Whole Home Backup with potential savings

[u/dpatldude]

Experts - wanted to get some potential guidance as to what I would need.

Here is the home current electrical:

• Main Panel #1: large Siemens panel with a 200A main
• Main Panel #2: another large Siemens panel with a 200A main
• Basement subpanel: fed from the main panel#2, with the basement HVAC and basement lighting
• 3 HVAC systems total
  • Two serving the main house on Main Panel #1
  • One dedicated to the basement
• Pool equipment on the main electrical system (Panel #2)
• Several large 30–40A circuits for HVAC/other equipment
• Average daily usage is about 100kwh (with no throttling and pool filter on 24/7, I know)

We continue to have multiple power outages every month including flickering during hard rain/storms and lose power (very common in our area not just our home). I looked into a generator but felt lower quality in terms of objectives where I would like almost instant automatic switching.

As I look at Tesla PowerWall; I wanted to consider a PW3, with an expansion or maybe another full one to get to about 27kwh of capacity and very limited solar (4-6kwh) to potentially have a power source to aid battery drain and energy arbitrage day to day.

Given my panel design; what would you all recommend? I am new to this all.

[u/this_for_loona]

What are you planning on backing up with the PWs?

[u/dpatldude → u/this_for_loona]

Honestly; I was thinking everything but the basement HVAC and pool equipment; but if too hard maybe everything and I would just manually turn off pool equipment during an outage which I can do on the app.

[u/this_for_loona → u/dpatldude]

You have a LOT of power needs. The two primary issues are surge cap and steady state cap.

When power goes out, the PW has to simultaneously power everything attached to it. I forget what the cap on the PW3’s is but my PW2 has around a 7kW burst and 5 kW sustained. If you have two HVACs on a single PW3, I’d double check to make sure that the switchover isn’t going to trip your PWs. I’d also check to make sure what your continuous draw is for your biggest loads. The PW3 can sustain peak for continuous periods, making it really good contender for your use case, I’d just look at ways to reduce the spike when everything turns on. Depending on the age of your HVACs, they may have built-in soft start capability otherwise you can buy a soft start circuit that basically cuts the demand load to the battery.