SolarEdge Daytime Solar Options during power outtage?

[DelcoMade]

Good Morning Everyone,

I recently had a system installed that provides 81% offset. We have 20 - 400W URECO FBM400MFG-BB Panels, with a SolarEdge HD wave inverter SE7600H. We were originally at 102% offset but the utility company would have had to do upgrades at my cost to allow the system. We were back and fourth with adding two batteries to back up the system in the event of a power outage but because of the cost and only 10 year warrantied batteries, we opted to not install a battery bank but were told they would be easily added (plug and play) at a later date.

Before agreeing on the system, I asked multiple times if there was an option for Daytime Solar in the event of a power outage, knowing the panels get switched off the grid to not back feed. I was told multiple times that the technology isn't there yet and that there are micro-inverters that store very little power and wouldn't be enough for anything. During the final installation, I spoke with the electrician (subcontracted) about future options. He explained that daytime solar is easily obtainable with the addition of a transfer switch and a control panel/box and explained how it would work. He also said that yes, batteries banks can easily added if the correct inverter is in place. He took the cover off the inverter to find that its just a basic inverter not equipped for a (plug and play) battery and or generator.

I asked my sales guy, why after all of our discussion about adding batteries in the future or possibly a generator, and being told that they could easily be added in the future (plug and play) that a basic inverter was added?

So finally my question, sorry for the long background lead up.

What would be needed to allow for daytime solar during a grid power outage and what else is needed to add a battery bank and or generator? Inside my invertor there appears to be a space that could accommodate some of the components included in better battery ready invertors.

Thank you in advance, I look forward to everyones input.

 

[JCSchwarb]

There are a number of ways to accomplish from simple, manual approach to complex automated. Your hybrid inverter supports up to 10 kWh battery thus it is very possible to reallocate extra PV production to your battery bank first before sending the remainder sharing back to the grid. If that is not feasible, then a separate All in one offgrid inverter can charge up your battery bank and you could switch your PV inputs. Did you need more tha 10kWh battery storage? If so, you would need another inverter, like an all in one.

Hope this helps in your planning and design phase.

Jay

 

[solar8484]

Good Morning Everyone,

I recently had a system installed that provides 81% offset. We have 20 - 400W URECO FBM400MFG-BB Panels, with a SolarEdge HD wave inverter SE7600H. We were originally at 102% offset but the utility company would have had to do upgrades at my cost to allow the system. We were back and fourth with adding two batteries to back up the system in the event of a power outage but because of the cost and only 10 year warrantied batteries, we opted to not install a battery bank but were told they would be easily added (plug and play) at a later date.

Before agreeing on the system, I asked multiple times if there was an option for Daytime Solar in the event of a power outage, knowing the panels get switched off the grid to not back feed. I was told multiple times that the technology isn't there yet and that there are micro-inverters that store very little power and wouldn't be enough for anything. During the final installation, I spoke with the electrician (subcontracted) about future options. He explained that daytime solar is easily obtainable with the addition of a transfer switch and a control panel/box and explained how it would work. He also said that yes, batteries banks can easily added if the correct inverter is in place. He took the cover off the inverter to find that its just a basic inverter not equipped for a (plug and play) battery and or generator.

I asked my sales guy, why after all of our discussion about adding batteries in the future or possibly a generator, and being told that they could easily be added in the future (plug and play) that a basic inverter was added?

So finally my question, sorry for the long background lead up.

What would be needed to allow for daytime solar during a grid power outage and what else is needed to add a battery bank and or generator? Inside my invertor there appears to be a space that could accommodate some of the components included in better battery ready invertors.

Thank you in advance, I look forward to everyones input.

There is no "plug-n-play" home battery solutions. If you want a home battery then plan for a significant to major construction project. Having said that, Tesla Powerwall is a leading home battery solution installed with SolarEdge so you want to check that out.

If you want generator, SolarEdge inverters have "Alternative Power Source" feature to support a generator as substitute for the grid. The caveat is that you must make sure you have enough loads to consume all solar power so it doesn't backfeed/damage the generator or connected electrical devices.

 

[Mike 134]

Can you provide the full model number of your inverter. Many HD models are grid tied only with ZERO ability to be used with batteries.

