Re: Thoughts about solar water heating
1.Can either of these (solar or tankless) be used to heat the recirculated water in my baseboard heating system?
Absolutely as long as you can supply sufficient temperature and volume for your system.
2.Since a tankless heater RAISES the current temp by so many degrees... would it make sense to use a solar heater and storage tank in line prior to a tankless heater to get an acceptable supply of really hot water... like for a nice hot shower?
3.Does it make sense to chain multiple electric tankless heaters together to get an acceptable temperature rise?
This has commonly be done. The drawback is the cost of equipment and power.
4.Would the electric tankless heater(s) seriously increase the number of solar panels needed to compensate for it?
This is a big yes. As a post on one of the other threads indicated the tankless heater they were looking at required 28,800 watts.
5.Can/should the oil burning boiler be kept in the line with cut-over valves as a backup system?
Again yes, the sun light like most things in nature is unpredictable unless you have a massive storage system.
6.Is this a potentially good idea... or would it take 100 years to break even?
That will depend on how it is done and how good your imagination is. A substantial savings can be realized with a small investment.
Be sure you live your life, because you are a long time dead.-Scottish Proverb