Peer check on truck camper solar install

[ripperj]

Anyone want to see if this makes the most sense.
Four 100w 12v Renogy mono panels
100/30 Victron SmartSolar controller
Two 100ah Renogy agm batteries for now
Magnum MMS1012 charger inverter

Going on the roof of a Northstar TC800 truck camper

I was going to connect two panels in series, then put the two sets in parallel, looks like the best compromise between keeping the current down and minimizing loses to shading.
Does the panel configuration make sense or is there a better way to go?
Thanks



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[Joe917]

Have you calculated your power needs?
Larger domestic panels will give more watts per dollar.
Don't get sucked in to one companies marketing, look for the best price on the best components you can afford.
Victron and Magnum are good choices.
6 volt golf cart batteries will give the most Amp hours per dollar.

 

[ripperj]

Ok thanks for the help
I didn’t really do any calcs for loading, but my previous camper had similar loads with the same battery capacity and worked out great. The previous camper had no solar though , so I needed to drive a ways or plug in.
The 400 watts looks like a good match to recharge the batts in a decent amount of time


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[broncobowsher]

Might want to step up to the 100/50 charger. The 100/30 is limited to 440W input power. Yes, you are under the limit at only 400W. But that is also Standard Test Conditions. That is 1000W/M2. I have seen solar data where in the summer the solar radiation can exceed that number. Having a little extra buffer so you are not running electronics at the limit also helps the electronics run happier and longer.

 

[228B]

If you don't have the panels yet, you might look at Newpowa's 210W panels. Dimensions are roughly 26.5" X 64.5"

I was going to do four Renogy 100W monocrystalline panels (I already have two), but saw the Newpowa and thought that mounting two panels would be easier than mounting four...

Having said that, I am nearly finished with my installation of these two 210W panels on the roof of a small trailer, and it was not fun. OK, it's fun now, but not while I was planking on the roof, trying to stay over one roof spar...

I'm keeping one of the Renogy stashed in my truck kit for emergency use for the truck's starting battery. My trailer 12V will be completely separate from the truck's 12V for the sake of simplicity and reliability (and redundancy?).

As for the panel mounting, if I had to do another trailer I'd first find the dough to have a rack welded to the wall studs. No more tedious and multiple measurements to ensure correct bracket mounting holes through the roof... ugh.

 

[228B]

* a roof rack custom welded then through-bolted using four of the trailer wall studs

 

[ripperj]

Thanks for the input. Too late on the panels . I could probably return the controller, but it’s rated for 4 100 watt panels.
I assumed because I’m flat mounting the panels that I wouldn’t max it out. Plus with 2 parallel sets of two panels in series , I won’t see max current

I’ll double check the two controller specs

 

[ripperj]

I took a look at those 210 panels, I probably would have gone with them had I seen them... thanks for the link


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[Buddha.]

If your batteries are mounted internally and you cant have them off gassing I would go with those sealed AGM types. If the batteries are mounted outside and vented I would go with dual 6v golf cart batteries.

The AGM batteries are about $100 more expensive (each)and the only benefit is that they’re sealed.

 

[LivinDaDream]

Anyone want to see if this makes the most sense.
Four 100w 12v Renogy mono panels
100/30 Victron SmartSolar controller
Two 100ah Renogy agm batteries for now
Magnum MMS1012 charger inverter

Going on the roof of a Northstar TC800 truck camper

I was going to connect two panels in series, then put the two sets in parallel, looks like the best compromise between keeping the current down and minimizing loses to shading.
Does the panel configuration make sense or is there a better way to go?
Thanks



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The only question I'd have about this is your battery choice...and it seems you've got more battery space than I do in my Lance 815. Why not a 100AH Lithium...you'd have the same (or more) useable power with only 30% of the weight and half the space. The price of those two AGM batteries is 60% of the price of a single premium Lithium drop-in battery...a no-brainer when you consider lifetime. No way I'd never go back to any lead-acid battery technology for my application. In fact about a week ago I installed a DIY 280AH battery pack in the same space that my BB Lithium had been occupying. As I've got my charge controllers/BMS charge/discharge limits set, I'm running it conservatively as about a 224AH system. May do a post about that separately.

