Unfortunately no, (It's a big heavy metal tank, at least 100 gal. It's up hill behind my place, so that if my pump goes out, I still have gravity fed water.), but along those same lines I did get a 50 gal. water heater and put it inside right next to my fireplace. It's not going to be used to heat my water, (that will be done by Ecosmart tankless and propane backup), but merely to keep it from freezing. I'm replacing the thermostats with 48v DC ones, and 35F thermostats, from Missouri Wind and Solar. I also installed one in my cistern as well and am hooking up my last solar panel to it PV direct, and am planning on insulating and enclosing it just like you mentioned. These heating elements will take 2 sources of power, so i'm also considering coming off of my battery box to the cistern element as well. I'm in the process of installing a 2000w 48v wind generator on a 40' pole as well, and am considering using the dump load from that to keep the cistern from freezing, but then during the summer I'll just have hot water, lol, so I don't think that will work, and I'm probably going to have to by dump load resisters instead.

Open to suggestions. This is one of the areas where I'm having problems figuring how best to do this. I'm not likely to finish this year now either. Times up, heading back to civilization soon,