I’ve got a similar setup:
I use several Eastron SDM230 kw/h meters and homewizard plugs to measure my connection to the grid (as I don’t have a smart meter), the power consumption of ‘heavy’ users (like a boiler, dishwasher, dryer, etc) and the productivity of my solar panels.
I’ve got 2 strings of solar panels, connected to a Growatt inverter. I’ve built a box with a power regulator that uses the power that normally would flow to the grid to heat up an electric boiler. So, this box feeds the boiler dynamically. I terms of safety I built another box that contains a 40 amp relay.
If the current coming from the Growatt exceeds 18 A it will switch off first the DC part of the Growatt by injecting a Modbus command (using a Waveshare RS485 to TCP converter). After 2 seconds the relay will cut off the AC side of the Growatt. The relay is a SSR relay with a cooling body attached. All being monitored by Homey Pro and using Shelly components for switching and monitoring temperature.
I also built a flow that calculates the amount of power being consumed and what is available.
If necessary, the Growatt inverter will be limited in % of it’s maximum capability. This is to prevent power injection in the grid. Still testing, but from 2027 in NL we are charged for power injection and ‘net metering’ will stop. If you’re interested I can share the setup in detail.
In this section there’s a bit more on the power regulator:
