PSA for people with Powerwalls - Run an off grid test

[BrettS]

So my solar/powerwall system was installed about 2.5 months ago, but I finally just got my PTO today. Given that my system was large enough to run my house off grid pretty much indefinitely (and given that I’m very impatient) I have been operating the system off grid for most of the time since the day it was installed. This has made me much more comfortable with the system and how it works while I’m off grid. I know how much power my powerwalls need to have in the evening to be able power to my house until sunrise and I know how long it will take to recharge the powerwalls during the day. (And the fact that if I have a very cloudy/rainy day then I might not get enough sun to fully recharge them). But having done this I feel confident that if I had to deal with an extended grid outage that my system would be able to carry me through and I would know when or if I need to cut back on my power usage, if necessary.

Now, I’m not sure that going off-grid for a full 10 weeks is really necessary However, if your system is big enough to support your house then it might not be a bad idea to go off grid for a few days just to get a feel for how things work and help inspire confidence in the system.

If you just have a partial home backup system then going off grid for a few days probably isn’t really feasible, but it could still be beneficial to go off grid for a couple of hours just to get a feel for how the system works and what still has power and how you might handle that situation if it was real.

 

[k-mal_808]

Congrats on your PTO. My system was just commissioned yesterday after having to replace a faulty TEG-v2(OG install was 2 weeks ago) and I plan on running an “extended off grid test” starting this weekend. Looking forward to seeing the system in action.

 

[BrettS]

Congrats on your PTO. My system was just commissioned yesterday after having to replace a faulty GW2(OG install was 2 weeks ago) and I plan on running an “extended off grid test” starting this weekend. Looking forward to seeing the system in action.

Good luck. Hopefully your test won’t be as extended as mine was

 

[k-mal_808]

Knowing Hawaiian Electric, it might be

 

[wjgjr]

Definitely something everybody should do and probably try out at least once on a seasonal basis to get a feel for the different behaviors and then repeat at least annually. In addition to getting a better feel for how your system works and the PWs perform during an off-grid situation, it helps to test and make sure everything will really work if and when you need it. It seems like during several of the recent disasters, there have been stories/reports of people finding out their backup systems were either never configured properly or had a failure. And once it happens, it is too late. It is kind of like testing the fire alarm.

 

[Electrph]

Good luck. Hopefully your test won’t be as extended as mine was

Sometimes you just need a lot more data points .. yea ...

 

[GHTech]

BrettS,

Good to hear the good news. While I wait for the inspections and PTO (installed Tue), I will test things off-grid as it is going to be a scorcher this weekend, and would like to have the 2 PW fully charged up in case of a power outage.

Regards,

GHTech

 

[BGbreeder]

CAL-ISO will thank you for not using power 3-8. They just issued a Flex Alert.
All the best,

BG

 

[niveknow]

What is everyone experience in "testing" the system before PTO? The Tesla panel guys said the electric company is activity monitoring the homes and would detect something like this and of course all the legal language with penalties, etc. without a PTO. I get it.. but I'm talking about disconnecting completely from the grid for hours during the day to see how the system operates. By disconnecting completely from the grid, we may not be "operating".

Anyone heard any big slaps from extended testing before PTO? I'd like to test for an entire 24 hr period. =)

 

[MorrisonHiker]

What is everyone experience in "testing" the system before PTO? The Tesla panel guys said the electric company is activity monitoring the homes and would detect something like this and of course all the legal language with penalties, etc. without a PTO. I get it.. but I'm talking about disconnecting completely from the grid for hours during the day to see how the system operates. By disconnecting completely from the grid, we may not be "operating".

Anyone heard any big slaps from extended testing before PTO? I'd like to test for an entire 24 hr period. =)

We had no meter on our house for two months while waiting for Xcel to give PTO. There's no way they could've monitored anything.

 

[wjgjr]

What is everyone experience in "testing" the system before PTO? The Tesla panel guys said the electric company is activity monitoring the homes and would detect something like this and of course all the legal language with penalties, etc. without a PTO. I get it.. but I'm talking about disconnecting completely from the grid for hours during the day to see how the system operates. By disconnecting completely from the grid, we may not be "operating".

Anyone heard any big slaps from extended testing before PTO? I'd like to test for an entire 24 hr period. =)

You will find a number of people (including myself) who operated off-grid before PTO and did not run into issues. That said, every utility is different, both in terms of the agreements you sign (some of which seem to be more explicit about operating off-grid) and how much they monitor. So, I would at least take note of the caution from the Tesla installer who might have local knowledge. However, he may have misunderstood/been confused about whether this was discussing on-grid operation vs. off-grid. It at least seems plausible a utility would be much more concerned if/when they notice power flowing into the grid (assuming the existing meter detects that) during on-grid testing versus noticing that your power draw has lessened, or zeroed, which should be the only way to detect off-grid testing.

