What you need to know before getting a Tesla Powerwall

There’s some good reasons why doing this is important. I’ve covered this in a previous video, but home batteries have limitations for their continuous power output. The Powerwall has a cap at 5kW continuous power with a peak load up to 7kW. These limitations are per Powerwall. So if you have 2, you’d have a max of 10kW continuous power output available. So you can probably see where I’m going with this. Take the number from your appliance tally and you’ll understand how many Powerwalls you might need to support 100% of your use if everything was running.

In my case, one Powerwall isn’t quite a enough, but that’s totally fine. It really depends on what your goals are with battery backup. For me I’m most interested in providing a base level of backup to keep things like the heat going in the winter during a power outage, and to keep the refrigerator from defrosting.

If you’re like me and your goal isn’t 100% coverage, there are a couple of options. One path is what I have here. This Powerwall is backing up my entire electric panel, so in theory everything in the house “could” run during a blackout … just not all together.

The other path I could have taken was adding a sub panel which would carve out essential load circuits. That sub panel could have had my HVAC, refrigerator, and a few other items in there. Then the Powerwall would only backup that group and everything else in my house would go dark in a blackout.

Going into this I had a basic understanding of that, but didn’t really think about it until I was well into the process of getting it installed. The installer I went with, which was not Tesla, didn’t walk me through my options. They were just going to do a straight install, but never even brought up other things I might want to consider doing. When I realized that was the case I started asking questions, which caused a brief delay to the installation date. This was my first road bump in the install process, which is why I bring it up. Make sure you do a bit of homework before you leap in because there’s no guarantee your installer is going to be proactive and inform you of your options up front.

Whichever path you choose for your setup, you might want to consider getting a soft start for appliances like your HVAC. As I mentioned, the Powerwall has a peak load capacity of 7kW, but when you push into that zone, you risk tripping the Powerwall’s emergency shutdown if you overload it when something like your HVAC kicks on in a blackout. Major appliances like that can have a sizable spike in power draw when the motor kicks on, so a soft start can dramatically shave off that power spike. Some installers recommend doing that as par for the course. Mine didn’t, but I may add one down the road. Again, knowing this kind of thing up front means you can ask the right questions of your installer.

And if you’re installing this with solar and want to ensure that your home can go indefinitely in a power outage, you need to make sure you’re balancing the battery’s power capacity with the output capacity of your solar panel system. If your solar panels can output more power than your battery can take in, the battery system will have to shut off the panels during a blackout at times to manage that intake. Otherwise it’s too much power for the battery to handle.

How prepared is your home

The second category of things to be aware of is all around how prepared your home is to handle a Powerwall. And the first thing you have to look into is … do you have a service disconnect switch? To my knowledge, I’ve never lived in a house with a separate service disconnect switch. It’s standard procedure for new homes, but all of the older homes I’ve lived in haven’t had one. They’re usually just gigantic switches near the power meter, or sometimes on the meter box itself. My house didn’t have one. The main circuit breaker in my panel was acting as the service disconnect too. Well, with a Powerwall, or any battery system for that matter, you’re going to need a service disconnect.

That bit me in the butt when one of the electricians stopped by the night before the install to scope out the setup in person. He spotted the lack of a service disconnect right away, which delayed the project significantly. They had to coordinate with the electric company for shutting off the service temporarily and had to install a disconnect at the same time as the Powerwall. I’m still not sure why they didn’t include any questions about this in the self-evaluation form I filled out, or why nobody caught it in the photos I took.

That’s the next big road bump that I experienced, which brings me back to asking a lot of questions up front. You can’t rely on your installer having procedures in place to mitigate that type of thing happening … but in my opinion, a good installer should have that covered, like having a simple question about service disconnects in the self-evaluation. If it’s required, they should confirm you have it upfront.

Happily, this next one wasn’t a road bump for me, but be sure you select a place with plenty of space. The Powerwall comes with a Gateway, which is what manages where the power goes. It’s the brain of the system. The gateway needs about 2 feet of width and 3 feet of height. And the Powerwall itself requires 4 feet by 5 feet for each Powerwall, and about 6 feet open in front of it.¹ And you need a really good Wifi connection in the area of the Gateway or an available ethernet jack for a wired network connection.

