Basking under the sun without operation and overheating of solar collectors in non-heating seasons will result in significant problems on the safety of district solar heating collection fields and lead to the service life decrement of the collectors. This discussion focuses on the temperature resistance of polyethylene plastic passive sunshade net and its influences on the core temperature of the collectors which is basked under the sun without operation. The proposed issue has been experimentally studied. The research results show that the polye

thylene plastic passive sunshade net has good long-term temperature resistance under 100 ℃. Besides

under a sunny weather in Dongguan city in June 2018

the temperature of the collector core plate without sunshade net is stable at 157.5 ℃. With a single-layer and a double-layer sunshade net covered

the temperature of the core plate dropped to 83.0 ℃ and 73.1 ℃ respectively. Hence

a single-layer sunshade net can effectively guarantee the safety of flat plate collectors in low-irradiation areas. Furthermore

the experiment also used the artificial sunlight source to simulate strong irradiation conditions which are over 1 200 W/m

2

in Xizang district. The test results showed that the temperature of the unshaded collectors’ core plates is stable at around 254 ℃. After being covered by a single-layer and a double-layer sunshade net

the temperature of the core plate dropped to 109 ℃ and 86 ℃ respectively.Accordingly

the double-layer sunshade net can effectively guarantee the safety of collectors in high-irradiation areas. In conclusion

the research results provide experimental research foundation for low-cost flat plate solar collectors’ protection strategies under overheating conditions.