I was looking into this and went to the Central Maine Power web site and found these FAQs: Question: I use a lot of hot water, even in the summer. Is it less expensive to heat my water in the summer with electricity than with oil? Answer: Yes, it is less expensive to use an electric water heater than to run the boiler just for the purpose of heating water. The efficiency of an oil-fired boiler used only to heat water is lower than when it's being used to heat your house as well. Although documented data regarding this efficiency is limited, a separate oil-fired water heater has an efficiency just over 50%. A boiler would have to operate at over 65% efficiency to heat water at a lower cost than an electric water heater." Question: I heat my water with oil. Should I switch to an electric water heater? Answer: Depending on how efficient your oil-fired water heating system is, it may be less expensive to use an electric water heater. Many people have an oil-fired boiler that provides space and water heating. For older, less efficient systems it will cost more to use oil. With electricity prices as of July 2008, it is also less expensive to use an electric water heater than a propane-fired one. If you only use propane to heat your water and not for space heating as well, electric water heaters can be a lot less expensive than propane-fired ones. To estimate your kilowatt-hour use for heating water with an electric water heater, go to our online energy calculator and page down to the water heater section. (Note: the efficiency measured when a boiler is serviced is the combustion efficiency. This is higher than the efficiency when it operates in the non-heating season.) So, maybe you shouldn't be using the 80+% efficiency numbers for comparison of water heating only. I do realize that they are going to try to present facts in their favor, but there were times where thay said there wouldn't be savings for the electric options. The link to their calculator is: http://www2.cmpco.com/EnergyCalculator/default.jsp Here is a link that might be useful: CMP heating FAQs

IF you have vents you have the right idea with getting a heatpump instead of straight A/C. Get a good high efficient single stage heat pump with demand defrost. This will handle a big majority of your heating. 15 seer would be good. I would want one that is one the quiet side since it will be running alot. Having a compressor blanket is a must. The propane option sounds nice, but propane is not cheap either. You would probably be better off with straight electric element as backup (probably just as expensive as oil or propane). The nice thing about the water heat is it is very even, quiet, and produces no dust. But you won't be using it very often since you will have the heatpump. Its up to you if you want to keep the oil base-board, get rid of the base-board altogethor. I'm not sure what the point of switching from oil to propane would do for the baseboard.

Ok, I took a standard electric water heater that the Energy Guide says will cost about $411 a year at 8.6 cents per kwh and converted that to 7.0 cents and came out with an estimate of $334 per year. The estimated number of kwh per year for that same scenario is 4779 kwh or about 16310727 BTU's number 1 fuel oil is about 134,000 per gal and If we guess the burner is 50% efficient in the summer it comes out to about 243 gals of oil for the year or $579. Your stated use is $540 a year so I'm guessing my calculations aren't far off. So: You could reasonably expect to pay $334 for electric (or a little less) or about $540 for oil. Now, you would need to get an estimate on the installation of an electric heater. I would recommend that you get one with 2" of insulation (fairly mainstream) and add a blanket to it for $20. This is much cheaper than buying a super insulated heater. A 50 gal GE "Energy Smart" heater, for example, is $340 at lowes. (that's not an endorsement-- just an example) For a small family, 50 gal should be fine unless you have a large tub, for example. Your installed cost will be higher because you will need to have the electrical run to the heater. Nonetheless, the savings will be about $200 a year and you will have hot water. I wouldn't put much more thought into tank life, etc. It will last about 12 years. When it's time to replace it, the replacement cost will be much less because the plumbing and electrical will be in place already. Here is a link that might be useful: Electric water heater

Typical panel services are 200 amps. You want to install 2 something's that pull more than half of your available service. That's not doable with a standard service, much less solar. And why 2? A well placed propane unit of the appropriate size is more than adequate for whole home usage.