I've noticed that a lot of dishonest people are selling things here. But I'm new to the math didn't add to 10, just read the information from the addition. It put out 13.5 volts, the highest I've gotten in the big sun. On average from 12 to 12.5, but the barley of any amp. Doesn't produce an amp, addendum says it exists. I have .184 amps and it was in the big sun fl. So amps times volts and you get watts and that gives you 2.2 to 2.5 watts max. So much for 10W but it will charge your phone tablet etc. It even charges your battery. Charge it forever (car battery). The fan is cool and comes with cool extensions. The round USB cable is hard to find in a regular store. Definitely didn't get it for my chicken coop. I don't have it, but I say it's worth it. I have all kinds of solar panels and solar powered devices so this goes well with my collection. Put it in your backpack and charge your phone while cycling or hiking. You can connect it to a charge controller, but you have to use a cable and then connect it to a round connector. I had extra. The only drawback is the lack of watts.