No batteries, no charge controllers, no settings, no adjustments.... Just solar panel to USB! Truly plug and play. The solar panel size doesn't matter, as long as it's over 10W. This little guy is extremely lightweight and compact, which makes it perfect for backpacking, hiking, and travel! It really packs a punch at up to 40W output, which means it can charge several devices at high speeds. It is also great for an emergency power supply for your home, campsite, tailgate party, or your latest home improvement project. Super lightweight: Just over 3oz makes this solar panel to USB adapter perfect for backpacking. Works with any solar panel over 10W. Fast charging for most devices with the QC3.0 protocol Up to 40W maximum simultaneous output (with a 100W+ solar panel) Natural convection heat transfer (no annoying fans) Includes miniature USB LED tester Over voltage, over current, over temperature, and short circuit automatic protections. Specifications Maximum output: (3) Standard ports: 5V 2.1A (1) QC3.0 port: 5V3A, 9V2A, 12V1.5A Supports Apple / Android phones and tablets as well as any other device that uses USB. Compatible with 12V or 24V solar panels. Required input voltage: 9-35V DC Maximum solar panel VOC: 35V DC Operating temperature range: -40F to 140F (-40C to 60C) Approximate efficiency: 85% Example: A 30W output must be supplied with about 36W input. (36 x 85% = 30W). Ingress protection: none. This product has small vent openings to allow heat dissipation. For similar waterproof versions, see chart in photos. Dimensions: 3"L x 1-7/8"W x 1-1/4"H Weight: 3.5oz