Powerwall 101

[jacobp]

Hello. I'm about to have two powerwalls installed at my home. I've searched for a primer on things to look out for during installation, setup, and operation, but I have not found anything. Does anyone know of a resource that will teach me what I need to know about Powerwall. Thanks.

 

[Ampster]

Can you see the frequency of the Powerwall or does the Solaredge provide any info?

 

[jrweiss98020]

Put them as close to your main panel as possible. Inside, in a basement, is ideal.

Your installer can give you tips on how to monitor them with the app.

 

[jacobp]

Put them as close to your main panel as possible. Inside, in a basement, is ideal.

Your installer can give you tips on how to monitor them with the app.

I was told by the installation department at Tesla, that the plans call for the units to be installed outside next to my electricity meters and solar panel inverters. The circuit breaker panel is located in the basement on the exact opposite side of the house.

 

[jjrandorin]

Hello. I'm about to have two powerwalls installed at my home. I've searched for a primer on things to look out for during installation, setup, and operation, but I have not found anything. Does anyone know of a resource that will teach me what I need to know about Powerwall. Thanks.

Im not sure exactly what you are looking for, but tesla has some videos on their site about powerwall:

How Powerwall Works | Powerwall Support

That link is to first in a series of information from tesla, you can navigate on the left side of that page.

As for specifics during installation, here is what I can think of off the top of my head:

1. Know where you would like the powerwalls installed. Your install plans that the installers have are in "general" terms. They show the electrical layout, and which wall the plans call for installation on (for example) but where exactly on the wall, and whether the conduit is hidden in the wall or not is not called out. If you want hidden conduit, it likely costs more.

2. Make sure you are aligned on what loads are being backed up and which (if any) are NOT being backed up. You dont want any surprises there. This should be on the electrical plans but you may have not seen them yet.

3. Ask for a copy of the electrical plan overview so you have it.

4. ensure the installers label the new backup loads panel. In my case, I had previously gone through and made p-touch labels for all of my breakers in my main panel, because I wanted to know what went where. This was before I considered powerwalls so was not "for" the powerwall install. When the installers saw my labeled panel, they made sure to label each breaker in the new panel with a number, AND gave me a piece of paper with the name of the label in the old panel to the number in the new panel, so I could easily re label. Very nice touch on their part to work with me so I would not have to re do all that work figuring out what went where, since "breaker 1" was not "breaker 1" in the new loads panel.

5. Ensure that you can see the flows in the tesla app before they leave. If tesla installers, they should be able to confirm the flows in the app are going in the proper direction during system commissioning. Sometimes they get the location of the CTs wrong, so the flows dont show correctly in the app. It can be fixed if its wrong, but better to verify it before they are done.

6. Ensure they show you how to powercycle the system (turn off powerwalls, reboot system etc) before they leave.

Thats all I can think of, off the top of my head. Pre congratulations!

 

[SSonnentag]

The installers asked me where I wanted the PWs installed when they arrived. I think the plans are just to get the permits approved. Nobody ever came out to inspect afterward.

 

[SSonnentag]

Only advice I have is to ensure your central heat/AC unit is NOT on the PW backup panel. Don't let the installers talk you into installing soft starts on them. We had a big mess getting our system repaired, replaced and the panel wiring adjusted once the installers got through frying things with our AC unit. Long story, but the ACs are now off the PW system and all is good again...with a brand new AC compressor billed to Tesla.

 

[jacobp]

Only advice I have is to ensure your central heat/AC unit is NOT on the PW backup panel. Don't let the installers talk you into installing soft starts on them. We had a big mess getting our system repaired, replaced and the panel wiring adjusted once the installers got through frying things with our AC unit. Long story, but the ACs are now off the PW system and all is good again...with a brand new AC compressor billed to Tesla.

That's interesting. We don't have traditional A/C. We have a geothermal system. I assumed that that system would be backed up by the powerwall. Is it the conventional wisdom not to back up a system such as a geothermal system?