 

[BlueMarblePA]

I was planning on doing the same. Solaredge SE7600H with grid tie, and then later add a Hybrid SolArk 15k and bring in the solaredge as AC into the generator-input of the Solark15k. Then, you can add 48V batteries as prices come down. And you can add DC Photovoltaic, and the Solark15K can be set to limit export (zero consumption) with the CT.

 

[ncsolarelectric]

SolarEdge has a battery energy storage platform that doesn't care which inverter was installed for grid-tied. When you add a SolarEdge battery backup, they provide additional battery inverter modules and batteries. That is the way it's done. They don't have a "plug-n-play" battery option and where NEC2020 is in effect, all energy storage systems over 1kWh must be UL Listed and installed by qualified installers.
Also, a system that can operate from solar only during the day works fine if the sun is shining full, but the power doesn't go out on those days. It goes out when it's overcast and raining, or windy. On those days, if you're lucky at the peak of the day you may get 1% of what it would normally produce. So if you have an 8kW system, you might get 80W to make a cup of coffee. Without batteries, it's useless during an outage unless the weather and timing is perfect.

SolarEdge ESS

 

[peufeu]

On those days, if you're lucky at the peak of the day you may get 1% of what it would normally produce. So if you have an 8kW system, you might get 80W to make a cup of coffee. Without batteries, it's useless during an outage unless the weather and timing is perfect.

Yes, without batteries it may produce enough power to run the freezer, but not to start it, so it's useless.

 

[darkskies]

Just as a point of reference... I currently have the SolarEdge inverter with Energy hub, BackUp Interface (BUI), 16 kwh LG battery, and a 10kW Generac generator. With the SolarEdge docs, it shows the generator, grid, inverter, and house load connected to the BUI. I was told by my installer, back in July 2021 (and they said this is what SolarEdge claims), that on grid outage, the system will run off battery, and when the battery gets low, the generator would kick in and would recharge the battery.

Of course at the time, I didn't have the battery yet, but after install, we found out that SolarEdge said the inverter would support a generator "with required firmware update". What the installer and I didn't realize was that they didn't have the "required firmware update" yet! As a result, I've been running with a temp sub-panel and ATS connected to the generator, as a work-around, essentially giving me critical load only backup, and no battery on grid power-fail.

Well, the firmware is finally available (July 2022, a year later), and I'm STILL waiting to get my installer out to update the firmware and re-wire things. They should be here next week or week after, as the current job they are on will likely have to pause due to weather.

I've got my fingers crossed as to having this working as described. I say that as the release notes for the firmware only show the generator connected to a third party ATS, implying that it would come on, once both grid failure, and battery getting low, and would not recharge the battery. It also implies the generator needs to be large enough to power the whole house. Maybe the release note is just showing another way to connect it, or maybe SolarEdge has change the planned functionality of the BUI. I'm hoping for the former, or I'm going to be even more angry with SolarEdge.

It's been a frustrating journey so far with trying to get a generator and battery integrated in (my old house had just PV and manual transfer with generator, and was fine).

I can update once (if?) this gets working, as a solution.

 

[400bird]

I can update once (if?) this gets working, as a solution.

Please report back results either way.
Good luck

 

[darkskies]

Please report back results either way.
Good luck

Will do either way. I'm trying to be optimistic in hoping that it will be "once" vs "if".

 

[Calsun]

The dealer should have selected an inverter designed to work with batteries like the Solis 5G inverters. It is all managed in the one box.

Key issue is not sending battery power to the grid and causing problems for the line workers trying to restore power. An automatic transfer switch is required by code and the question is whether this would also work to isolate backup batteries at your house.

I would never ever trust the opinion of a sales person about anything other than the price. You need an electrician familiar with solar and with standby generators and battery backup systems to do the design work.

Inverters that work with batteries are designed to manage the charging of the batteries automatically and they require specific batteries be used. Simpler to add a standby generator and the cost will be no more than for adding a battery backup system to your house. The generator can run for days or even weeks whereas a battery bank will be able to provide power for only a few days of normal use.

