Installation Done - Solar = Grid, House = Powerwall?

[jjrandorin]

Thanks all again for your feedback.

My system included a "whole home backup" where they installed what looks like a 2nd 200A panel? Regardless, I tested the "Disconnect from Grid" in the Tesla app just now and then went around the house checking each room to see if there was something not getting power (turned on/off lights, fans, TVs, checked kitchen appliances, fridge, etc.) and everything seemed to be working as no issue.

Is this the safest bet for me to operate until PTO?

During the day, solar would supply my house and excess goes to the batteries until full. I'm assuming when the batteries are full, the solar system will scale down to match house consumption and slowly start using the batteries as solar ends. Before I go to bed, I will plan to reconnect to the grid in case for some reason the batteries don't last us throughout the night and we have to consume from grid. Then in the morning when I wake-up, disconnect from the grid again through the app. Rinse and repeat until PTO.

This would allow me to consume the energy from the system/batteries, without the risk of pushing excess to the grid pre-PTO. Thoughts? Would the above put any kind of unnecessary strain on the hardware by doing this?

Yeah thats a good plan and would work. Whether the solar scales to the home load, or, basically shuts off (and the batteries cover the home load until they drain a bit and allow the solar to come back on) depends on how its setup, but what you are proposing would work fine if you were trying to obey the rules.

It shouldnt put any strain or anything on the hardware. the only issue I see that you could run into, is "what frequency is your electrical power when off grid, and how does the various items in your home tolerate it?"

By default, most Tesla installs have the off grid frequency at 65hz when its forcing the solar to turn off, and many electric items (microwaves, residential battery backups, some things with motors, etc" dont like 65hz power very much. Its getting into the weeds a bit here, but this is also something good to find out now, with a kill a watt (or similar) type plug in device which will show you what frequency your home is running at (power wise).

You can get tesla to adjust the frequency down if its too high, or may need to engage your solar installer since it wasnt tesla to find what its set to. You can also find out if it can curtail power (as you mentioned) or if its only "on / off".

Its probably good to do some off grid testing on your new install, so that you know how everything operates, whether you can start up your AC unit(s), etc.

You could also just say "screw it" and choose not to obey the rules, lots of people do that too (which is what your installer is telling you). Just depends on your risk tolerance. I am fairly risk averse for a few different reasons, but one of which is, "I" tend to be the "one who gets caught" doing stuff that "everyone else does, no problem, even though we are not supposed to".

So, I tend to be very careful, myself, about this type of thing. YMMV on it of course.

 

[yblaser]

The only down side with running off-grid is that as the PWs fill up the micro-grid frequency will go up to 65 Hz unless Tesla has changed the default setting. Some electrical equipment might not like that high of a frequency and certainly your clocks will run fast.

I had my 8.16kW w/ 2 PW2s installed in Oct 21 by Tesla and they left everything running on install day. My PTO wasn't until Feb 22. I mainly managed not to export by running in self powered mode, draining my PWs overnight charging my EV, charging another EV during the day to consume some of the solar, and occasionally trying to increase my house load when necessary. It did help that this was during the lowest solar production months of the year. There was probably a few days in that 4 months that I exported a couple of kWh. We did go on vacation a couple of times during that period and I just turned off one of my 2 solar inverters to reduce the amount of solar production to better match my vacant house usage.

 

[Vines]

Thanks all again for your feedback.

My system included a "whole home backup" where they installed what looks like a 2nd 200A panel? Regardless, I tested the "Disconnect from Grid" in the Tesla app just now and then went around the house checking each room to see if there was something not getting power (turned on/off lights, fans, TVs, checked kitchen appliances, fridge, etc.) and everything seemed to be working as no issue.

Is this the safest bet for me to operate until PTO?

During the day, solar would supply my house and excess goes to the batteries until full. I'm assuming when the batteries are full, the solar system will scale down to match house consumption and slowly start using the batteries as solar ends. Before I go to bed, I will plan to reconnect to the grid in case for some reason the batteries don't last us throughout the night and we have to consume from grid. Then in the morning when I wake-up, disconnect from the grid again through the app. Rinse and repeat until PTO.

This would allow me to consume the energy from the system/batteries, without the risk of pushing excess to the grid pre-PTO. Thoughts? Would the above put any kind of unnecessary strain on the hardware by doing this?

We have installed more than 3k systems all around the bay area and never operate them before PTO. It's so little gain for a rather large risk.

If you physically flip the main breaker that is probably acceptable but PGE would still probably say no. "Go off Grid" is an electronic setting relying on contactors working and that would not stand up to official level scrutiny.

I would 100% not operate any system before PTO unless totally isolated from the grid by the main breaker. Even when you do, likely the system will shift frequency to 65 hz unless the installer changed it. That frequency can damage electronics, especially with prolonged duration. Verify it with either tesla or your own multimeter.

Not sure why your installer is so caviler about PTO, but hopefully they knew about setting your frequency to 62.5 hz.

 

[HardHitter]

If I disconnect from the grid through the main breaker, does that address the 65hz issue referenced or is that only the case when you disconnect through the app?

