I recently built a backup power system for my home using four 72 Watt solar kits and four Deep Cycle Marine batteries. These systems have been working well for the past couple of years. So much so that I switched the two main lights we use in the house (the S.O. keeps them on from dusk 'till 10 p.m.) over to run full time on two of these systems. I thought maybe this setup would be a good idea for people in need of light during power outages, disasters, or even refugee camps. So I set about looking for smaller versions of my home setup. I found a reasonably sized 10 Watt photovoltaic panel, a cheap pules width modulated (PWM) charge controller, a 5 Watt 12 volt LED buld and a small, 12 Volt, 8 Amp-hour Solid Lead Acid battery. Solid Lead Acid!? Yes. Why not Lithium based? Well, several reasons. Reason one is cost. To keep this project to a minimum cost and allow it to be accessible to those who really need it, you can't beat the price of a SLA battery for performance. Two, It's not THAT much bigger or heavier than lithium batteries. Three, reliability. I've had some pretty poor reliability with most other rechargeable batteries. Lithium always seems to have inconsistent charge and discharge rates. Other rechargeable batteries just don't seem to last as long per charge. Four, availability and ease of replacement. SLA is pretty easy to find; Radioshack (those that are left) BatteriesPlus, Amazon. You can get them anywhere. So yes, I decided to use a Sealed Lead Acid battery in this project.

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