You can modify the HME chargers if you can solder by pulling out the 12v 3 prong regulator from the circuit board and soldering in a new 9v. Or make your own. All you need is a Plano Ammo box, a small 12v battery, 9v regulators, a plug and solar panels.
The plug is a 4.0x1.7mm. I couldn't find...