List of AC RETROFIT capable inverters

[fafrd]

You should further divide "ac retrofit" between CT only, or cut into the meter line. With the latter, if you have to cut the line (like victron), you might as well put the AIO there (and not move the ac pv).

I believe ‘retrofit’ by definition means no change to the primary power distribution circuit.

If you are having to cut into the main grid feed wires, that’s a showstopper (much more expensive, involved install).

If adding the battery-backup inverter is no more involved than adding an L2 EVSE, that qualifies as a ‘retrofit’ install…

CT sensors or external energy meter only - no cutting into the meter line.

Your original cite of the sol-ark manual does NOT say it cannot "ac retrofit". It says the ac pv on the grid side is independent of the Sol-ark, and the sol-ark doesn’t control it.

In the ac pv sol-ark document I posted that you dismissed, it discusses ac pv on the grid side. Put a ct between the meter and first connection, turn off grid charge, set limit to home, and then you can use the Limiter function to charge the battery from excess ac pv.

That sounds as though Solark supports retrofit installations.

Retrofit cannot ‘control’ grid-tied PV on the AC-input side.

Retrofit can ‘control’ export-to-grid from grid-tied PV on the AC Input side, at least as long as the battery has empty capacity to absorb all excess energy that would otherwise export to grid.

I can't test it, but neither have you tested any of your "documented" options.

 

[fafrd]

I like your earlier definition of :"charging a battery from AC export power (‘adaptive charging’)."
an off grid inverter that offered that would be cool but I doubt it since they don't usually have CTs

I have been waiting for inverters with adaptive charging to absorb excess grid-tied energy before it exports to grid for almost 3 years now…

F

Thread 'New class of zero-export AC-coupled battery inverter (Huayu)'

Nov 20, 2021

I just stumbled onto this, and as far as I know, it is the first example of the new product class I have been pineing-for / predicting: https://m.huayu-solar.com/Content/uploads/2021694206/PDF/AC-Coupled-Quick-Installation-Guide.pdf

This AC-Coupled battery inverter being introduced by Huayu, the HYH-3K/3.6K/5K-AC, supports 2 CT sensors, one for incoming grid energy (grid load) and a second for incoming PV generation.

This should allow it to be programmed for zero-export by charging the battery with all excess PV generation beyond that needed to serve loads (so Pcharger = Psolar -...

• fafrd
• Replies: 21
• Forum: General Battery Discussion

 

[DIYrich]

what do you mean by "cut into the line"?

If you have to put something in-line with the grid, like a shunt. In reviewing the victron energy meter, it uses CT, and you don't have to cut into the line. From the diagram, it looks like it is inserted into the line.

it also says that in a grid side coupling scenario that all the power of the gt inverter is pushed to loads and the grid. I would be happy if it works but no one has tested it.

Sound like generic definition to me. It is technically correct. Ac pv pushes to the grid line, and Sol-ark takes from the grid line.

Additional hardware (install the supplied ct's in the proper place), and inverter settings are required to measure and store the excess. That may also interfere with other modes, other people may care about (charging from grid).

 

[1201]

I have been waiting for inverters with adaptive charging to absorb excess grid-tied energy before it exports to grid for almost 3 years now…

F

Thread 'New class of zero-export AC-coupled battery inverter (Huayu)'

Nov 20, 2021

I just stumbled onto this, and as far as I know, it is the first example of the new product class I have been pineing-for / predicting: https://m.huayu-solar.com/Content/uploads/2021694206/PDF/AC-Coupled-Quick-Installation-Guide.pdf

This AC-Coupled battery inverter being introduced by Huayu, the HYH-3K/3.6K/5K-AC, supports 2 CT sensors, one for incoming grid energy (grid load) and a second for incoming PV generation.

This should allow it to be programmed for zero-export by charging the battery with all excess PV generation beyond that needed to serve loads (so Pcharger = Psolar -...

• fafrd
• Replies: 21
• Forum: General Battery Discussion

That's very interesting. I think the solution is only now really starting to come into it's own as millions of existing grid tie systems start looking to add batteries due to the slow phase out of net metering

 

[1201]

If you have to put something in-line with the grid, like a shunt. In reviewing the victron energy meter, it uses CT, and you don't have to cut into the line. From the diagram, it looks like it is inserted into the line.

