$600 gets your house on solar power

$600 gets your house on solar power

Eastbayray 5 comments

Reading an interesting/informative article by Rex Ewing titled “Piecing together a spanking-new $600 solar-electric system,” we were appalled that this pioneer of alternatives to standard grid living could be the same Rex Ewing who played guitar in the naughtily brilliant SHAGNASTY band.

Fortunately its a different Mr. Ewing — a knowledgeable practitioner on the maturing frontier of solar applications…..and this is what he had to say:

Got 600 bucks hiding in an old book somewhere? Maybe it’s time to bring electricity into that little homestead you’ve got tucked away in the woods. But wait a minute, you say, with justifiable hesitancy. Solar-electric systems all cost thousands, don’t they? No, just the expensive ones.

Logs, Wind and Sun: Handcraft Your Own Log Home ... Then Power It with NatureLogs, Wind and Sun: Handcraft Your Own Log Home … Then Power It with Nature – by Rex Ewing

Would you like to run a few lights, maybe a tv/DVD combo or a small computer? How about some moderately-sized power tools? An investment of $600 will get you there with all new components, as long as you don’t crank your expectations up too high. How? Read on.

First off, for the sake of simplicity we’ll assume the system is for either a generator-run workshop, or a weekend cabin, since that’s really where a $600 solar system belongs. In this way the PV module can spend more time collecting energy than you’ll spend using it, so you can invest less money in energy production (PV modules) and more money in energy storage (batteries).

But what components do you need to buy, and how much are they going to set you back? Fifteen minutes of surfing on the Internet turned up the following items. I’m sure a more thorough search would produce even more favorable results:

One Uni-Solar 32-watt amorphous-silicon PV module, 12 volts: $180.00

One Morningstar 6-amp charge controller, 12 volts: $40.00

Two Deka 92 amp-hour sealed batteries, 12 volts: ($130.00 each) $260.00

One Aims 800-watt modified sine wave inverter, 12 volts: $65.00

TOTAL: $545.00

This leaves you with $55 for wire, battery cables, mounting hardware, fuses between components, and the miscellaneous odds and ends that are always needed for any project of moderate complexity. What can you expect from this bargain-basement system? First I’ll explain the components, then we’ll take it out for a theoretical test drive.

Summing-up the parts

First, the 32-watt amorphous silicon PV module. I chose amorphous silicon, as opposed to crystalline silicon, for its superior performance in low light conditions, since you’ll want to capture every ray of sunlight you can. It’s nominally rated at 32 watts, but for reasons too complicated to explain here, the most power you’ll ever see it produce with a standard charge controller is around 25 watts. This peak production will be for the two or three hours that straddle midday, when the sun is highest in the sky. Though output varies with the seasons, this small module will produce between 0.15 and 0.20 kWh of power each sunny day; considerably less during cloudy periods. So, in a reasonably sunny climate, you should be able to count on about one kWh of energy per week, give or take. What can you do with that much-or that little-energy? Keep reading.

Next in line is the 6-amp charge controller. The positive and negative leads from the PV module go into it, and the + and – leads to the battery come out of it. A simple, inexpensive charge controller like this one does exactly two things: it charges the batteries without overcharging them, and it prevents electrical current from running backwards from the batteries into the PV module during the evening hours. While the latter function could be easily performed by an inexpensive blocking diode, if you want to be able to leave your system for days or weeks at a time, you’ll absolutely need the chargeconditioning capabilities of a charge controller.

Now for the batteries. You’ll want sealed gel-type batteries, even though they’re pricier than flooded lead-acid batteries. Why? Two reasons: first, you won’t have to build a sealed box to keep them in; a box which would have to be vented to the outside to prevent the buildup of flammable hydrogen gas. secondly, you won’t have to worry about all your water cooking out if you have to leave the system alone for a few months while you’re off exploring the headwaters of the Amazon.

With a rating of 92 amp hours each, the two batteries wired in parallel (+ to +, and – to -) will store a total 184 amp hours, or 2.2 kWh of power (12 volts x 184 AH = 2,208 watt-hours, or 2.2 kWh). You’ll never be able to use all that power, however. In fact, the most you’ll want to discharge the batteries on a regular basis will be about 50 percent, though if you occasionally have to dip a little deeper into the wattage reserves it certainly won’t hurt anything. To be certain, you should test the batteries from time to time with an inexpensive multi-tester. If they’re below 12.25 volts after sitting idle for a few minutes with no load, they’ll need rest and recharging before being asked to do much more work.

That leaves the inverter. If you only wanted to run a few lights and a TV, or a laptop computer with a car adapter, or even an RV-type water pump, you could get by without the inverter, but the extra cost for DC lights or a 12-volt DC television would probably pay for the inverter, anyway. Besides, you’ll inevitably want to run something that needs 120-volt AC (especially if the system is going in a workshop), so bite the bullet now and buy the thing.

A $65, 800-watt inverter lacks many features common on more expensive inverters, such as batterycharging capabilities, so you won’t be able to plug a gas generator into the inverter to give your batteries a little pick-me-up. Also, the modified sine wave it produces is but a crude approximation of the graceful, undulating waveform the power company (or a fancier inverter) sends through the lines, and some sensitive electronic devices may not work well, at all. But for most of the things most of us use electricity for, the modifiedsine-wave inverter will be perfectly satisfactory.

Okay…what can it do?

As you may have noticed, the usable power stored in the two batteries is roughly equal to a week’s output from the single 32-watt PV module, so each week you’ll have around one kilowatt-hour of stored sunlight at your disposal. What can you do with it? One kWh will run a 20-inch tv for 20 hours, a portable stereo for 100 hours, a laptop computer for 40 hours, or a 12-watt compact-fluorescent light bulb for 80 hours.

The 800-watt inverter (with a 2,000-watt surge capacity) will run a small vacuum cleaner, a drill or a small drill press, a sander, a jigsaw or small band saw, but not a large circular saw. It will handle many toasters and coffee makers, but not all. A blender would be child’s play for this inverter, a microwave an impossibility. A hair dryer on low, yes; on high, forget it.

And when I want more?

With the exception of the inverter, this system can be easily expanded. Any number of similar modules can be wired together in parallel, so long as the modules are of the same wattage. The 6-amp charge controller can manage up to three 32-watt modules, and extra charge controllers can be wired into the system, in parallel, as your lust for power begins to swell.

Batteries, of course, are always happy to see their numbers multiply.

But alas, the inverter is what it is. It cannot be connected to another inverter to provide more power (though more expensive models can be), nor can it be configured to operate at a higher input voltage, should you ever get ambitious and change the system voltage to 24 or 48 volts. On the other hand, at $65, does it really matter? A slightly-used 800-watt AC power source that can draw power right off the battery is a handy accessory any vehicle would be proud to have tucked away next to the spare tire.

So, while you’re saving up to buy the deluxe 4000-watt pure sine-wave inverter with battery charging capabilities, enjoy the little $600 starter system that got your foot in the solar-energy door, and try to imagine where it all might lead.

Colorado discusses how to assemble a spanking-new $600 solar-electric system. The system is good for either a generator-run workshop, or a weekend cabin.




October 11, 2005 at 3:52 pm

I would like to take a slightly different approach to setting up a small yet robust system. Think of it as solar with an attitude.

We left the unsustainable and hectic life of the Florida Palm Beaches with 26 years of the Three P’s (planning, preparation, and practice) under our belts, and headed for the Appalachian foothills of Alabama to homestead 21 acres of wooded countryside. Our first challenge on the electrical energy front was supplying our needs for lighting, weather alert radio, and fans (you would have to live here in the humid southern summer to appreciate this). The three reasonable alternatives would be grid hookup, fossil fuel generator, or solar – our creeks not being of sufficient flow and hundred-foot plus high forest made both hydroelectric and wind power impractical. Raye and I took the environmental and financial cost of clearing the power company’s required 60 foot right of way through our woods, or the more esthetically pleasing buried cable, as the target expense to beat if we were seriously going solar. Just as Mr. Ewing points out, none of this is really cheap upfront. Perhaps that is what separates many a homesteader from those who are not-it is not the shortsighted worldview, but the long term.

For photovoltaic panels we chose the SP75 made (at the time) by Siemens. These robust mono crystal-line-type cells have been around since the invention of solar cells; and they have proven themselves tough, long-lived, and efficient. Shop around. Look for a bargain-and be patient! We were able to purchase four panels for under $300 each-a great price seven years ago. These were mounted to a homemade tower made from scrapped components: 16 feet of four-inch galvanized schedule 120 pipe; bearing and frame from an old tossed satellite dish, a commercial heavy-duty linear actuator, recycled square aluminum tubing, and an inexpensive tracking circuit built by Duane Johnson of Red Roc ( http://www.redroc.com ). For storage, unlike Mr. Ewing, we kept the costs way down by using five pairs of six-volt golf cart batteries ($46 apiece as opposed to $130). Some argue that these are “beginner batteries.” Well, over six years later these little guys are still kicking electrochemical butt-an expectancy well within the upper lifespan of the lower capacity expensive ones.