 

[jacobp]

Im not sure exactly what you are looking for, but tesla has some videos on their site about powerwall:

How Powerwall Works | Powerwall Support

That link is to first in a series of information from tesla, you can navigate on the left side of that page.

As for specifics during installation, here is what I can think of off the top of my head:

1. Know where you would like the powerwalls installed. Your install plans that the installers have are in "general" terms. They show the electrical layout, and which wall the plans call for installation on (for example) but where exactly on the wall, and whether the conduit is hidden in the wall or not is not called out. If you want hidden conduit, it likely costs more.

2. Make sure you are aligned on what loads are being backed up and which (if any) are NOT being backed up. You dont want any surprises there. This should be on the electrical plans but you may have not seen them yet.

3. Ask for a copy of the electrical plan overview so you have it.

4. ensure the installers label the new backup loads panel. In my case, I had previously gone through and made p-touch labels for all of my breakers in my main panel, because I wanted to know what went where. This was before I considered powerwalls so was not "for" the powerwall install. When the installers saw my labeled panel, they made sure to label each breaker in the new panel with a number, AND gave me a piece of paper with the name of the label in the old panel to the number in the new panel, so I could easily re label. Very nice touch on their part to work with me so I would not have to re do all that work figuring out what went where, since "breaker 1" was not "breaker 1" in the new loads panel.

5. Ensure that you can see the flows in the tesla app before they leave. If tesla installers, they should be able to confirm the flows in the app are going in the proper direction during system commissioning. Sometimes they get the location of the CTs wrong, so the flows dont show correctly in the app. It can be fixed if its wrong, but better to verify it before they are done.

6. Ensure they show you how to powercycle the system (turn off powerwalls, reboot system etc) before they leave.

Thats all I can think of, off the top of my head. Pre congratulations!

Thank you very much. Very helpful.

 

[wjgjr]

That's interesting. We don't have traditional A/C. We have a geothermal system. I assumed that that system would be backed up by the powerwall. Is it the conventional wisdom not to back up a system such as a geothermal system?

I don't think it's the conventional wisdom. We have an A/C, Tesla installed a Sure Start device, and so far it is working just fine. (Interestingly, our A/C is advertised as "solar ready", but that was apparently for a specific type of solar, and Tesla couldn't use that option, which claims to only need 16 Amps.) But others have had major issues, so it is worth investigating and trying to ensure that if you move forward with a soft/sure start option that it is compatible with the compressor.

 

[BrettS]

In my case here in Florida there was no way I would have installed the system if it wouldn’t backup my heat pump. Having cooling during a power outage is one of my big use cases. My system was just installed this week and they did not install a soft start unit on my compressor. I was actually outside while the electricians were discussing it.

They looked at the ratings panel of the heat pump to see the LRA, then they actually connected a meter to it and asked me to stop and then restart the compressor so they could measure the starting current. Then based on those numbers they decided that my four powerwalls could handle it without a soft start. They also had me stop and restart the compressor while they were doing the off grid test to confirm that the heat pump was able to start without issues.

 

[gpez]

In my case here in Florida there was no way I would have installed the system if it wouldn’t backup my heat pump. Having cooling during a power outage is one of my big use cases. My system was just installed this week and they did not install a soft start unit on my compressor. I was actually outside while the electricians were discussing it.

They looked at the ratings panel of the heat pump to see the LRA, then they actually connected a meter to it and asked me to stop and then restart the compressor so they could measure the starting current. Then based on those numbers they decided that my four powerwalls could handle it without a soft start. They also had me stop and restart the compressor while they were doing the off grid test to confirm that the heat pump was able to start without issues.

I think the meta advice here is just to be very planful about what you put on the critical loads and what you leave off. Consider what you need, what you want, how much it costs, and what the tradeoffs are.

