My DIY Off-Grid Tiny House

[Grinder]

Following a recent Shoutbox conversation, I sorted through pictures and listed some details of my DIY off-grid tiny house, in case anyone here might find it interesting. I’ll be happy to answer any questions you might have.

When:
Purchased ten acres in Oct ’96 and began researching all aspects of efficient home design and construction; off-grid power system design, construction and maintenance; off-grid living; self-sufficiency; etc. Left SoCal in March ’98 and camped with dog in E-150 cargo van (belongings in 9’ x 11’ shed). As ground thawed, began digging 2’ x 15’ x 23’ crawlspace with shovel and digging bar. Poured pads and piers in early May. Framing in early June. Dried-in by mid-June; then insulation and sheetrock. Tired of camping, anxious to move in, and loathing the prospect of mudding, painting and flooring, I went ahead and built makeshift cabinets and loft bed over bare sheetrock and subfloor (and wouldn’t get around to mudding, painting and flooring until summer of ’05). Renovation in Summer/Fall ’15. Listed for sale Dec ’15. Sold in two weeks.

Where:
25 miles east of Flagstaff, Arizona. Three miles from paved road. 5,630 ft elevation (dry, high desert climate).

Why:
Affordable, low-overhead, no-mortgage, pay-as-you-go homeownership. Interest in renewable energy and efficiency. Escape urban SoCal.

Structure details:
Passive-solar design (naturally warm in winter and cool in summer). Solar-south-facing sliding glass door with overhang naturally maximizes winter solar gain and eliminates summer solar gain. Whirlybird ceiling vent for effective summer evening convective cooling. 18,000 BTU direct-vent propane heater, for cloudy winter weather (otherwise, solar gain alone keeps house 65 – 85 degrees in winter), at a rate of roughly 30 gallons of propane per year, at 70 - 75 degrees.
Exterior dimensions - 12’ x 20’ (240 ft^2).
Galvanized painted steel roof.
2” x 10” roof joists, R30 fiberglass + 1” R-Max (foil-faced rigid insulation), 15/32” OSB sheathing.
4” x 10” + 2” x 10” header (sliding glass door).
2” x 6” wall studs, R20 fiberglass + 1” R-Max, ½” sheetrock (8’ x 10.5’ ceiling height).
2” x 12” floor joists, R30 fiberglass, 1¼” T&G subfloor.
4” x 12” perimeter joists.
Six reinforced concrete piers on 24” pads.
2’ crawlspace with 2” R-Max perimeter insulation with corrugated metal exterior (completely rodent-proof).

Electrical power system and load details:
Summer ’98, began with two 65W PV panels, four 220AH 6V batteries (12V system – DC lighting, bag phone, boombox), 30A PWM PV charge controller (12V), 250W inverter (for small AC loads), 2,500W gasoline generator (for battery bank charging, power tools, stereo/home theater + subwoofer). Ice chest “refrigeration.” Propane burner (no oven) in shed for cooking and water heating (haul own water in 100gal tank, and then transfer to ten 6-gallon jugs stored indoors). Makeshift “shower” in corner under loft bed (heat water in pot, add to cold water in 6gal jug). Makeshift “sink” (with 6gal jug and 5gal bucket drain).

Spring ’99, added two more 65W PVs, upgraded to four L-16 (390 AH 6V) batteries and swapped ice chest for Igloo thermoelectric cooler. Though TECs are notoriously inefficient, I managed to greatly enhance performance and reduce energy demand by allowing Igloo fan to pull cool air from bottom of crawlspace (while venting warmed air just beneath subfloor), additional insulation, and an Omron programmable timer I had lying around. 2hrs on/2hrs off, with occasional forced on, worked quite well.

Spring ’01, rewired system to 24V, added 12/24V converter (for 12V loads), upgraded to 40A PWM PV charge controller (24V), added 2,400W “modified sine wave” inverter/charger (for all AC loads and battery bank charging), began field testing a 900W wind turbine and 30’ guyed tower system on behalf of my employer, and upgraded to a 3cu ft refrigerator-freezer (using considerably less energy than the enhanced TEC).

