Thank you all for your answers, finally by reading all this I think to take a resistance of 1000w, delay it on the programmable internal relay of my transformer in order to make it work in equivalent of 700w. This will allow me at a lower cost to recover a little energy lost when ...

Hello, I am in an isolated site, I have a 1250w solar system, I am installing a double exchanger tank (solar + boiler on stove). I have a Multiplus 2 inverter from Victron, programmable to manage the relay when the batteries are full. I haven't made it yet...