Solar pulling from grid vs Powerwall [in small amounts]

[George75]

Unless florida is much different than other places in the US (possible, I dont know) that "2c for export" is likely at true up, not as a running total. You typically get retail rates as credit for net metering, at the same rate you would be purchasing from at that time. The only time you actually get that "2c at true up" is probably at the end of your net metering period, if you still have credit on your account at that time.

You can check, but thats the way it works almost everywhere else in the US. That means that you are buying and selling at the same rate when you see that, but may be paying non bypassable charges on that energy if your plan has those.

Unsure how or why it works like this here. Surrounding utilities e.g. municipal give only 2c. That's their wholesale rate. My utility does it's true up at the end of each month. I confirmed this with them. They pay only wholesale rate. Why it isn't like a 1 for 1 even though they charge us a "connection" fee is beyond me. Solar at least here in central Florida just isn't worth it if you don't have a Powerwall.

 

[George75]

Out of curiosity I checked my grid usage on Tuesday, self-power mode and a clean grid usage or rather no usage except for those 3 very short, small spikes.
As other mentioned must be an auto checking as it seems to happen every day at different times and past Sunday only one spike.

Yes it's auto checking but mine is doing this every other second. I've set PTO to Yes in the app (I have PTO from my utility) so I have a full days worth of data for Tesla to see it not working.

What's interesting is it only does this while the solar is producing. Once the sun is down it stops pulling from the grid every few/other second. It just runs of the battery. If I set PTO to No it pulls from solar and battery then the grid it does not check every other second. If I set PTO to Yes it does as described. It'll probably pull about 2kw per day. Which means I'll need to sell back at least 4kw to my utility to break even.

 

[jjrandorin]

I answered this already, I have PTO.

Yes, I remember that you did. The answer you quoted above was in relation to "Why does it not export anything when I set PTO to NO?"

 

[yblaser]

I don't have any inside knowledge here but it seems dubious that the system would push/pull from the grid to make sure it is still there. There are easier and faster ways to verify the grid status.

I run in self powered mode most of the time myself and while the instantaneous values on the main screen in the app shows occasional push/pulls from the grid it does not add up to any total usage if you look at the historical data on the grid usage. I had assumed these small amounts pushed to or pulled from the grid were a combination of rounding errors in the app and the Tesla power control system slightly lagging rapid changes in demand.

If the above is true the question would then by why does this not happen when export is set to NO. This option is only available with the PW2+ so maybe Tesla uses a different algorithm or hardware that is better able to match quick changes in demand in this mode. Again this is complete conjecture on my part.

If I recall correctly I did see measurable average grid draw in self powered mode once when we were running a sous vide immersion bath overnight and the rapid on/off of the heating element was causing this draw even though the powerwalls had plenty of power left.

 

[jhn_]

If I recall correctly I did see measurable average grid draw in self powered mode once when we were running a sous vide immersion bath overnight and the rapid on/off of the heating element was causing this draw even though the powerwalls had plenty of power left.

Also run in self powered and am familiar with these sorts of things. If the house is not already running on battery and there is a quick draw from the house that the gateway cannot supply from the powerwalls for whatever reason (ie - too quick and batteries cold), it will pull from the grid to satisfy the demand and not cause a local brown out or drop.

So to the OP, maybe there is something on your load side that is causing the Gateway some grief? What happens if you leave export on, are in self-powered mode, sun is charging the batteries and you see the spikes but then turn off all the loads in the house (but leave the main panel, grid, gateway, and powerwalls all online and active)? Do you still see the frequent grid draw?

 

[George75]

Also run in self powered and am familiar with these sorts of things. If the house is not already running on battery and there is a quick draw from the house that the gateway cannot supply from the powerwalls for whatever reason (ie - too quick and batteries cold), it will pull from the grid to satisfy the demand and not cause a local brown out or drop.

So to the OP, maybe there is something on your load side that is causing the Gateway some grief? What happens if you leave export on, are in self-powered mode, sun is charging the batteries and you see the spikes but then turn off all the loads in the house (but leave the main panel, grid, gateway, and powerwalls all online and active)? Do you still see the frequent grid draw?

There no change, even with everyone off it keeps pulling small amounts from the grid every few seconds. I've already turned off everything. It is repeatable and consistent e.g when I toggle PTO in the app. The pulls from the grid match exactly the hours solar is producing and stops when there's no light.

