Homebrew "BMS" ESP32 + SmartShunt to SMA Pylontech CAN bus on Sunny Island

[mafu]

Not solved it but as I my SI's are solely off grid I just add 1V to the BMS target V. So my JK PB BMS is set to 56.2V and the SI5048 reports target V as 55.2V. If the PV output is maxed out at Bat 55.1V with low house loads then the SI lags in increasing the Frequency and before the Inverters come under control of curtailment the V can overshoot to 55.8V. The JK PB BMS does not get alarmed as 55.8V is still below 56.2V, the cell balancing is activated. In addition I also monitor the Frequency on s Raspberry Pi and turn on a 3kw water heater at 50.6htz via a Wifi shelly relay which drops the batt V pretty quickly. The water heater gets turned off as the frequency drops below 50.4htz. I may add a timer so the water heater stays on for min 10 mins to reduce the on/off cycling.

Nice. I have made a device with an arduino that measures AC frequency and using a SSR will activate a dump load in a proportional way.

This would work for a resistive laod like a heater.
This is what the controler I made looks like. The top connection is AC in and the second one is the SSR output. What I like of it is that you can connect any load you like as long as you can cool the SSR and on any electrical outlet (my system provides electricity to multiple houses). I am now making one that will have a temperature sensor and a 12v fan output to cool down a heatsink and controll a larger laod, but if you like I can share it

 

[Consumerbot3418]

Nice. I have made a device with an arduino that measures AC frequency

I’d appreciate if you would share more details. Using an IC, or…? If so, which type? I’ve got some 48V chargers that I control with CAN using ESP32, but presently command them remotely using frequency reported by inverter. Would be nice to have it all be self-contained.

 

[mafu]

I’d appreciate if you would share more details. Using an IC, or…? If so, which type? I’ve got some 48V chargers that I control with CAN using ESP32, but presently command them remotely using frequency reported by inverter. Would be nice to have it all be self-contained.

I use a full bridge rectifier, altough it could be done with a diode too, and an optocpupler to find the zero crossing of AC. I use the other side of the optocoupler as a trigger signal for Arduino external interrupt and measure the period/frequency (you need a pullup resistor, I am using arduinos internal pullup on the interrupt pin). And later based on that control a 1Hz PWM signal to the SSR.
The code can easily be modified for an on/off with a hysteresis on frequency to avoid oscilations due to frequency reducing when you turn on a load.
This is my github repository, altough it is not fully up to date with documentation (I originaly was controling with a triac and phase angle control). At the moment I am traveling and can't get new images of my osciloscope to better document how it works. But will do it as soon as I am back home.

I use an arduino nano, but you could also use the atmega328p chip directly and make a dedicated board to reduce size. That is the next step I am going to work on. And maybe leave some gerber files so you can order your own PCB online. But do not have time right now, so maybe in a month.

 

[1201]

@Consumerbot3418 I've been using home assistant for a few months now and love it. I've got my PV data into it via solar assistant mqtt.

I just got some esp32 and I would love to be able to get the sunny island data and some automations going.

Would you be willing to to share your code and help me out? Thanks!

 

[kommando]

To get data out of a SI6048US you will need a RS485 piggyback inside the SI and then either a Webbox or a Raspberry Pi running Yasdi2mqtt to make the data accessible.

If you only want Frequency then you just need a frequency meter with possibly Modbus so it can be sent to HA or similar.

 

[1201]

To get data out of a SI6048US you will need a RS485 piggyback inside the SI and then either a Webbox or a Raspberry Pi running Yasdi2mqtt to make the data accessible.

If you only want Frequency then you just need a frequency meter with possibly Modbus so it can be sent to HA or similar.

Actually I don't need to get data out of the sunny island. I do have a webbox and piggyback card but what I need to do is to be able to fake the soc like @Consumerbot3418 is doing to control when the sunny island connects to the grid, and the charging rate.