SolarEdge Daytime Solar Options during power outtage?

UPDATE...

Recap...

In normal operation, the grid, generator, solar panels and battery via inverter are connected to the BackUp Interface (BUI), which connects these sources to the main panel. With the sun out, power comes from the panels, and battery (if enough charge), and potentially some from the grid, if not enough power to run the house. Once the sun is down, power comes from the battery (if above the 20% charge setting), and/or grid.

When there is a grid outage, the expectation is that the system will disconnect from the grid, and power the house from the battery. When the battery hits 20%, the inverter will trigger dry contacts on the BUI to open the circuit for the generator's power sense lines, which are connected to the main panel. The generator senses an outage, spins up, and will power the house. Hopefully the transition from battery to generator will be smooth.

Since I last wrote, we have not had an opportunity to test this backup operation out... until now.

Tuesday, the system went into WeatherGuard mode, and the battery, once charged to 100%, was not used, once the sun went down, reserving it any potential storm (as expected).

Wednesday, at 5am, with 6" of heavy snow over night, and very high winds, the power went out. I was expecting the system to run on battery for at least 10-12 hours, like it usually would do.

Well, the generator came on and ran for less than a minute (30 seconds coming up to speed), turned off, and then after a few seconds came back on and repeated the cycle continuously!

From what I could tell, the system detected the grid outage, and showed that the battery was in "backup mode", but the battery was not supplying power to the house! It remained at 98%, but the house had no power. As a result, the generator's power sense lines, connected to the main panel, detected a loss, and it powered up. Once up to speed, it started supplying power to the house. Of course, the generator's sensing lines then "saw" the power that it generated, and turned the generator off after 10 seconds or so. Now, the sense line detected no power, and it started back up.

Since the sensing lines are connected to the main panel, my work-around, was to shut off the breaker, so that the generator thought there was no power and would run continuously. At 7am, we lost internet too, so there was no way to tell what was going on with the generator or inverter, other than to look at the LCD display on the generator and LEDs on the SolarEdge gear (the box reports everything, via the Internet to SolarEdgfe, of which I can then go to their monitoring web site to see status/alarms/etc).

The outage lasted for almost 36 hours. I found out that the power had come back on, because the power glitched as the BUI switched from generator to grid, and the Internet came back up, of which I have a custom app running on one of my servers and it polls the SolarEdge API for my site and could report that the system went from FAULT -> ON GRID. I then, turned the breaker back on, so that the generator would see that we had power and would shut off.

So, it detected the outage (and return of grid), and sourced the house with generator power, but it did not send battery power to the house during the outage (like it does. when we have grid).

Frustrating, as I was hoping this was finally working. It's not...

You didn't test it?

Also I find it hilarious that manufacturers of backup solar inverters use "the cloud" for everything... modbus ftw...

peufeu said:

You didn't test it?

Also I find it hilarious that manufacturers of backup solar inverters use "the cloud" for everything... modbus ftw...

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How do you test a grid outage?

darkskies said:

How do you test a grid outage?

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Flip the main breaker between my house and the grid.

When the installer was integrating this together, there didn't seem to be a way to disconnect JUST the grid to test the backup mode.

As I understand it, the grid, inverter/battery, and generator are connected to a SolarEdge BackUp Interface, which feeds the main panel. There is a breaker (obviously) on the BUI, but I think it disconnects all sources from the main panel (rapid shutdown?). There's no schematic of this BUI, so I can't tell, if there is some way to simulate a backup situation.

The installer didn't seem to be able to test that either (they could simulate low battery, but opening the relay to the generator sense lines, to ensure the generator would come on).

I agree, that making these devices all cloud operable is a bad design. It makes it great to remotely monitor and diagnose the system, but once the internet is down, they are useless. They do have a SetApp program that runs on your phone, and can connect to the built-in wi-fi of the inverter, but I only have homeowner access and can just view some system info and cannot make any changes or control things.

Hmm I think we have a case of different legislation around here (France) you must have a general grid disconnect/breaker, in a place the firemen and emergency services will easily find like next to the door. If you have PV you have to slap a big sticker on it that says so, I assume this is to inform them they have to make the expendable intern handle the firehose.

In fact this breaker is "property of the utility". The utility smartmeter can also cut the power, either manually or via not paying the bill. Thus its's quite easy to test...

Ironically the only stuff on the backup port is the freezer and the circulator for the heating... because the old central heating wood furnace (backup for my heat pump) will run without electricity, but the circulators won't.

Did the installer really build your system without any way to test it?

peufeu said:

Hmm I think we have a case of different legislation around here (France) you must have a general grid disconnect/breaker, in a place the firemen and emergency services will easily find like next to the door.

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Yeah, you're required to have a main breaker on the US, location on the premise isn't dictated other than height from the ground. Warning stickers in solar stuff is required too.

peufeu said:

If you have PV you have to slap a big sticker on it that says so, I assume this is to inform them they have to make the expendable intern handle the firehose.

