The need of a higher role of solar energy within the energy mix in the coming decades obliges the collectors to increase their performance and reliability. It is demanded that the solar absorbers, as the key component of solar thermal collectors, should be low cost with high efficiency for extended lifetimes under different kinds of environments. Commercially, there are presently two main types of solutions as selective solar absorbers coatings for low temperature applications: coatings obtained by physical vapour deposition (PVD) and by paint coatings (PC). These coatings present different physical and chemical characteristics. Therefore, it is important to know how these commercial coatings degrade over time in different environments.

Results obtained with two different PVD coatings and three PC, under different accelerated aging tests, are presented. The aging tests performed included different environmental stress corrosion conditions: temperature, humidity, chlorides, sulfur dioxide and nitrogen oxides. The chlorides and the gases SO₂ and NO₂ affect distinctly the different selective coatings.

Cyclic variation of corrosion promoting gases (sulfur dioxide and nitrogen dioxide), higher humidity, salt spraying and drying seem to be an aging test that reflects the different environments where the solar thermal collectors are exposed. In addition to the contaminants, drying/wetting cycles also play an important role in degradation mechanisms of absorber coatings. So, the international standard ISO 22975-3 needs to be revised to include cyclic conditions with these contaminants.

在未来几十年中，太阳能在能源组合中发挥更大作用的需求迫使集热器提高其性能和可靠性。太阳能吸收器作为太阳能集热器的关键部件，要求其成本低、效率高，以在不同环境下延长使用寿命。在商业上，目前有两种主要类型的解决方案作为用于低温应用的选择性太阳能吸收涂层：通过物理气相沉积 (PVD) 获得的涂层和通过油漆涂层 (PC) 获得的涂层。这些涂层呈现不同的物理和化学特性。因此，了解这些商业涂料如何在不同环境中随时间降解非常重要。

展示了在不同加速老化测试下使用两种不同的 PVD ​​涂层和三种 PC 获得的结果。进行的老化测试包括不同的环境应力腐蚀条件：温度、湿度、氯化物、二氧化硫和氮氧化物。氯化物和气体SO ₂和NO ₂明显影响不同的选择性涂层。

腐蚀促进气体（二氧化硫和二氧化氮）、更高的湿度、盐雾和干燥的循环变化似乎是反映太阳能集热器暴露的不同环境的老化测试。除了污染物之外，干燥/润湿循环在吸收剂涂层的降解机制中也起着重要作用。因此，需要修订国际标准 ISO 22975-3 以包括这些污染物的循环条件。