Wednesday, February 6, 2008

My Survival Cabin - Powering a Cabin

No Power

There was no gird power available on the 5 acre parcel chosen for the cabin. The nearest utility power lines were a distant six miles. Running grid power to the cabin was cost prohibitive and thus not possible. It did not make sense to pay more for the power access than for the land itself. Alternative power sources were going to be necessary. At first alternative power appeared to be equally costly but after considerable research and some big reality checks on usage it became a manageable project that would not bankrupt me.

The Small Cabin at Bear Ridge was illuminated in the summer of 2003 with kerosene lanterns. Kerosene lanterns make reading easy and the light is nice and warm. A Dietz 75 hour kerosene lantern gives off good light and do not need filling that often. I have two of these kerosene lanterns at the cabin and one at my house and would highly recommend this product. I still use them on evenings when I am looking for that bright warm candle quality light kerosene lanterns produce. The Dietz Lanterns will burn lamp oil, kerosene or citronella oil when the bugs are a problem.

When construction was started on the Big Cabin at Bear Ridge, I reevaluated the lighting and general power needs. In addition to lights, I wanted to power an efficient laptop, charge the cell phone and listen to Sirius satellite radio. Luckily, the neighbor has SkyBlue satellite internet access and they let me jump on their wireless when needed. A directional wireless antenna is necessary on my end but the signal strength is very adequate.

Generator Power

In the beginning there only needed to be enough power for the weekends. Two deep cycle 75 amp hour batteries ($45 apiece) supplied plenty of power at that point. The batteries were transported back to Denver and charged in the garage during the week. A 3500 watt generator ($250) was added and the batteries were charged every few weeks. The addition of the generator allowed the for the use of 120 volt high amperage appliances such as vacuum cleaner, electric chain saw, table saw and air compressor.

The air compressor was a life saver. Cabin construction goes ten times faster with air framing nail guns and air roofing nail guns. Nail guns are a must have, I can not imagine construction without them. You can purchase a gas powered air compressor but I recommend a 20 galleon 120 volt air compressor ($160). For the cost of a gas powered air compressor, you can purchase a generator and electric air compressor. You need the generator anyway.

Solar Power

It was determined that three 45 watt solar panels ($200 apiece) with a 30 amp charge controller ($100) would be sufficient for my weekend cabin. 135 watts delivers a little over 7 amps per hour of charging time. If you count on six good hours of charging per day, the three solar panels can put 42 amps away daily. This was plenty to charge the four 115 amp hour deep cycle 12 volt batteries ($60 apiece). Each battery furnishes 115 amp hours for 460 amp hours in the pool to draw from.

To determine how many amp hours you will need take the watts of the device and divide by 12. A 60 watt bulb uses five amps per hour. If you took that 60 watt bulb and left it on for six hours in the evening, it would draw 30 amps of power from your pool. The next day when the sun was out you would need to replace those 30 amps with the solar panels. You should not be using 60 watt incandescent bulbs but you get the idea. Here is a rough break down in amp of what the cabin currently draws. Everything at the cabin runs on 12 volt DC.

Three 20 watt halogen lights kitchen

5 amps

3 hrs

15 amps daily

Two 5 watt florescent lights living room

1 amps

4 hrs

4 amps daily

One 1 watt LED reading light bedroom

.2 amps

5 hrs

1 amps daily

Sirius Radio

1.5 amps

6 hrs

9 amps daily

Cooling Fan

2 amps

6 hrs

12 amps daily

Water pump

6 amps

1/2 hrs

3 amps daily


6 amps

3 hrs

18 amps daily

Total daily amps

62 amps daily

Notice that the total amps used per day is greater than the total amps being put back into the system with the solar panels. This is fine if you are only visiting on weekends and the batteries could be replenished during the week. It is not comfortably sufficient for full time living.

The total amps could be reduced greatly if the fan was not used and the kitchen lights were replaced with LED spotlights. The laptop is usually fully charged for the weekend and most of the time it is not even used. Notice that the great power hungry conveniences are not present. This design will not operate a washing machine/dryer, refrigerator, microwave, electric coffee maker, and etcetera. This is a relatively inexpensive solar power system that you can install for under $1500. Backup power is provided by the generator which only needs to be used when there have been several days of heavily overcast skies. You must have a backup power system either a gas generator or a small wind power generator.

Wind Power

I could live year round at Bear Ridge if the above energy saving items were implemented and if a few additional solar panels were added. A small wind generator would also really help. There is a constant breeze at Bear Ridge and an efficient wind generator would run around the clock and really help during the winter months when daylight is short. If the money is right I will be purchasing a modest wind generator ($600). Your basic wind generator delivers up to 400 watts or 27 amps in ideal conditions.

Big Upgrade

Sorry but I will need to do the rest tomorrow night.


theotherryan said...

In some ways you are blessed about not having an easy grid power solution. Having all of the cheap easy power that you want would have lead to a high usage energy cabin which would be very hard to economically power with an off gid option.

Working the other direction going from zero power to some power is much easier to pull off.

I whole heartedly agree about nail guns but think their tendency to ovepenetrate leads to leaking roofs so I would only use them for framing and the like.

I've heard (did a report in 8th grade or something) that 2 sources of alternative energy is the way to go because theres no way to tell if there will be a week of overcast days in a row or no wind.

Great post!

Oldman in the boonies said...

Excellent post. Makes me want to get my dead butt going on my solar system as well.

I made the basics of a good sized rain water harvesting system last summer.

Anonymous said...

Another great entry. Fast becoming my favorite blog. I burn with jealousy when I read about your cabin. Someday...

Future Farmer said...


What kind of fridge are you going to use ? I have been using a 12 volt dc unit with compressor .

BigBear said...

Glad you all enjoyed.

Future Farmer,

I don't use one yet. All the extended periods I have spent there were in the winter. I am going to be getting a very efficient AC unit this summer but I will talk about more when I finish this post...Which was supposed to be today but didn't work out so hopefully tomorrow I will finish it up.


Anonymous said...

I live in crowded and dull Britain and you really don't know how lucky you are to be able to get out and enjoy the freedom of off grid living in your own cabin. Next time you get there (hopefully next weekend!) spend a little time doing nothing, looking around and thanking God (or the Higgs-Bosun if you believe in that sort of thing)about your good luck.Well done mate.