Overall, my installation experience was not great. It wasn’t one big thing that caused problems. It wasn’t one person’s fault that I got hit with lots of delays. It wasn’t 100% the installers fault … and I’m not blameless in this either.

The Powerwall arrived at my home on July 29th, but wasn’t installed and activated until November 20th. Almost 4 months. Some of my late questions caused delays. The lack of a service disconnect switch caused more delays. Some really bad communication issues with my installers left me in the dark for the better part of 7 weeks. They fixed that, but one of the giant issues behind the scenes was 2020 itself. COVID caused issues for my installer and made scheduling very tough. But my favorite moment of the whole thing. The day they installed the Powerwall the electrician discovered that there was a missing part … a communications wire harness, which probably costs about a $1 (or less). So the whole thing was setup, but couldn’t be turned on for several more weeks because of that one tiny part. And when the final setup was completed a different electrician ran a new set of communication cabling on the outside of the conduit even though the previous electrician supposedly already ran some inside. I’m not thrilled about that … but the system works. If I get a second Powerwall, I’ll most likely get that fixed up.

But to be very clear, my experience isn’t normal and none of you should think this is what your experience will be like too. Since this was a referral reward, I was given the option of having Tesla install it, or selecting my own installer and they’d ship it to me directly. That’s the path I went. For all of you out there, your installer will show up with the Powerwall on the day they install it, so you won’t have a Powerwall sitting on your garage floor for months … me … I chose my option … poorly. I should have let Tesla do it. As for the cost, the installation cost $2,500 including the cost of installing the service disconnect switch. That would have made the total cost with the Powerwall and Gateway about $10,500. The price is going to vary based on your specific situation and what you want done, like having a sub-panel installed for essential load carve outs, and any other upgrades needed to support a home battery. I got installation quotes that ranged from the $2,500 I paid up to almost $7,000, so shop around.

First Impressions

So how is the Powerwall? Well, it’s kind of awesome. I’ve only had it up and running since the end of November, but I’m super impressed by it all ready. If you’ve seen any of my solar panel videos, where I go in depth on how my system has been working out, you’ll know that the winter time is my lowest solar production. So this time of year isn’t going to keep my battery full by any stretch … BUT … I’m very excited for this as just a battery backup for winter power outages. Anyone that lives in the Northeast knows what I’m talking about. Nor’easters, freezing rain, strong winds, really heavy wet snow, it can all take down tree limbs and power lines, so power outages aren’t uncommon. In my area they might only last for a few hours, but we’ve had a couple that lasted for a day or two.

The Powerwall has some really nice controls for managing this type of thing. I absolutely love the Tesla app UI for this, by the way. I’m mesmerized by the Power Flow screen that shows exactly where your energy is coming from and going. I can’t stop checking it out. I even figured out how to get it showing up in Apple Home. Anyway, in the app you can configure how the battery should work. There’s three basic modes: backup-only, self-powered, and advanced. Backup-only shouldn’t need an explanation. Self-powered, which is what I have it set to, will store excess solar power production for use when there isn’t sun. In here you can configure how much of the battery should be reserved for backup power. Since this is the lowest point of the year for me for solar production, and I want to maximize the backup potential for storms, I’ve set it to 50% for now. The Advanced option is really meant for people who have time-of-use rates. It will charge and discharge the battery to maximize savings for you. Where I am in Massachusetts, we don’t have time-of-use, so that’s not a good option for me.

But within the first couple of weeks of having this up and running we got a really bad snow storm that came through. Really heavy, wet snow and high winds, which ended up knocking out power for lots of people around New England. We didn’t lose power, but I got to see Storm Watch in action for the first time. The system detected the storm warning and automatically charged my battery up to 100% the night before the storm and kept it there for the duration. Locked and loaded and ready to go. That alone made the long wait so worth it. It’s that type of automation for emergency backup that got me so excited for the Powerwall.

There’s a lot more I could go into about this, but I’m going to wait until I’ve gone through the winter and gotten some better solar production as well. I’ve also applied to be part of a virtual power plant system with my Powerwall, so I’m hoping to be able share about that as well.