In operation, this device has all met: measurements are accurate and verläslich, even for TV Standby 1W would correctly displayed. Also 0.5W and 0.7W have been measured correctly.
The biggest problem is in my view the display. Unfortunately it is very difficult to read it! In the outside area with the smallest solar display is completely unreadable: because it is not LCD, but passive screen with predefined matrix as in hand watch. In strong sunlight, you simply see all segments light up and all the numbers appear simply as "8". Viewing angle here is from my experience only about 2 degrees! But even in the home is difficult to read when ceiling lighting is on. I have the device always with dark cloth covering so that all lateral light source are insulated, and after a long search for correct position of head, eg behind the refrigerator erweisst to be very difficult.
For this agony I wanted only 3 stars awarded, but then decided on 4.