I am new to off grid living and currently use a growatt SPF 5000 charger/inverter. In the winter time when power is tight I find it difficult to judge the amount of power I have available coming in from the panels. For example I see my batteries charging at 1.5kw but I can switch on a 1kw fan heater without reducing the charging rate so the power was there to be had. I would like to be able to dump excess power to devices like hot water tanks and heaters are there any devices that can help with this?