When a charger says this:
Fast Charging Technology: PowerIQ delivers the fastest possible charging speed up to 2.4 amps per port or 3 amps overall under direct sunlight. 21 watt SunPower solar array is 21.5-23.5% efficient, providing enough power to charge two devices simultaneously.
And it claims to work with this list of products:
Solar for iPhone 7 / 6s / Plus, iPad Pro / Air 2 / mini, Galaxy S7 / S6 / Edge / Plus, Note 5 / 4, LG, Nexus, HTC and More
I take that to mean that they have figured out how to trick the respective phones into accepting the higher charge rate. I have bought non-Apple automotive chargers for my IPad, and those third parties figured out how to get the IPad to charge at the highest rate...