bobah1248

3) Moved from EmonCMS (cloud-based) to Grafana running on-premises. While EmonCMS was great for start, Grafana has way more capabilities and on-prem solution is a nice way to get rid of that monthly OPEX that was associated with the cloud-based solution. By the way, I went for 64bit OS and 64bit InfluxDB2, in order to be able to run integration jobs (stats) on larger datasets.

A few examples from the GUI:

 


Works on internet-enabled mobile phone too:

Hi guys,
did a couple of updates to my lab in the meantime:

1) There was a sale on batteries, so I've added some more Pylontech US3000C bricks to my setup. It's 56kWh now. Note that the rack on the left is still empty:
2) I was not satisfied with the plastic distribution board that I originally used. Main reason was that I needed to add some new components in and there was no free space left. Therefore, I ditched the plastic box and rewired everything in the new Eaton distribution board that is made of metal. This board has a space for 196 modules, if I recall correctly, so I hope that it will last.

Here are some schematics that I reverse engineered from Anern Victor Max 10.2kW inverter. Should be very similar to Axpert VM models. Of course, part references and connector pinouts are different. Also ADC and GPIO assignments do not match genuine Voltronic's.
The SCC board schematic is complete - PV boost circuit, voltage and current measurement, AC power supply and bus soft start circuit.
Then there's a schematic of the two power supplies on the main board - this inverter uses an auxillary 150V power supply to start from the battery.
Also a I attempted to trace the analog part of the control/DSP board. This was little bit harder as there were no printed part references on the board. But all op-amps are there, nothing important (for understanding the circuit function) should be missing. [15/Aug/2025 added the remaining "digital" part]
I think there will be some errors, so every feedback is appreciated. I can provide KiCad project files if anyone is interested.

Not exactly 175V but I can see two limits related to grid voltage in 64.xx firmwares. The first one depends on setting 03. For APL, grid is considered "lost" at 90V and recovers at 100V. For UPS it's 180V/170V.
Then there are the following limits for exporting to grid which are set depending on the country:

lower limit
upper limit
India
195.5V/200.5V
253V/248V
Germany/South America
184V/198V
264.5V/250V
These are hardcoded in the firmware and cannot be changed by any serial command. The only way to change them is to modify the firmware, which would only be possible if we had the original one for this inverter.

I'm glad I got the point across. 😄

This can be checked in simpler and less dangerous ways.
For example, measure the voltage using AC voltmeter between the L terminals of the inverter input and output (then between N terminals) - if it is about a couple of volts or lower, then the bypass relay is closed.
Another way is to switch parameter 03 ("AC input voltage range") from APL mode (90-280VAC) to UPS mode (170-280VAC), then wait until the voltage in the network drops below 170V (this happens to me on one phase every day) and look at the bypass icons, input and output voltage, you can measure with a voltmeter as in the previous case.
Any way, I checked both of them and can say - if bypass icon present on inverters display, the grid relay and load relay are closed.

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I believe the same, that is exactly how it generally works.
But there will be at least two places with limits:
first is the selected table of grid codes and their parameters, here reported via ZZ parameter.
second would be the minimum enforced by the firmware itself.
Reason: with my inverter, I can select grid code via GUI, and this changes the min voltage value. Apart from that, I can override min voltage value manually. But cannot go under 175V anyway. So, there's a secondary check.
BTW: all these checks work even if you talk to inverter via serial protocol. Once you sent command with values that are out of range it returns an error and the command is not accepted:

I am 90% sure that it is shorted for the following reasons:
the output voltage is equal to the input voltage to the inverter
the screen shows the "bypass" icon
The only difference is that the inverter pumps in as much solar energy as the household consumers need (according to its output ammeter). At the same time, the input ammeter shows fractions of an ampere, which means no export (and import, if there is enough solar energy)
In any case, forcing the relay to close is a very bad idea: it explodes IGBT transistors, burns IGBT drivers and even control transformers inside the inverter ☹️

Hmmm. What would happen if you keep grid relay forcibly closed during the drop under 175V?
Maybe if will work.
Maybe it will produce kind of "relay stuck error"
Or, maybe it will burn....and you will finally have a reason to find and buy a better inverter ;)

I agree.
When my inverters burned out, I thought a couple of times how I could implement the inverter control program myself.
But it seemed like a colossal amount of work that would take about six months.