I logged into the gateway to verify what the app has is accurate and it is. I double checked what the app started for consumption and the meter matches.

 

[iorchii]

There no change, even with everyone off it keeps pulling small amounts from the grid every few seconds. I've already turned off everything. It is repeatable and consistent e.g when I toggle PTO in the app. The pulls from the grid match exactly the hours solar is producing and stops when there's no light.

I logged into the gateway to verify what the app has is accurate and it is. I double checked what the app started for consumption and the meter matches.

Please share screenshot(s) of your prior day(s) Grid data.

 

[jboy210]

Ok I give up, sun is up and it's back to pulling every few seconds from the grid when it absolutely doesn't need to. This might be normal behavior but I don't understand why. Why pull power from the grid if there's solar and battery to pull from. Why isn't it doing this if I switch PTO to No. It only does this and consistently when PTO it set to Yes. It's annoying because that's extra power from the grid I'll have to pay for that I shouldn't. It's not a lot of power but most utilities here in Florida give you next to nothing (2c) for anything you export.

I wrote a little script that logs the Gateway's current flows. I see my system pulls from the grid every 10 minutes or so, not seconds. It usually pulls 0.1 kW for less than one interval between checking (10 second). I assumed it does this to verify the grid was still operating. Over a day it only pulls small fractional of 1 kWh so I have never bothered to pursue it since1 kWh runs $0.20-$0.43.

 

[jgleigh]

Similar experience for me. I see about 0.3 kWh from the grid and about 0.3 kWh sent back to the grid on a day I'm fully self-powered and not exporting. The power monitors have some defined accuracy and also don't react instantly to load changes.

 

[charlesj]

I wrote a little script that logs the Gateway's current flows. I see my system pulls from the grid every 10 minutes or so, not seconds. It usually pulls 0.1 kW for less than one interval between checking (10 second). I assumed it does this to verify the grid was still operating. Over a day it only pulls small fractional of 1 kWh so I have never bothered to pursue it since1 kWh runs $0.20-$0.43.

It's interesting that yours is so consistent, more or less. Mine doesn't show any regularity and on 1 to 3 spikes in a day, very short.

 

[daniel]

I'm not technically knowledgeable enough to provide details of my system, or to mess around with settings. But I can report that my system periodically and briefly draws 100 watts from the grid or sends 100 watts back to the grid. I'm allowed to send a "small amount" back to the grid for load balancing. So I assume that "load balancing" is the reason. I was told that the system cannot respond quickly enough to changes in demand, either up or down, and that's why it has to send or draw small amounts to/from the grid.

However, the total amount drawn from the grid is never more than around 20 kWh/month IIRC, and so I never have to pay more than the minimum billing amount. There was one month it was 37 kWh, which might have been due to a two- or three-day storm, but still didn't go over the minimum.

 

[George75]

I wrote a little script that logs the Gateway's current flows. I see my system pulls from the grid every 10 minutes or so, not seconds. It usually pulls 0.1 kW for less than one interval between checking (10 second). I assumed it does this to verify the grid was still operating. Over a day it only pulls small fractional of 1 kWh so I have never bothered to pursue it since1 kWh runs $0.20-$0.43.

That's exactly what mine is doing only it's like it was set to seconds not minutes.

 

[George75]

Please share screenshot(s) of your prior day(s) Grid data.

This is today's data as of 5pm and yesterday. As you can see night time no solar production it pulls nothing from the grid unless there's more demand than the PW can handle. Sunup and solar production begins even with 45% on the PW this morning it starts pulling on and off non stop all day. It'll do this until solar production stops then it just stops pulling from the grid every few seconds.

I'm going to reach out to Tesla tomorrow to try and get some updates. I'm not leaving it like this until whatever time they decide to look at it. Tomorrow I'm back to setting PTO to No which stops it pulling from the grid. The downside is I have to keep checking the app. Once the PW is almost full or full I set PTO back to Yes to it'll export.

I do have PTO from the power company and I did get an email from Tesla telling me my system was now fully operational. Logging into the Tesla website it still shows waiting for power on. Hopefully that's a Tesla website thing and not something someone at Tesla needed to do causing this anomaly.

 

[jjrandorin]

This is today's data as of 5pm and yesterday. As you can see night time no solar production it pulls nothing from the grid unless there's more demand than the PW can handle. Sunup and solar production begins even with 45% on the PW this morning it starts pulling on and off non stop all day. It'll do this until solar production stops then it just stops pulling from the grid every few seconds.

