Any chance you might consider one of the new hybrid solar/9kWh battery storage systems?
The up front cost would run about $34K, but after the Federal 30% tax credit and NHPUC rebate are applied you'll be out of pocket $21K, about twice what a good whole house generator will cost. With a hybrid solar/storage system however there will be no fuel to buy and store, no yearly maintenance contract needed, it's silent, and when properly sized will also knock your electric bill down to near to zero for the next 40 years.
If this is of interest you can get more details on from the tab of my webpage titled, "
Energy Storage and the NHEC".