Here in the pacific northwest A/C is a nice to have but is a huge energy suck so for me I left it off the Powerwall. I also left off the 240v/50a EV charging outlet - if the power goes out overnight I don't want my EV draining the Powerwall, in an emergency I can charge off of a backed up 120v outlet.

My PV system is medium sized (8.6kw) and I have only 1 Powerwall so that played in to my decisions as well. If I had a 15kw system and 5 Powerwalls I probably would have put everything on.

 

[MIT_S60]

Only advice I have is to ensure your central heat/AC unit is NOT on the PW backup panel. Don't let the installers talk you into installing soft starts on them. We had a big mess getting our system repaired, replaced and the panel wiring adjusted once the installers got through frying things with our AC unit. Long story, but the ACs are now off the PW system and all is good again...with a brand new AC compressor billed to Tesla.

Did you ever get an understanding on why the soft start didn't work on your AC? It's a pretty strong statement to just say don't backup any AC with PWs.

 

[SSonnentag]

Our 5-ton AC draws about 28A when running, but nearly 130A on startup. It would take 5 Powerwalls to put out enough power to start our 5-ton AC. So the "solution" was to install a soft start to allow our 3 Powerwalls to start the AC. My understanding of soft starts is that they ramp up the voltage over a few seconds to reduce the initial current surge. In our case, it caused the Powerwalls to trip off due to over-current and after a few dozen or so failed attempts by the Tesla installers, the compressor itself went up in smoke. It would take 2 Powerwalls to run a 5-ton unit AFTER the compressor was started. There is just no way 3 units can reliably support the startup of the compressor. All of this was after I had told Tesla, in writing, that the AC unit was not to be backed up, and had confirmation, in writing, that it would not be. So Tesla bought us a new compressor and rewired things as they had agreed to.

In my OPINION, you should not run a heat pump off your Powerwalls UNLESS you have a minimum of 1 Powerwall per ton of AC capacity. 3-ton AC, 3 Powerwalls. And then only if you have soft starts installed as well since you may have other power draws active as well.

 

[ElectricCyclist]

Our 5-ton AC draws about 28A when running, but nearly 130A on startup. It would take 5 Powerwalls to put out enough power to start our 5-ton AC. So the "solution" was to install a soft start to allow our 3 Powerwalls to start the AC. My understanding of soft starts is that they ramp up the voltage over a few seconds to reduce the initial current surge. In our case, it caused the Powerwalls to trip off due to over-current and after a few dozen or so failed attempts by the Tesla installers, the compressor itself went up in smoke. It would take 2 Powerwalls to run a 5-ton unit AFTER the compressor was started. There is just no way 3 units can reliably support the startup of the compressor. All of this was after I had told Tesla, in writing, that the AC unit was not to be backed up, and had confirmation, in writing, that it would not be. So Tesla bought us a new compressor and rewired things as they had agreed to.

In my OPINION, you should not run a heat pump off your Powerwalls UNLESS you have a minimum of 1 Powerwall per ton of AC capacity. 3-ton AC, 3 Powerwalls. And then only if you have soft starts installed as well since you may have other power draws active as well.

I have a 3 ton unit whose specs state around 84 LRA (Locked Rotor Amps) and I am currently in design for a 2 powerwall system. I am looking to get the whole whole backup so lets see what their design comes in with my AC unit. If your concerns are justified I might need to exclude the AC unit out of the backup but I hope that isn't the case.

 

[wjgjr]

I have a 3 ton unit whose specs state around 84 LRA (Locked Rotor Amps) and I am currently in design for a 2 powerwall system. I am looking to get the whole whole backup so lets see what their design comes in with my AC unit. If your concerns are justified I might need to exclude the AC unit out of the backup but I hope that isn't the case.

