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By Root 699 0

installed, you would have to wire a cigarette-lighter-type plug onto the lead wires from the photovoltaic panel. These are available from any electronics-supply store, such as Radio Shack. Typically with DC wiring the red or white wire is positive, and that would go to the “tip” terminal on the lighter plug. (Note: Be sure to double-check the polarity with a volt-ohm meter before plugging it in!) The cigarette-lighter plugs and jacks are ubiquitous, but if you are handy with a soldering iron, I recommend switching to Anderson Powerpole connectors. These are compact, genderless connectors that do not pop apart unexpectedly—as cigarette lighter plugs are prone to do. One nice thing about jump packs is that they have a built-in charge controller. (A charge controller is a bit of circuitry that prevents overcharging a battery.) If you upgrade to larger-capacity storage—such as a standard car battery—either add a charge controller to the circuit or be very careful about checking voltage regularly during charging so that you don’t “cook” your battery.

I use an AccuManager 20 battery charger. It is a “smart” charger—so it will not overcharge your batteries. It comes with both a twelve-VDC cord (with cigarette-lighter plug) and a 120-volt AC (VAC) adapter. The charger has six channels, so it can simultaneously hold four AAA, AA, C, or D cells, and two nine-VDC batteries.

You can recharge at least twenty AA cells from a jump pack that is fully charged. With a five-watt photovoltaic panel it might take two or three days to charge your jump pack. A ten-watt panel (or two five-watt panels wired parallel) works much better, and a twenty-watt panel works even better still. Your ability to “make do” with a smaller panel depends on your budget, how many batteries you need to keep charged, and your time available to reposition the panel to keep it in full sunlight throughout the day. To keep your jump pack charged, I recommend the small PV panels available from Northern Tool and Equipment.

Solar Battery Chargers

Depending on your budget, battery-charging solutions can run from micro to mini to maxi. The inexpensive solar chargers sold by Ready Made Resources work fine as a micro solution, but be advised that they are not waterproof. I recommend setting these up on a windowsill inside a south-facing window. In my experience, it is best to buy at least two of these chargers, since they charge slowly, via “trickle charging.”

Moving up to the mini solution, there are 6.5-watt flexible (amorphous) photovoltaic (PV) panels. Even modest-size PV systems with a small deep-cycle battery bank can make a huge difference in providing small-scale lighting and battery charging for crucial security measures such as radios and night-vision equipment. There are so many LED lights, battery-charging trays, and various pieces of electronic gear available that will run directly from twelve VDC or from a DC-to-DC converter that you might be able to skip the expense of a full-up system with a large AC inverter.

If you have a bigger budget, Ready Made Resources and other vendors can also supply larger prepackaged PV power systems, either with or without an AC power inverter. (Without an inverter, PV systems will provide only twelve- or twenty-four-volt DC power.) Ready Made Resources even has experience designing maxi systems—six-kilowatt or larger.

Keep in mind that grid-tied PV systems will be eligible for a 30 percent federal tax credit in the United States. Many states also offer their own tax credits (dsireusa.org). In some states, such as Florida and California, the combined federal and state tax credits may reduce your expense by as much as 70 percent when all is said and done.

Photovoltaic Power Systems

There are essentially three types of photovoltaic power systems:

1. Stand-alone

2. Grid-tied

3. Grid-connected but stand-alone-capable

Of the three, the only type that I do not recommend is grid-tied. These systems—typically without a battery bank—leave you vulnerable whenever the power grid goes down. If you want to sell power