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Limiter inverter with RS485 load setting
#11
Any news? Do you know how the checksum is calculated?
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#12
Have not had chance to look at this yet, awaiting response from Soyo..

The brand is listed as soy-source or the primary very slow website is www.soyo-dg.com

The single unit has had 381kWh though to date
The two parallel units have had 142kWh each through them, so 284kWh.
The last (oldest) unit has had 701kWh though and is about a year old.

All in 1,366kWh though the small inverters.
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#13
No reply at all from the seller / company... nice.. in spite of that.......

Working !!

Checksum is 264 - byte5 - byte6 ..... which gives byte8
Why 264, still to work out.

Periodically (as random as the lottery) the units seem to send out a 15 byte packet, which contains the battery voltage and other stats like this : 23 01 01 00 00 01 DB 00 A1 00 DD 64 02 CA 01

23 header ?
01 header ?
01 header ?
00 header ?
00 header ?
01 battery voltage high byte
DB battery voltage low byte
00 amps high byte
A1 amps low byte
00 scooby no idea
DD AC voltage low byte (to test further due to issue with reading)
64 best guess is Hz x 2, i.e. 50Hz = 64 hex = 100
02 guessing this is 2 for 20C offset for temperature.... who the f writes code like this ?
CA internal temperature (magic number format of C x 10 above 20C rounded up, i.e. 103 = 10.3 rounded to 11 + 20 = 31C)
01 some sort of status bitmask

Divide battery voltage number by 10 to get actual value to 1 decimal place

Separate notes :
The fans in the 900W units turn on around 3-4C before the 800W units.
600W max output at 47.5V terminal input voltage (low voltage derating)
Multiple units on an RS485 bus, you have no idea which unit sent the 15 byte data packet
Multiple uinits on the same meter, the update frequency of the meter reading slows down (to confirm with test)

Checksum calculation (with 8 byte array, zero first value) :
invBytes(7) = (264 - invBytes(4) - invBytes(5)) And 255
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#14


4 Units operating, 3 of them under control and one pre-set at 200W output (assuming 30W loss)

Loads are added up, add in 30W loss and subtract off the 200W fixed inverter output. This result is then divided by 3 and sent to the inverters as the output setting and now shares the load evenly between all 3 units so I should now be able to net off 2600W or more (4th unit can go to 750W, so absolute max 3150W).

Few changes to do, but will see how it runs for the next few days.

The 4th unit is set close to the lowest overnight loading so overnight all but the 4th unit effectively turn off and make most use out of the adjustable output.
Solardad likes this post
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#15
Bit more of an update and additional discoveries.

Discovery 1 - the inverters add up the kWh energy throughput purely based on the command value recieved even if this value is impossible to actually output. I wondered why I was seeing differences in the readings over a few days until I had a look at what the inverters thought they were doing. End result, a very poor unrelaible kWh reading.

Discovery 2 - the protocol has no real error checking and any errors are acted upon. Send the unit a packet with a command to output 80kW, fine, max output. 9MW, fine.

The units could do with basic error checking on the data packets, however they still seem to otherwise run ok, so a fix that may turn up in the future. Maybe in a year these units will be far better than the GTIL units for DIY builds rather than comparable.

Running all (meter and inverter) of the RS485 to Ethernet adapters in server mode avoids any hassles with firewalls from wherever you run your code to control them.

Setup the serial ports as 4800 baud,
input buffer for the meter of 8 bytes with a timout of 50mS (if no byte within 50mS then flush the buffer if you don't have 8 bytes)
input buffer for the inverter of 15 bytes with a timout of 50mS (if no byte within 50mS then flush the buffer if you don't have 15 bytes)

You can always do sense checking in the meter reading values (or just use meter reading value from another source) before sending a command to the inverters.

Efficiency is not as bad as I first thought, but still worse than using my 6kW unit.
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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