As you would expect, having snow covering your solar panels will decrease the production of energy, since a PV system needs sunlight to be able to work. However there’s no need for alarm.
The snow should not however harm your panels, as long as you make sure to install them properly. Panels are built to withstand a certain amount of weight, and you can check the datasheet of your solar panels to see what their rating is.
Although there are ways to safely remove the snow off your system, as long as you install your solar panels at an angle, combined with solar panels giving off heat, the snow load should slide right off them after a period of time and produce energy at a normal rate. In fact, the snow can provide natural cleaning to your solar panels, as the snow will bond with any dirt and slide it off as it melts.