Run Your House Minimally Using Solar Power

Unless you have $20K (US) or more to invest, running a typical household "off grid" is not possible; what many people take for granted as "essential", such as air conditioners and refrigerators, are huge energy-sucking monsters. But, if you're willing to pare down to the bare essentials, you can break free from the electrical grid and begin a life of energy independence. Those who are already living out of their cars, vans, or mobile homes have a head start on this, and can put these ideas to use immediately.

Steps

  1. If you have a car, get yourself a solar trickle charger to keep the battery topped off whenever the sun is shining. This is a good first step in the right direction; as long as the PV panel is 20 watts or less, there is little danger in over-charging the battery (and the resultant boil-off of the electrolyte) even without a charge controller.
  2. Find devices that will run directly from 12VDC. For example:
    • Many "boom boxes" accept 8 cells, which means 12V; you can make battery eliminators and run these directly off your car battery.
    • Linksys WRT54G and WRT54GS routers all accept anywhere from about 5V upwards to 30V or more, and use a size M coaxial connector (5.5mm x 2.1mm), center positive, which has become a de facto standard for 12V low-wattage devices. With one of these, you can extend your range of wifi access significantly, so you don't have to go without WikiHow as you learn energy independence.
    • Many devices and tools that nominally run off 6V to 24V will run off 12V, although it can be very risky to run a 6V device at double its rated voltage. One item that seems to work is the Panasonic RP-SPT70 active speaker system, shown in the battery eliminators article. An 18V device that works off 12V is this Run an 18V Ryobi Tool Using a Car Battery.
  3. Some 6V items can be used in series to safely run from 12V, for example these $8 LED "tent lamps" from Walmart, using a slight variation of the battery eliminator idea; note that the two pieces of dowel in the middle are connecting the two lamps in series.
  4. For devices that just can't be shoe-horned into a 12V system, you will need an "inverter", which changes 12VDC to 120VAC. Realize in this case you aren't getting something for nothing; the 12V side of the circuit will be drawing over 10 times the current that the AC device uses. Unfortunately, most laptops will need to be run this way unless you purchase a special power adapter, sometimes called an "Auto/Air Adapter", that directly converts 12V to the 18-24V required by the computer.

Tips

  • Start small and build up, but keep an eye on your battery voltage. If it goes below about 10.5V, it's probably not going to come back to full power again. Before this happens, start thinking about getting some deep-cycle storage batteries.
  • Old 6V golf cart batteries can be ganged together in pairs to make good deep-cycle 12V batteries.

Warnings

  • It is wise to observe building and electrical codes, not only for your own safety but to avoid fines and/or eviction.
  • You can ruin devices by plugging them willy-nilly into 12V without looking at the circuit first. If it has any kind of microprocessor, chances are it can't take anything over 5V. And if its electrolytic capacitors aren't rated for at least 12V they will probably lose their "magic smoke".
  • A typical 12V solar panel can put out 18 to 22 volts peak. Take this into consideration if you're trying to run devices directly from the PV panel without a battery and/or charge controller in the circuit to stabilize the voltage.
  • Don't even dream of running a desktop computer unless you have 200W of solar or more. Laptops, especially "netbooks", are far more energy-efficient, and are dropping in price every year.
  • Danger of fire and/or explosion is minimal but still nothing to be careless about.

Things You'll Need

  • Solar panel(s)
  • Batteries, if you intend to run anything after dark. A car battery will work at first, for low wattage or short term, but your first upgrade should be to deep-cycle storage batteries
  • Solar charge controller, especially if the total output of your panels is 20W or more
  • Wiring, 10 gauge stranded recommended minimum for small installation
  • Power inverter, for running AC devices

Related Articles

Sources and Citations

  • This research was made possible, in part, by a land grant from the City of the Sun Foundation, though the specifics of the research were not coordinated nor endorsed by COSF.
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