 

[darkskies]

Electrician finally was over here today. He got a few things done...

- Finally registered my LG battery, so I get the extended warranty.
- Gave me admin access for my site, so that I can now modify the battery reserve setting (it was at 80%, changed to 20% and turned on the weather guard feature).
- Updated the firmware for generator support.

He mentioned that it indicates that there is a generator interface, but does not appear to be working as expected (I didn't get to talk to him much about that).

It appears that the BackUp Interface still is not doing what it was advertised to do...namely act as the central point for switching between solar/battery, generator, and grid. The release notes for this firmware show the BUI connected to a third party ATS and generator, instead of the generator connected directly to the BUI.

The big question is whether SolarEdge is putting out the firmware as a stepping stone for the BUI to work with a third party ATS and generator now, and later updating to what the original design is supposed to be, or if they are throwing up their hands and treating this as the final solution. I asked the electrican for my installer to try to find out more about that, if possible from SolarEdge (whom I trust less and less each day). The installer has been livid as much as myself, being told this BUI would work for my application, only to find out the "required frimware update" is not avaiable (for over 1.5 years now).

We talked about options and there looks like two choices of which I asked them to come up with proposals, so that we can discuss, review, and make a decision.

1) Install an whole house ATS (which they have in stock now) between the BUI and main panel, for a generator, as shown in the releases notes. This is the easiest to do, gives the option for later reconfiguring, if SolarEdge ever gets the BUI working as promised. However, this configuration will not allow recharging of the battery by the generator, and requires the generator to handle the whole house load. The original design, called for a 10kW generator, with the understanding that it would be used to recharge the battery, during extended outages. I've asked them to see about the sizing of the generator in this configuration, and whether they need to install a larger generator.

2) Switching to SolArk, which this installer also sells now-a-days. This requires changes at the panels (they have SolarEdge optimizers), I think may also have the same question of generator sizing, and I think the battery I have may not be compatible (LG RESU16H Prime). The electrician mentioned that the SolArk does support selling of RECs (I guess no revenue grade meter built in, like the SolarEdge unit). I'm guessing a separate revenue grade meter may be needed there. Not a big thing, as NH doesn't give much $ for RECs. This would be a much larger change, and a real concern about the battery.

I'll see what they come back with, but I suspect it'll take them a bunch of time. Will post, once I hear more.

 

[SolarGoat]

I have a lot of experience with these types of set ups. Unfortunately SolarEdge won’t let you but the Energy Hub inverter is backup mode until it’s passes the “battery self test”. So in short as of now you have to have a battery to do back up. (Software not hardware) SolarEdge has a transfer switch called the Back Up Interface (BUI). That transfer switch, with an energy hub inverter and a solaredge battery or lg battery is a great setup.

 

[darkskies]

That's what I have, and Energy Hub Inverter, Back Up Interface, Generac generator, and LG battery.

The issue I have, is that I cannot connect the generator to the backup interface (yet) it seems. We were told from SolarEdge (back in 7/2021), that a firmware update was needed for the BUI/Inverter to work with the generator. That firmware was available last July (7/2022), but the release notes do NOT show the generator connected to the BUI, but instead, connected to a third party ATS, which is not what we were told as to how this should work. The generator was supposed to be connected to the BUI and supposedly, when grid fails, the house is powered from battery, and then when that is depleted, by generator, which would recharge the battery as well.
'
The SolarEdge data sheet shows the following (very little detail), and their other documentation talks about the BUI being used to support a "whole house" load:

Here is what the release note that just came out, shows as a configuration:


As a workaround, and because the installer couldn't get a hold of a whole house ATS at the time (12/2021), they installed a subpanel with ATS, connected critical circuits to that panel, and connected the generator, so we have generator backup for only part of the house.

I'm trying to get them to propose how to get to the original design goals, with either a replacement with SolArk (I doubt they will do that, given battery used and cost), or applying the solution mentioned in the release note and hope that SolarEdge later gets the desired solution mentioned in the datasheet and brochures working, and we can then remove the ATS.

I hope I am describing the issue correctly - not really experienced with Solar, other than this is my second house using it, and I try to understand the configuration the best I can.

