When a raindrop falls on the solar panel and then rolls down, it creates friction on the surfaceof the panel, which can then be turned into electricity.
雨滴落在太阳能电池板上，然后滚落下来，此时它与电池板表面产生摩擦力，这种摩擦力可以转化为电能。
2
The general low level offriction on ice allows a skater to glide along the surface smoothly without friction stopping the motion as soon as it's begun.
冰面上摩擦力通常较低，这使得滑冰选手一俟启动，就能不受摩擦力牵绊，顺畅滑翔冰面。
3
If indeed the friction coefficient is independent ofsurface area, then when I tilt them they should start to slide roughly at the same Angle.