I work as a home repair contractor, and autumn becomes a very busy season for me as lots of people want to get things done before the rain begins. So I have not had any time to work on projects.

I did discover on a very overcast day, the device will only charge to about 2.9 volts, maybe more if in light all day... but the panel used in this project is rated 5v, 30mA, in full direct sun, it really only provides 15-25 mA.

On a very overcast day, current is only about 0.5 mA, and voltage much lower. Where I live we get about 6-8 months a year of such weather... It got me looking into energy harvesting IC's. But this project will not expand into that.

The device can be fully charged in about 10-20 min if placed directly under a bright lamp indoors.

I think all I will do on this project in the near future is assemble one of the PCB devices, and once all is tested release PCB files for that as well as update guide to reflect PCB assembly.

I am thinking of a more advanced handheld device to port TGRK to, using either STM32, or ATMEGA328P instead of attiny85. As this device will have either an LCD character display or OLED screen, it will use a LiPo battery for energy storage instead of a supercap. But will still retain solar charging capability, in addition to usb charging. 

This new device will have a 16-20 key keypad for programming on the device. As character variables will be a new feature, as well as on screen programming, instead of modifying bytes bit by bit, we can type in keywords as they appear in the keyword table, and the interpreter will convert the text representation to the integer keyword code. Because of this the interpreter will have to be modified, but I do intend to make TGRK programs somehow compatable between devices.