 

[peufeu]

Quick look at "Energy hub" with "Prism technology" manual: it seems to be the usual hybrid inverter, with one AC port that does both grid-tied and backup. It talks about an external relay to connect Neutral to Earth in backup mode, which is normal and expected, that must be in the BUI.

These inverters contain only one physical inverter circuit:

- In grid-tied mode, the relay connects the inverter "output" to the grid,
- In blackout/backup mode the relay connects the output to the backup loads and also connects neutral to ground so your RCD works and you don't get zapped. In this case the inverter and backup loads are disconnected from the grid, so when the grid is restored it takes a little while to resynchronize and reconnect.

I put quotes around "output" because it's a bidirectional inverter that can also charge the batteries from the grid, so it's really an AC input/output port.

Here's a Victron for comparison, my Solis S5 is similar, the difference is the backup/grid relay is inside the inverter so it has two ports (grid/backup); Yours has an external relay in the BUI. It's the same stuff, in two boxes instead of one. Well the Victron has 2 AC outputs, but that's not important.



This inverter can work in two modes, grid tied and backup.

In backup mode it just outputs AC voltage which is rather simple to do. It behaves as an AC voltage source.

In grid tied mode, it's more subtle: its output is connected to mains voltage, and it can both consume power and inject power into the grid. This is done by letting the grid set the instantaneous voltage and adjusting the inverter AC output current in real time. Since the grid has very low impedance and is able to supply or sink a lot of power, the inverter has no choice really, it can't set the voltage on the grid, instantaneous grid voltage is whatever the grid says it is. All the inverter can do is push some current into the grid or pull some current from it. If current has the same polarity as voltage then it draws power to charge the battery, with opposite polarity it injects power into the grid

OK but where's the problem? The grid has a very low impedance, but this isn't the case with a generator, and a generator isn't designed to absorb power. So when the solar inverter is tied to the grid, it's not really a problem if it draws or injects too much power: the grid will source or sink it.

For example my Solis uses a smartmeter for export management. It reads the smartmeter every second, and then adjusts its output power to compensate for whatever power the house is using. So, when a 2kW load like the water heater switches off, it takes about 2-3 seconds for the inverter to adjust its output power, but until that happens , it still produces the power that this load used to consume, and this power goes into the grid. So when the water heater switches off, I get a spike in export power, about 2kW high and 2-3 seconds long.

That's not a problem for the grid, but for a generator it would definitely be a problem, because it can't absorb power, so voltage would rise until either the inverter detects an overvoltage fault and disconnects, or something blows, most likely the generator.

My point is, what you want to do requires a bit different hardware than what the typical hybrid inverter has. It needs to measure load current in real time (not one update per second from a modbus smartmeter) and adjust its output power very quickly (maybe ~100µs or the like) so when a load is switched off the inverter immediately stops outputting the power that this load used to consume in order not to overload the generator. It's not impossible to do, lots of inverters do it including Victron and many cheap Chinese ones, basically it needs a fast current sensor and possibly a few other parts, but it has to be designed into the circuit right from the start because it's not possible to install a fast current sensor with a firmware update. It could probably work with a current clamp, but definitely not with a smartmeter that updates every second.

So basically for this gear to do what they said it would do, which is use battery and generator at the same time in a smooth and user-friendly way like you (the customer) expect it to work, run your generator efficiently to power the load and charge the battery so you don't have to waste gas running the generator for small loads..... it needs to know the house load current in real time. Maybe 10-100kHz bandwidth. Then, because it knows its own output current (it has to measure it in order to work as a grid tied inverter) it can make the sum of the two to calculate generator current, then with these three items (load,generator,self) it will have all the information required to make stuff work, assist the generator in case of high load, or charge batteries if the load is low and the generator has power to spare.

The Victron above has one grid/generator port and load ports, so it can measure all the currents internally. However, yours is split in two boxes, and in the manual, I don't see how that will be done, and worse, the cable from the inverter to the BUI only has RS485 and 12V... If the RS485 is just to transmit orders like "turn on relay" then how is the required information about current being transmitted? Unless maybe they run it at several Mbps, who knows. The inverter has a connector for a current clamp, but it normally goes on the grid, so in a blackout it will be useless and it would need another one anyway to measure house power.

