Yes, Solar energy can be used during rainy season.
It is true that heavy cloud cover somewhat reduces the solar energy that reaches the ground ,and the solar panels. How ever rain do wash and clean the solar panels from dust, and the energy that passes thru the clouds is still very high and allow solar systems to operate.
We in Lumos Global advice our customers to monitor the state of charge of the Lumos system battery, using the user interface on the init LCD. using the User interface they can monitor both level of charge as well as rate of charge or discharge. By that they can manage the amount of energy they are consuming and adjust it to the changing weather conditions.
So, yes, you can use solar systems, while applying monitoring and common sense.