Propane is terribly inefficient and makes generators and vehicles very thirsty. You will loose 20-30% output and it will burn twice the fuel as any other spark ignited fuel. . The advantage is the fuel is easy to store without going bad. The best option is if you are on a natural gas line to hook up to that but that can be interrupted by something like a fire or earth quake. The best option is still Diesel, the fuel contains more energy per gallon and if it gets dirty can be simply filtered back to being useable again. (We call it fuel polishing) the absolute best is my buddies hydroelectric system he powers his Kodiak rural home with. He simply throws the turbine into fast water in his creek and it works flawlessly. Produces over 30 KW nearly year around. Other than that a good modern Diesel powered generator is the best and most efficient. I have supplied generators to both emergency standby systems and to remote operations that are 100% generator supplied for 30 years. With proper planing and design, they can be very efficient and trouble free. Diesel is easy to store, safe and simple to get delivered. (Also no road tax on generator Diesel) The weak part of solar is still the batteries, there really isn't anything more efficient than the old wet Cell lead acid. Eventually there may be a breakthrough and whoever does it will be an instant billionaire but with all the energy being extended to find the answer, few have been developed. So I usually advise my clients to design there homes to be energy efficient first, solar can be effective with government assistance but never be without a solid generator base backup......and Diesel is the best fuel so far.bolus, do you have NG or Propane available?
The reason I ask is to mention I have a Honda super quiet gen converted to run on propane and hooked to a transfer switch. The propane conversion was great fun to install and works very well, and I can still run it on gasoline if need be. This could be a good backup to the solar.