My take on this:

- Marketing sold the feature, then told Engineering to do it
- Engineering replied "well duh you should have said so before because we're gonna need to add a bit of hardware for this"
- Oh crap we've already sold thousands of these, can we do it with just a firmware update?
- No.

Anyway:

How many relays in your BUI? Can you post a pic of what's inside if it's visible when you open the cover to wire it?
In the previous post, the first schematic shows the BUI has 4 AC ports (grid, home, generator, inverter), the second one shows 3 AC ports (grid, inverter, ATS). How many ports does the BUI actually have?

Note your inverter also has DC inputs, so it should be possible to feed generator power via the PV string inputs with a little bit of hacking. This may carry a "slight" risk of blowing it up though, along with lethal voltages on the generator if its neutral is tied to chassis.

 

[darkskies]

Great information, some over my head, but I'm trying to learn and I think I understand what you are saying about the issue with generator connection. From what I've read, the BUI supports up to three inverters, each with up to two batteries. The install manual for the BUI has this info:

Backup Interface (optional) - controls disconnection of house loads from the grid and integrates the following components to enable grid-tied solar backup and Smart Energy Management:

• Energy Meter - is used by the inverter for export, import, production and consumption readings, and for Smart Energy Management applications, such as: export limitation, time-of-use profile programming and maximizing self-consumption.
• Auto-transformer - handles the phase load balancing.
• 200A microgrid interconnection device - disconnects the house loads from the grid in case of a power outage.
• Generator hardware support - supports connection for up to 15kW alternative power supply. Generator connection requires supporting inverter firmware.

I wish they had a functional/block diagram so that I could better understand how the BUI works.

Clearly SolarEdge marketing was pushing something that was not completed yet (as attested by my installed using this for my home in 7/2021 and SolarEdge still doesn't have it all worked out).

Both myself and my installer (I'm one of two customers with this setup) are furious about this business practice. As an owner, I'm trying to work with my installer on how to make the best of this situation and meet my design requirements (solar revenue to offset electrical costs, whole house generation on grid-fail, and reduction in propane use of generator through battery consumption).

 

[peufeu]

my design requirements (solar revenue to offset electrical costs, whole house generation on grid-fail, and reduction in propane use of generator through battery consumption).

Yes these are pretty common sense requirements, I mean that's how it should work...

This manual you linked looks like it was written by several people with different opinions about the topic lol. There's an illustration of the BUI which has a port for the conduit to the generator, then no other mention anywhere of where the wires from said generator should be connected inside the BUI. It's weird.

The plot thickens with this appnote: at the end it shows all the possible ways of connecting a generator, some of which sound like they'd do what you want, but the descriptions are so remarkably opaque I have no idea what it's supposed to mean...

It looks like SolarEdge sells a gizmo that might fix the problem. Disclaimer: I have no idea if it'll work or be compatible with your stuff.

Anyway. In the previous post I tried to explain this stuff without getting too technical, I think you got it.

I'm trying to reverse-engineer what can or cannot be done with firmware updates to try to understand if Solaredge was lying (or clueless), and figure out what you can or can't do with what you have.

But I forgot something. I was too focused about doing it like Victron where the solar inverter can assist the generator, ie power consumed by the load can be shared between the generator and the inverter. In this case the inverter is outputting power into a circuit with both load and generator, so it has to be extra careful that all this power goes to the load and not into the generator, which requires the extra hardware I wrote about.

That's nice, but it's not what you need, I mean you got a 10kW generator, it doesn't need any help. So, if the inverter could be persuaded to never output any power when the generator is connected, this extra hardware requirement would disappear. All the inverter needs in order to do that is to know its own output current, voltage and power in real time, which it already does. And the firmware needs to know it's connected to a generator and not the grid, so it will not use the (mandated by law) grid quality measurements it would normally use, which wouldn't work with a generator.

So what is possible with a firmware update (no new hardware) would be a system with two modes...
- Generator is connected or disconnected with ATS, relay, whatever. This determines the working modes:
- When generator is disconnected, solar inverter powers the whole house. Generator cannot assist.
- When generator is connected and running, it powers both the house and the inverter. The inverter does not output any power, it only consumes power to charge its battery, it cannot assist the generator.

