In CA, the model design does NOT involve batteries so the cost is much lower. Bobodu I know has batteries (old technolog around here) Even in overcast days, solar energy gets through. The power is sent onto the grid to offset your electricity bill. You get a rebate if your net upload exceeds your usage -- but you get a discount based on your total upload anyway. State of CA has tax rebates which really help too.
The best way is to call Solar Alliance (very active in CA) and ask!