In any case, before trying to cheat the firmware, I turned to this forum to understand what consequences could await me, in addition to understated readings and generation of undervoltage when working without a grid (according to my calculations, when setting 220V, the inverter in offline mode will produce almost 209V; and this is just the tip of the iceberg that i can see now).

I also thought that instead of constantly overvolting, I could temporarily connect resistors. This is like a kickstarter for hysteresis - inverters turn off export when the voltage is below 175V, and turn on again when the voltage is above 195V or so.
This would allow me to restore export when the voltage temporarily dropped below 175V, but then returned to 185V. And because of hysteresis, export does not resume.
Thus, I could push the inverter to resume export, fooling not the entire inverter, but only a part of it and for a very short time (connect a "patch" resistors for a few seconds)

The AC input voltage does indeed feed into many of the inverter's calculations. I certainly don't like the idea of trying to force the invrerter to do things it was not designed to do, by fudging the measurement resistors or by other means. Inverter firmware is more complex than many people imagine.

Just one note to add: the root cause of why there is no 220V on the grid during the day is that other people are drawing too much current from the grid and the power line to the utility transformer is too long and thin. This causes voltage drop due to line resistance.
The fact that ppl are using voltage stabilisers makes this even worse, as the stabiliser is just pulling even higher current from the line, in order to make a proper voltage (technically being auto-transformer with a servo).
The propper fix is:
to improve quality of the cable between you and the transformer,
or make it shorter,
or getting your own powerline from the same transformer.
...but I am sure that none of the above are manageable...

Thanks a lot - I have the same vision for AC input and output, as well as HVBUS does not affect when the AC output voltage is lower than the HVBUS

Yes, I have seen threads on this forum where this was worked out in great detail and appropriate conclusions were made.
Anyway, thank you very much for mentioning this point.

I agree with you 100%.
This is exactly what I tell my friends who complain about the energy supply company, but at the same time do not want to limit their electricity consumption to improve the situation ☹️

This has already been done - I am literally 15 meters from the grid transformer, I laid short but thick cables to the power grid, I distributed the export so as to somehow balance the voltage on the phases of the power grid. But the power of the power grid transformer does not correspond to the all-season load.
It would be better not to torture my inverters, but to wait until the grid transformer burns out and the power supply company replaces it with a more powerful one 😈😈😈

Yes, that would be the simplest, and best (IMHO) solution. One can choose to boost a car's engine to deliver nearly double the horsepower it was designed for, but then the engine just won't last. Even without modifying the engine, it would still not last very long if you continuously kept the revs on the red line - I know... did just that in my younger days with an old motorbike after drinking too much rum 🫠☠️
So, throttle back on your power export when conditions require, and your inverters will last much longer.

Input ADC yes
Output ADC yes
HVBUS ADC no
I doubt that there will be fixed voltage ratio of HVBUS to Output that is checked. IMHO, these inverters just measure the output and then loopback. Since the output voltage depends on the loads too, loopback and PWM duty cycle will be used to adjust voltage on the fly.
Shifting about 10V down should be feasible.
Most of the times, there's a relay between output of the inverter and the grid.
Inverter matches the grid frequency and phase by shifting PWM timing.
Then it matches the voltage by altering duty cycle.
Finaly, when all of this is matched, it closes the relay.
The above is nicely visible on a dual-channel scope.
For the export of active power to happen, inverter increases its output voltage a few volts above the grid voltage, while keeping the phase and frequency locked. This forces the energy to flow back to the grid.
PS: On top of that, proper hybrids have an option to change phase angle between the current and voltage, which results in injection of some amount of apparent power to the grid. Sometimes, grid operators demands this function to be available via remote control of large PV installations, as they use it for grid compensation.

Unfortunately, I've never come across the part of the firmware that deals with exporting power. And since my own older inverters don't have this capability (at least they're not designed to), I have little incentive to research it. I've had a few quick goes at finding it, with little success.

