Ionic liquid based dye-sensitized solar cells (DSSCs) were exposed to outdoor irradiation for seven months (April-October, 906 kWh/m(2), latitude 46 degrees 2'39.39 '' N, longitude 14 degrees 29'18.28 '' E) under short-circuit, open-circuit, and quasi maximum-power-point regime. As a reference we kept a series of DSSCs in the dark at room temperature under open-circuit regime. The performance of the DSSCs was evaluated indoor under standard test conditions prior to ageing, twice during ageing and after ageing. Additionally, the electroluminescence and transmittance imaging were used to follow the evolution of local defects with ageing. Operating regime has a strong influence on the ageing of DSSCs but despite this the performance of DSSCs remained remarkably stable. The exceptions were cells aged under short-circuit regime, which led to a significant decrease in J(SC). This resulted from the degradation of the dye molecules and a decrease in the tri-iodide concentration in the electrolyte. (C) 2013 Elsevier B.V. All rights reserved.