Yeah I found that, it is a cool project but like all the other Diverters I have found, the dump load is either a switch or heating water. The problem I was trying to solve was "dumping" that energy into a battery where i actually want it which requires gaining full continuous control over an AC Battery charger.FYI, OpenEnergy PV diverter has been around for years now and I believe it already supports most of what you want to do. Most of the people using it are also in UK. Check out https://docs.openenergymonitor.org/pv-diversion/index.html.
Some Hybrid inverters can let you do that if you talk to them over CAN perhaps using pylon tech protocol but a hybrid inverter is a very expensive AC battery charger and I was trying to get way from installing an inverter on the grid for legislative purposes. Straight AC chargers off the shelf dont give you control over the amps in a meaningful way. They also don't tend to be very high wattage, the ones that are are very expensive ~£1000-£2000