I've been harvesting solar heat everyday for the last 6 weeks or so. Harvesting heat from the sun is going to a bit difficult for the next few weeks. The sun has dipped low enough that it doesn't reach the house for hours. There's a massive conifer growing in the backyard of the neighbor across the street, and you can see in the pic that at 10:30 in the morning, it shades my prime southwest windows. Until the calendar gets to the other side of the Solstice, there just won't be morning sun for me to collect.
The overnight lows have been hovering in the mid-40s for a while, now, but the daytime highs have ranged from the low 60s to the mid 70s (and brilliantly clear, too!). I've resisted turning on the heater-- opening and closing drapes and putting dark blankets below the windows has been bringing plenty of heat into the house. Not long after we moved into it, I realized this house was as leaky as a lean-to. I weatherstripped and plugged holes and added a little bit of trapped-air space. This helped the heater from running constantly to running a few times an evening.
Today, however, is the day. Just now I've turned on the central air, and set it to 65.