Not if the pole gets wet.
why would it get wet ?and i am sure alex will respond to this post .
During use a telescopic pole will generally stay dry, but it can get wet in use for two reasons:
1. The weather - if it is raining then the surface of the pole will get wet.
2. The angle of use. With the shallow angle of the pole when cleaning solar panels etc. it may happen that water can run back down the brush head and on to the pole. This would really depend on exactly how the work was being carried out.
The chance of getting an electric shock from a standard working Solar Panel is very very low - If a shock was received from a damaged panel it would usually be from just the output of the single panel which would generally not be sufficient to kill you. Using a pole with an insulated base section would protect you even further even if a solar panel was damaged in some way. The only time the pole would not protect you is if it was wet along its entire length and down on to the handle section that you were holding.
On the continent cleaners regularly use carbon poles on such solar panel arrays and have been doing so for many years. These panels have to be well isolated as otherwise when it rained they would all short out!