Ice storms frequently come through our area, so I wanted affordable emergency lighting in case of a power outage. I settled on a 3-watt LED light bulb, wired to a 12-volt, 8-amp-hour lead-acid battery. The light was $32 and the battery was $20. The battery will run for about 32 hours before needing to be recharged. I keep it plugged in so it’s ready to go. A good charger costs about $25.
I liked the backup lighting system so much that I bought a second battery and two more lights. In case of longer power outages, I added a 15-watt monocrystalline solar panel and a high-quality charge controller for about $100 total. The three lights completely illuminate our safe room, and the solar panel charges the battery in less than a day.
Steve Sorell
Berea, Kentucky
For another DIY, solar-powered lighting plan, have a look at Easy DIY Solar Lighting. — MOTHER EARTH NEWS
At MOTHER EARTH NEWS, we are dedicated to conserving our planet's natural resources while helping you conserve your financial resources. You'll find tips for slashing heating bills, growing fresh, natural produce at home, and more. That's why we want you to save money and trees by subscribing through our earth-friendly automatic renewal savings plan. By paying with a credit card, you save an additional $5 and get 6 issues of MOTHER EARTH NEWS for only $12.95 (USA only). 
Missouri Wind and Solar has everything for battery back up power and they'll design a system for you, big or small. 417-708-5359 or www.mwands.com
i would really appreciate it if you could post your sources/vendors for these items. thank you.
Steven Harris at www.solar1234.com have some really good guides and informative podcasts about batterybackups. Well worth listening to. Johan from Sweden