In designing a new solar system for my RV I am weighing panel size vs quantity. I recent years the cost of panel designed for residential and farm use have come down in cost and up in out put. You can now buy a large 400+ watt panel for under $300 while a 100 watt panel will still cost $150-200. Assuming real estate is not the issue. what are the reasons for considering smaller panels vs larger one? For example: an 800 watt array using 300-400 watt panels (2-3) has fewer connections that the same out put system made with 100 watt panels (8).
Solar panel size vs quantity for mobile applications
- Thread starter 1holaguy
- Start date
sunshine_eggo
Happy Breffast!
100W
Pros:
Not ignoring real estate as that's typically critical on an RV. The smaller panels can sometimes be "tetris'd" into more PV for a given square footage considering roof protrusions.
100W panels are typically 36 cell and have finer granularity on an array configuration. 6 100W in series hits the sweet spot of typical 145-150Voc MPPT.
Cons::
100W panels require more roof penetrations for a given wattage.
100W panels typically cost more $/W.
Pros:
Not ignoring real estate as that's typically critical on an RV. The smaller panels can sometimes be "tetris'd" into more PV for a given square footage considering roof protrusions.
100W panels are typically 36 cell and have finer granularity on an array configuration. 6 100W in series hits the sweet spot of typical 145-150Voc MPPT.
Cons::
100W panels require more roof penetrations for a given wattage.
100W panels typically cost more $/W.
Paul_R
Solar Enthusiast
I find that 200w panels tend to be the best choice for an RV roof, considering size constraints and weight. And there's a lot more wind load on a 400+W panel so RV construction and mounting systems need to be up to the task. Most RV's and commercial mounting systems ain't.
robstrom
New Member
On my cargo trailer build, I went w 2 x 420 watt. I had a roof w only 2 small obstacles of my doing ( dome vent n woodstove exhaust). I had steel roof beams to drill into, you're rv won't. Biggest you can make fit!!
Will ( and others) have youtube videos about securement to rv roofs.
Will ( and others) have youtube videos about securement to rv roofs.
PlanetExcellent
New Member
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- Sep 16, 2021
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- 43
I wanted a couple of 250-300 watt panels on my travel trailer to reduce mounting and wiring complexity. The ones that were available from SanTan were too big to fit, and then I found out that the shipping was going to be about $200 which would negate any savings. I ended up going with 2x 210 watt panels by Newpowa via Amazon, and I'm very happy with the choice. Agree with Paul_R, I think the 200 watt size is the sweet spot for size/fit, performance, and weight/handling while installing.
MrThisIsME
Solar Enthusiast
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- Aug 8, 2022
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Not sure I saw it mentioned but your battery voltage / roof space comes into play on an RV roof as well. Say you had a 48v system (meaning the MPPT would want to see 60-150Voc), three large panels (3S) will push the upper limit for 150voc; close enough that it is not advisable. 4 large panels would work (2P2S) but you do not have the space.
MrThisIsME
Solar Enthusiast
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- Aug 8, 2022
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If you do some playing around with the Ironridge product and their tools, you will find that the same four bolts that hold down a 500 watt panel are the same 4 bolts that hold down a 200 watt panel. They are rated at something like 130mp both.
You want to consider the series parallel configurations you can make. If you have 3 panels, you'll be stuck in a 3p configuration which may mean too much current for your charge controller. Having 4 lower power panels allows you to have options in configuration. Of course, you can design your system so that a 3p configuration won't be an issue to you.
I used a CAD tool to model the roof of my RV and prospective PV panels. The original plan was four 200 watt panels. But the modeling showed that I didn't have room for four panels. I switched to two 320 watt panels instead. Not as many watts, but it worked out on the roof.
I use ground deployed panels for when I need more power from solar.
I use ground deployed panels for when I need more power from solar.
Paul_R
Solar Enthusiast
I made cardboard templates to verify fit.