I’d like to use PV panels connected to a resistive underfloor heating. The system should be fairly small (one room) built from 4 panels 300Wp (mpp voltage 32.6V). During the night the underfloor heating should/could be powered from mains supply, based on a setpoint temperature. The expectation is that for many nights it might not need to be turn on at all due to a heat accumulation in the floor mass, but the option to do so, would be great.
I’d like to use a hackable system that allows me to learn and later maybe expand to other areas (adding batteries, more power etc). What can I use from the available designs? I am looking at the MPPT 2420 HPX and I could fit into the input rage by series-parallel connecting the PV panels for around 65V at which point I’d need to be able to take in maybe 20A tops. I have some freedom in building and connecting the heating elements but overall power should be adequate to the panels - 1.2kW - which seems a bit stretch.
What would I have to change to be able to base my system on the designs available here?