For me, the biggest plus is being able to get back to 100% charge very quickly on days of partial sun. I've got 3-100W Renogy panels on my camper roof (in series) and two more 100W panels (on a separate MPPT controller) that I can sit in the sun if I'm camping in shade. My typical overnight power usage (refrig, lights, laptop and electronics recharging) is about 300-400WH and I can put that back in my battery in a couple hours of full sun. You generally can't dump that much power into lead-acid and get your battery back to full charge that quickly. Something to think about that is often overlooked and hard on lead-acid batteries.

Cheers!

 

[ripperj]

Had I known that my charger was going to get banged up in transit and then exchanged, I’d have gone with lithium. I believe the new charger has the lithium profile( I got a good price on the original because it was new old stock)
I’ll stick with these batteries for now, although I could probably return them.


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[228B]

You generally can't dump that much power into lead-acid and get your battery back to full charge that quickly. Something to think about that is often overlooked and hard on lead-acid batteries.

Not exactly. Take an Odyssey AGM, for example: There is no limit to inrush amperage during the bulk charge phase (up to +/- 80% SoC)... that can be massive power.

It's the *absorption* phase of charging lead acid AGM batteries that is the time sink. In some cases (per brand), four to six hours!

I'm not at all certain how a LiFePO battery should be charged, therefore I have avoided them. I have overheard some who own LiFePO (Lithium Iron Phosphate, NOT Lithium Ion or Lithium Polymer) think there's no harm at all to completely discharging them. How long can they be left in a discharged state before charging them fully before they are damaged?

Thanks for your time in reply.

 

[Rando]

One of the beauties of LiFePO4 is that the charge requirements are much simpler than lead acid. One or two stage charging to 14V is all you need, no float, no temperature compensation, no equalization or any of that stuff. They will generally accept full charge current up to ~95 - 98% SOC before it begins to taper. There is also no harm in storing LiFePO4 at partial charge indefinitely, so unlike lead it doesn't matter if you don't have 4-6 hours to get them through absorb. And while it is true that odyssey can take a very fast (bulk) charge, most deep cycle AGMs recommend a charge current between 0.2 - 0.3C, meaning 2-3 hours of bulk charging before you get to the another 4-6 hours of absorb. This is a big deal if you charge by a generator or alternator.

 

[LivinDaDream]

True, you can dump a lot in up to around 80%, but it's that last 20% that you need to get in there to not greatly reduce AGM battery capacity. They really do need to be brought up to 100% charge regularly and aren't really a good fit for a system that doesn't have a good means to bring them to 100% in short order if you significantly discharge them. I'm generalizing a bit, LiFePO doesn't really care as long as you stay below .5C charge rate and whatever discharge rate the cells and BMS will accommodate. Never exceed voltages are 10V on the low side and 14.6 on the high side, though for safety and longer life, I operate my DIY pack between 12.6 and 13.5 and that gives me about 80% of the max capacity of my cells without pushing to extremes. If you look at a discharge curve for the cells I'm using, there are "knees" at 12.6V and 13.5V and a very flat area between those points in the charge/discharge curve. Going above or below those points doesn't gain you much and affects your overall longevity. Rando typed his reply while I was typing this and touched on some of the same issues. If you can spring for the upfront cost, there is no better solution and long term, I have no doubt that it's a much more affordable solution. As I mentioned in my first post, there was no way to get the performance, convenience and simplified charging regimen that I have with any lead-acid option...none!

Take this video for what it's worth, but it's hard to argue with their methodology and results...https://www.youtube.com/watch?v=iy3hga_P5YY

Cheers!