In an emergency--a REAL emergency, not just loss of power--photovoltaic (PV) arrays can play a part in backup power. Here in the Salt Lake Valley, communities expect to operate without outside assistance for as long as three weeks. Earthquake damage could leave us without road connections, utility-transmission lines, water reservoirs, and other necessities, so we prepare with regular drills and test communications and rehearse organizational and response situations.

Photo courtesy of Marty Bahamonde/FEMA.

During an emergency, we won't lose all power. Vehicles unable to travel anywhere can yield 12-volt batteries for radio communications and for small power inverters to keep critical medical equipment running. Vehicles will have enough gasoline to keep batteries charged for a few days. After that we will need alternate-charging capabilities, such as PV arrays. Vehicle batteries cannot undergo a deep discharge, so they will need frequent "topping off" charges.

I found a 60-watt battery-charging PV module on the Internet for $260 and I can build or buy a charge controller unit. The combination of the two should let me keep 12-volt batteries charged at least for communication work. Today most communication equipment runs from a 12-volt power supply.  Thankfully I don't have any other equipment that will need power, but I might buy a small 120-volt inverter just in case.

You can find similar backup chargers made for campers, recreational vehicles, and boats. A Google search will locate suppliers. I noticed several on Amazon

Now comes the decision about where to keep a battery-charging PV array. I'll probably put it near our emergency supplies and assume we can get to them, and I'll build an box for the PV array to help prevent damage from things falling off nearby shelves.

Even if you live in an area not threatened by hurricanes, tornados, earthquakes, floods or other disasters, you should prepare for emergency situations that leave you "on your own" for more than a few days. The Federal Emergency Management Administration (FEMA) has a Web site specifically for emergency preparations and planning. Visit: www.ready.gov/.

The city and county of San Francisco have a site, http://72hours.org/, where you can find information about preparations and types of emergencies to prepare for. Many people and organizations emphasize an emergency "kit" for 72-hour (3-day) self sufficiency, but I recommend a kit for at least 10 days. Remember to include medications and accommodations and food for pets. The American Red Cross Web site (www.redcross.org) includes information "Preparing and Getting Trained," that includes emergency-supplies checklists.  You can find equipment suppliers locally or turn to online suppliers via a Google search for emergency preparedness supplies. Some companies sell complete emergency kits, but I found it less expensive to buy supplies individually.

Along the lines of training, I recommend Community Emergency Response Team (CERT) training. For more information, visit: www.citizencorps.gov/cert/training_mat.shtm. Usually a community or local group sponsor CERT classes and exercises. Technically minded people also might consider obtaining an amateur-radio license so they can provide communication assistance in an emergency. The American Radio Relay League provides educational and study materials and oversees a group of volunteers that administer multiple-choice exam tests. (The FCC dropped the Morse code requirement some time ago.) Visit: www.arrl.org/licensing-education-training. --Jon Titus