Power from the sun: not that difficult; not that expensive.
What follows is a basic, nuts-and-bolts look at solar electricity taken from our 12 years of working with it.
First, solar electricity has nothing to do with water. When many people hear "solar" they think of solar hot water heaters which have been around a lot longer than solar electricity. Solar electric panels are called PV panels for "photo" (light) "voltaic" (electrical).
Solar electric cells are made of thin slices of silicon, the same material as beach sand. When sunlight strikes these little pieces of semi-conductors, electrons are freed from the silicon's atoms. Electricity is created. With more of these cells hooked together, more electricity is made.
Solar electric panels have many cells. A solar electric system has several panels. Electricity from these panels travels by wire to a bank of batteries where it is stored for use at night or on cloudy days. A charge controller prevents the batteries from becoming overcharged.
The nice thing about solar electric or PVs is that when you need more power, it is easy to add more PV panels or more storage batteries. If you can splice all the positive (+) wires together and all the negative (-) wires together and make sure they go to the positive and negative posts of the batteries, that's basically it. This is a DC or direct current system. Electricity flows in only one direction.
Cars and boats use this system most often with 12 volts. To change this electricity into regular household or AC (alternating current) electricity, it must go through an inverter. These amazing, newly efficient devices take 12 volt DC and turn it into 117 volt AC.
Photovoltaic panels are-not so new. They were invented to power early satellites sent into orbit in the 1960s. Why isn't something that's been around this long being used more?
It's not the technology. That's pretty much the same, although new ways of production have made PVs cheaper. Most people say PVs cost too much, although an average home solar electric system costs less than a new car. The car depreciates, but the PV system pays for itself in saved electric bills. Scientists have predicted that PV panels could last 100 years. Depending on the type of battery and how well it's treated, the only replacement cost of the system is new batteries every 15 to 20 years.
One cost rarely taken into consideration is environmental. When traditional fossil fuels are used there is a cost to the health of our bodies and our planet. And, in whose backyard will we store a nuclear power plant's radioactive wastes for the next several thousand years?
The cost of a PV system depends much on the lifestyle of the people using it. At current prices, a PV system would be out of place in a house that uses an electric stove, electric water heater, or any use of electricity to produce heat. Many fewer PV panels would be needed when a house uses gas for cooking or heating or when using a super-efficient refrigerator like a Sunfrost or the new Whirlpools (that aren't yet widely available).
I suspect that more houses don't have PV electricity because of lack of knowledge. You don't just go down to the local solar electric store and order your system. Most components are ordered through catalogs and most local electricians are not familiar with how such systems work. Some utility companies are experimenting with photovoltaic electricity on a small scale, but they own the systems. They won't be helping people set up their own PV systems. Utilities can buy coal, oil, gas, and plutonium, but nobody owns the sun. This is the major factor why more people don't have their own PV electric systems. Power companies are not in business for their health (or ours). Some companies offer leased PV systems for remote homes, but these end up costing more than if the homeowners bought the system outright.
People would be surprised to learn how much conventional power generation, especially nuclear, is propped up by government funding. Lobbyists and PAC's have much influence promoting coal and nuclear. Solar electricity for households has received no break from the government since the 70s. It was former President Carter who allowed people installing home PV systems to claim an income tax deduction of 40% of its cost. Carter also had solar hot water panels installed on the White House roof. Upon election, Reagan got rid of the tax deduction and had the panels removed from the roof.
Getting started with PV
What are the nuts and bolts of putting together a solar electric system? Where can you get the information necessary to put your system together? In the early 80s we read a solar electric article in Mother Earth News and wrote to their list of suppliers. We read The Solar Electric Home by Joel Davidson. We asked lots of questions and the suppliers were happy to answer them.
Our family started with three panels, two batteries, and a charge controller. Over the next few years we added to our system as our needs increased.
The first year we used only 12 volt DC and 12 volt appliances. Then we got an inverter to provide 117 volts AC. We still use 12 volts for powering half of our lights, some fans, miscellaneous items, and an efficient 12 volt submersible water pump in our well.
First, you must have a place to put your PV panels--a place that faces south and is never in the shade. Many people choose their roof. A framework made of metal or pressure treated wood should be sturdy and adjustable, to aim it down in the winter and up in the summer. Some frames are available that actually track the sun throughout the day and return to sunrise position before morning. These tracking frames reduce the number of panels needed.
