12% efficiency. This wouldn't be safe to use on a windshield, but if used on all the other windows in a rig, it would bring in at least 30-50 watts (am guesstimating big time here), and even though this isn't that much, it is wattage obtained without having to add panels.
Maybe it could be used on a windshield as an "eyebrow tint", where the top part of the windshield is tinted, while the critical area to see out horizontally is untouched. The glass expanse on a lot of "A"s is large enough that having the sheer amount area available would get in at least 100 watts... good enough to at least keep the house batteries topped off when in storage.