With many hybrid systems you can also use the generator to charge the solar system batteries through the inverter, in case you get a few cloudy days. The solar panels also ensure that the batteries remain at peak charge if the RV or boat is not used for long periods of time. A hybrid system, especially for boats, can also consist of wind generator and solar panels. Most put out too high a voltage after the batteries are charged, and will fry the batteries if left on continuously. Some battery manufacturers will not warranty batteries that are charged from a converter.
Most small converters consists of little more than a step-down transformer and a rectifier.
However, most people find that the hassle of getting up on the roof and setting the mounts and making sure the RV is always parked so the panels can face due south is more of a hassle than it's worth unless you are going to be in one place for a long time. The tilting mounts cannot be left up when traveling. A single 100 to 120 watt panel, such as the Siemens SR100 or Kyocera KC120 would also be a good size. The Unisolar US-64 is a good choice for hot weather climates such as the US deserts and southwest. 1 - panel mounts for roof mounting.