Start with what you want to back up
Backup comes in two flavors. Essentials only, or whole-home. The big draws that drive the number up are central AC and EV charging.
One Powerwall
One unit keeps the critical loads alive through an outage. Refrigerator, lights, outlets, internet, and a furnace fan. It is the right call for essential backup and time-of-use savings.
Two Powerwalls
Two cover most homes, including a stretch of air conditioning and a fuller slice of the house. This is the common whole-home setup in California and Arizona.
Three or more
A large all-electric home with AC, an EV, and a pool runs three or more. The goal is carrying the real load on a hot afternoon without rationing.
Solar size matters too
In a multi-day outage, your battery only lasts if solar refills it each day. A bigger backup target needs enough panels behind it to recharge. We size the two together.
How we size it
We look at your backup goals, your load, and your solar, then recommend a number with the math behind it. No overselling a fourth unit you will never use.
See our Tesla Powerwall installation services, model it with our Powerwall cost calculator, or get a free Powerwall quote.
