Motorhome generators can be grouped according to a variety of different factors, such as size, generating capacity, fuel source, and whether they are portable or built-in. The three main fuel sources for motorhome generators are gasoline, liquid petroleum gas (LPG), and diesel. In most cases, a motorhome generator will use the same type of fuel as the engine in the coach so that they can share a storage tank. Built-in generators are typically wired into the motorhome electrical system and often have automatic switching capability if the rig is plugged into shore power. Portable generators can sometimes be plugged into the electrical system, though it is often easier to simply use these units to directly power individual appliances.
The size and power output of a motorhome generator often corresponds to the length and capacity of the recreation vehicle (RV) because the presence of more people and appliances can require more power. Small motorhome generators often put out around 2kW, and large units can produce 13kW or more. The amount of energy that the generator is capable of producing directly relates to how many appliances it can run at once. Some very large motorhomes have three air conditioning (AC) units and a variety of other appliances that can all be operated at the same time with a heavy duty generator set.
Most motorhome generators use the same type of fuel as the engine that runs the coach. This allows the generator to draw fuel from the same tank as the engine. The generator intake is often at a higher level in the tank than the engine intake, which can prevent the generator from draining all the fuel.
Since motorhomes commonly have a liquid petroleum (LP) tank to run the stove, fridge, and water heater, some RVs have built-in LPG generators. These generators can be plumbed directly into the LP system in the same way a diesel or gasoline unit can draw fuel from an existing tank. LP generators are sometimes also useful in travel trailers and fifth wheels because those RVs typically lack gas tanks but have LPG on board for cooking and heating purposes.
It is also possible to obtain portable motorhome generators for supplemental power or use in a rig that lacks a built-in unit. These small generators are often rated at 2kW or less, though some can be chained together to offer larger amounts of energy. Portable motorhome generators sometimes have receptacles to plug the RV electrical system into, though they can also be used to provide power to individual appliances. Built-in motorhome generators are often expensive or difficult to repair or replace, so portable units can be a viable option in many circumstances.