This study aimed to provide a droplet dust removal cleaning method of photovoltaic module with low water consumption to strengthen the popularization of superhydrophobic coating in arid areas. A prediction model of droplet dust removal water consumption based on bond number is established. The water consumption of photovoltaic power station with superhydrophobic coating is predicted. The water consumption and economy of main cleaning methods on photovoltaic power station in five provinces of Northwest China is compared and analyzed.& nbsp;The results showed that droplet dust removal cleaning method has a broad prospect. Only 0.0383 L/m(2) water is needed to clean the superhydrophobic photovoltaic glass. Compared with manual and water jet cleaning methods on all photovoltaic power station in northwest of China, droplet dust removal cleaning method can save 1.63 x 10(5) m(3) and 5.66 x 10(5) m(3 )water in a cleaning cycle, 1284 and 11,362 million Yuan respectively in a year.

This study aimed to establish an experimental system to strengthen the popularization of flat-plate solar air collectors. Flat-plate solar collectors have been studied for years, but economic researches based on energy grade are insufficient. Using the analogical principle of fan, the relationship between the air mass flow rate and the power consumption of a fan was built. Taking net heat production and economy as the criteria, the influence of air mass flow rate on the collector system was studied. The relative coefficient of the energy grade, which can provide a balance point between the power and the heat for the net production analysis of the system, was defined. The heat production benefits and the power consumption costs were used to evaluate the experimental system using four cities as examples. On the basis of this evaluation method, the impact of energy grade on the economics of the system was studied.