Let me first say I have very limited solar power experience. I need a light for my goat barn and a light for a similar sized cabin.What is the cheapest simplest possibly expandable solution using battery, solar panel and a dc light.....what could I get from salvage? I do have a battery charger already (one with clamps). Anyone rotate car batteries on commute to work? 40 mile drive for us in the near future..... Your wisdom is appreciated!