This one is from my local electronics nerd shop which i trust. I can only speak about germany, but generally i have never had inaccurate ratings on solar panels, as that would be fairly illegal i think. I installed a few 2x400W sets for people and they all ended up putting out more than 800W peak power. Idk why these small scale ones should be any different. Ofcourse the rated 90 Watts will only be reached under clear sky with a good sun angle and not too much ambient heat.