A dump load (aka diversion load) is not necessary for the turbine to operate, however, it can be used if you have the need. Typically the turbine is not used with a dump load as the control board inside the turbine recognizes when the battery is full and shuts the turbine down. However, if you have use for extra power in the form of heat when the batteries are full, you can use a dump load controller such as the Morningstar TriStar TS-45 or TS-60 and a dump load (typically large resistors that heat air or water for a hot water tank).