Jonathan Bellows

8x20
nailed hardboard panel to wall then covered with white panels and painted
used 2" followed by 1" styrofoam in walls
12 volt DC refrig - uses a lot of battery
bathroom across rear
water supply tank and water heater under sink

The power for the fridge is DC. I originally wanted one that could run off of DC or gas, but when it came time to get one, the "DC only" one was what was available to me. I didn't want to wait and risk stalling the project, so I got it.

As for the lights, you are correct - they are all LED lights except for the ceiling fan, which runs off of AC. All of the power coming out of the battery is 12 volts DC, although I do have wiring in place that'll enable me to install an AC inverter in the future. Right now, though, all of my AC power is coming from an extension cord that runs to the garage.

Basically, the lights, the water pump, the fridge, the fan for the heater, and the cigarette lighter wells (that I use to plug in my cell phone) are all DC.

The TV, the regular outlets, and the ceiling fan are all AC.

The little fireplace, the stove, and the water heater are all propane.

The DC battery can charge through the solar panels or through a trickle charger that plugs into an AC outlet. The AC power can come from either an extension cord to the garage or, eventually, through an inverter from the DC battery. Basically, the idea is to have both AC and DC systems interconnected so that as long as I have access to either one, I can run both.

I have my 3 15-watt panels hooked up to a single deep cycle marine battery that I bought off the shelf at an auto parts store. Not exactly a well-researched system! However, it's all enough to power my lights, my water pump, the blower on my furnace, and to charge my cell phone at night. Michigan skies are notoriously overcast in winter (90% of the time) and even in those conditions the panels keep up. I DO remember having to plug a trickle-charger in at one point last winter because the battery got low, but so far this year has been just fine.

My panels do NOT generate enough power to run the fridge (which I basically don't use now because of that) or my laptop. The fridge drains the battery in a couple of hours, whereas the laptop draws twice as much energy in an hour as the panels could produce at their theoretical maximum output. Given that I got the panels on sale for less than $170 at Harbor Freight, I can't expect TOO much from them!

My old Harbor Freight panels. Each one produces 15 watts for a total of 45 watts. The new Kyocera panel on the right, though, produces 3 times as much as the other three combined. That's a 135 watt panel sitting there, and I've got 2 more on the way. That'll give me 450 watts of power generation total, which means I should be able to give my batteries at least 900 kwhs a day in the dead of winter (more in summer.) When I was checking my usage at my Uncle's place, I was using anywhere from 800 to 1,500 kwhs a day, depending upon what I did. I've since purchased a much more efficient ceiling fan, and am going to be running on more efficient DC power

mini mobile cottage

Water Heater - Precision Temp RV 500, there is a good article on the RV Doctor Blog on this water heater.
Toilet - Biolet I chose to go this route on the waste disposal issue. Primarily because of availability and cost. These are available at Home Depot, here.
Stove - I went with a two burner Seaward model 2277
Heater - The large P12000 fit my need (I hope) from Dickinson Marine
Water Pump - Aqua Jet WPS Flowmaster 5.0 from Johnson Pump
Trailer - Customer build for less then a new off the lot that I would have to modify anyway. MS Metal Works

From a needs perspective those are your key investments, that being said the only thing on that list that is AC is the Biolet. Everything else is DC which then would require you to have some sort of DC power plant. While there are several options here, I chose to go the solar route. I have primarily used two sites and the Solar Living Sourcebook as my resources to go solar. The two sites are Backwoods Solar which has been excellent to deal with, very prompt shipping and super customer service, and Go Green Solar. I had a challenge trying to match up equipment and emailed Go Green with a question and in 30 minutes had a detailed explanation of my issue. Both have been very reliable to buy from over the web. My bet when all said and done the Solar decision will have added $4000 to the budget.

Solar Panels - Kyocera 135 Watt (2) bought them from Backwoods
Charge Controller - Blue Sky Solar Boost 2000E
Battery Monitor - Tri-Metric 2025RV
Inverter - Samlex America was the brand, the one I bought was 1500-watt-12v Pure Sine Wave TN1500-112F

Other key bits of info that were important to me:

Towing Regulations for all around the Country can be found at Towing World

Best book ever on your shit and how to deal with it. Humanure Handbook

And as you probably already know, YouTube is a great place to get info. I have used it extensively for building tips and solar insight.

best results came from Star drive screws. I can say emphatically that that is an awesome suggestion. While I am using nails on most of the framing, all plywood attachment is with screws, and a lot of the large gap fastening and angled 2x4 fastening has all been done with screws.