I am sure someone else will also agree, but trying to use solar to run electric heaters is never going to be economically worthwhile. Photovoltaic power is never cheaper than the grid. I would guess to cover the heaters would require a few thousand dollars worth of panels, batteries and charge controllers, not to mention the high current inverters. By the time the investment paid for itself it would be past time of replacement for the hardware. Solar is never to reduce electric bills, it is for backup power in ares where the grid is not reliable. Propane is probably still cheaper in the long run in fact, unless you are trying to only heat certain areas. Having grown up in an old adobe farmhouse  my suggestion would be to use the whole house heat to keep the house in the low 60s, and use the space heaters to supplement in the areas you are using at the time. Using electric to warm up the bedroom or bathroom for example are efficient uses of such heaters, as would deb using it to heat your ham shack.  I do this of rmy shack, and leave the house at a cooler setting, since i am in the one area most of the time.