We’re all probably familiar with the Pareto principle: you get about 80% of the results from the first 20% of effort. Sometimes it’s called the 80/20 rule, and probably a few other things besides. A while back a friend pointed out that not only does the Pareto principle hold, but that powers of this ratio work as well. For example, Pareto squared would give 64% of the results from the first 4% of effort. Since then I’ve been mulling this idea over in regard to solar power.
Taking this even further, I put calculator to paper and made a table. Starting with a $100 per month electric bill, it shows about what you can expect for each power of 0.8 and 0.2 down to some ridiculous level. Now, all of these numbers are rough-and-ready, but as the currently fashionable phrase goes, they’re directionally correct. Anyway, here we go:
Start with a $100 electric bill at $0.13 per KW-H, and in round numbers it's 25 KW-H per day. Figure on 5 hours per day of sun; that’s the average in a lot of the U.S., though it will vary. Look up “insolation chart” and you’ll find what you need. So to make 25 KW-H over 5 hours, it’d take a 5 KW system. The “P” column is the “Pareto to the power” column.
W-H/day P %lifestyle %pwr size solar comment
25K 0 100 100 5 KW baseline, normal living
5K 1 80 20 1 KW still a pretty big system
1K 2 64 4 200 W easy, cabin-sized system
200 3 51 0.8 40 W pretty small
40 4 41 0.16 8 W dinky, portable
Don’t get hung up if something’s 20% or even 50% off, the idea is to examine the Pareto-to-some-power principle and look at a few directionally correct round numbers.
The first system, 25 KW-H per day, is doable with a professional solar install. Get your checkbook out. But you know, for some rich geezer who wants to get off-grid and not worry about hurricane season, it’s not a bad way to go. I’d admire the system and want to be the guy’s neighbor.
The second line is a pretty big and it too might mean a professional install. You’re not going to run an electric water heater or heat pump on this one, and even running a stove for very long is not doable. But you can run a refrigerator, the control electronics and fan on a gas furnace, and pretty much everything else within reason on this system. No central AC, deal with it, but you might run a window unit a little. Honestly, this is about the level of power consumption I grew up on. Like the Pareto principle says, it’s 80% of the base standard of living.
The next line, “Pareto squared,” is where things get interesting. This is at the DIY system level and lots of us here have something like this. You might get by with a small 12v refrigerator, a laptop computer, LED lights, 100 watt ham radios for hours, CB, etc. off this with no problem, and with some budgeting you can watch a movie in the evening. Even running a microwave oven for 5 minutes here and there isn’t out of the question. Pretty useful, it’s right at about 64% of a “normal” modern lifestyle, and seems nice compared to other extended outage options. Also, if you have a generator, you can run a few larger items, say refrigerator or room AC, recharge batteries, and be pretty much back at the 5 KW-H/day lifestyle — as long as the gasoline lasts.
The next line, “Pareto cubed,” is where things get tight. This is about the size of one of those Harbor Freight systems. You can do a lot with it though: lights, recharge cell phones and AA batteries, talk at 100 watts on ham during half-hour comm windows or use a CB all day long. Couldn’t really watch a movie, but it’d be no problem to run a battery radio for entertainment and news. You could run a laptop and a cell phone wi-fi some on this. Yeah, you’d have to really watch your power usage, but with lights and all it’s an OK life, and right on 51% of the baseline.
The last line, “Pareto to the fourth,” is getting down to a minimum, but compared to zero power it’s still really good. This is about the size of one of those Goal Zero notebook systems that uses a 4x AA pack for its battery “bank.” Look at what it can do: a reading light at night, recharge a cell phone, charge batteries for an AM/FM/SW radio. What’s more, it’s portable. It’s a lot better than most of the poorer first-worlders had it a century ago. Right in keeping with Pareto, you could call it 41% of the modern life.
OK, that ran long. I haven’t put out a good mega-post in a while though, and this Pareto-to-some-power has been rattling around in my brain for a while. Thoughts?
