Noah's Minimal Solar Power System

This is a solar system I originally put together for use in the desert during Burning Man 2003. I now use it to power reading lights, my computer monitor and whatever other small things I feel like. It's the most inexpensive system I could put together while remaining practical.

At the time of these photos, I was staying temporarily with friends after a fire forced me out of my apartment. This installation is therefore non-permanent to the most extreme extent possible, which bears consideration. This page, I hope, will point out that small solar systems can be so simple, it's not even necessary to have a permanent installation.

Photovoltaic Panel

You don't need a very sophisticated setup for small solar systems. This one starts with just a single panel I put in my friend's garden.

It simply rests in the yard. The metal frame is aluminum, so it won't rust. To figure out the best place to set it up in your yard, just go outdoors at noon time. Then, aim the panel so it's facing the sun. Intuitive!

To hold it up, I simply use a piece o' metal I found in their shed. It's heavy enough that most wind won't blow it over.

Charger

A piece of sunlight-resistant wire runs from the panel to this black box.

The box has a little screen on it that tells you much sunlight you're getting...

...and how full your battery is.

Battery

A battery is also attached to the charger. It's in that white box. It's the same size as a car battery, and looks like one, but it's got different guts. It's more suited for solar energy. It weighs a little less and can be discharged deeper without killing it. Normal car batteries die if you discharge them very much.

I keep the battery on the driveway so dew in the grass doesn't wear out the cardboard box it's in right now.

As you can see, it doesn't take up much of the yard and looks kind of intriguing. Everyone who walks by takes a look. Some people even ask me about it.

What do I do when it rains? I place the battery and charger underneath the panel. It shields them from light rain. In heavy rain and snow I'll have a little more protection.

Inverter

Solar energy essentially uses a style of electric power called DC. Most of your household appliances use another style of called AC. Converting from DC to AC is trivial. Just get one of these silver boxes from Radio Shack or anywhere else called an inverter. It attaches to the charger and lets me run my computer monitor.

You can either run your existing electric lights with an inverter, or you can make the system even simpler and buy DC lights. In that case, you plug them directly into the charger without an inverter. I don't have any yet, so I can't show you any pictures of them.

Technical Specs and Prices

This system lets me run 100 Watts for three hours on a full charge. In good sunlight, it takes about four to five hours to charge. Since I live in New England, there are trees and hills everywhere, which in conjunction with scattered clouds, lengthen the charge time to a full day. On a typical day, I bring the battery outside and connect it to the panel, then leave it while I go to work. When I get home, I bring the battery inside my house at night, use it for the lights, monitor and speakers in my room until the charge gets down to about 50%. Some people have asked me why I carry the battery around. The answer is simply that I don't want to dangle an extension cord out my friend's window. Nor do I wish to make any permanent modifications to their house.

I am extremely thrifty, so I shopped around to find the absolute best deal I could on these components. The solar panel was $277 at Parts on Sale. That comes out to $3.70 per Watt, which is the cheapest you'll find anywhere! I'm confident of this, but if you find something cheaper, please tell me, because I'll want to buy some! I looked high and low for this. The panel is a 75 Watt PhotoWatt on sale.

Since I bought my battery, I found an even cheaper place to get them. As I'm writing this, I checked the webpage of Solar Expert.com, and found the prices and had just come down even further. Hurray! You can now get the same battery I got for $76.53, or some slightly larger ones for astonishingly low prices. They get cheaper per Amp hour the larger they get. Again, I've looked around, and if you can beat this, I'd be very happy to find out where! My battery is a 49 Amp hour Concorde SunXtender PVX-490T.

The charger I got from Solar Seller. It's the cheapest one I could find that had the informative screen on it. I highly recommend getting a controller with a screen for your first setup. You really need it to get a feel for how quickly your batteries are charging, etc. At the time, it was $37.50. It was surplus though, so they probably won't last long. It is a Steca 8 Amp Charge Controller. BTW, Solar Seller also has lots of DC lighting equipment.

The inverter I use is no longer sold at Radio Shack. They sell some models now which are cheaper and have larger capacity. Cobra also sells an inverter with impressive specs and price, but I haven't used it.

Money-Saving Tip #1. If you'd like to get an even better deal on solar panels, you can buy two 75W panels for $247 each from parts on sale above. That will give you a system that charges twice as quickly, or to put it another way, only requires half as much sunlight during the day to charge.

Money-Saving Tip #2. To find the best price on batteries, I set up a simple spreadsheet to divide cost by capacity. I found there's a subtle dip in dollars per Amp hour for the 104 Amp hour battery. In other words, it's a good deal.

Colophon

Since my higher-resolution camera is in boxes in my friend's garage at the moment (fire...), all pictures on this webpage were taken with my casio WQV-3 Watch Camera. In a way, the watch is a metaphor for the webpage, because it's small and simple, yet turns out to be valuable.

The HTML for this webpage was written by hand by myself, using emacs in a terminal window under FreeBSD. I was running Secure Shell under Win2k. I was connected to the server via several T-1's, through 13 hops of the Internet, including nodes on AT&T, Level 3, and RCN's network.

Links

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a good band

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