What I'm learning about DIY Enphase and Hoymiles Microinverters

[svetz]

I don't know that it's good to mix the Hoymiles into an IQ8 array. As the IQ8s will supply the phase they should output power just fine. But getting power is only one part of it. While connected to the grid I wouldn't expect any problems.

But, there might be some issues to think about while off-grid.

I suspect you're thinking as many do, that the IQ8s are throttling via frequency shifting. It's true they support UL1741 and the power company can throttle them that way. If the Envoy controlled the IQ8s via frequency shifting, you'd be correct that mixing the two would be fine.

But, I suspect if you check the frequency you'll see it's not shifted when they're throttled under Envoy control. Off-grid with my IQ7s throttled back, I still see a frequency of 60 Hz, so suspect they are controlled via powerline rather than frequency shifting. This makes sense as the throttling needs to occur very fast to control surges, far faster than a couple of cycles.

I can see where you might be able to engineer around this. I believe the Envoy figures out how to throttle down based on voltage and the CT readings, so even though the Hoymiles are at full power the IQ8s may still throttle down accordingly. If your Hoymiles add-on is engineered such that it never exceeds the minimum power consumption then no worries about that. Similarly, if the IQ8s throttle down to zero then the Hoymiles should flip off via UL 1741. So that seems okay too. Can't wait to see what you find.

Which leaves the surge issue. This is a big unknown for me and may or may not even be an issue. I don't expect this to be a big puff of smoke, it'll more likely be a silent and slow killer of all the electronics (but it would only be a problem off-grid, which probably isn't that often). Surges occur when devices (like your air conditioning) turn off. The power input needs to throttle back instantly and the surge needs to be absorbed. Off-grid inverters and generators are all designed to handle the surge for the power that they can generate (as they aren't designed to operate in tandem with other power sources there's no need to handle anything bigger). That is a 5 kW generator can handle 5 kW of energy switching. Not an EE, so hopefully did some justice to the explanation.

The reason why there are maximum limits to the number of IQ7s an IQ8 battery can handle is the IQ8s handle what they can produce, plus a little more to accommodate about 1.4 IQ7s. The IQ8s should therefore be able to handle so many watts of energy from the surge potential created by the Hoymiles. So, again possible with some careful engineering.

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What's with all those screws on the bottom? The unit is outside in the weather... it should be super water-tight. Not crazy about the LED either. I'd pot around the edges, led, and all the screws.

Update: Just occurred to me you might be planning to do solar shedding (e.g., relay to turn off the Hoymiles while off-grid) to avoid problems or right-size the engineering.

 

[ncsolarelectric]

I don't know that it's good to mix the Hoymiles into an IQ8 array. As the IQ8s will supply the phase they should output power just fine. But getting power is only one part of it. While connected to the grid I wouldn't expect any problems.

But, there might be some issues to think about while off-grid.

I suspect you're thinking as many do, that the IQ8s are throttling via frequency shifting. It's true they support UL1741 and the power company can throttle them that way. If the Envoy controlled the IQ8s via frequency shifting, you'd be correct that mixing the two would be fine.

But, I suspect if you check the frequency you'll see it's not shifted when they're throttled under Envoy control. Off-grid with my IQ7s throttled back, I still see a frequency of 60 Hz, so suspect they are controlled via powerline rather than frequency shifting. This makes sense as the throttling needs to occur very fast to control surges, far faster than a couple of cycles.

I can see where you might be able to engineer around this. I believe the Envoy figures out how to throttle down based on voltage and the CT readings, so even though the Hoymiles are at full power the IQ8s may still throttle down accordingly. If your Hoymiles add-on is engineered such that it never exceeds the minimum power consumption then no worries about that. Similarly, if the IQ8s throttle down to zero then the Hoymiles should flip off via UL 1741. So that seems okay too. Can't wait to see what you find.

Which leaves the surge issue. This is a big unknown for me and may or may not even be an issue. I don't expect this to be a big puff of smoke, it'll more likely be a silent and slow killer of all the electronics (but it would only be a problem off-grid, which probably isn't that often). Surges occur when devices (like your air conditioning) turn off. The power input needs to throttle back instantly and the surge needs to be absorbed. Off-grid inverters and generators are all designed to handle the surge for the power that they can generate (as they aren't designed to operate in tandem with other power sources there's no need to handle anything bigger). That is a 5 kW generator can handle 5 kW of energy switching. Not an EE, so hopefully did some justice to the explanation.

