NASA has been working on electrostatic panel cleaning system. I don't know if it has been tested in space or is on the Insight or not. This item was written in 2010 so there has been some time for the technology to improve:
From Science Daily's Self-cleaning technology from Mars can keep terrestrial solar panels dust free
In a report at the 240th National Meeting of the American Chemical Society (ACS) on August 22, they described how a self-cleaning coating on the surface of solar cells could increase the efficiency of producing electricity from sunlight and reduce maintenance costs for large-scale solar installations.
Working with NASA, Mazumder and colleagues initially developed the self-cleaning solar panel technology for use in lunar and Mars missions. "Mars of course is a dusty and dry environment," Mazumder said, "and solar panels powering rovers and future manned and robotic missions must not succumb to dust deposition. But neither should the solar panels here on Earth."
The self-cleaning technology involves deposition of a transparent, electrically sensitive material deposited on glass or a transparent plastic sheet covering the panels. Sensors monitor dust levels on the surface of the panel and energize the material when dust concentration reaches a critical level. The electric charge sends a dust-repelling wave cascading over the surface of the material, lifting away the dust and transporting it off of the screen's edges.
Mazumder said that within two minutes, the process removes about 90 percent of the dust deposited on a solar panel and requires only a small amount of the electricity generated by the panel for cleaning operations.