Have you looked at solar installations? A 15KW generator seems like overkill and a $15,000 solution to cover the occasional emergency power outages I suspect could be spent more prudently.

A 4KW solar kit, which feeds back into the electrical grid can be had for around £3,300 in the UK. Nothing like getting paid for the excess electrical power generation. With energy efficient appliances an average base load less than 0.5-1.0 KW (excluding heating and cooling) is easily achievable. LED lighting has steadily improved in the last couple of years for example. The Solar PV could then be switched to a back up battery system for electrical lighting, entertainment, comms etc during emergencies.

http://www.buypvdirect.co.uk/PV_Packs/3.4kW_Perlight_Solar_PV_Kit

Typically if a Solar PV kit like this if installed by yourself the pay back break even time to cover the initial investment would be less than 7-8 years.

If having a buried LPG tank is possible then the installation of a condensing high efficiency boiler and hot water central heating installation combined with a preheating solar tank system would further improve efficiency to point that your LPG deliveries might even be more cost effective than heating supplied via the it would seem unreliable electrical grid tie connection.