@bobah1248 I hear you... but look at it from another angle - you just want to keep the inverters from throttling down, thus keep their power elements below about 60-65 degrees C. If they are currently heating up to 70-75 degrees C during the day, then you just need to cool them down by 10-15 degrees, and the current cooling down systems (heat sinks, built-in fans, additional fans, etc. etc. should take care of the rest.
Have a look at this thread: https://powerforum.co.za/topic/29611-cooling-sunsynk-5kw/

The final chord was that these inverters have smart fans.
I bought one in early January in an online store at a very high price. Unfortunately, its delivery was delayed and I still have not received it.
In addition, it turned out that:
- the power of the ordered fan is lower than those installed in the inverters
- 3 such fans completely burned out in two inverters
Fortunately, I managed to get around the problems to some extent:
1. In one fan, the feedback "slightly burned out", due to which the fan was not able to reliably report that it was rotating (it was visible in the system as jammed with error code 01).
For it, I added a resistor in the connector so that it would help this contact reach the required levels.
This fan was installed in an inverter, where the other 2 were working.
2. From the other two fans, I managed to assemble one. Unfortunately, neither the speed control nor the feedback worked on it.
Therefore, I assembled a fan control circuit, depending on the temperature on the sensor.
At first, I wanted to assemble a circuit on an operational amplifier/comparator, which would turn the fan on or off.
But it was boring and then I decided to install an additional controller that would completely emulate the operation of the fans from the inverter's point of view. Unfortunately, my workload at work would not allow me to spend enough time on this.
And then it dawned on me - I can use a DC-DC converter, which will be controlled by NTC.
No sooner said than done, and now I have 3 of these modified DC-DCs installed in the inverter, controlling 2 native and 2 additional fans.
I made the following settings:
- smooth regulation of rotation speed (cooling flow and noise volume)
- at a temperature of 25'C, the fans have 5V, which corresponds to 20% of its speed
- at a temperature of 45'C, the fan has all 12V, which corresponds to 100%
With such settings, the inverter with such coolers is about 10'C colder than the one with the factory fan configuration.
And some photos

Hello everyone!
First of all huge thanks @BritishRacingGreen, @Coulomb and @Maxo for the circuits and the helpful guides with steps to revive inverters.
I have crawled a long way, getting bumps and bruises.
And in the middle of the way I came across this forum and forums.aeva.asn.au. After which I just ran along the beaten path.
What do you think might happen if a 6 kV power grid feeder suddenly drops to a 0.4 kV household power grid feeder?

 


You will all be right - nothing good can be expected.
I managed to restore almost everything, including the diagnostics and repair of which was not touched upon or described on this forum. But I faced the impossibility of bringing the TMS320F2809 microcontroller back to life on the control board. At first, I did not know what firmware it should have, and so I somehow managed to buy 2 new control boards. Unfortunately, before I found this forum, I successfully burned one board (the main board supplied +12V instead of +5V).
Today I managed to fully start one inverter 😆.
And as a thank you, I would like to share my experience on this forum.
But before that, I want to bring the second inverter back to life by flashing the TMS320F2809 microcontroller with the correct firmware.
@Coulomb, can you please help me with flushing firmware to TMS320F2809?
The working inverter says these firmware versions: U1 64 03, U2 38 04.
I fixed all dead chips (that powered directly from +5VDC). I have TMS320F2809 and TMS320F2808 chips as well XDS100V2 programming tool. So, I need right birary image or hex file with bootloader and main firmware. Or steps to burn those if they in separate files. Not sure if I also should lock JTAG with some password.
 EDIT: fixed measurement units - kW (kiloWatts) replaced with kV (kiloVolts), so 6 kiloVolt feeder (6000VAC) drops on 0.4kiloVolt feeder (220VAC/380VAC)

@Coulomb Thank you very much for your detailed answer.
Both inverters have:
2 independent MPPT
1 AC input
2 AC outputs (main and second wia coufigurable relay)
1 DC battery port
firmware supports parallel connection (include 3 phase mode), LiFePO4 batteries 15 and 16 cells and communication with its BMS
I attached some crazy pics of the shit I was struggling with 🤪. Hope you enjoy it 😂😂😂

