I'd like to make a Led that lights up by solar panel
Red LED's require only ~1.6-2.0 volts to light. The solar panels on "dollar store" solar-powered LED lights should produce about that voltage, at a few mA current. Just connect the two wires from the panel to the LED, observing polarity.

The current from the solar panel is so low that no dropping resistor is needed. Use a long wire, so the panel can be in the sun, and the LED in a dimly-lit room, since the LED will not be too bright.

If you know a prisoner in a deep dungeon, or a troglodyte such as Gollum, this would be useful to let her or him know when to count another day of confinement.