I'll add my $0.02 vote for solar as well. There is LOTS of DIY info on solar out there. 2 years ago, I replaced my LP hot water heater with a DIY solar system which also has a small 40 gal electric tank as "standby". I do not have hydronic heat running off the solar, but run the domestic hot water off it. The solar "loop" is a drainback system with 80 sq. ft. of commercial collector on the roof and a 250 gallon storage tank. The circulator is a Grundfos Alpha and is controlled by a differential controller. The tank typically sits at 150 degrees with a 160 degree high limit. Drainback means when the circulator is not running the plain water in the solar loop drains back to the storage tank and the collectors are empty. This is the freeze protection. The domestic cold water runs into a 100' 3/4" copper pipe heat exchanger loop in the storage tank, then feeds into the standby heater. Water delivered to the standby heater is typically in the 130 to 140 degree range, and the standby heater very rarely comes on.
When we first turned the system on, I forgot to turn on the breaker for the standby heater and the system provided all of our hot water needs (family of 4) for nearly 6 months before I realized the standby heater was off!
In the future, we may add some under-floor hydronic loops to the system, the 80 sq ft of collector is way more than we need for DHW. On a typical sunny day the circulator only runs for a couple of hours at most total to "top up" the temp on the storage. In the 18 months since we installed the system, our energy costs have dropped 15% (price adjusted).
Because we all LOVE pictures, here's some...
When we first turned the system on, I forgot to turn on the breaker for the standby heater and the system provided all of our hot water needs (family of 4) for nearly 6 months before I realized the standby heater was off!
In the future, we may add some under-floor hydronic loops to the system, the 80 sq ft of collector is way more than we need for DHW. On a typical sunny day the circulator only runs for a couple of hours at most total to "top up" the temp on the storage. In the 18 months since we installed the system, our energy costs have dropped 15% (price adjusted).
Because we all LOVE pictures, here's some...