Perovskite solar cells are a promising new technology for large scale energy applications. The current major challenge for commercialization is increasing the device lifetime under real working conditions. State-of-the-art perovskite solar cells are prepared using TiO2 as electron selective contact. In sealed devices, however, a reversible UV light activated performance degradation mechanism was observed. In this study, it is demonstrated that replacing TiO2 with a SnO2 electron selective contact enables stable perovskite solar cells working under UV light in an inert atmosphere. Contrary to previous reports on SnO2 based perovskite solar cells, it is shown that a mesoporous electron selective contact is required to achieve UV stable perovskite solar cells.