Question Is 1 Powerwall worth it?

SoFlaModel3

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I was fortunate to win a Founder's Series Powerwall through the Tesla Referral Program and after a long wait it's finally shipping today. I do not have solar and my roof is 24 years old so I won't consider solar until the next roof (or next house). I live in South Florida where hurricanes and bad storms do lead to power outages from time to time, though (*knock on wood*) we really haven't had any issues in years with power being out for more than a few minutes.

In doing some limited research, I came to find that a minimum of 2 Powerwalls is required for "whole home" backup as well as supporting HVAC.

To that end, with a single Powerwall, I would basically need a sub-panel and select things that are important to keep powered in my home.

Living in South Florida, if my AC is out and I lose that steady stream of 72F air, I'm leaving the house anyway so I don't think I'll get value in keeping the lights on.

Do you think its worth it to keep and install anyway?
 

garsh

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Are you able to keep just the AC running with a single powerwall?
 
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iChris93

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Do you have time of use rates? Could see some savings charging in off-peak and running down during on-peak.
 

SoFlaModel3

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Are you able to keep just the AC running with a single powerwall?

I don’t believe so. I haven’t done extensive research, but my understanding was that the power draw from the A/C required a minimum of 2 PWs to support.

Do you have time of use rates? Could see some savings charging in off-peak and running down during on-peak.

We do, but electricity is so cheap here that would probably be a slow play to equate to any value. Also would mess with my charging cycles on 2 cars / 1 wall charger.

First world problems, right? 😎
 

Bigriver

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A powerwall is 13.5 kWh and I think it can deliver 5 kW. For me, that is enough to accommodate an air conditioner and most of the basics of my house. A single one could not handle my electric dryer, though, which spikes my house usage over 5 kW. And obviously no EV charging. I have 2 powerwalls and I believe they are set up to be able to supply at a rate of 10 kW. So we are able to still do laundry, cook, have a/c on, etc, without having to think about it.

My first reaction is that yes, one PW would be worth it. I think the real value of the powerwall is as a backup generator. I absolutely love no power outages. For me, a single unit could last more than half a day, as my base (no a/c) usage is a little under 20 kWh/day. Air conditioners are real hogs, tho, so your ability to keep things going in South Florida might not be so good. My a/c is a load of another 1.5-2 kW. Of course that can vary based on the system size and efficiency. If looking for post hurricane support that might be no power for several days, the powerwall without solar to replenish it would be of little help. But then again if you wanted it just for critical loads, you could easily keep a refrigerator and some lights going for a long time. And fans are very low energy consumers. For me, it has been a wonderful bridge to dealing with the occasional grid losses.

I know nothing of the practicalities and cost of installation, which would ultimately determine if it is worth it.
 

JasonF

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As a resident of Florida, most of the power outages here are either less than an hour (equipment failure) or several days (devastating storm).

Unfortunately we're not quite there yet with renewable sources being able to handle that second scenario. You would need a huge and very expensive bank of batteries in order to make it several days, or to combine solar and smaller battery array and hope the clouds don't hang around long enough to cause the batteries to drain. A propane whole-house generator with the fuel is still going to be orders of magnitude cheaper**.

What would be nice for a single Powerwall is if you do get a generator installed, and you wire the Powerwall so it provides "in between" power - that it will take over when the mains gets interrupted, and can hold out for short outages, or can provide power while the generator starts up and gets to speed.

** The asterisks are here for the future. I hope someday that enough homes have solar, and the power companies become friendly enough to it, that neighborhoods can form "power cells". Multiple neighbors with solar power can feed their excess into a neighborhood ballast (which could be a battery, or a super-capacitor, of even something mechanical) that can soak up excess demand, or during a massive storm or quake caused power outage, can keep the neighborhood running independent of the grid. Power companies could benefit by not spinning up excess plants to fill demand, and by having repair crews not be forced to do shoddy repairs just to get power working again in the middle of a storm.
 
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NR4P

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To answer your question, 1 Powerwall is worth it but not for whole home backup. Consider your central A/C system has maybe a 60A breaker pair on the compressor. It pulls lots of juice to start up, enough that lights sometimes dim. The big capacitor helps it but you need about 40A+ to start it. So one PW is not enough.

I could see it for short back up and, keep the refrigerator running. Where I live I lose power for about an hour every few months. FPL is terrific but the grid is not perfect everywhere. It could make a good short term back up. Also, get creative. Route your appliances through it (not the dryer) and it will be a nice UPS with some surge protection.

I have a whole home generator propane system, buried the tank. No natural gas on my street. In 8 years it ran a few days straight after Irma and loved the A/C, Satellite TV etc. It was put in before my Tesla and it could do that but I would have to remember to turn off the A/C for a bit. The wall connector draws what, 48A alone. Ouch. We live nearby so if you want advice on that route, let me know. I know the ups/downs. And so glad we did it. The wife one that battle and I keep thanking her. And the FPL power was out 330a-5am yesterday and I slept right through it. Didn't even know until I saw PF on an appliance during the 10 sec takeover.
 

JasonF

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I have a whole home generator propane system, buried the tank. No natural gas on my street. In 8 years it ran a few days straight after Irma and loved the A/C, Satellite TV etc. It was put in before my Tesla and it could do that but I would have to remember to turn off the A/C for a bit. The wall connector draws what, 48A alone. Ouch. We live nearby so if you want advice on that route, let me know. I know the ups/downs. And so glad we did it. The wife one that battle and I keep thanking her. And the FPL power was out 330a-5am yesterday and I slept right through it. Didn't even know until I saw PF on an appliance during the 10 sec takeover.

I was out of power for nearly 4 days when Irma came through. I lived in Kissimmee then, and the utility there (KUA) is still using power technology from the 1970's, so lots of overhead supply lines and no auto-reclosers - if one of the overhead supply lines breaks, the entire network goes down. And go down it did, the moment the winds gusted above 60 mph, 8 hours before the storm itself even got here. I was happy I had a generator for that.

I didn't have a Tesla then (there was no Model 3 and I couldn't afford an S); but the plan I would follow is to fill the car battery to 100% the night before the storm arrives and then unplug the car so it doesn't draw off of the generator if the power goes out. It will have enough range for a few days, or at least long enough until one or two Superchargers come back online, or my power comes back, or work gets power so I can charge at the dock behind there. If the situation is somehow worse than that (which would be incredibly rare in Central Florida), including stuff like no power for weeks or no civilization left, it's also enough range for an emergency evacuation.
 
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Garlan Garner

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Are you able to keep just the AC running with a single powerwall?

I could probably keep my Central Air running with a powerwall IF the powerwall was powerful enough to start it.

My neighbor has 1. ( a single one ) and his central air unit won't start it. He has to connect to ComEd here in Chicago then start the air conditioner...then disconnect ComEd and it will continue to run.

When he starts his air conditioner with power wall alone.....the compressor outside just clicks and clicks and clicks.


The powerwall could probably start and run any window unit or a very small BTU central air unit. Who knows?