at a time, it seems worthwhile. You won't pick up any charge while you're driving down the road though.

                    -Jerud

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                    • #11
                      Thanks! Yeah, she's a cool rig. Not perhaps as reliable or off road worthy as an old 7.3l econoline with a front axle (or my rock solid old cummins for that matter) but I can walk around in it! Yes, the roof tapers quite a bit. I will have a custom rack fabbed. Yes, "short" wheelbase. The 170" offers a bunch more space, but the 144" is pretty maneuverable, surprisingly so. And I need that ability for the project sites I'll be on. Stock tires for now. I'm bleeding money everywhere getting this thing ready that that will be one of the last things I handle. Probably when I wear out the first set. I'm not going to be doing any rockcrawling anyway, just don't want to be stuck crossing a wash in the middle of the desert.

                      About stealth, now that Walmart has opened their lots for camping, there's hardly a city in the country where you can't crash without issue. As matter of fact, I camped exclusively in walmarts on my last drive across country. Gross.

                      No other vents or anything up top. I'm planning for full usage of solar. If I can't get sunpower panels, I'll probably put 4 of those narrow Zamp panels, which will still clog my roof, but give me only 640w. Lame. My exhaust fan will go on the rear door (or possibly the roof if I go the Zamp route), and I may put an intake on the floor, but that's scary.

                      EDIT- OR, I could do 3 Invensun 220w panels for a measly 20w gain. Don't know about sourcing them.

                      Cheers,
                      Alex
                      Last edited by Withalligators; 02-25-2018, 06:12 PM.

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                      • #12
                        How about 4 of these?: http://sepbatteries.com/topoint-190-watt-mono-cell
                        They are 32"x62", 35lbs, 72cell, will sell less than a pallet, and a great price! $600 shipped for 760w atm.

                        Downsides are manufacturer oob and high Voc (172v if all in series, so wire 2s2p for 88v and feed into mppt that can actually operate at mpp above 72v)

                        P.S: Be sure to design your racking with an airspace under the panels for cooling when parked, but with a deflector to keep too much air from getting under them while driving as that can create lift. The rake of your roof is a benefit and I would not level the panels, ramping up toward the back will cause air when driving to push down on them rather than lift. If you want to get fancy, design the left or right side or both to tilt up when parked with hydraulics The rack has to be custom built anyway...
                        Last edited by SupraLance; 02-27-2018, 01:28 AM.

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                        • #13
                          I called SEP about the top point 190watt panels and they say they are out of stock and they are no longer being produced! I wonder if anyone is still making a panel around 200 Watts with a width less than 36"?

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                          • #14
                            I doubt it, requires 5"cells so your looking for old unsold stock. 60cell panels in the 225-265w range are probably your best bet, 3 of them at 39"x65" can get you near the same total as the Topoint. SEP lists several that size, Trina, RECsolar, Hanwa, etc but they only list the 230-240w versions. That still gets you in the 700w range though. One of the websites I was on had a 255w 60cell Trina, but I can't remember which one. Downside here will be you need to run all 3 in series into a controller that can handle the voltage (not a cheapie).

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                            • #15
                              Someone pointed out a guy on CL selling Sunpower 215W panels. I can fit 4 / 860W up there, so I'll do that until I come across some of the higher wattage ones. I'm going to need help finding a good controller though.

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