Greetings to Tashkent!
First of all, original Voltronic MAX E 11K is the off-grid inverter, with just a minimal grid-interaction capabilities: https://voltronicpower.com/en-US/product/detail/axpert-max-e-twin-11kw
It can export some energy to the grid, but it's just a side-effect. Well, it is possible that your clones were altered by the manufacturer in a way that allows them some degree of export control but it will never be the same like having a purpose-designed machine.
Using a proper hybrid inverter would give you more options to adjust export parameters. Speaking of Voltronic, their hybrid line is InfiniSolar PLUS, another brand worth looking is Deye. IMHO, Deye should be able to answer some of your questions about operational voltage range for the grid export, as they have working customer support.
Anyway, the 170V minimum, when the inverter stops feeding into the grid, is dictated by so called grid standards aka grid codes. Every country is using one of these standards to manage their grids. And when comissioning an inverter, installer has to pick a proper national grid code from the configuration menu in order to be compliant. Most of the hybrid inverters have manual overrides too, but you can't go too much low anyway as firmware is imposing limits.
Examples from a hybrid inverter:


So, the proper solution to the export problem would be to find and use a hybrid inverter with a suitable manual override range

This will work, normally there is an AD converter with a voltage divider sensing the line voltage. Altering this divider you simply "decalibrate" voltage measurements. One of the side-effects will be incorrect power reporting, as the power is being calculated on the fly, via reading voltage and current. But that's not a big issue.

There is no silver bullet.
A) Cheap but complicated: Technically, all the grid-codes and limits are being stored in the inverters firmware. Just find someone who is able to decompile, analyze and patch a firmware for you and you are done :D
B) Propper but expensive: Get a better hybrid inverter(s).
C) Smart but not cheap: Emulate a small hydro power. Use a spinning generator coupled with a motor, simple gearbox and electronic rpm regulator. For the generator part, the easiest is to pick 380V 3-phase asynchronnous motor, designed for 1350 rpm. If you connect this motor to the grid, it starts to spin normally. But when you couple it with a second motor, that will increase rotation to roughly 1700 rpm then the asynchronnous motor becomes the generator and starts to feed the grid. More rpm, more power. No need for complicated "phase-locking" to the grid, asynchronnous generators are just super-simple. Since I see that you are using Hass.IO, you can implement precise power control using it.

About the cooling issue and 80% vs 50% power-throttle:
Thermal derating is normal, of course. Difference between the inverters might be caused by:
location of the internal temperature sensors
heatsink and thermal paste
if both inverters are paralleled, the firmware may decide to load master inverter more than slave one. Aalthough 80 vs 50 percent is too much I'd say.
Adding a water cooling sounds like a nice DYI project, but keep in mind that there's high DC voltage inside the box. One drop of water and box is done...and the operator might be done too.
In reality, water cooling just transfers heat to some other place, where the heat must be extracted from water before it is cycled back. The only cooling medium with virtually unlimited capacity is the ambient air. Therefore, if you don't have a river or swimming pool in your backyard, you will need a secondary heat exchanger and air-blower that will cool the water. Even if you plan to heat 1000L of water for showering, you will need an extra cooling loop that will take over once that 1000L becomes too hot to be used as coolant.
If you think about all the water cooling details and gotchas, it's actually much easier to fix the air ventilation. Just blow ton of ambient air directly to the inverter from bellow, collect hot air in the top and blow it out.
BTW: some of the Axperts were designed in a way that air was sucked from the top and blowed down below. That's a stupid design, because normally the air at the ceiling is way hotter than air at the floor level.

i test all eeproms chips from same control board with problem: i can read data but i cand write, i try erase chip but data still there, chips are broken. i place new chip with data from bad chip, remake serial and inverter work very good. will see in 60-90 days if problem is. Also, monitoring software no report anymore "eeprom fault"!

Serial number can be changed ! Settings also. also i read chips 24256, i put backup here. Use only memory 24256, or M24C256  32k
 
8Kw_good.bin 11kw_good.bin

This is what the result looks like.



I would like to supplement the instructions of @BritishRacingGreen with a list of steps for diagnosing and repairing the inverter parts that I had to repair and that he did not touch.