[philb]

As your batteries age, they won't store as much power like when they were new. That's also the heart of your system and its downfall.

Check out these sites:
MidNite Solar Inc. Renewable Energy System Electrical Components and E-Panels
Solar Electric Power Discussion Forum by Northern Arizona Wind & Sun
BuildItSolar: Solar energy projects for Do It Yourselfers to save money and reduce pollution
Fieldlines.com: The Otherpower discussion board - Index

Lots of information.