I doubt the performance specification as well. Heating is way to slow for 15KW. 15KW at 230V input voltage, assuming 80% efficiency, would result in 80A supply current. Standard single phase fuse in Europe is 16A (you may find 25A in industry.) Thats a 1/5 of the rated power. 15KW/5 = 3kw. that matches the heat up time seen in the video much better .
