I am in the final phases of decision around installing PV panels. Someone suggested adding powerwall and confused me. I dont particularly care for backup power capability. I don't have an EV. Location: Northern California. Solar System Capacity: 4.9 kW DC. Considering one powerwall. Cost without powerwall: $17000; w/ powerwall: plus 8000. (This is before tax credits and SGIP rebates). Based on my last two years bill (PGnE), annually, i use about 3000 kwH during peak hours (3-8 pm), and 6000 kwH during off peak hours. Does it make financial sense to have powerwall? I read that it can be charged only from solar (not the grid). Does that offer enough on-peak/off-peak arbitrage opportunity? Sorry if my questions sound dumb. Trying to educate myself quickly before signing the contract. Thanks for your help!!!