Not that most people in the chilly north can necessarily exploit solar for heating (via a heat pump), but it would be interesting to add the fossil-fired boiler + solar-fired heat pump to the mix of what @MaheshAtSense has been looking into regarding load shifting..
@markhovis73 is using a “pre-fossil” (or I guess you would call it never-fossil!) pellet-fired system in an impressive integration with solar geothermal.