The reason why there are maximum limits to the number of IQ7s an IQ8 battery can handle is the IQ8s handle what they can produce, plus a little more to accommodate about 1.4 IQ7s. The IQ8s should therefore be able to handle so many watts of energy from the surge potential created by the Hoymiles. So, again possible with some careful engineering.


What's with all those screws on the bottom? The unit is outside in the weather... it should be super water-tight. Not crazy about the LED either. I'd pot around the edges, led, and all the screws.

Update: Just occurred to me you might be planning to do solar shedding (e.g., relay to turn off the Hoymiles while off-grid) to avoid problems or right-size the engineering.

Until recently, Enphase had screws on the bottom too. It's potted on the inside. I think one of these labels is covering where the potting was pushed inside and air let out. It's IP67 rated.
Running off-grid with the IQ Battery, I'm not worried about the Hoymiles causing issues. The battery is there to absorb the energy, just like if the Hoymiles was a generator. It's when the IQ8's are running in Sunlight Backup mode without the battery, that's where throttling down is important but I think that once the IQ8's have throttled back to practically zero with just enough to keep the microgrid running, the HM will start pushing the microgrid voltage out of range and will shut down, then take 5 minutes to come back. That's my current hypothesis. I'm waiting for full sunlight to try it.

 

[fromport]

Which leaves the surge issue. This is a big unknown for me and may or may not even be an issue. I don't expect this to be a big puff of smoke, it'll more likely be a silent and slow killer of all the electronics (but it would only be a problem off-grid, which probably isn't that often). Surges occur when devices (like your air conditioning) turn off. The power input needs to throttle back instantly and the surge needs to be absorbed. Off-grid inverters and generators are all designed to handle the surge for the power that they can generate (as they aren't designed to operate in tandem with other power sources there's no need to handle anything bigger). That is a 5 kW generator can handle 5 kW of energy switching. Not an EE, so hopefully did some justice to the explanation.

The reason why there are maximum limits to the number of IQ7s an IQ8 battery can handle is the IQ8s handle what they can produce, plus a little more to accommodate about 1.4 IQ7s. The IQ8s should therefore be able to handle so many watts of energy from the surge potential created by the Hoymiles. So, again possible with some careful engineering.

The DSP in the IQ8 is about 1000x more powerful then the IQ7.
That is imo the reason the IQ8 is able to generate microgrid without batteries and still be able to work with surges if needed.

Also: As you pointed out, IQ[678] use PLC to communicate with the envoy and can modulate power through that.
But that is not controlled by the envoy on a cycle-to-cycle basis afaik. That is up to the IQ inverter itself, although it gets information N times per [time unit] about a general limitation of power production.
If that fails: voltage goes up too high, someone should initiate freq shift.
I suspect that will happen when IQ & Hoymiles will be combined.

 

[Ampster]

Enphase's IQ8 microinverters are hybrid inverters (e.g., work while the grid is up or down even without battery)

Yes that is one narrow definition of hybrid. I would describe it more like the SMA secure power option. It probably helps to sell IQ8s.

 

[ncsolarelectric]

The DSP in the IQ8 is about 1000x more powerful then the IQ7.
That is imo the reason the IQ8 is able to generate microgrid without batteries and still be able to work with surges if needed.

Also: As you pointed out, IQ[678] use PLC to communicate with the envoy and can modulate power through that.
But that is not controlled by the envoy on a cycle-to-cycle basis afaik. That is up to the IQ inverter itself, although it gets information N times per [time unit] about a general limitation of power production.
If that fails: voltage goes up too high, someone should initiate freq shift.
I suspect that will happen when IQ & Hoymiles will be combined.

So far, the HM-350NT is working flawlessly. It was definitely plug-n-play. I just replaced one IQ8+ with the HM-350NT on a separate branch circuit, plugged in the module and the trunk cable, and when the sun came up it worked. Normally, my Enlighten App's Live Status shows maximum 2.9kW, but since the HM is about 50 watts higher power, I expect 3.04kW, and since noon the Live Status has been at 3.0kW. The system is obviously operating above normal.