I'm going to reach out to Tesla tomorrow to try and get some updates. I'm not leaving it like this until whatever time they decide to look at it. Tomorrow I'm back to setting PTO to No which stops it pulling from the grid. The downside is I have to keep checking the app. Once the PW is almost full or full I set PTO back to Yes to it'll export.

Thats quite a bit more than I see. Do you have anything with a pump / motor that cycles that your powerwalls might not be able to cover the startup load on?

 

[George75]

Thats quite a bit more than I see. Do you have anything with a pump / motor that cycles that your powerwalls might not be able to cover the startup load on?

I'm in a 6 year old single family home, no pool, no wells, no pumps. The home is quite energy efficient. I live alone so no other persons charging anything. Even with the AC coming on the PW easily handles that at night. I just checked it now and PW is at 100% so it's exporting vs importing. So started charging my car to see if it'd pull from the grid again. It pulled from the panels and PW however I'm willing to bet once that PW drops below 100% it'll go back to pulling 0.1kw every few seconds.

 

[jjrandorin]

I'm in a 6 year old single family home, no pool, no wells, no pumps. The home is quite energy efficient. I live alone so no other persons charging anything. Even with the AC coming on the PW easily handles that at night. I just checked it now and PW is at 100% so it's exporting vs importing. So started charging my car to see if it'd pull from the grid again. It pulled from the panels and PW however I'm willing to bet once that PW drops below 100% it'll go back to pulling 0.1kw every few seconds.

Yeah, when I was commenting on "grid pull" earlier in this thread, I must have missed that you were talking about "every few seconds". As mentioned by several in this thread, its normal for it to sync with the grid every so often, but your last charts show basically constant pulling from the grid, so it doesnt look right to me, nor what others have experienced on a "frequency of pulling from the grid" basis.

Hope you get it figured out.

 

[George75]

Yeah, when I was commenting on "grid pull" earlier in this thread, I must have missed that you were talking about "every few seconds". As mentioned by several in this thread, its normal for it to sync with the grid every so often, but your last charts show basically constant pulling from the grid, so it doesnt look right to me, nor what others have experienced on a "frequency of pulling from the grid" basis.

Hope you get it figured out.

When the PW is at 100%, at least on this test it pulled nothing from the grid because it was exporting. I got the PW down to 97% and back to pulling from the grid to handle the load it handles fine if I set PTO to No. It's frustrating more so because I can't fix it but for now I'll flip PTO back and forth in the app to try and hold it off pulling from the grid. I think a few days worth of data should be enough for Tesla. One strange data point I found and it's just one (so far) is I have an export to the grid at like 4am. It's dark here at 4am and the PW reflects the same load being applied for a few seconds.

 

[George75]

Absolute radio silence from Tesla after I opened my ticket. My service advisor responds without issue but has no information from tech support. I was told to wait they are monitoring. About two weeks ago I get a notification to schedule a service call, zero information as to what's going on. Service call will be near the end of November for an issue reported back in September. Hopefully when they send someone out they can explain what is causing this.

I'm still toggling PTO from Yes to No and back again depending on the status of the battery. Had I not been doing this I'd have been importing power I didn't need. Having said that I got my first electric bill with about 3 of the 4 weeks of the billing period where I had PTO. My bill went from around $200 to $14.

 

[George75]

After multiple appointments set and rescheduled by Tesla they finally got someone out here. Guy shows up and hasn't really any idea what's going on and thinks it's an app issue, then phantom draw (yes my irrigation system that's 6 years old constantly needs 100w of power lol) then metering. Long story shot I run him through what I've gone through, show him PTO set to Off and it stops pulling 100w from the grid, PTO Yes and it pulls almost constantly. Inform him if the PW is at 100% that constant pull from the grid stops, if it's dark it stops regardless of the PW state of charge. If the PW is less than 100% and it's light out, it pulls from the grid. If there's a phantom draw I haven't found it and neither has he.

He still thinks it's metering even though I've told him I've tested that theory, the meters (both of them) match, the app matches and the gateway matches. However I have to assume he's not just stabbing in the dark which is what I think he's doing after he called another tech. I believe the issue I have is either by design and intentional, a bug (most likley) or configuration/misconfiguration.

 

[George75]

I've been informed my issue has been escalated up their design team for possible redesign of my system.