At first we used a charge controller with all the bells and whistles. Because our initial cottage was placed under the nearly total shade of old-growth forest, the tracking tower and panels were located some 300 feet out into an acre clearing used for gardens, chickens, orchard/vineyard. Even with very large gauge wiring from panels to batteries some power loss was expected, but this was the tradeoff to placing the cottage out of the baking sun. We eventually found that the system worked much more efficiently without the controller and (as pointed out by the folks at HomePower.com) we just let the batteries bubble more often. Obviously, for us at least, this did not cause our batteries to be damaged. The small inconvenience of adding distilled water on a monthly to bimonthly basis depending upon the season was little to pay for the simplicity of the system.

So what can you push with this simple little system? Well, we run two cottages and a 40-chicken chicken house. In the cottages there are several lights (one 8W, two 22W, two 32W 12VDC fluorescents, and four incandescents); two 108ft^sup 3^ displacement fans for the shower and the composting toilet respectively; two computers running on 12VDC; auto CD/stereo; DVD player, weather alert radio, nickel metal hydride battery charger for camera, walkie-talkies, flashlights, portable players, and everything else. For those appliances using 120VAC we have two modified-sine inverters. A400W for Raye’s sewing machines and just about any other small appliance. There is also a 750W inverter for small tools, a grain mill, and the 52-inch Hunter ceiling fan. Our chicken coop is illuminated with a twin 15W tube fluorescent ceiling light for keeping enough light hours during winter in order to keep the hens producing eggs. There is also another of the 108ft^sup 3^ fans in the coop that keeps the odor out and cool air in.

Mr. Ewing’s system is quite inexpensive at $600 and could meet the needs of folks requiring a small or backup power load. Ours, including all the wiring, components, etc. had to come in under the $4,000 cost of getting the power company grid set up out in our place-a target we met at nearly half cost. Part of the savings was the result of doing all the work ourselves, part looking for bargains and salvageable components. The panels are guaranteed for 25 years, and (like Mr. Ewing pointed out) with a similar insignificant decline in output over that time to no less than around 80% quoted output. Think about this: after 25 years even at 80% there will be quite sufficient power to run all our stuff. The components were already paid for at purchase. And, paid for themselves several years back, too! Our primary future costs will be the battery replacement, which amortized over five to seven years comes out to only $5.50 to $7.70 per month.

Like much of what we have been doing out here, the photovoltaic system for the cottages has been just another laboratory for our semi-underground home which is now nearing completion. We modeled the house system from that of the cottages, and have purchased 10 SP75 panels and a 2000W inverter for it. The cottages will continue to be powered by the smaller system when we are in the house. Guests in the first cottage, and renter(s) in the second, will continue to reap the environmental, financial, and reliable benefits of going solar. When our good neighbors lose power because of downed trees during storms, etc., we usually do not even know until a day or more later. Not only have we been without power interruption for nearly seven years, we still have hundreds of mature hardwood trees that would otherwise have been cleared.

We hope that our learning experience with an alternative energy system will encourage others to consider jumping off the grid if their situation is similar. We would also like to hear from others working towards a sustainable lifestyle and living off the land.

Our system costs

SP75 Mono Crystalline Photovoltaic panels (4): $300 each.

Stowaway 220Ahr 6 volt battery (newer ones rated 200Ahr: $46 each.

Cobra model P12000 2000W (4000W surge) mod-sine inverter: $185.

Vector model VECC043 750W (1500W surge) mod-sine inverter: $75.

Vector model VEC031POB 400W (800W surge) mod-sine inverter: $35.

LED based tracking circuit (Redroc. com): $35

Scrounged components, wiring, miscellaneous components: $200

Blumthal and Blumthal take a different approach to setting up a small yet robust system using solar with an altitude. Here, they detail how they left the unsustainable and hectic life of the Florida Plam Beaches with 26 years of the Three P’s (planning, preparation, and practice) under their belts and headed for the Appalachian foothills of Alabam to homestead 21 acres of wooded countryside.



October 13, 2005 at 11:42 am

Thanks for all the specific information – it’s so useful. I’m gathering ideas to get as near off-grid as possible in a more suburban setting. Fantastic to hear about people really doing it!


Inexpensive DIY Solar Power – The $600 Kit – Brokekid.net

October 17, 2005 at 12:11 am

[…] ould pay and still end up with enough solar juice to run some things around the house? The Off-Grid weblog answers that question. For $600, you could get yourself enough solar power each week (ab […]



October 17, 2005 at 3:13 pm

OK, who is going to package this $600 system into a crate so I can go sell it door to door with the Scion66?


» Blog Archive » Podcast Numero Quatro…

October 31, 2005 at 3:12 am

[…] Pics. – ROKU M500 Soundbridge – iPod Nano Nano – iPod Nano Lockup Fix – Dell Latitude D510 – $600 Solar Starter Kit. – Treehugger Article – InFocus ScreenPlay 4805 – “The Untouchables” […]


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