We have a 3-ton unit with 72 LRA startup, and two powerwalls are just fine with the sure start Tesla installed - in testing, I don't see any noticeable power spike above its running level (about 2.2kW for us.) Beyond the sure start, the big considerations with powerwall + A/C are understanding how much of your 10 kW continuous power (5 kW/powerwall) the A/C will use and being comfortable with that, and understanding how long your powerwalls will last with A/C. With 13.5 kW/h capacity per powerwall, we could probably run our A/C plus minimal loads for around 10 hours with no solar. So it should mostly cover an overnight outage but anything longer depends on generating more power. For us, that was acceptable.

 

[jacobp]

Thanks everyone for your comments. My geothermal system is the WaterFurnce Series 7. It features a variable speed compressor. The compressor LRA is 12.0 and the drive LRA is 28.0. Given this data and the fact that I'm getting 2 powerwalls, will I be OK if I include the geothermal system in the backup plan?

 

[SMAlset]

Our 5-ton AC draws about 28A when running, but nearly 130A on startup. It would take 5 Powerwalls to put out enough power to start our 5-ton AC. So the "solution" was to install a soft start to allow our 3 Powerwalls to start the AC. My understanding of soft starts is that they ramp up the voltage over a few seconds to reduce the initial current surge. In our case, it caused the Powerwalls to trip off due to over-current and after a few dozen or so failed attempts by the Tesla installers, the compressor itself went up in smoke. It would take 2 Powerwalls to run a 5-ton unit AFTER the compressor was started. There is just no way 3 units can reliably support the startup of the compressor. All of this was after I had told Tesla, in writing, that the AC unit was not to be backed up, and had confirmation, in writing, that it would not be. So Tesla bought us a new compressor and rewired things as they had agreed to.

In my OPINION, you should not run a heat pump off your Powerwalls UNLESS you have a minimum of 1 Powerwall per ton of AC capacity. 3-ton AC, 3 Powerwalls. And then only if you have soft starts installed as well since you may have other power draws active as well.

We have a 2014(?) Carrier 5-ton AC unit here in California and I spoke to one of theTesla Energy guys in AZ who said he had one also at his house (developments from the same time frame) and his unit runs off the soft-start that was installed. I have seen a post somewhere in this forum area from another Carrier owner who had to have a Carrier “soft start” unit purchased and installed. I’m sure for anyone in this position there is a workable solution. I understand that the “generic” units don’t work with all makes/models. I also have read of an install or two where the installers made errors and that was the reason it wasn’t working. It happens, just hopefully not to you. We are still waiting to be added to the scheduling so can’t yet say how ours AC is working. Best thing is to inform TE in advance of your Make and Model so,they can be prepared with parts that will work with your unit. I’m sure they have a database at their end by now for any set up that has not been working out.

One of the things TE will be asking you as you proceed are photos and info on your main panel (to learn the make and model of it and what it is powering). They will ask what you want as essential for PW backup and details on make/model and photo of rating panel on the equipment (like your AC unit) if you want it backed up.

 

[miimura]

Thanks everyone for your comments. My geothermal system is the WaterFurnce Series 7. It features a variable speed compressor. The compressor LRA is 12.0 and the drive LRA is 28.0. Given this data and the fact that I'm getting 2 powerwalls, will I be OK if I include the geothermal system in the backup plan?

Yes, it seems that should work fine with 2 Powerwalls.

 

[wjgjr]

Thanks everyone for your comments. My geothermal system is the WaterFurnce Series 7. It features a variable speed compressor. The compressor LRA is 12.0 and the drive LRA is 28.0. Given this data and the fact that I'm getting 2 powerwalls, will I be OK if I include the geothermal system in the backup plan?

The only question I would have (and am not familiar with the details of geothermal systems) is will the compressor and drive kick on at the same time? If so, that means a demand of 40A, and the 2 powerwalls max out at 30A each, so 60A for 2. If you tend to have other high-draw items running (I'm thinking things like an electric stove/oven, or electric dryer) it is possible there could be an issue. Tesla might express a concern if the system turning on is such a large percentage of capacity.