 

[BrettS]

What is everyone experience in "testing" the system before PTO? The Tesla panel guys said the electric company is activity monitoring the homes and would detect something like this and of course all the legal language with penalties, etc. without a PTO. I get it.. but I'm talking about disconnecting completely from the grid for hours during the day to see how the system operates. By disconnecting completely from the grid, we may not be "operating".

Anyone heard any big slaps from extended testing before PTO? I'd like to test for an entire 24 hr period. =)

To some extent, it may depend on the utility. I have seen some people post the wording from their interconnection request and it explicitly states that they are not allowed to run their system before PTO. If you signed something like that, then you probably should wait to turn on your system.

I definitely would not run your system in such a way that you could export power back to the grid before you get PTO. Even if it’s not specifically called out in your agreement I think it’s clear that it would be in violation of the terms.

However, personally I had no problem running my system off grid and disconnected from the utility before I got PTO. As far as detection goes, I don’t think they have any sort of magic detection systems, but I think it could be detected if someone was looking for it, simply by looking at your power consumption. Most utilities have smart meters now so you can see your power consumption in 15 minute or hour intervals throughout the day. If you went off grid for 24 hours your power consumption would drop to 0 for an entire day. If they were actually looking for that I think they could assume that you might have gone off grid to turn your system on.

In my case I operated mostly off grid for 2.5 months before I got PTO. My consumption went from 2500-3000kWh per month to 200-400kWh per month. I’m sure that if anyone was looking for it they would have realized what I was doing, but in my case, at least, the utility didn’t care. They never questioned it and I had no problem getting PTO.

In fact, I was off grid and my system was fully operational for the city inspection, the utility inspection and when the utility came to change out the meter and no one batted an eye. The city inspection was scheduled and I had planned to turn off the system and go back on grid before the inspector came, but he showed up more than an hour early and I hadn’t turned off the system yet.

The utility inspection wasn’t scheduled, but I knew he could be coming any day, so I had been keeping a close eye outside and I was hoping that I might be able to see him pull up and shut it down before he came to the door, but I saw him arrive and I’ve never seen someone park and get out of their car so quickly. He was out of the car and on the side of the house before I could even get my shoes on.

One thing that was kind of funny was that outside unit for my heat pump was right next to the meter, so when the guy came to switch out the meter he pulled the meter and the heat pump kept running. He kind of did a double take and looked quite confused and I just said “Oh, the batteries probably took over”. That lead to a bit of a conversation about the tesla powerwalls and exactly how they work. He said that he had heard of them, but never seen them before, so I opened my garage to show him the batteries and we talked about them for a little while.

All that said, I think it really depends on your utility. I think it is definitely conceivable that they could detect you operating your system off grid, but I question whether they really would go through that trouble or do anything about it, especially if you were just doing a 24 hour test. So as long as your interconnection request doesn’t explicitly state that you can’t turn on the system before PTO then personally I think you should be fine doing a test.

 

[GaitherBill]

So, to ask the "dumb" question. The proper way to do an off grid test is to disconnect your TEG from the grid.

Do this by turning off power at the disconnect between your meter and your TEG.

Or, if you don't have that, we don't, turn off the master breaker in your TEG?

 

[zƬesla]

So, to ask the "dumb" question. The proper way to do an off grid test is to disconnect your TEG from the grid.

Do this by turning off power at the disconnect between your meter and your TEG.

Or, if you don't have that, we don't, turn off the master breaker in your TEG?

I'd turn off the utility breaker on the outside of the house. That way there's no question and no worries about power going to grid.

 

[nwdiver]

If you just have a partial home backup system then going off grid for a few days probably isn’t really feasible, but it could still be beneficial to go off grid for a couple of hours just to get a feel for how the system works and what still has power and how you might handle that situation if it was real.

Agreed... especially since ~110% of people have no clue what a kWh or kW are; Being off-grid is a good way to learn.

 

[niveknow]

To some extent, it may depend on the utility. I have seen some people post the wording from their interconnection request and it explicitly states that they are not allowed to run their system before PTO. If you signed something like that, then you probably should wait to turn on your system.

I definitely would not run your system in such a way that you could export power back to the grid before you get PTO. Even if it’s not specifically called out in your agreement I think it’s clear that it would be in violation of the terms.

However, personally I had no problem running my system off grid and disconnected from the utility before I got PTO. As far as detection goes, I don’t think they have any sort of magic detection systems, but I think it could be detected if someone was looking for it, simply by looking at your power consumption. Most utilities have smart meters now so you can see your power consumption in 15 minute or hour intervals throughout the day. If you went off grid for 24 hours your power consumption would drop to 0 for an entire day. If they were actually looking for that I think they could assume that you might have gone off grid to turn your system on.

In my case I operated mostly off grid for 2.5 months before I got PTO. My consumption went from 2500-3000kWh per month to 200-400kWh per month. I’m sure that if anyone was looking for it they would have realized what I was doing, but in my case, at least, the utility didn’t care. They never questioned it and I had no problem getting PTO.

