Wednesday, March 18, 2009

For the Survivalists: How much gasoline is one Solar Panel worth?

Ok, first, what is the Kilowatt*Hour equivalent of a gallon of gas?

A Gallon of gas contains 114,000 BTU/gallon per Wikipedia (and other sources).

So, 1kWh is ideally equal to 3412 BTU, but no Generator is ideal. The generator's conversion efficiency is measured by its "heat rate," and the common range seems to be centered around 8,000-11,000 BTU/kWh. For this estimation I took a very efficient generator and used 8000 BTU/kWh (about 43% Efficiency).

Using these numbers gives a Total Energy Output/Gallon of 114,000 BTU/Gallon * 1kWh/8000BTU, or 14.25 kWh/Gallon.

Cost: $2.50/Gallon. This gives Cost/kWh = $2.5/14.25kWh = $.18/kWh

Now, let's look at a single 200Wp Solar Panel over one year at a 17% Insolation location (like in Massachusetts).

200Wp * .17 * 1Year = 34W*Year = 34W*Year*365Days/Year*24Hours/Day = 297.8kWh
Cost: $800/Panel. This gives Cost / kWh = $800/297.8kWh = $2.68/kWh

Woah! Ok, so obviously the Solar System doesn't pay off in a year. Going out 25 years, though, (assuming 10% average degradation over that time) gives a total of 6700.5kWh produced over that time for a total 25 Year Cost/kWh of $0.12/kWh.
For another comparison, over 25 years this single solar panel will produce the equivalent of 470 Gallons of Gas, or at this rate, 19 Solar Panels (3800Wp) will produce the equivalent of a gallon of gas per day.

Of course, this isn't exhaustive. I didn't compare costs of the generator involved, or of the installation and inverter costs for the Solar (this will at least double the cost for Solar Energy, but Government Incentives will bring it back down quite a bit). The focus here is a comparison between energy output over time. The point being, it's a potentially valid hedge for those that might be worried about future disruptions in such things like the supply of gasoline for generators. Prior to such a time, there are choices to be made, and in the case of a very long term potential outage, Solar Panels will provide much more energy than a person could even safely store in the form of Gas for an extended period of time. I also didn't account for such things as Interest on debt, because a Survivalist isn't necessarily going to care about that. If the time comes that they are preparing for, they know that money just might not worth what it is at the moment, and a working light bulb may be worth alot more.

Of course, remember that if you're one of these people, the neighbors will know that you have Solar Panels (or a Generator), and they'll want in on it. Therefore, the best thing we can all do now, is to do everything possible to make sure that not just "we" have a system, but to make sure that as many of our neighbors have them, too. Desperate people are dangerous.

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1 comment: said...

Great articles on comparing solar W and Wh to to equivalents in gas etc. I will continue reading. I wan to do an article where the real net present value of future long term use of a generator or a solar installation are compared.