We have a new geothermal system and need to know how big or what kind of generator to get?
how much load is in question would be the first unknown you have to find out. ie whats the max amp draw of the system, then what accessories do you run? circularlating pumps? controls? lights? frzr? refrig? hot water? could be done by heat pump.
You might want to look at a soft start/intellistart module. Most heat pumps, geo or otherwise pull 3-4 times the start amps(also known as LRA) vs the run amps(RLA) an intellistart module will often make the initial start up amps only 1.2 times the run amps so you can size your generator smaller.