grid assisted off-grid

[verdegeo]

I am setting up a 42 panel system with m215 inverters. The initial purpose for the system is to provide supplemental heat to the house in winter, either by powering 240V baseboard heaters, or a standard 40 gallon hot water tank in series with my propane boiler. I intend to mount the panels about 60 feet up on the side of my barn silo in a semi-circular arrangement, run the AC lines down conduit and combine them in the adjacent barn. I have 4/0 4/0 2/0 underground cable from the barn to my house 1300 feet away, specifically to bring the solar power to the house. I do not intend to export power onto the grid. Is there a device, something like a blocking transformer, that would fully isolate the solar setup from the grid but still provide trickle current (from the grid) so that the m215 inverters will work? Also, I don't want the grid side powering the heaters if the solar output is low, the grid electricity is too expensive, and heat would be provided by my woodstove or the propane boiler anyhow. Considering that there is a substantial voltage drop over 1300 feet of about 15 volts at 60 amps, should the device be located at the house end or in the barn? I prefer the house end because I would like to disconnect from the grid at the barn, I dont use much electricity down there anyhow and they charge a lot each month just to be connected. No batteries involved for the solar setup for now. If the thermostats on the baseboard or hot water heater turn off, do I still have to dump the solar current somewhere or do the m215 inverters autoregulate?

 

[Ampster]

The device you may be looking for is a second generation Envoy that can be outfitted with current transformers and programmed for zero export. The best location for that would be near your main service panel so that all your loads would be offset to the extent there was solar production.
You may need to do some research on Enphase specifications to confirm that the version of M215 micros you plan on using, can be configured for zero export. I know that the IQ7 micros can be programmed and they are only compatible with an Envoy designed to work with them.