My preference for diesel strikes some as odd, inasmuch as they will have an LP tank for other appliances. LP stand-by generators are very popular, so why not? Here is my reply to a recent inquiry.
You can use an LP generator if you like. Here are the reasons I prefer diesel.
1. Diesel engines are low maintenance and long lasting. The machines I have built use Kubota Tier-4 engines. The engine has an air filter and a fuel filter. I recommend an oil change every year and replacing all fuel lines every 3 or 4 years. You can pass this thing down to your great grandchildren. By the way, I also specify a brushless alternator. Think low-maintenance.
2. Diesel engines are non-carbureted. Carburetors are a royal pain. My bend pushes me to lean toward bullet-proof systems that deliver, last, and require little in return.
3. I’ve not found a quality LP generator that can be recoil started. The bullet-proof formula requires a generator that can be started from a battery OR via recoil. Start batteries die. Pull ropes are a good backup. Think options.
4. Diesel is a stable, non-volatile, high-btu fuel. I include a 55 gal drum filled with treated fuel, along with a hand-crank iron transfer pump. If you maintain your fuel, it will last 10 years and provide you with between 4 and 5 years of support.
5. An LP generator will be in competition for fuel with all your other appliances that use LP. Your battery DEPENDS on a reliable generator. If your power system depends on LP and something interrupts the supply, you lose.
6. LP engines are very popular in stand-by generators. Off-grid demands a back-up generator. It is a different machine. Generac makes an 8kW propane standby generator and an 8kW propane backup generator. The latter costs twice as much. It is more than twice the machine (but still does not meet my specifications). LP generators can’t be made to meet the bullet-proof formula; Single cylinder, air cooled, diesel, starts from a battery or a rope, and has a brushless alternator.
7. But your requirements don’t have to match mine. It depends on your reason for wanting grid-independence. If you want bullet-proof to be part of the package, an LP generator will be a chink in your armor. If you are not interested in armor, don’t worry about the chinks.