What I don't understand is why this isn't being reflected in Today's Power graph on either Enlighten or Enlighten manager. The graph tab does not match the Live Status, where it usually does. The graph shows 2.7kW where Live Status shows 3.0kW. I have the L1 line for both branches going through the CT in the IQ Combiner 4. It is definitely measuring the current when it provides the Live Status or that would say 2.7kW like the graph. So for some reason, the graph is getting data from the nine IQ8+ inverters and not directly from the actual CT? That's weird.

 

[fromport]

What I don't understand is why this isn't being reflected in Today's Power graph on either Enlighten or Enlighten manager. The graph tab does not match the Live Status, where it usually does. The graph shows 2.7kW where Live Status shows 3.0kW. I have the L1 line for both branches going through the CT in the IQ Combiner 4. It is definitely measuring the current when it provides the Live Status or that would say 2.7kW like the graph. So for some reason, the graph is getting data from the nine IQ8+ inverters and not directly from the actual CT? That's weird.

That is a setting in enlighten:

 

[svetz]

Yes that is one narrow definition of hybrid. I would describe it more like the SMA secure power option. It probably helps to sell IQ8s.

An IQ8 can switch between grid-tied and off-grid modes, the very definition of hybrid inverter. On a clear day the maximum power of an IQ8 array is close to the full power of the array, so nothing like SMA's secure power's 2 kW max. Google Enphase's sunlight backup for more.

With a battery, the maximum possible power of Enphase's Ensemble is the array plus the battery. So, there's nothing gimmicky about it that I can see. In fact, a hybrid inverter AC coupled with Enphase would be limited to the string inverter's maximum rating, so the Enphase solution seems technologically superior in some cases and at worst equivalent. At least until you get to cost, they are expensive.

 

[svetz]

...Normally...s maximum 2.9kW, but since the HM is about 50 watts higher power, I expect 3.04kW, and since noon the Live Status has been at 3.0kW....

You'd probably need to run it few days to get a good average, it's really difficult to be definitive with all the possible impacts of air mass, temperature, humidity, etc.

Any output data from the Hoymiles panel?

The graph shows 2.7kW where Live Status shows 3.0kW.

One is probably the sum of the data from the microinverters, the other is probably the report from the CT.

 

[ncsolarelectric]

You'd probably need to run it few days to get a good average, it's really difficult to be definitive with all the possible impacts of air mass, temperature, humidity, etc.

Any output data from the Hoymiles panel?


One is probably the sum of the data from the microinverters, the other is probably the report from the CT.

Today, the peak power was 26 Watts higher than the highest recorded day since the system was turned on. There was fog this morning with a hazy stratosphere all day, so it was not a peak performance day. In terms of energy produced, today was the highest production kWh since July 15th. Which was also the previous record for peak power that day. So at 26W above the previous record and not 50 as I was expecting is not comparing apples to apples due to the weather, as you mentioned, but the Hoymiles HM-350NT outperformed the IQ8+ on the first day. I'm going to leave it there for 7 days so I can get a decent comparison provided the weather holds, before releasing my full review video.

I haven't even hooked up the DTU yet. I need an installer account set up so I can provide myself with a user account and I forgot to ask in advance. Apparently, as I was told, it isn't needed unless you live in CA or PA where they want total control of the grid.

You are correct about the data and I thank @fromport for explaining that to me above. It was very helpful. Now, everything is correct and matches the meter, not the data from the IQ8s. They differ apparently due to the voltage drop from the inverters to the monitoring point because the inverter data reports higher power and voltage than the meter data.

 

[Ampster]

In fact, a hybrid inverter AC coupled with Enphase would be limited to the string inverter's maximum rating, so the Enphase solution seems technologically superior in some cases and at worst equivalent

I am a fan of Enphase but my Outback Skybox can have 5kW of DC coupled solar and 7.5kW of AC coupled micros. That is 12.5 kW from a 5kW hybrid inverter system, so I would not call the Enphase technologically superior or even equivalent.

 

[svetz]

... the Enphase solution seems technologically superior in some cases and at worst equivalent....

... Outback Skybox can have 5kW of DC coupled solar and 7.5kW of AC coupled micros. That is 12.5 kW from a 5kW hybrid inverter system, so I would not call the Enphase technologically superior or even equivalent.