This is not perfect, it has several missing features, but it is much better than your current situation where the generator can't charge the inverter's batteries at all. It can optimize gas use. And it guarantees the inverter will not output power into the generator, because the inverter doesn't output power at all. Kinda brute force solution, but... well.

Extra feature #1: The inverter still does not output any power (keeps the generator safe) but it can vary battery charging power/current instead or just going with the preset value.

If the inverter can measure generator output power, either directly or by measuring house load power and adding its own input power, then it can reduce power used to charge its battery if the house load gets near the generator's maximum, or maybe to keep the generator at its maximum efficiency point.

If the generator's overcurrent protection breaker is slow, or if you just intend to keep it at its maximum efficiency point which is below its maximum output power, creating a "safety buffer", then the inverter can adjust its power slowly and it will still work, so this feature can be implemented with a slow modbus smartmeter, which means it can be done with a firmware update and either reusing the smartmeter you already have or putting in a new one.

If the inverter has to react very quickly in order to not trip the generator's protection then we're back to requiring fast current sensors which can't be installed with a firmware update.

Extra feature #2: power assist a la Victron: not possible without extra hardware in the inverter. Unless you have a constant load that is always on, then the inverter could inject power to compensate for that without running the risk of injecting power into the generator, but that won't happen in a house.

Anyway. So it's probably possible to do a reasonable proportion of what you wanted with the hardware you have, with the few restrictions I just mentioned. If it requires some hardware like maybe an extra smartmeter, honestly Solaredge should just give it to you for free.

I think you should show these posts to the installer.

But it should work......... insert ominous music..... if the firmware wants to let you do it of course! lol, these devices tend to do what they want, not what you want, it's a bit of a trend... which means you and the installer are going to need help from Solaredge. I mean really, the documentation I linked above is hot garbage, unusable, someone needs to fix that. This means Solaredge will need some motivation. Since you're not the only guy with this problem, I mean nationwide or worldwide, and they sold a feature that doesn't exist, someone in their offices is probably clenching hard at this moment thinking about class action lawsuits. And really, a solution that solves your problem would also solve theirs, so perhaps they can spare a few hours of engineers' time to answer your questions...

 

[darkskies]

Thanks for the detailed and informative post!

That app note you mentioned, is what was posted when the firmware update was available and after reading it, caused me concern. It seems to be advocating only having the Generator work with a third party ATS and not tying into the BUI. Through the tiny window on the BUI, I can see there is a generator connection possible (along with inverter connections).

It makes me wonder (optimistically) whether they've made some changes to support a generator, in an interim measure, and will later support the "final" solution that SolarEdge has been advocating since day one.

I'm wondering if (maybe hoping) they have all the needed hardware, but have not completed implementation of the firmware to control said hardware. From my experience with software development in embedded systems, that's a very optimistic proposition. It always seems that one finds hardware mods needed, once things are implemented.

Interesting link on the Site Power Controller. Looks like something for an industrial market. I wonder if that works with this residental solution, or if the BUI is supposed to provide some of that functionality.

The BUI is really a black box to me. I wish I had a better understanding of what it has and can do. The installer mentioned that it has a bunch of meters built in and that the BUI is what reports production for REC purposes.

There still is so much I've got to learn about this.

 

[peufeu]

I might be ranting a little bit, but the state of solar hardware is kinda hilarious. The documentation linked above is so bad I have no idea what the BUI is supposed to do, it sounds like you have to open it and look inside to know how it's supposed to work. If your installer is as interested as you are in solving the problem, perhaps you can open it together and investigate (I guess he has the magic fingers that don't void warranty).

It shouldn't take years to make a firmware update for something like this...

 

[Bradeyboy]

Hey Darkskies,
They came out with another application note 3.0 dated April 23 and now shows direct connection and talks about latest firmware and how it is supposed to behave. Still minimal on technical details like connections and programming, especially for different generators. Originally they promised a list of compatible generators and we have not seen that yet. Fingers crossed things will start coming out now.