The SmartTalk Solar from Griffin Technology is, at first glance, a simple Bluetooth speakerphone. The unit measures slightly over 3.5 inches in length and just a bit under 2 inches wide (comparable to the footprint of a business card) and is about .5 inch thick. It has four buttons for volume up and down, mode select, and a large multifunction button -- so called because the multifunction button is used for virtually all of the device's functions. The face of the unit is also home to a small loudspeaker and a hidden echo-canceling microphone. In the box, you'll also find a 12-volt-to-USB charger and a short length of Micro-USB cable.
Harnessing the power of the sun
However, on the back of the unit (where standard speakerphones have a visor clip) the SmartTalk Solar features a photovoltaic cell -- more commonly known as a solar panel. That's because the SmartTalk Solar's standout feature is that it can be charged with the power of the sun. Rather than a visor clip, the SmartTalk Solar ships with a transparent plastic cradle that leaves an opening for the solar panel and attaches to your car's windshield with a pair of suction cups.
If you find yourself worrying about the SmartTalk crashing down on you while you're driving, know that the unit weights next to nothing and the suction cups will only release the device from a clean windshield with significant effort on the part of the user.
According to the user's manual, charging the SmartTalk Solar using only direct sunlight takes about 9 hours, so you'll probably want to do at least the initial charge with the included 12-volt-to-Micro-USB charger. I was unable to find published talk and standby times for the SmartTalk Solar, and because it lacks a battery status indicator, you're pretty much left guessing what the charge level is until the low-battery warning pops. That said, because the SmartTalk Solar is constantly charging when used during the day, that didn't become an issue during my testing.
An automatic standby function turns the unit off after 2 minutes when no phone is paired and reactivates the SmartTalk and pairs with your phone again when its accelerometer-based motion sensor detects that you've reentered the car. The ideal way to use the Griffin SmartTalk Solar is to mount it on a discreet corner of your windshield and just leave it there, always charging.