Solar Panel array options. Size, voltage etc.. - Ram Promaster Forum
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post #1 of 20 Old 05-18-2019, 03:35 PM Thread Starter
gringobombero
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Solar Panel array options. Size, voltage etc..

Hello all. Hoping the experts here will chime in on roof top solar panel array options. I'm looking to at 300w minimum and had decided on a single 60 cell, 300w 65''x 39'' that would fit very nicely right at the front of the roof. It would be mounted to my unistrut low profile roof rack so I can ensure I can clean debris out from underneath to avoid corrosion issues. Currently there are availability issues so I'm rethinking a multi panel configuration. My question is, what are the benefits with a multi panel (low voltage) array vs a single panel high voltage setup? Certainly cost is less with the latter. Oh and yes a quality MPPT controller in either case.

Last edited by gringobombero; 05-18-2019 at 03:52 PM.
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post #2 of 20 Old 05-18-2019, 09:31 PM
RobPromaster
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Sound like you and I are thinking along the same lines.
There was a Home Depot Grape solar day sale the other day that was tempting but I did not bite.
Was thinking a single 300 though I probably could get away with a 200w setup.
The voltage is another thing, 24 is an option but 48 might be better.
Of course quality components!!! But do not rush quality, they make panels every day, mostly better...

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post #3 of 20 Old 05-18-2019, 11:49 PM
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The main advantage of having multiple panels is it lowers the chance of a total loss of output due to shading. One would assume that if 10% of a sinlge panel is shaded you would lose 10% of your output, but in reality you might lose nearly all of the output from the panel.

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post #4 of 20 Old 05-19-2019, 01:17 AM
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I will be mounting 2 Renogy 160 Watt panels using the forward and center OEM connection points on our 136. These panels are short enough to fit between two of our 8020 crossbars. Here is the CAD layout: https://www.impact3d.com/Promaster13...G160_front.pdf. I hope to share some photos in the next few days.

All the best,
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post #5 of 20 Old 05-19-2019, 08:33 AM
RobPromaster
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Impressive drawing Hein.
I picture a single panel 2-300w with side tabs glued to the roof. With maybe a soft fairing on the front edge.
Close enough to the rear camera housing to eliminate the need for a roof penetration.

However, still considering a front and rear roof vent.
Or a front skylight and a rear powered vent like the LeMans that you carry Hein.

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post #6 of 20 Old 05-19-2019, 10:07 AM Thread Starter
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Yes, nice CAD rendering! I suspect your eagerly awaited van mount adaptors are part of the equation. I couldn't wait unfortunately and bit the bullet on the Vantech mounts. Yes I went for all ten of them. I've elected for some beefy steel unistrut, had it powder coated which looks sexy as ****. Your two panel 330w option is one I've considered. Substantially higher cost than the single 300w high voltage panel however, but the fit is a tad better than the 65x39.
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post #7 of 20 Old 05-19-2019, 10:12 AM Thread Starter
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Originally Posted by JohnnyRambles View Post
The main advantage of having multiple panels is it lowers the chance of a total loss of output due to shading. One would assume that if 10% of a sinlge panel is shaded you would lose 10% of your output, but in reality you might lose nearly all of the output from the panel.
Thanks Johnny! I've also heard that partial shading of one panel actually has a larger impact than output of just that panel. I'm not positive however, just seem to recall reading that at one point. The only other concern I've read about is if there was damage to one (hail or whatever) that you could still disconnect it from the array and get by on the other until you find a replacement. I think that's remote enough not to be a concern however.
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post #8 of 20 Old 05-19-2019, 10:39 AM Thread Starter
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Originally Posted by Hein View Post
I will be mounting 2 Renogy 160 Watt panels using the forward and center OEM connection points on our 136. These panels are short enough to fit between two of our 8020 crossbars. Here is the CAD layout: https://www.impact3d.com/Promaster13...G160_front.pdf. I hope to share some photos in the next few days.

All the best,
Hein
DIYvan
My install will be almost identical. Just substitute Unistrut and vantech mounts. So a cost comparison of the Renogy [email protected]= $438 USD vs Canadian Solar [email protected]= $183 USD.

IMHO much better w/$ value going with the latter and the difference pretty much pays for all of those pricey Vantech adapters!

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post #9 of 20 Old 05-19-2019, 04:18 PM
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Isn't the shading a bigger problem when wiring in series than parallel for a multipanel setup? Always a positive and a negative.
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post #10 of 20 Old 05-19-2019, 04:37 PM
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Yes it is. If you want higher voltage then buy higher voltage panels and wire them in parallel. The common panels many of us buy are 17+- volts but lots of configurations can be bought.

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