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peufeu said:

Hmm I think we have a case of different legislation around here (France) you must have a general grid disconnect/breaker, in a place the firemen and emergency services will easily find like next to the door. If you have PV you have to slap a big sticker on it that says so, I assume this is to inform them they have to make the expendable intern handle the firehose.

In fact this breaker is "property of the utility". The utility smartmeter can also cut the power, either manually or via not paying the bill. Thus its's quite easy to test...

Ironically the only stuff on the backup port is the freezer and the circulator for the heating... because the old central heating wood furnace (backup for my heat pump) will run without electricity, but the circulators won't.

Did the installer really build your system without any way to test it?

Click to expand...

The normal PV and battery part was tested well - a standard product that SolarEdge sells. However, the BackUpInterface is I think SolarEdge's attempt to integrate with whole house generators and batteries. SolarEdge advertised this BUI, and I bought a system with it in July of 2021. Of course, on the inverter data sheet, they had an asterisk saying the BUI and generator integration would work "with required firmware upgrade". At the time, it was hard to get a generator and batteries (supply chain issues), so the system was built and integrated over 6-9 months. When we got to using the generator (late 2021), we (installer and me) found out that the "firmware" wasn't ready yet.

SolarEdge kept saying they're working on bugs... should be available soon...etc. In the interim, the installer connected the generator to a 100A panel with ATS and redirected critical circuits over, so that we had some backup capability on outages. It's been a long and painful saga over the years.

Finally, SiolarEdge finally indicated that they had firmware that should work. My installer came out, connected the generator to the BUI and removed the ATS panel, restoring circuits to the main panel. Because of the generator design, a relay was needed to allow the BUI to control when the generator can be actived. This was mentioned earlier in this thread.

At the time, I was also having issues with the battery bricking. I personally think there was an incompatibility between the inverter and battery, as the inverter is supposed to download the lastest firmware into the battery and we'd get cases where that would not happen, and LG wqould send out another battery (I think I'm on my third one). Another painful thing.

The point being, it was hard to have all the pieces functioning at once. When we finally did get it going, the only thing they could test was simulating the BUI triggering the relay, causing the generator to run. I don't know I the installer was/is able to do any more testing. so, it was left with waiting for a storm, to see if things worked correctly - we knew the generator would work, if there was no battery power.

Well, it didn't. The installer will come out next week, and work with SolarEdge to troubleshoot the issue. I've been asking them if there is some way to simulate the grid outage, without shutting down everything.

I do know that there is a switch on the outside of the BUI that does a rapid shutdown of everything, just like there is one outside the house, by the meter for fire department access.

darkskies said:

the BUI and generator integration would work "with required firmware upgrade".

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Oh crap

These smart devices, they do what they want, but it's never exactly what you want

darkskies said:

there is one outside the house, by the meter for fire department access.

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That's the one you'd use to disconnect the house from the grid and simulate a blackout.

peufeu said:

Oh crap

These smart devices, they do what they want, but it's never exactly what you want


That's the one you'd use to disconnect the house from the grid and simulate a blackout.

Click to expand...

I though that the switch on the outside was part of the rapid shutdown - killing everything, much the same as what the switch on the BUI does?

I'll ask the installer when he comes this week...

I have the same (or very similar) equipment as other posters in this thread - SolarEdge inverter, 10kwH LG battery, etc — and recently bought a generator hoping to connect it to the same critical loads panel that the LG battery powers as my primary backup source when the grid goes down. My generator is just an inexpensive Costco Champion brand generator, so I don’t have any dreams of auto-failover. But this thread scares me with the tales of poor manufacturer support for what I’d consider basic (and promised) functionality. I don’t want to risk damage to the inverter or battery by running the generator. If I am willing to come out and manually flip a transfer switch, and then manually start the generator, shouldn’t I be able to do that without risking any of the solar equipment or grid? I assume I’d just put in the transfer switch disconnect between the inverter and the critical loads panel.

So, my use case would be: The grid goes down and the SolarEdge inverter automatically switches to LG battery backup until the battery reaches its low-level cutoff. Then the house goes dark and I go out and flip the transfer switch, flip on the generator, and go back to bed. Is there any reason that can’t work?

I'm assuming you have the SolarEdge BackUpInterface (BUI) of which the battery and inverter are connected? The Solar Edge App Note for Generator Integration shows several scenarios, where the generator is connected between the panel and the BUI and uses a manual (for manually started generators) or automatic (for auto start generators) transfer switch.

From what it shows, it SHOULD run on solar/battery and then allow you to switch to generator (assuming you have it configured and have the latest software).

In my case, the generator is directly connected to the BUI, which is supposed to act as an automatic transfer switch. The benefit there, is supposed to be that, when the battery level gets to a configured level, the generator would turn on and power the main panel AND recharge the battery.

