Solar Power Your Home For Dummies
Book image
Explore Book Buy On Amazon

Solar photovoltaic (PV) modules are ideal for charging batteries. The electronics are minimal, and the costs are low because of it. When a vehicle sits around without being started up for a while, its battery grows weak. If the battery is old, it's even worse. If you have an old truck, car, or RV that doesn't get started very often, a solar charger may be a very cheap and effective way to recharge those neglected batteries.

For $40, you can get a solar battery charger. A PV module plugs in to the cigarette lighter jack, and you lay the module out on the dashboard in the sun. While you're gone, it trickle charges your battery. A solar charger won't overcharge your battery, so you don't have to worry about removing it, even when the vehicle is running. But it probably won't revive a dead battery, although it won't hurt anything to try.

Auto batteries cost around $80. With the $40 solar charger, you get more lifetime, up to 50 percent more, so there's a reasonable payback. But how much is it worth (in peace of mind, not to mention the costs of a tow-truck visit) not to get stranded when you can't get your car started?

Standard, off-the-shelf batteries cost around $0.75 apiece. The cost for 100 throw-away alkaline batteries is $75, plus trips to the store to buy them. And batteries have nasty chemicals, such as lead and acids. You run across an environmental issue with 100 batteries.

Rechargeable batteries cost $4 apiece, and the good ones issue the same charge as a throw-away. A solar charger costs $40, but the charge cycles are free. You can charge a good rechargeable battery over 500 times. (Note that the number 500 applies to devices like remote controls, which don't take much current; if you're drawing a lot of current and running the batteries down to their minimum, expect more on the order of 200 times.)

The cost for a rechargeable battery and 100 charges is $44, which is already a better deal than alkaline. But here's the best part: The cost to charge the next 100 times is zero. And the next, and the next. After 500 free charges, you may need a new battery, but that's only $4.

Alkalines cost about 20 times as much as quality rechargeables to operate. (Cheap rechargeables have much worse payback, so avoid them.) Spend some extra money on quality batteries, and it's a good investment.

The time to charge batteries (most devices charge four at a time) depends on how much direct sunlight you receive. Setting up near a window is often good enough if you don't need a lot of batteries. If you use a lot, you need direct sunlight. Kitchen bay windows are convenient candidates.

Keep a reserve of charged batteries. Buy twice as many as you need; it doesn't cost more because you go twice as long before you need to buy new batteries.

About This Article

This article is from the book:

About the book author:

Rik DeGunther is the founder of Efficient Homes, an energy auditing and consulting firm. He holds a BS in Engineering Physics and dual Masters degrees in Applied Physics and Engineering Economic Systems. Rik is also the author of Energy Efficient Homes For Dummies and Alternative Energy For Dummies.

This article can be found in the category: