Enabling Modbus on the SolarEdge inverter

My Domoticz installation used to polled the SolarEdge cloud API to get the solar production stats of my SolarEdge SE4000 inverter. This stopped working sometime last week. Because, there now is a new -- limited -- free API. You can do up to 2000 calls a month. Which is not a lot. There are other plans available but then you have to pay up. A lot. The cheapest plan starts at 100 USD / month. I got the free API working but it's limited, and it didn't sit right with me. This is my inverter, right? Why should I pay for my data that they collect and (probably) sell? Time for Modbus. Modbus is an open, royalty-free industrial communication protocol originally published in 1979 by Modicon. It allows industrial electronic devices—such as programmable logic controllers (PLCs), sensors, actuators, and human-machine interfaces (HMIs)—to exchange data with each other. I have always known about Modbus, but I had never implemented it. Enabling Modbus is as simple as opening a port on the inverter,…