In the case you specify, the powerwalls can not take in the power the PV is generating and then shut down.. but you have first hand experience with that. Its unlikely the OP ends up in that situation, but yeah its possible based on system design.
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Powerwall 2 - Outage “Switchover” Delays?
- Thread starter Freakyguy666
- Start date
In the case you specify, the powerwalls can not take in the power the PV is generating and then shut down.. but you have first hand experience with that. Its unlikely the OP ends up in that situation, but yeah its possible based on system design.
Are we talking under 5 seconds? Under 10 seconds? I’m curious why it would take so long to shut off the PV and power back on the PWs alone?
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Thank you, but I think your statements are contradictory.
Recall the question is in essence, “is there any scenario in which the PV will remain running immediately after an outage?”
Your answers: “this is based entirely on the state of charge of the powerwalls.” “When you are off grid (and only when you are off grid) and your powerwalls are fully charged the system will always turn your PV off, until the powerwalls can drain down a little to make sure they have capacity to store any excess power that may be generated when the PV is turned back on.”
Per Tesla: “the soc of the PWs are irrelevant at the moment the outage occurs; the PV will ALWAYS Reboot (which typically takes ~2-5mins) immediately after an outage.” “There is NO SCENARIO in which the PV would remain in production mode immediately after an outage—even if the PWs are at 20% when outage occurs”.
Also per Tesla: “the timing of the reboot of the PV is dependent on the demand from the Home & the level of charge of the PWs and the “quickness” of your inverters in coming back online. Most require several minutes.
You also wrote: “whenever the powerwalls are fully charged (about 98% and above) the system will shut off your PV system.”
“Whenever” needs to be clarified to mean “during an outage”. Clearly if one is connected to the grid/utility while PV is producing and PWs are charged to 98%+, the system would not shut off the PV.
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Thank you. That is now Tesla’s official position on the matter.
Funny thing is when PW were first introduced, they were described as allowing your PV to continue producing uninterrupted thru an outage.
I wonder if most customers realize that their PV systems will ALWAYS Turn Off immediately after an outage?
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Correction, I believe you meant to write “I believe in all cases, that first swap over with batteries at 100% and PV, would trigger the PV system to shut down.”
So let’s say we amend your scenario slightly so that the House Load were 4kW, and all else equal, would that cause the “go dark” issue you’re describing? Especially given the fact that PWs have a 7kW capability for short periods of time.
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woferry
Member
If you think about it, it's the only thing that makes sense. The inverters are looking at the exact same grid the Gateway is. When the grid fails, the inverter(s) will sense this just like the Gateway does, and they will go offline as they're designed to on a grid failure. But when the PW-supplied microgrid comes up, provided the PW hasn't shifted the frequency beyond what the inverter(s) consider acceptable, they'll do their 5-minue check for a stable grid, and then start producing again. That's what happened with my system during simulated grid outage testing (throwing the main breaker). And the inverter log display showed it detected the line voltage at very low levels (like 5V or less) as the cause for the shutdown.
So normal devices/appliances that aren't watching the grid looking for faults would hopefully ride-out the Gateway's islanding and start of the PW's microgrid unaffected (though obviously not all things do), but something that's intentionally monitoring the grid looking for faults will see the grid loss and take action, there's really nothing the Gateway could do to stop that, since it has to see the grid fail before it can actually do anything about it. Inverters are on a 'hair-trigger' to shut off by design, consider that they'll curtail and/or shut down at 60.5Hz, when even most UPS's consider 63Hz "OK", and normal devices will run (even if not so happily) off even higher frequencies.
Correct, that is what I ment to type.
"Turn off for at least 5 minutes". Important distinction because in the scheme of "does my home have power during an outage" that 5 minutes doesnt matter, really (because the powerwalls would be powering the home during that time).
I think the 7kW is an output (temporary) peak capacity. My references were to PW input limits. Based on the Tesla app, when on-grid, I only see at most 10kW go into the (2) PWs with any extra energy not used by the house going to the grid. So, a 4kW house load with 14kW PV production would likely work although any overcharge would cause the shutdown during an outage.
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The specs do say 7kW peak both for charge and discharge. Where I imagine this potentially could come into play is if you are off-grid, sending ~5kW to a single PW, then a cloud passes, dropping production temporarily, followed by a spike with the cloud edge effect. If it spikes to 6-7kW, that may not knock the system offline assuming it settles back to or below 5kW quickly enough.
From my experience I stand by what I wrote. I have been spending a lot of time with my system off grid over the last month and a half or so. However, I also have been doing short stints on grid as well, so I’ve been going back and forth quite a few times recently. I go off grid by throwing the service disconnect to simulate an outage. If PV is powering the house and the powerwalls are at less then 98% the PV stays operational every time. There may be some situations where an outage will cause the PV to reboot, but certainly from my experience it doesn’t happen every time.