Equivalent as a 5 kW IQ Battery and 7.5 kW of microinverters gives 12.5 kW, same as a Skybox.
Superior in the same way a Skybox is superior to the "hybrid" inverters that came before it and are still sold.

Regardless, the IQ8 dual mode isn't a sales gimmick as you suggested anymore than the Skybox is.

 

[ncsolarelectric]

I am a fan of Enphase but my Outback Skybox can have 5kW of DC coupled solar and 7.5kW of AC coupled micros. That is 12.5 kW from a 5kW hybrid inverter system, so I would not call the Enphase technologically superior or even equivalent.

I didn't do my research when I learned about IQ8s sunlight backup. I didn't know I could get a Sungold or MPP and do the same thing without a battery. I seriously could have saved like $8000 with one of those and had a much more powerful sunlight powered inverter.

 

[svetz]

Anything you can share about Hoymiles API? I'm particularly interested if they can be throttled via the API to eliminate the excess parts in https://diysolarforum.com/threads/adding-an-ess-to-enphase-enlighten-system.42737/post-541929

 

[fromport]

Today, the peak power was 26 Watts higher than the highest recorded day since the system was turned on.

Last week I had some interesting evidence of cloud focusing on a cloudy day with a higher peak then normal.
Normal day:

Peak is just under 15 Kw

Last week with a lot of clouds:

Over 19kW !
That is a peak 30% higher on a cloudy day then on a bright cloudless day ;-)

 

[svetz]

Last week I had some interesting evidence of cloud focusing on a cloudy day with a higher peak then normal...That is a peak 30% higher on a cloudy day then on a bright cloudless day ;-) I've seen that here too with my weather instruments ... but my microinverters clip around ~300W so never actually get bonus power from my 330W panels temporarily outputting 400W.

Yesterday hit 1285 W/m², normal is ~1000 W/m²

 

[ncsolarelectric]

Anything you can share about Hoymiles API? I'm particularly interested if they can be throttled via the API to eliminate the excess parts in https://diysolarforum.com/threads/adding-an-ess-to-enphase-enlighten-system.42737/post-541929

I'll keep you posted. As I understand it, the Export Control can throttle the output to zero-export. It requires a Chint meter and an RS485 cable to the DTU. I don't know that there is an API but I've asked for one because the Chint meter isn't UL Listed. I ordered one on eBay and it will arrive from China in mid-Aug. If there is an API, I'm hoping to get it to work with a different meter or microcontroller as well.

 

[fromport]

I've seen that here too with my weather instruments ... but my microinverters clip around ~300W so never actually get bonus power from my 330W panels temporarily outputting 400W.

Yesterday hit 1285 W/m², normal is ~1000 W/m² View attachment 103920

Unfortunately my weather station never registered the peak

I have several string inverters that are not all filled to max ratio. That is why it was able to go 30% up.
My enphase m215 inverters have 260 watt panels and max out at 225 watt each.

It is a wonderful hobby ;-)

 

[Ampster]

Equivalent as a 5 kW IQ Battery and 7.5 kW of microinverters gives 12.5 kW, same as a Skybox.

Last time I checked, batteries were measured in kWhs? Yes, equivalent in terms of output but not equivalent in terms of storage. My Skybox has a 42kWh pack and I can incrementally add more capacity at a much more economical figure, without having to add inverter capacity. I don't know where the technological superiority is that you were referring to? The Encore is just an AC coupled battery much like the Tesla Powerwall. It also scales up like the Powerwall because inverter capacity is added as you add storage capacity. It is kind of cool that they use micro modules so it is not one big inverter that could fail. It is a different system than a bidirectional inverter with a built in transfer switch and a Generator port. I love my IQ7s and now that I have them AC coupled with my Skybox and I still have room for more within the limits of my Skybox ability to AC couple. If I added enough that took me beyond my AC coupling capacity I could always have some of them go direct to my main panel and I would lose their generation capability when the grid is down.

No doubt the Ensemble and the Powerwall fill a need for many, at least based on the popularity of the Powerwall and similar AC coupled offerings like the Ensemble that have followed.

 

[Ampster]

I seriously could have saved like $8000 with one of those and had a much more powerful sunlight powered inverter.

