Solar hot water panel update - today it was -14F when I got up and it was sunny all day reaching a temperature around 14F around 4PM. The water temperature at the collectors was a maximum of 114F - the best we've ever had. The water going into the (radiant) floor was a maximum of 97.5F. By the end of the day today, the temperature of the slab was 61.5F. So we had the best performance of the solar water heaters on the coldest day of the year.

The hot air panels were running around 106-114F all day. Having snow on the ground really helps give the maximum heat.

The building temperature was around 65F at the end of the day today with the solar water heat, solar air heat, and corn stove all running.