Update at Our House-- Solar Hot Water

This brief post will keep us close to home. I noted our new solar hot water system a few weeks ago, stressing our modest expectations for winter performance. I have to say I'm pleasantly surprised.
Today, December 6, the temperature in our town topped out in the 30s, we got three inches (up on this high hill, we get more) of wet, icy snow last night, and the winds were gusting to 15 miles or so as the day wore on. I checked the panel temp this morning after hearing the snow and ice avalanche off the collectors at 9 AM or so. 100 degrees on the return fluid thermometer.
Cutting to the jelly, I just ran hot water at 105 from my kitchen tap. One day of performance, 80 gallons of shower-ready water. Two 4x7 Stiebel Eltron flat plate panels (evacuated tubes are nice, but not necessary) two 40 gallon stainless holding tanks with heat exchanger coils for the solar fluid. One Caleffi (pricey, but very flexible) solar differential pump control. Very short connecting pipe (under ten feet total) between the panels and the tanks, located on my roof and in my attic, respectively.
As we near the solstice, and as temperatures drop into the teens and oughts, performance will certainly drop. But it won't drop to zero. We'll get pre-warmed water for the boiler to finish off on every sunny day from now until March equinox. I hope, after that, we'll be getting near total solar hot water for some months.
So--- a few thousand dollars (I, a seasoned solar contractor, did the installation myself) in equipment, a prime roof spot oriented within 15 degrees of south, a relatively un-obstructed morning horizon (the afternoon sun is hampered by some tall trees), a solar day extending from 9 AM to about 3 PM, and this is what we're getting for an energy harvest. DEP figures concerning hot water as a proportion of total household energy are being revised upward, to a possible 25%. If that's so, and I believe it in our case, I'll look for a 25% drop in our fuel oil usage this winter. And, at nearly 60, I expect to bequeath this system to a future owner someday, still running, still harvesting that blessed free energy from God's own fusion bomb, the sun.