Yes, like the Tesla Powerwall the Ensemble is more expensive but fills a niche market for those that already have Grid Tied systems.

 

[ncsolarelectric]

Yes, like the Tesla Powerwall the Encore is more expensive but fills a niche market for those that already have Grid Tied systems.

Just as there is a niche for peak shaving without battery backup. I think this is easy to do with these HM microinverters and since that is how I use my Enphase battery anyway, it would work well after I add more panels to my system.
My utility charges $0.077/kWh but only pays $0.044/kWh for what I send back. It pays for me to keep and use as much as I can, but there are times when the load is very low when nothing is on, and times when the water heaters (2), fridges (2), oven/range, and hot tub are all on at the same time. I need to keep that energy I'm sending back when the power is low, or they'll take 43% of it for free!
PS: I'm uploading the Day 1 Testing video now to my channel.

 

[ncsolarelectric]

I'll keep you posted. As I understand it, the Export Control can throttle the output to zero-export. It requires a Chint meter and an RS485 cable to the DTU. I don't know that there is an API but I've asked for one because the Chint meter isn't UL Listed. I ordered one on eBay and it will arrive from China in mid-Aug. If there is an API, I'm hoping to get it to work with a different meter or microcontroller as well.

I found out this morning that in the US we can use a CCS Wattnode Three Phase Meter (Via CT) which has UL Listing. It's pricey though, over $400 + CTs.

Attached is the Technical Note, spec, and here is a link. LMK if you know how to program this thing. I've got no experience programming devices like this for RS485 communication. I'm learning slowly.

 

[svetz]

No doubt the Encore...

AFAIK, Enphase doesn't have a product called "Encore". But perhaps it's what's coming next?

...Equivalent as a 5 kW IQ Battery...

Last time I checked, batteries were measured in kWhs?

As you well know, since you describe it in your post, the "IQ Battery" is a DC battery plus a hybrid-inverter (and other stuff) in one unit and therefore is measured in terms of both power (kW) and energy (kWh). The discussion was to point out equivalence in terms of power, not energy.

... I don't know where the technological superiority is that you were referring to? ... just an AC coupled battery ...

You've switched from an inverter/microinverter discussion claiming the IQ8's ability to generate power while off-grid was nothing more than a sales gimmick to a battery discussion?

You take umbrage at "Superior" when what the post says is "superior in some cases and at worst equivalent...." and the follow-up post clearly delineates "superior" not to your Skybox which is a very advanced design, but to older "hybrid" inverters that cannot combine power?

In short, I'm disappointed in this dishonest discourse where you're expanding and changing the conversation to "win". I'm not going to be a party to further disruption of this thread regarding that matter and suggest if you want to brag about how great the skybox is and how inferior Enphase is that you start another thread.

 

[svetz]

Attached is the Technical Note, spec, and here is a link. LMK if you know how to program this thing. I've got no experience programming devices like this for RS485 communication. I'm learning slowly.

Linking @GXMnow as he's the only one I can think of that has successfully programmed with modbus and he might be able to supply some pointers. He also has Enphase and is AC coupled so will probably be interested in your IQ8 microinverters mixed with Hoymiles microinverters.

 

[svetz]

Thanks for running that low-wattage off-grid experiment. That was super exciting and very encouraging.
I posted a comment there, but I'm suspicious that the "consuming" is correct, could be like you were seeing earlier where the output isn't truly from the CT. Possibly @fromport knows if there's a setting like he had in #81.

I'd really like to see the Hoymiles output during that test, if the Hoymiles is throttling back that's seriously big news. I've based the "it doesn't use frequency shifting" based on my digital meter's reading, but it could be my meter isn't accurate enough. Do you have a clamp meter you can measure the amps on the Hoymiles output?

 

[Ampster]

AFAIK, Enphase doesn't have a product called "Encore".

I changed my comment to read Ensemble. My apologies if I sounded like I was trashing the IQ8. I have been using IQ7s for several years and recently installed another 23 to AC couple with my hybrid. I have had good support from Enphase.

If I read the initial comment by @ncsolarelectric the IQ8 can not natively generate power without the addition of the System Controller 2? He does describe it as pricey but I do not know how much it adds to an installation? That may be the technology that you were referring to?