Spring ’02, *returned wind turbine to employer and added four more PVs and 8-panel pole-mount (for all eight PVs).
*While there is almost no better place in the US for solar energy, my site was marginal in terms of wind energy; and my battery bank was far too small at that time to make much use of available wind energy (strong wind for days in Spring and fall). I was also very concerned about possible heightened lightning risk presented by a 30’ tower …and had grown tired of hearing the thing pointlessly swish, swish, swishing in low wind.

Summer ’02, upgraded to a used 2,100lb 36V forklift battery (which I reconfigured to one 12V bank of six 2V cells, and one 24V bank of twelve 2V cells, and then electrically linked to each other via the aforementioned 12/24V converter), and added an 1,100W pure sine wave inverter.

Summer ’03, swapped 3cu ft fridge for full-size 19 ft^3 refrigerator-freezer.

Fall ’03, added eight more 65W PVs and another 8-panel pole-mount, upgraded to 70A MPPT PV charge controller, and managed to get my hands on another 2,100lb 36V forklift battery (which I also reconfigured to one 12V bank of six 2V cells, and one 24V bank of twelve 2V cells, and then combined them with the other reconfigured 36V battery into three paralleled 24V banks of twelve 2V cells.

Fall ’04, I added four 130W PVs on a homemade ground mount, and another 1,100W pure sine wave inverter. Installed 2,500gal polyethylene water tank and plumbing to crawlspace (at 3’ depth, to prevent freezing in absolute worst-case circumstance). Began having water delivered. Used hose from crawlspace trapdoor to fill jugs indoors.

Spring ’05, began field testing 250W wind turbine on 27’ and 48’ guyed towers (on behalf of employer). While it did work well, outside of particularly windy conditions it had very little noticeable effect on my power system.

Summer ’05, after having saved enough money and vacation time for an extensive home-improvement project, I finally got hot and cold running water (and drain-back water spigot, with no plumbing in exterior walls, for zero freezing risk): Installed a 24V DC pump, 6-gallon 2,000W 120V AC water heater (used for batch-heating only – not powered 24-7), proper shower, proper kitchen sink and countertop, freeze-proof greywater drain system, an efficient front-loading washing machine, AC lighting, porcelain tile floor, tape, mud, texture and paint …though I didn’t get around to installing trim until Summer-Fall of ’15.

Fall ‘06, purchased two PVs (165W and 175W) and a 30A MPPT PV charge controller from a friend, and installed the two PVs on a homemade ground mount …for a grand total of 1,940W rated PV, producing an average of about 10 Kwh/day. Took down 250W wind turbine (as I was making more PV power than I could use). Added a large toaster oven and a hot plate (both 120VAC), and began cooking in house for the first time, and cooking in shed only when batteries are low.

Spring ’11, sold the four 130W PVs and ground mount (low on cash).

Summer ’11, sold the 165W and 175W PVs, MPPT charge controller and ground mount (low on cash), and installed a 700W wind turbine and 30’ guyed tower I happened to have on-hand (forklift batteries being in such bad shape by now, and having sold 860W of my PV power, I suddenly needed all the power I could get).

Fall ’11, scrapped worn out forklift batteries and installed twelve 220AH 6V batteries (wimpy, but all I could afford at the time).

Nov ’15, replaced the above twelve 220AH 6V batteries with twelve new ones.


Comments? Questions? Discussion? Please feel free...


June 1998:

[Grinder]

1999:

[Grinder]

2015:

[Grinder]

2015 (continued):

[DavidRam]

THAT, is brilliant!

[BigAl205]

I would love to do something like this, but I'd probably do an earth shelter. How is you commute? Do you work from home?

[Grinder]

THAT, is brilliant!

Thank you! It was quite an experience.

[Grinder]

I would love to do something like this, but I'd probably do an earth shelter. How is you commute? Do you work from home?

Though quite picturesque, and zero traffic (except sometimes on I-40, with winter road conditions, construction), the 30 to 35 mile one-way daily commute was perhaps the worst thing about it, and was by far my greatest expense. I don't live there anymore (sold in 2015 and moved to Vermont).

Earth shelter would have been nice in a much warmer climate. There's real four-season weather in high-altitude Northern Arizona.

[jrwalte]

I know who to call if I need to 'disappear'

I need to be closer to civilization as I want my 400Mb+ internet connection but I'd like to do solar / whole home generator.

[diy.phil]

wow that is so neat/nice!