In fact, I was off grid and my system was fully operational for the city inspection, the utility inspection and when the utility came to change out the meter and no one batted an eye. The city inspection was scheduled and I had planned to turn off the system and go back on grid before the inspector came, but he showed up more than an hour early and I hadn’t turned off the system yet.

The utility inspection wasn’t scheduled, but I knew he could be coming any day, so I had been keeping a close eye outside and I was hoping that I might be able to see him pull up and shut it down before he came to the door, but I saw him arrive and I’ve never seen someone park and get out of their car so quickly. He was out of the car and on the side of the house before I could even get my shoes on.

One thing that was kind of funny was that outside unit for my heat pump was right next to the meter, so when the guy came to switch out the meter he pulled the meter and the heat pump kept running. He kind of did a double take and looked quite confused and I just said “Oh, the batteries probably took over”. That lead to a bit of a conversation about the tesla powerwalls and exactly how they work. He said that he had heard of them, but never seen them before, so I opened my garage to show him the batteries and we talked about them for a little while.

All that said, I think it really depends on your utility. I think it is definitely conceivable that they could detect you operating your system off grid, but I question whether they really would go through that trouble or do anything about it, especially if you were just doing a 24 hour test. So as long as your interconnection request doesn’t explicitly state that you can’t turn on the system before PTO then personally I think you should be fine doing a test.

Def wouldn't run it in a way that would put power back to the grid and be dangerous for anyone else. More of completely disconnecting from the grid for extended test windows as you did for your 2.5 months waiting for PTO. I think that's the extend of the electric company's ability to monitor is to see if someone was actually looking.. the drop in consumption. I'm not sure what my interconnect request language which I assume would read something like "...would not operate...". Does "testing" count if I'm not operating as a far as selling back. lol

 

[BrettS]

Def wouldn't run it in a way that would put power back to the grid and be dangerous for anyone else.

Just to be clear, even if you were to feed power back to the grid it would in no way be dangerous. The system has a lot of safeguards in place to stop it from being dangerous and, of course, all of those safeguards are still operational even before you have PTO.

I think the risk of feeding power back to the grid is more of an issue where you clearly don’t have permission for your system to interact with the grid and if they did notice and questioned it I think that would be a lot harder to defend than having your system completely isolated while you were testing.

Does "testing" count if I'm not operating as a far as selling back. lol

I think testing is certainly allowed before PTO. My installers fired up the system to test it before they left, even to the point of allowing the system to feed some power to the grid. However, it was only operating that way for a reasonably short time as the installers verified that everything was working.

I think the question is more of what counts as a test? Is the homeowner allowed to do their own test or just the installer? Is testing for 2 hours ok? For 24 hours? For 2.5 months?

In the end I think it comes down to your own comfort with saying something like “well, I thought that testing my system while it was completely disconnected from your service wouldn’t be a problem” in the unlikely event that someone from the utility says something.

 

[niveknow]

Just to be clear, even if you were to feed power back to the grid it would in no way be dangerous. The system has a lot of safeguards in place to stop it from being dangerous and, of course, all of those safeguards are still operational even before you have PTO.

I think the risk of feeding power back to the grid is more of an issue where you clearly don’t have permission for your system to interact with the grid and if they did notice and questioned it I think that would be a lot harder to defend than having your system completely isolated while you were testing.



I think testing is certainly allowed before PTO. My installers fired up the system to test it before they left, even to the point of allowing the system to feed some power to the grid. However, it was only operating that way for a reasonably short time as the installers verified that everything was working.

I think the question is more of what counts as a test? Is the homeowner allowed to do their own test or just the installer? Is testing for 2 hours ok? For 24 hours? For 2.5 months?

In the end I think it comes down to your own comfort with saying something like “well, I thought that testing my system while it was completely disconnected from your service wouldn’t be a problem” in the unlikely event that someone from the utility says something.

Well said. Since you "tested" for 2.5 months. What does your smart meter read when you log into it for details. You mentioned getting down to 200-400 kWh /month while testing. Does your smartmeter actually reflect that? In otherwords, does the meter run during testing period or only during actual draw from the grid? I'm assume it only draws actual from grid, but double checking.

My panels should be fully connected up on Tuesday when they come back for the PW install. I'm really interested in testing some afternoons first .. and maybe get to a 24hr block later in the week because I want to see what peak solar looks like this time of year from a data perspective. PTO may be weeks away so losing out on this data point until next year.

 

[BrettS]

I never logged into my smart meter directly, but I checked what it was reporting by logging into my account at my utility. I was not off grid for the full 2.5 months. I did go back on the grid at times (mostly for car charging) so the 200-400kWh was power that I used from the grid while I was on grid. If I look at my daily consumption reports from my utility I have a lot of days with 0kWh and a few days with 30 or 40kWh, depending on how long I charged the car.

 

[aesculus]

If you just have a partial home backup system then going off grid for a few days probably isn’t really feasible, but it could still be beneficial to go off grid for a couple of hours just to get a feel for how the system works and what still has power and how you might handle that situation if it was real.

PG&E already gave me plenty of opportunities to test this over the last several weeks.