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MODBUS to LTE-M, LoRaWan, Helium, WIFI Solarcontroller

Tingkart

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Dec 12, 2021
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I needed a way to monitor and control some solar powered stuff in the mountains for western Norway so I made a MODBUS to LoRaWan, Helium, LTE-M or WiFi the PCB that read and writes values from the EPEver range of solar controllers over the mobile network using LTE-M (CAT-M1) EPEver MODBUS the unit works on any MODBUS RTU or RS-485 enabled controllers or equipment.

The PCB uses the pycom.io range of microcontrollers so the PCB can fairly easily be programmed to use LoRaWan, LTE-M, WIFI and BLE communications to stream solar charger data.

modbus.jpg

I currently send battery temperature, battery voltage, solar W, charging battery and load output to keep the data usage on my mobile plan to a minimum. With some tight packing of the time series the controller only uses 2 MB pr. month with a transmission every 5 minutes to keep data costs low. PCB excepts 7-42v DC inputs and uses a 100mv peak when transmitting so getting power from the EPEver plugs works fine. Connect 4 wires and the unit starts transmitting over the cellular network, takes about 1 minute to set up.

Data is streamed to tingkart.com to visualizing IoT data directly on my phone, iPad or desktop systems. Since I know where solar systems are placed I can get weather data and calculate watts pr. m2 and over time calculate expected solar yields. How much I would expect the panels to output with current weather conditions but also estimation on how much they will produce the next days given weather forecast. You can do a lot of interesting things with this data like calculate if panel production has dropped over time (dirt/debris/snow buildup) to recommend cleaning or generate alerts for stuff like battery temperature, voltages and warnings from the unit.

I made the off grid solar monitoring solution I wanted but now I am wondering if anyone else could be interested in the technology or has this been solved better by someone else.

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Awesome!

something similar is still on my wish/todolist. Many existing stuff relies on regular 3G/4G, and not on LTE-M / NB-iot which I think is going to be the future. (and is from a price point of view more interesting since you're buying data based on a total amount, and not on 30-day subscriptions)

I'm not using the load output of the Epever (since it's only 30A) so for me, the solar controller won't be the primary subject. I'm more interested in interfacing with the VE.Direct of my Victron BMV, and/or the JDB BMS (to read any individual cell voltages / drift / cell temp)
 
I agree putting this stuff on your 3G/4G does not make a lot of sense, just too expensive and you do not really need that kind of resolution on your measurements.

I use a flat rate EUR for 10 years plan (500 MB) from 1nce.com that is working really well as long as I am disciplined about the messaging protokolls.

Could do LoRaWan over Helium/TTN to post you messages if you have coverage in your area. Or you could set your own gateways.

Have not looked at Victron BMV or the JDB BMS, do they support serial communication?
 
Yes. The JDB has bluetooth, you might even be able to use the pycom to wirelessly connect.

Victron (not only their BMV, but also other products): https://www.victronenergy.com/uploa...unication-with-Victron-Energy-products_EN.pdf

victron has fully documented their interfaces and protocols


For the JDB BMS (used by many DIY builders, = Overkill Solar), but also used by many commercial vendors for their 'off the shelf batteries', there is documentation available, eg using BT to connect to a ESP32



I think Victron support would make it very nice, since that's used for a lot of offgrid installations. Victron does provide remote stuff, but that's using their own portal and requires regular internet access. (and thus causing more traffic), while for general monitoring (plain values) LoraWan, NBiot or LTE-M is a better option (where I personally would prefer LTE-M or similar above LoRaWAN due to the better coverage).
For a stationary setup, LoRaWAN might be an option if you have coverage. My setup is in a van, thus roaming and coverage is more important.
 
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Thanks @DJSmiley for the info and I really like your solar van project.

I absolutely despise working with BlueTooth, copper just more sense for my old crusty brain.

Victron exposes a bit of CAN to communicate maybe I should build a version with the SN65HVD230 to work with their devices and maybe open up for some other CAN related applications. Hope I can find the time to play around with this, solar over radio is a lot of fun to work with.
 
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