... In the most direct "blue sky sunlight". Also, the tube containing the water pumped up not really tight and stable. Since I have installed in good faith to the function, the pump is already in the fountain, I have now connected a small power supply unit and the visibly weak dimensioned solar cell is replaced by a small power supply, now klappts. Even the riser I additionally sealed so that the water will not get pushed in the connectors. Too bad I had to get a stronger 220V pump price.