I see what you mean about the confusing diagram. Yes, the meters use cts

Sound like generic definition to me. It is technically correct. Ac pv pushes to the grid line, and Sol-ark takes from the grid line.

Additional hardware (install the supplied ct's in the proper place), and inverter settings are required to measure and store the excess. That may also interfere with other modes, other people may care about (charging from grid).

Well we can only hope @Lt.Dan tests it for us

 

[DIYrich]

Upon further thought, Tesla's Powerwall 3 along with their Meter Collar (if approved by your utility), can fit your definition of "AC Retrofit".

Pull the meter. Put the collar on. Replace the meter. Hook everything up to the Collar. Best of all worlds. Doesn't disturb existing wiring (think of it more like a Meter upgrade). AC PV will work even if the grid is down (assuming the AC PV is UL1741SA). Even works with the integrated meter/panels.

 

[zanydroid]

Upon further thought, Tesla's Powerwall 3 along with their Meter Collar (if approved by your utility), can fit your definition of "AC Retrofit".

Pull the meter. Put the collar on. Replace the meter. Hook everything up to the Collar. Best of all worlds. Doesn't disturb existing wiring (think of it more like a Meter upgrade). AC PV will work even if the grid is down (assuming the AC PV is UL1741SA). Even works with the integrated meter/panels.

Yep.

So would Enphase 5P with Enphase meter collar, depending on whether retrofit is obligated to be cross-vendor.

 

[Lawrence_SoCal]

Retrofit cannot ‘control’ grid-tied PV on the AC-input side.

Are you sure about that? I'm thinking about PW3s and being able to use PowerLine communication with Enphase MIs to curtail PV output...
so maybe not all AC coupled/grid-tied PV systems, but if AC input is Enphase (for example) and using compatible battery/inverter system which is configured to communicate directly with the micro-inverters, then that 'disproves' your assertion [depending on what you mean by 'control']

I'm one of those with an existing SPWR/enphase IQ7HS system, and a 45 year old Arrow Hart flush-mount exterior 100/125A combo meter/load center So this conversation is very relevant to me.

 

[1201]

Upon further thought, Tesla's Powerwall 3 along with their Meter Collar (if approved by your utility), can fit your definition of "AC Retrofit".

Pull the meter. Put the collar on. Replace the meter. Hook everything up to the Collar. Best of all worlds. Doesn't disturb existing wiring (think of it more like a Meter upgrade). AC PV will work even if the grid is down (assuming the AC PV is UL1741SA). Even works with the integrated meter/panels.

Maybe. There are at least two conditions an inverter has to meet to be capable of "ac retrofit"

1.can it adaptively use the excess output of an already existing,in place ,grid tie inverter to charge its battery?

2.can it discharge from battery into the main , grid connected, panel to reduce or eliminate draw from the grid?

 

[zanydroid]

Maybe. There are at least two conditions an inverter has to meet to be capable of "ac retrofit"

1.can it adaptively use the excess output of an already existing,in place ,grid tie inverter to charge its battery?

2.can it discharge from battery into the main , grid connected, panel to reduce or eliminate draw from the grid?

If the older PowerWall version that are AC couple only (no MPPTs) couldn’t do that, Tesla would have sold very few of them.

The Collars are a streamlined version of the larger Gateway / MIDs, that do not require rewiring of a main panel to add CTs and support whole house backup. They include CTs, islanding relay, and control logic to do the needful.

So long as POCO approves the collar on their side of the system.

 

[Balderdashian]

The sbs is a battery inverter only meaning it doesn't have it's own pv. Ie not turnkey. It interfaces with existing pv and i don't see where it's required to be a sunny boy. The meter doesn't know or care what grid tie inverter is producing power.

The diagrams in the paper show a "Sunny Boy US", but if the battery unit can work with the meter without it then you're right this should be on the list.

 

[Balderdashian]

You should further divide "ac retrofit" between CT only, or cut into the meter line. With the latter, if you have to cut the line (like victron), you might as well put the AIO there (and not move the ac pv).

You don't have to cut into the line with Victron. The energy meter uses CT sensors and then communicates to the GX over a data cable.

 

[1201]

If the older PowerWall version that are AC couple only (no MPPTs) couldn’t do that, Tesla would have sold very few of them.