 

[taphil]

Flip it and find out

As I said earlier, that's how you understand the system works and what it's capable or not capable of. Flipping the switch basically simulates a power outage. What happens and what freq the power output changes to or stays at depends on the current state of the system (solar output, PW charge status) when it happens. There's old threads about it, including info about 65Hz interfering with UPS backups and getting Tesla to change it to 62.5Hz.

 

[taphil]

You'll also need a meter of some sort or KillAWatt to measure the freq.

 

[jjrandorin]

If I disconnect from the grid through the main breaker, does that address the 65hz issue referenced or is that only the case when you disconnect through the app?

Neither will address that.

 

[HardHitter]

So I checked my PG&E usage stats on 9/14, the day the installers finished, and was surprised that PG&E is already providing me credits? Take a look at the attached screenshot.

At 11:00 AM that day, the installers shut my power off to do the load transfer for the whole home backup. The power came back on around 3:00 PM and you can see it starts providing me credits. I didn't think it got turned on until 5:00 PM because that is when the installers asked for me to enter my password on their phone to login and configure the system.

I noticed that when I got access to the app, the excess solar was pushing back to the grid and that's when I posted to this thread asking if this was OK or not. When the first reply came in from taphil at 5:31 PM explaining "Under time based control setting, during peak hours, solar panels will send all output to the grid to maximize production credits." I switched it to Self-Powered mode and from that time on, solar and my batteries powered the house for the remainder of the day.

So a few questions:

1. This should confirm that I have a bi-directional meter correct? If I didn't, these stats wouldn't reflect credits I would think
2. From what I understood, PG&E wouldn't start giving any credits until after PTO. In this example, why is it providing credits?
3. To avoid getting credits from PG&E pre-PTO and getting flagged, now I really need to make sure nothing of excess gets sent to the grid. The system I have is oversized and I had to micromanage going "on/off grid" yesterday to avoid the excess solar going to my grid after the batteries reached full charge by ~1:00 PM yesterday. The batteries started at 4% for the day and by 1:00 PM they were full and that is when I went "off grid" since my home was only consuming ~1kW and solar was producing close to 10kW. I reconnected back to the grid around 2:30 PM to top off the batteries which drained to 95% and by 2:45 PM, the batteries were full again and I disconnected from the grid again until around 5:30 PM where the system was still generating 0.3kW, but it was less than the 1.0kW house consumption so I was safe from any excess. It's now 5:45 AM the next day, (Sept 16) and I ran off my batteries and they are currently at 69% so it is clear I am able to easily last until the next day solar production on batteries alone. I don't want to micromanage my solar system until PTO to avoid sending power back to the grid, but still want to take advantage of the power generated/batteries so I no longer have to use anything from the grid. What is the most efficient way in accomplishing this?

 

[Vines]

So I checked my PG&E usage stats on 9/14, the day the installers finished, and was surprised that PG&E is already providing me credits? Take a look at the attached screenshot.

At 11:00 AM that day, the installers shut my power off to do the load transfer for the whole home backup. The power came back on around 3:00 PM and you can see it starts providing me credits. I didn't think it got turned on until 5:00 PM because that is when the installers asked for me to enter my password on their phone to login and configure the system.

I noticed that when I got access to the app, the excess solar was pushing back to the grid and that's when I posted to this thread asking if this was OK or not. When the first reply came in from taphil at 5:31 PM explaining "Under time based control setting, during peak hours, solar panels will send all output to the grid to maximize production credits." I switched it to Self-Powered mode and from that time on, solar and my batteries powered the house for the remainder of the day.

So a few questions:

1. This should confirm that I have a bi-directional meter correct? If I didn't, these stats wouldn't reflect credits I would think
2. From what I understood, PG&E wouldn't start giving any credits until after PTO. In this example, why is it providing credits?
3. To avoid getting credits from PG&E pre-PTO and getting flagged, now I really need to make sure nothing of excess gets sent to the grid. The system I have is oversized and I had to micromanage going "on/off grid" yesterday to avoid the excess solar going to my grid after the batteries reached full charge by ~1:00 PM yesterday. The batteries started at 4% for the day and by 1:00 PM they were full and that is when I went "off grid" since my home was only consuming ~1kW and solar was producing close to 10kW. I reconnected back to the grid around 2:30 PM to top off the batteries which drained to 95% and by 2:45 PM, the batteries were full again and I disconnected from the grid again until around 5:30 PM where the system was still generating 0.3kW, but it was less than the 1.0kW house consumption so I was safe from any excess. It's now 5:45 AM the next day, (Sept 16) and I ran off my batteries and they are currently at 69% so it is clear I am able to easily last until the next day solar production on batteries alone. I don't want to micromanage my solar system until PTO to avoid sending power back to the grid, but still want to take advantage of the power generated/batteries so I no longer have to use anything from the grid. What is the most efficient way in accomplishing this?

1. Yes, this means you have a bi-directional meter.
2. This is not a bill, this is your meter data that PGE uses to create a bill.
3. Wait for PTO before sending power to the grid. You have the best answer in my replies already.

