All of our solar chargers have a battery that stores power and delivers it to your devices on demand. The battery provides a stable power source at the right Voltage to charge your devices. The battery can be re-charged from the solar panels or other power sources like an AC or DC charger.
Our Arc 10W solar charger provides a regulated USB output directly from the solar panel and it works well with most smartphones in our camera chargers in sunny conditions. In hazy or overcast conditions, we suggest connecting through a battery as the output can cut in and out.
There are some exceptions - it is possible to charge many older, non-smartphones (especially Nokias) directly from any 6V panel. And some rugged laptops like Panasonic Toughbooks will charge from both the Voltaic V88 battery and any 18 Volt solar panel.
All in all, while some devices may be able to charge directly from solar, we recommend using a battery for consistent results.