My system is configured this way (finally), but the installer could not test with the battery and simulate a grid outage. When the battery was swapped out (another long story), the installer told me it was all good to go. I wasn't sure how to simulate an outage, so I had no way to verify.

In the last outage 2.5 weeks ago, it switched right to generator, and did not use the battery, which was sitting at 100%.

I've been hounding the installer since, several times a week, to come out and troubleshoot the issue with SolarEdge (of which I opened a case). It sounds like the BUI cover can be removed and then internally disconnect (switch?) from the grid to test battery failover. When the installer gets here, I want to see how that is done and have them verify grid to battery failover, battery + solar operation with no grid, generator switchover when battery hits 20%, and generator charging of battery.

I'm not holding my breath - the installer takes FORVER to get out here.

I think I do have the BUI, but from this thread it sounds very iffy that the SolarEdge firmware would work properly anyway. So I’m thinking an old-fashioned manual transfer switch is less money and less hassle. I admit having the generator charge the LG battery would be a great benefit if it worked…but that’s a big if. Also, my generator is not a pure sine wave generator so I’m not sure what the power it puts out may do to the apparently sensitive inverter/battery eldctronics.

As I understand it, without the BUI, when the grid goes down, it will stop generating power from PV AND the battery. The BUI disconnects from the grid. The big question (in my case) is whether or not the firmware will connect battery to main panel, when there is no grid power. Right now, it flips directly to generator.

Previously, I (temporarily) had grid, battery, and PV connected to the backup interface, which supplied the main panel. Off the main panel, was a sub-panel with critical circuits and an ATS. When the grid went out, the ATS would trip and generator would power the critical circuits. That, unfortunately, was not using battery, when the grid was out.

I waiting to find out i the final solution will work in my setup.

Update on my site...

About three weeks ago, we had a grid outage, and with a fully charged battery, the system instead of running off battery, went right to generator.

I opened a case with SolarEdge and contacted my installer. After a few days, SolarEdge responded and told me to have the installer come out, and in the interim, they were updating the firmware of inverter 4.19.36->4.20.32 (two revs newer). The release notes for 4.19.36 had indicated "seamless transition to backup", which is why we thought it would have worked previously, but it was not. I don't see anything in the 4.19.39 or 4.20.32 that mention anything about backup changes, but maybe it was a small change and not reported.

Today, the installer showed up and connected to the inverter. SetApp initiated another update, which updated the firmware to 4.20.36 (one rev newer). Again, I don't see anything in the release notes, about backup related changes. In any case, this is what we saw...

There is a pull switch on the BackUp Interface that disconnects from the grid. We had a mostly cloudy day, 42% charge on our 16 kWh battery, and the house load was close to 1kW.

Upon disconnect, there was about a 2-3 second delay and it switched to battery AND PV. As the cloud cover was fluctuating, it would switch from powering the house from PV to battery to both. Looked good, and the battery was actually slowly charging.

To simulate the battery hitting the low charge limit, the installer changed the configuration so that the limit was a few percent below current charge. We then flushed toilets (well for water), ran microwave oven, turned on table saw, drill press, grinder, and a few other tools to start drawing down the battery. PV was bouncing between 500W and 2.5kW, so we were trying to draw more.

Eventually, it hit the limit and switched over to generator (I can't recall how fast, but seemed quicker than from grid to PV/Battery). Again, seemed to work well. The only issue was that, looking at the monitoring app on my phone it only showed how much PV was producing and that it all was going to battery. There was no indication of the house consumption, like I'd see if on grid, PV, and/or battery.

We were not able to test the system, when running on generator, switching back to battery at some point, once the battery is charged back up. It was late in the afternoon, and with the mostly cloudy sky, it would be hours before PV could recharge the battery, if at all today.

Grid was then turned on. It takes like five minutes to switch back to grid. Installer said that it monitors/tests grid power and PV, before switching to grid + PV.

Before leaving the installer set the configuration to switch from battery to generator, when battery is at 10% (factory min is 6%).

I reported back to SolarEdge, as to what happened and mentioned these comments/questions:

1. There is no reporting of consumption, when running on generator and that I expected that it would, since generator is tied into the BUI.
2. The generator powered the house, but was not recharging the battery, which their documentation indicates that it is supposed to do that.
3. I asked them what the charge level of battery would have to get to, in order to switch from generator, back to battery. It didn't seem to be programmable from SetApp, according to the installer.

So, 95% of what we expected to see was working. It was switching to battery on grid fail, and then to generator. The battery was getting recharged by PV. The big item is #2, whereas #3 is minor (assuming it switches back), and #1 is a nice thing to have, but not required.

Congrats! Glad it's finally working. Sad that it took nearly a year and a half.

400bird said:

Congrats! Glad it's finally working. Sad that it took nearly a year and a half.

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Actually almost 3 years since initial install (7/2021)!

Hopefully they will continue to improve the firmware to report consumption during generator backup, and can configure generator to charge battery as well as power house.