Yes, that’s true. My entire post was intended to discuss what would happen when the system was off grid, so I meant that comment to apply to an off grid scenario, but you are absolutely right. The PV will only be shut off by the powerwalls reaching full charge when the system is off grid.
I do not know, but I would have guessed it behaves like a circuit breaker such that it could sustain 6kW for longer than 7kW. But I've only seen the datasheet that states 5kW continuous/7kW peak, with no further detail.
It appears that your experiences are in direct opposition to each other!
BrettS says that in his experience the PV remains in production, whereas Woferry has tested their system and found that the PV “reboots” upon an outage (which is what Tesla is advising).
Clearly someone is mistaken, no?
bkp_duke
Well-Known Member
More than likely they are both right . . . for their specific circumstances.
Devil is in the details, and they probably have significant differences in their Solar+PW configurations.
My PV remains in production when there is an outage. Then after 5 minutes I see the three of my inverters (Delta Solivia) shut off solar production while the SolarEdge inverter stays online and producing. 5 minutes later, the Delta inverters come back online.
If you jump to about 3:14 in the above video, you can see that the solar is happily producing at 12.4 kW during an outage. Then the Powerwalls try the grid again. The Delta inverters stop producing while the SolarEdge continues to produce. Around 8:56, the Delta Solivia inverters start coming back online. Then at 9:25, there's another 'outage' and the cycle repeats.
I think this is correct. The thing to remember is that the PV will shut off and “reboot” when it detects disturbances in the line. Over/under voltage or over/under frequency. In fact, this is how the powerwalls shut off the inverters... they raise the frequency until it gets above what the inverters are willing to tolerate.
So I guess what I am saying is that the powerwalls will purposely shut off the inverters when they get fully charged and your system is off grid. They will also purposely shut off the inverters if you go off grid when the powerwalls are fully charged.
The powerwalls will not attempt to shut off the inverters if you go off grid when the powerwalls are not fully charged. However, that’s not to say that it’s not possible that the inverters will still be shut off... it’s just not the powerwalls doing it. As I said above, the inverters are sensitive to line disturbances, so it’s quite possible that whatever caused the outage also caused enough of a disturbance to shut off the inverters. I haven’t seen this happen when I just turn off my service disconnect, but that’s a pretty clean outage. It’s also possible that other brands of inverters or models would be more sensitive to that change and could shut off.
In the end, it doesn’t really matter. When the outage happens your house will continue to have power, whether that’s from PV, the powerwalls, or some combination of the two. If the inverters do shut off when the outage happens they should come back on again in a short time. Typically they have a 5 minute delay to restart, but it could be a little longer than that if your powerwalls were fully charged at the time of the outage as it would wait 5 minutes after the powerwalls were drained to 97%.
The detail is really in the firmware and the specific numbers are inside the grid profiles the inverters are set to.
There are cases where the newest grid PV profiles will "Ride Through" some disturbances, but not others.
Older firmware inverters are much more digital, either on or off. Also, this is something that can be changed with the right software tools, though its not legal to go out of the box that UL sets forth as safe. It can happen anyway (such as setting a California inverter to Hawaii code settings, as a simple example)
There are cases where the newest grid PV profiles will "Ride Through" some disturbances, but not others.
Older firmware inverters are much more digital, either on or off. Also, this is something that can be changed with the right software tools, though its not legal to go out of the box that UL sets forth as safe. It can happen anyway (such as setting a California inverter to Hawaii code settings, as a simple example)
May add that beyond safety and compliance certifications (UL included) there are interconnection agreements that can stipulate how your system must behave during abnormal grid conditions including outages.
It seems that the behavior of the Gateway is related to the loc in the PWs relative to the Load from the Home & PV production.
Given the above, here’s a scenario: The PV is producing 10kW, the PWs are charged at 50%, and the Home is drawing 5kWs at the moment that an Outage occurs.
I would expect that if things go according to expectations, within a few minutes of the outage the PV would certainly be providing 5kWs to the Home & 5kWs to the PWs.
The Question: all else equal, what would happen if the outage remained in place long enough for the PV to FULLY Charge the PWs? Would the Gateway recognize the excess energy and shut down the PV and revert to power SOLELY from the PWs?
Given the above, here’s a scenario: The PV is producing 10kW, the PWs are charged at 50%, and the Home is drawing 5kWs at the moment that an Outage occurs.
I would expect that if things go according to expectations, within a few minutes of the outage the PV would certainly be providing 5kWs to the Home & 5kWs to the PWs.
The Question: all else equal, what would happen if the outage remained in place long enough for the PV to FULLY Charge the PWs? Would the Gateway recognize the excess energy and shut down the PV and revert to power SOLELY from the PWs?
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