Wednesday, April 19, 2017

Solving the Air Conditioning Problem

I'm not totally pleased with myself, but I have managed to produce a little electricity for the cabin.  I have some problems to solve, but for the most part, we will not swelter in the spring and summer heat, and if we want to, we can run a light or two.

Solar is Pricey

I really poured over the information regarding "off the grid" solar power. In a word, "expensive." This is Texas, and there is no way in hell we can make it through a summer night without A/C. However, it would take about 10 - 15 deep cycle marine batteries to run one 10,000 BTU window unit. I would likely need about 4 - 6 100 watt solar panels to keep them charged.  Probably more.

To figure the watts of a 10,000 BTU window unit, I use this formula:
BTU / EFR (energy efficiency rating) = watts
My window unit is:
10,000 / 11.5 = 870 watts
Truthfully, I'm going to call that 1,000 running watts with something like 1700 starting watts.
I want to run an A/C for about 10 hours because Tammy and Elizabeth like to sleep in (and I will if I'm depleted enough by the city lifestyle).

My watt hours = 10,000

Deep cycle battery - about 1500 watts 
Since I don't want to completely deplete my batteries every night, I can only use 80% of the juice.

Cheap deep cycle battery - $80.

Add a mess of solar panels to charge the batteries at about $140 a piece.

This got ridiculously expensive very fast.
Although we're holding out on running electricity to the cabin, the solar price tag did not stop me from hobbling together a short term solution.

4,000 Watt Generator

I did not buy the best generator on the market, but I did get a great deal on a 4,000 watt generator from Home Depot. One of my workmates ran a deal on the homepage of, and I jumped at the price. It works, but it is persnickety. It has to have just the right oil level and just the perfect fuel to oxygen mix, and after cranking my arm off, it will start, and it will run the A/C!

This particular model will run on gasoline or propane. I plan to use only propane because it's cleaner, and I'm hoping that will reduce the battle to start the thing over the long run. Also, it's important to note that a generator will be marketed at it's peak wattage; not it's running watts. In reality, this is a 3500 watt generator. On a 20 gallon tank of propane, it should run the A/C for 10 hours.

Once again - expensive, but not as expensive as a full on solar set up. We're at the cabin a few times a month. $40 in propane is still cheaper than a hotel room. Besides fuel costs, and cranky cranking, this thing is heavy. Moving it around is a workout. I bought some casters, and hopefully, I can make them work so we can roll it, and only lift to put it in the truck or cabin. So don't go lookin' to steal my generator. It's "portable."

It's also loud, so next project will be to build a little enclosure that helps buffer the noise it makes. We also need to protect it from rain when we're using it.

Let's see how long it takes me to freak out and call the electric co-op to run the lines...

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