Yes, you can - artificial light (e g flashlight) is capable of charging your solar lights. The speed that the flashlight will charge the solar light depends on the brightness. An average flashlight emits 100 lumens, so it will take much longer to charge your solar light as compared to being outside. As a comparison (in lumens), the average flashlight is 6.7% as powerful as a cloudy day and .1% as powerful as a sunny day! An average flashlight emits 100 lumens, so it will take much longer to charge your solar light as compared to being outside. As a comparison (in lumens), the average flashlight is 6.7% as powerful as a cloudy day and .1% as powerful as a sunny day!