You're right. The powerwall 2(maybe other powerwalls too) had cts for grid draw and cts for external solar production and would charge from solar. Pretty cool. I'll add it to the list.

 

[Balderdashian]

Yep.

So would Enphase 5P with Enphase meter collar, depending on whether retrofit is obligated to be cross-vendor.

This is a good question. I have an Enphase Envoy with both the production and consumption CTs. If I can think of an easy way to run some errant external current through the production CT and turn off my IQ8 inverters and see if the Envoy still reports consumption and production data on the API, I think it's a safe bet that the 5P can work as an AC retrofit for non-Enphase grid-tie inverters.

 

[1201]

This is a good question. I have an Enphase Envoy with both the production and consumption CTs. If I can think of an easy way to run some errant external current through the production CT and turn off my IQ8 inverters and see if the Envoy still reports consumption and production data on the API, I think it's a safe bet that the 5P can work as an AC retrofit for non-Enphase grid-tie inverters.

The cts should record the current accurately. What the system does with the data(does it charge the battery?) is a different story

 

[Balderdashian]

The cts should record the current accurately. What the system does with the data(does it charge the battery?) is a different story

How else would the battery get charged? I mean, yes I can say with 100% certainty the 5P can be programmed to only charge from solar in an Enphase system. That would be the most absurd thing in the world if it couldn't. The question is whether or not it can do it with non-Enphase inverters.

 

[zanydroid]

This is a good question. I have an Enphase Envoy with both the production and consumption CTs. If I can think of an easy way to run some errant external current through the production CT and turn off my IQ8 inverters and see if the Envoy still reports consumption and production data on the API, I think it's a safe bet that the 5P can work as an AC retrofit for non-Enphase grid-tie inverters.

I would sort of give 25% odds that it accidentally works but is not supported.

FWIW someone probably knows on r/enphase / can give a reference for where to look. Instead of blind non-Enphase owners leading each other like often happens here.

Enphase definitely supports granular retrofit within their own ecosystem. Look at the Solar + Battery Without Backup column. By granular I mean you don't need to buy every component. 5P + IQ Combiner is enough to do self consumption (AC retrofit). And it even goes back to M-series with the appropriate add-ons and hemming/hawing

https://support.enphase.com/s/question/0D53m00009UqI1iCAF/technical-documents-for-installing-5p-batteries-without-system-controller-3

https://enphase.com/download/compatibility-matrix

Another way of thinking about it is, how does the new IQ8 gateway and 5P work with pre-IQ8 microinverters when on-grid? I think there is a janky standard-ish way to do it.

Does 5P frequency-shift IQ7s and M250 (if those are 1741SA), or is it obligated to use IQ8 PLC control of output, or does it use the older proprietary control scheme (not sure what it is).

The line of thinking here is, the pre-IQ8 Enphase microinverters are not really native to the IQ8 ecosystem anyway, so there would be hints as to how a non-Enphase product might interact.

Overall Enphase mostly cares about backwards compatibility with their own stuff (and IQ8 was such a big departure that one might argue this was a discontinuous generation and they bit the bullet on screwing their customers a bit, to allow things to advance. The Enphase forums are full of complaining from owners that were sold System Controller 2, only to be told that they can only use practically discontinued batteries with them)

 

[zanydroid]

FWIW post #1 doesn't specify "must be cross-vendor", so Enphase passes.

 

[fafrd]

That's very interesting. I think the solution is only now really starting to come into it's own as millions of existing grid tie systems start looking to add batteries due to the slow phase out of net metering

For sure. The NEM 3.0 ruling about a year ago was a major stimulus to develop and deliver this capability (cost-effectively).

 

[fafrd]

Are you sure about that? I'm thinking about PW3s and being able to use PowerLine communication with Enphase MIs to curtail PV output...

Oh, that’s different. That’s all walled-garden type of stuff. Enphase + Tesla may be one of the few cross-garden examples. That’s all proprietary and co$tly stuff…

Frequency-shift is an open standard - no license or permission needed (the only kind of solution I’d ever consider).

so maybe not all AC coupled/grid-tied PV systems, but if AC input is Enphase (for example) and using compatible battery/inverter system which is configured to communicate directly with the micro-inverters, then that 'disproves' your assertion [depending on what you mean by 'control']

I'm one of those with an existing SPWR/enphase IQ7HS system, and a 45 year old Arrow Hart flush-mount exterior 100/125A combo meter/load center So this conversation is very relevant to me.

