This paper presents a novel whey drying plant assisted by solar energy. In Italy, the whey is mostly used for feeding pigs and, regrettably, in the worst cases, it is discharged against the regulations to avoid significant disposal costs. Current technologies for the whey drying process are very polluting and expensive. Therefore, it is necessary to evolve the technologies for such processing to safeguard the environment and reduce operating costs. The plant is equipped by concentrated solar collectors which process the heat necessary to evaporate the whey in a vacuum dryer at a temperature equal to 65°C. In addition to the solar collectors, a boiler is present. The processed product is then deposited in a storage tank for its conservation. This thank is kept at a low temperature by an Ice Tank and an absorption refrigeration (H2O-BrLi) chiller. The warm water, which is heated by the field of the solar collectors, feeds the absorption chiller. A photovoltaic system electrically assists the pumps, thus making the entire system energy sustainable. The dynamic simulation of the processing of this drying plant is carried out by means of the TRNSYS software for the entire year. Solar fraction and efficiency of collectors are evaluated.