Attar et al. [67] used a TRNSYS simulation to evaluate the performances of a solar water heating system (SWHS) for green-houses according to Tunisian weather. The SWHS were two solar collectors, with a total surface of 4 m2; a storage tank of 200 L and a capillary polypropylene heat exchanger integrated in the greenhouse. Results of simulation revealed that the temperature at the collector outlet decreases when the tank volume increases. Moreover, decreasing the exchanger inlet flow rate was a good solution to reduce heating losses. They suggested a flat plate col-lector and a 200 L tank as the best storage system to increase the inside air temperature of the greenhouse by 5 °C and provide suitable conditions for growing tomatoes. Additionally, Kıyan et al.[68] developed a mathematical model (Matlab/Simulink) to investigate the thermal behavior of a greenhouse, which is heated by a hybrid solar collector system. This hybrid system contains an evacuated tube solar heat collector unit, an auxiliary fossil fuel heating unit, a hot water tank, control unit and piping units. This model has been developed to predict the storage water tempera-ture, the indoor temperature and the amount of auxiliary fuel, as a function of various design parameters of the greenhouse such as location, dimensions and meteorological data of the region. Results of simulations indicated that revising the existing fossil fuel system with the proposed hybrid system was economically feasible for most cases and it has a positive environmental impact; however, it requires a slightly longer payback period than expected.