Reference
Remaining Capacity = (1 - degradation)^age x 100
Module Book Value = Cost x 35% x max(0, 1 - 8%/yr x age)
Recycle Value = Panels x (recycling fee + material recovery)
Material: Al ~$1/lb, Cu ~$3.50/lb, Si ~$0.50/lb
Salvage = max(Residual Value, Recycle Value)