On 04 Nov 2012 17:12:37 GMT, Han wrote:

I have a 150 Watt inverter and finally got a friend to help hooking it up
to the furnace (we went 99 hours without power in NE NJ, 07410). Furnace
is natural gas-fired, circulating hot water. The inverter hookup worked
fine, but I had to have the engine running, of course. It is OK for
short emergencies, but I'd like better. Will be looking ...

You are obviously using something less than 150 Watts and that's only
when it's running. Think about a 100 W solar panel. If your ''on''
time is less than 50%, you should be good to go with not all that big
a battery. In fact you would never discharge it very much so you
should get good service life.