It's called a 30W max panel. but the box, listing and instruction manual clearly indicates the maximum wattage available via USB-C (under ideal conditions at 12V) is 18W. I get maxed out at 18W in ideal sun conditions. So you might think the total power output of 30W is obtained by plugging in a USB-A device while also using USB-C. WRONG. I plugged in a USB-C device and maxed out at a charge of 18W. Then I plugged in another device via USB-A. That device started charging at 5W but the USB-C would drop down to 12W, for a total wattage charge of <=18W. I can remove the USB-A device and the USB-C raises back to 18W... plug in the USB-A again and it drops back to 12W.
I have other panels that are 40W and they truly output closer to their specification (I get 38W via USB-C on those panels). Why put a charging mechanism of 18W on a 30W panel and then sell it as a 30W panel. Avoid this and all ELECAENTA panels.