</font><font color="blue" class="small">( The batteries need to be placed in a watertight box in the ground. )</font>
Hey Rich, could you tell me why the batteries need to be underground?
Those nice Concorde batteres could go anywhere. <trying to envision how they would fit under my bed>
If it were me, and I were forced to bury them, the first thing I would look at would be a light wood frame, sheeted with 1/4" marine ply and wrapped in fiberglass cloth/polyester resin. In other words, boat construction. Sealing would require a stainless or brass wing nut every few inches around the perimeter of the lid.
I have a very small but very effective solar outfit that powers everything in my tractor shed, which is off grid. Although I'm delighted with it, I will never venture into anything bigger.