After mounting the panels they must be grounded. Run a copper wire between the frames and connect it to a ground rod. Then, with wire, connect all the positive terminals together, and then all the negative terminals. Use number 10 Romex W wire. Use the black wire for positive and white for negative. This is standard in a direct current system.
The PV panels can be bought for around $300 each or as low as $160 used and guaranteed. Some scientists estimate that PV panels will last a hundred years, but all they know for sure is that ones from the early 60s are still producing electricity, although at 10 to 20% less than their original output.
Next, the power must be stored for times of power usage during the night and on cloudy days. The standard lead-acid marine or golf cart battery is most often used, mainly because it is the cheapest, easiest to find and lasts at least 10 years. Pairs of six-volt batteries are commonly used. Locally, they cost $58 each.
Better batteries are available. They weigh more, cost more, last longer and usually require quantities such as six two-volt batteries to make the standard 12 volt system. In the 1930s (through the early 70s), the Edison Battery Company produced one-volt, nickel-iron batteries. Many of these batteries are still in use, some lasting more than 60 years!
Batteries need to be kept warm in the winter, yet be well-ventilated to let hydrogen gas escape. We built an insulated box in the ground with double, screened plastic pipe vents. It holds twelve six-volt batteries, but at present we find four to be adequate.
Connections between the batteries should use thick wire soldered to the connector ends and sealed against corrosion. Three or four times a year distilled water must be added to each battery cell. Or special caps can be bought that eliminate water replacement.
Besides the panels and batteries, the other major component is a charge controller used to prevent the batteries from being overcharged. A main disconnect switch and fuses are a must for safety. All connections must be clean and tight and protected from corrosion for the easy flow of electricity. A wall-mounted volt meter with a push button is handy for checking how full your batteries are. An amp meter will show you how much power is being used.
The system described uses 12 volts, but many of our electrical needs are for 115 volts. An inverter changes 12 volt DC to 115 volt AC. Early inverters were a weak link in photovoltaic systems, but great progress has been made in recent years. The new inverters are tough and efficient, using much less power than ones of the past. A rugged 2500 watt inverter costs $1,000, which is about as much as a new car depreciates the first minute you own it.
How do you get your PV system? There are many small dealers around the country who will look at your needs and help you design your system and sell you the parts. You can buy solar electric books and design one yourself. You can read informative catalogs such as the one put out by the Real Goods company. You can subscribe to HomePower magazine which is filled with how-to articles and profiles of people living off the power grid.
After we had used solar power for seven years in our very small house, we were ready to build a bigger house. We bought extra PV panels and planned to expand our system. Imagine our surprise when no bank would loan us money to build our new house unless we hooked up to the power grid. But we don't need it, we said; we've never had an electric bill! Still, we wanted the house and agreed to the hook-up. Now we pay an average $20 a month to the local electric company.
But, when the storms come and everyone in the neighborhood has lost their power, we're not left in the dark and our pump provides plenty of water. That's because our new house is also wired for 12 volt solar electricity as well as for grid power.
Our entire PV system (panels, wiring, controller, inverter, lights, and gauges) cost around $3,600 and we've used it for 12 years with no problems. That works out to $25 a month for the past. All future electricity is free!
We like showing folks our system, but even after explaining everything, it's surprising how often we get the standard responses to solar electricity: "Maybe when the technology improves," they'll say, or, "Maybe when the price comes down."
I think the real reason is that it takes some effort to learn about it, to plan for it and to figure out how to put it all together.
For more information:
Home Power Magazine (The Hands-on Journal of Home-made Power), PO Box 520, Ashland OR 97520, 800-707-6586.
Dankoff Solar Pumps (for great 12 volt pumps), 505-820-6611.
Backwoods Solar Electric Systems, 8530 Rapid Lightning Creek Rd., Sandpoint ID 83864, 208-263-4290.
Trace Engineering (for fine inverters), 360-435-8826.
Real Goods, 966 Mazzoni St., Ukiah CA 95482-3471, 800-762-7325.
Also be sure to check the display and classified ads in Countryside.
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||solar power for the homestead farm|
|Publication:||Countryside & Small Stock Journal|
|Date:||Jul 1, 1997|
|Previous Article:||Salads as an analogy for homesteading.|
|Next Article:||The sweet smell of success has the aroma of garlic!|