 

[Hedges]

they support ac coupling but they dont support ac retrofit where the pv inverter is in parallel with the hybrid, on the grid side.

Hardware obviously capable, firmware maybe not.

Using CT at utility meter, SolArk can let its DC (and possibly AC) coupled PV backfeed into house wiring and supply loads elsewhere in the house, while aiming for zero import, zero export. It only has to export current to the house, never has to charge its battery with current from the house, to prevent export.

That's where firmware possibly would choose not to charge battery and suck down power from GT PV mounted elsewhere in the house (existing system.)

oh wow, the sunny boy storage does have this capability. I never knew. ill update the list. watching videos It actually looks like the SBS was designed for this specific purpose.

from the manual:
The Sunny Boy Storage uses the connected battery for the intermediate storage of excess PV energy in the SMA Flexible Storage System. For this purpose, the Sunny Boy Storage receives the feed-in and purchased energy data from the energy meter. This data is used by the Sunny Boy Storage to control the charging and discharging of the battery.

The sbs is a battery inverter only meaning it doesn't have it's own pv. Ie not turnkey. It interfaces with existing pv and i don't see where it's required to be a sunny boy. The meter doesn't know or care what grid tie inverter is producing power.

Maybe @Hedges can provide some clarification

Works with any GT PV inverter backfeeding grid. SBS just charges battery seeking to achieve zero export, and discharges seeking zero import.
That's its setting out of the box (which doesn't necessarily help people with time of use rates but might depending on PV production and loads timing.)

I've spoofed it with a wire through the CT backwards supplying a space heater, so it thought that was export.

The extra feature you get with recent model Sunny Boy having Speedwire (Ethernet) is an RJ 45 cable between SBS and SB can be used to curtail PV production, if zero export is required.

The diagrams in the paper show a "Sunny Boy US", but if the battery unit can work with the meter without it then you're right this should be on the list.

To function, needs SBS + WattNode.

If you want full backup, need ABU which contains relay and auto-transformer. (backup lite, PV only, is just an extra outlet.)
And of course some GT PV inverter, hopefully supporting frequency-watts.

SBS does work, but I've had issues with firmware when I set "Power Profiles", time of use to Force Charge or to limit import/export to different levels.

I think the latest version of firmware does work, but it doesn't permit negative numbers for import limits. That had been an undocumented feature to support Forced Export (for super-peak credits.)

With SBS now discontinued, SBSE (battery + PV) may do all the same plus DC coupled PV.

 

[Balderdashian]

I would sort of give 25% odds that it accidentally works but is not supported.

I can see in Home Assistant that the Envoy's API reports discrete CT production and consumption sensor data whether there are micros available or not. Whether or not the 5p uses this or can be configured to use this I do not know.

 

[Balderdashian]

Another way of thinking about it is, how does the new IQ8 gateway and 5P work with pre-IQ8 microinverters when on-grid? I think there is a janky standard-ish way to do it.

If you look at the compatibility matrix:

Compatibility matrix | Enphase

enphase.com

IQ7 is fully supported when the grid is up, but more interestingly the 5p supports M-series so long as you have an Envoy S Metered (which just means an Envoy with both production and consumption CTs). This strongly suggests that it will work with any inverter and can rely just on the meter data, so the 5p is an "AC retrofit" solution.

 

[zanydroid]

Yes the IQ8 communications likely is just for proprietary ramping and maybe production monitoring. Some combination of ramping plus fast response / grid forming capability on IQ8 allows a much higher AC coupling ratio than generic AC coupling (which is 1:1), but that’s for a different discussion thread.

You need CTs for either net or consumption monitoring. Need enough points to solve the algebra for net power usage and then drive the control loop.

 

[1201]

If you look at the compatibility matrix:

Compatibility matrix | Enphase

enphase.com

IQ7 is fully supported when the grid is up, but more interestingly the 5p supports M-series so long as you have an Envoy S Metered (which just means an Envoy with both production and consumption CTs). This strongly suggests that it will work with any inverter and can rely just on the meter data, so the 5p is an "AC retrofit" solution.

looked more into it and it does say its compatible with other string inverters using the Cts so I will add it to the list.