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Solar Skoolie Shopping List - Big Items

2020-04-17 by: Mike

Skoolie. Off Grid Boondocking RV.

This is something I get asked about a bit, We own a small (B+) RV with about 400 watts of solar and 200+ah of AGM battaries and a 2k watt inverter. I run the generator if we need AC, which is rare. I've helped build off-grid homesteads and skoolies for others. Former "BioMedical Engineer" and currently a geek/maker, but not a licensed electrician. Not much of such projects is by code anyway. but it is a good guide. This is my opinion, worth exactly what you paid for it.

Go big, for your home.

If this is a skoolie (School Bus Conversion) or tiny house, or large RV and you are living in it. the answer is: You want as much as you can fit and afford. Go 48 volt DC for batteries, the conversion to 120VAC is more efficient and you can get 12vdc efficiently via some 48v to 12v converters for lights and water pump and basic electronics. Some decisions drive others, it's all got to work as a system. I'm picking "Magnum" brand inverter and MPPT charge controller because the work well together and seem to be quality made. I have some experience with them. Prices are approx as of this article April 2020.

Magnum Energy MS4448PAE 4400 Watt, 48 Volt Pure Sine Wave Inverter/Charger
Converts DC battery to AC, and will charge batteries from AC.
Magnum PT-100 MPPT Charge Controller
Solar in (up to 180 VDC!) to charge batteries and feed inverter
Magnum Energy Advanced Remote Display w/Cable
Sometimes included with above in the package. It communicates/controls both.

That's the heart and brains of your system for about $3500. Buy new or certified refurb. You don't want these if they have been abused by someone and returned. Next are batteries and solar panels. You will need at least 4 12vdc 100+AH batteries or 8 6vdc batteries. Sometimes you can find deals on data center or telecom "pulls" but they are physically a different size. What you chose depends a lot on where they are going and that -may- depend on where you are. Batteries may need to be "inside" in the great white north. In most places, a steel or aluminum battery box outside/underneath is a good choice. Near where your inverter/charge controller is is a good choice, It's a fat stiff cable between them. Personally, I like standard "AGM" or deep cycle batteries. But there are some awesome exotic choices.

Pick one of these:
Duracell Ultra Platinum AGM BCI Group 31M Deep Cycle, 4 at 105AH each.
size of large car batteries
$250 each = $1000
Duracell Ultra Industrial 6V Deep Cycle Battery, 8 at 250-370AH each.
Huge, both in size and capacity
$200-300 = $1600 to $2400
Trojan T105 Battery 6vdc, 8 for 225ah total$200 each or $1600
Trojan T105 Battery 6vdc, 16 for 450ah total (2 strings)$200 each or $3200
Exotic example: Eclipse 48V 100AH LiFePo4$3840
Insert other exotic battery tech here. If interested in "Exotic". an option would be a Tesla Powerwall. for about $7k-$10k.

Solar panels.. Size/efficiency and mounting matters. Fitting on the roof of a Skoolie or RV is an exercise in comprimise. Personally, I really like glueing flexible panels on the roof. It's worked well for me and they don't stick up. Lets do some math, with panel size and efficiency as a selector. The goal is 2500+ watts of solar. More is better.

Renogy flexible 12v 160watt. $270 21% 59.2x26.5x0.08in. 1568.8 sqin/10.9sqft or: 14.67 watts per sqft at $1.68 per watt. Expensive but low profile and only needs a big tube of glue to mount. 16 panels is 2560 watts at a cost of $4320 and need 176 sqft. Smaller panels, possibly fit roof better?

Heliene 370W 72M Monocrystalline PV Module. $300 77"x39"x1.57 and approx 50lbs. 3003sqin/22.6sqft. 16.36 watts per sqft at 0.81 per watt. 8 panels would be 2960 watts at $2400. These are expensive typical size panels, but are efficient for their size and cost. As you only have so much space, you go for the more expensive panels that provide more power per sqft. These are typically USA made panels.

Panasonic N330 HIT Module, $390 each. 62.6 × 41.5 × 1.6 in at 41 llbs. 2594 sqin or 18sqft = 18.33 watts per sqft (more efficient than above)
8 panels would be: 2640 watts and $3120
10 panels might fit (smaller panels) and would be: 3300 watts and $4000.

I used approx pricing, and sourced these descriptions, data and prices from Amazon.com, WholesaleSolar.com and BackwoodsSolar.com - There are other sources. As helpful humans, the BackwoodsSolar.com people get high marks. Batteries from Batteries Plus (don't laugh) and BackwoodsSolar.com - There are other sources. Shipping matters.
Small stuff: You'll need wire, circuit breakers, transfer switches, and some things I'll add here later. Plus lighting, water pump, etc.. a minimum of $3k of misc if buying new at big box stores. I'll try to make a list of that as well when I can.