Hey it worked!  Finally put together my new solar-powered ultra-high power LED and it’s sweet!  The solar cell is 1W and the LED runs at 2W, so for every two minutes of sun you get one minute of light!

The end-to-end energy efficiency is a bit low, so don’t try to string a bunch of these together with LEDs lighting up solar cells.  The LED is about 20-25% energy efficient and the PV is about 15% efficient, making the system probably 2-3% efficient at recycling light energy.  Just for fun, I added a mode to drive the LED exclusively with PV power.  Here with room lights:

Long-live the photon battery device!

• PV cell: 2 parallel strings of 12 Si solar cells with reverse blocking diode
• LED: Cree XM-L2 with thermal substrate, basic optic  and 0.5/2 ohm resistor switch
• Battery: 3-cell NiMH with bypass switch