 

[jjrandorin]

I don't want to micromanage my solar system until PTO to avoid sending power back to the grid, but still want to take advantage of the power generated/batteries so I no longer have to use anything from the grid. What is the most efficient way in accomplishing this?

You either:

1. flip your main breaker so that you are completely off grid (not clicking the button in the app) if your system is such that you can run 100% off grid at all times,...... or

2. Dont turn the system on at all (wait for Permission to operate, which is what you are supposed to be doing)....... or

3. Micromanage flipping the main breaker off and on etc, but that isnt going to work as you will invariably miss some time, etc.....or

4. Ignore it all, backfeed to the grid and take a chance that PGE wont care / wont deny your permission to operate because you were operating the system before permission.

Thats it. Safest is #2. (which is what @Vines who works for a company that installs PV / Powerwalls in Nor Cal, is telling you).

 

[HardHitter]

Going to be a dumb question but which one is the main breaker? I'm going out of town for the weekend and I know with solar and battery it can run 100% off grid. The installers took breakers from the main panel and installed a new 200A box inside the garage but they never explained anything after all said and done, just said "don't touch anything" Is it it the 4 bar breaker inside the main panel outside next to the meter or did they relocate it to the new 200A box inside the garage where it says A/B at the top?

 

[jboy210]

FWIW, my Tesla roof install was left in a similar state a couple of years ago. I called them about it, and they said you should just open breakers to the grid. But for a while I did "test" the system by filling the Powerwalls, charging my cars, cooling the house, and then when I finally ran out of places to put electrons opened the breaker. Bill went to near zero.

Enjoy your system.

 

[HardHitter]

Ok well I flipped the 4 bar at the main panel and it disconnected from the grid but I was expecting Solar to be generating still and not just discharge from the batteries the entire time. So I flipped the connect back on and now I have a connection to the grid but no solar production?

 

[power.saver]

Ok well I flipped the 4 bar at the main panel and it disconnected from the grid but I was expecting Solar to be generating still and not just discharge from the batteries the entire time. So I flipped the connect back on and now I have a connection to the grid but no solar production?

It can take at least 5 minutes for solar to resume after flipping the breakers. So wait a little bit.

But I see only 1 PW in the photo, and you said you have 10kW of solar. That is higher than recommended for 1 PW, so it may not work when the breaker is open. The PW can only accept up to 5kW. Typically, you need 1 PW for each 5kW of solar.

I think my previous suggestion of leaving the solar off and everything else on is best, because you have not determined if you can run off-grid with the solar / PW combination you have installed.

 

[taphil]

Like I said above, read the 65Hz UPS thread in this forum. It'll explain how the system works. Depending on the current state of the entire system (solar production, PW charge level, house usage), the transition from on- to off-grid may or may not be seamless. Under the best conditions, the transition is seamless and you'll notice a fractional second blip. Under other conditions, there is a 5 min period where solar is powered down rapidly for safety reasons while PW slowly ramps up to provide household needs, after which solar output will restart and throttle to match PW charging and house needs. From my understanding, the throttling is of the solar array is controlled by the power frequency, hence everything relates to all the info contained in the 65/62.5Hz thread.

 

[Vines]

Going to be a dumb question but which one is the main breaker? I'm going out of town for the weekend and I know with solar and battery it can run 100% off grid. The installers took breakers from the main panel and installed a new 200A box inside the garage but they never explained anything after all said and done, just said "don't touch anything" Is it it the 4 bar breaker inside the main panel outside next to the meter or did they relocate it to the new 200A box inside the garage where it says A/B at the top?

Wow, holy crap is that how they left your service panel? There are exposed holes everywhere with live parts right there for anyone to touch! This couldn't possibly pass inspection already in San Jose?!

The main breaker is the one in your 8041 picture. Be very careful there and do make sure they install the proper breaker slot plastic plugs to make this panel safe.

Take a picture of the sticker under the lid there of the panel with all the holes in the deadfront, as it looks like a 200A subfeed lugs connection for a panel that might not have been designed for it. Most of the time, those 200A center fed panels are not designed to take a 200A subfeed connection on the bus as your installer did. The sticker inside of the door should say something like "Max Branch Circuit Breaker 100A"

 

[wwhitney]

Even when you do, likely the system will shift frequency to 65 hz unless the installer changed it.

Is that setting exposed at the local installer interface? Or does Tesla have to make the change at the backend?

Cheers, Wayne

 

[Vines]

Is that setting exposed at the local installer interface? Or does Tesla have to make the change at the backend?

Cheers, Wayne

You or the installer has to call and tell Tesla the model number of the inverters you have installed on-site. It's on our internal QA checklist as one of the items the lead installer is to take care of before we leave the installation site.

 

[cwied]

You or the installer has to call and tell Tesla the model number of the inverters you have installed on-site. It's on our internal QA checklist as one of the items the lead installer is to take care of before we leave the installation site.

FWIW, I was just able to get the maximum frequency changed using online chat.