Snow on your solar collectors
"I've read somewhere that evacuated tubes collectors get covered in snow but Flat plate collectors don't".....
.. don't believe the hype... both types of collectors, evacuated tube and flat plates will at some point collect snow in winter. If you have a few days of snow that will make both Evacuated Tubes and Flat Plates be covered in snow, then they won't produce much heat until the snow goes.
Look at the picture below
Do solar collectors get covered in snow?
.. this is another common misconception...."Flat Plate Collectors will shed the snow"
Look at this picture. Its a glorious day outside, has been for a few days and the Flat Plate collectors are still covered in snow.

The Flat plate people tell you that snow slides off their collectors, it is supposed to do this because the plate collectors are not insulated like the tubes. Any heat in the flat plate collector can radiate back into the sky warming up the collector and hence the snow sometimes slides off. It is this reason (that they are not insulated) that makes then very in-efficient in cold and cloudy climates. They can produce 12X LESS heat than a tube collector in cold and cloudy condition.
The point is, don't believe the hype... both types of collectors, evacuated tube and flat plates will at some point collect snow in winter. If you have a few days of snow that will make both Evacuated Tubes and Flat Plates be covered in snow then they won't produce much heat until the snow goes.
What you have to think about is that the other 51 weeks of the year when there is not snow on them. In cold climates evacuated tubes produce much more heat. - Read more.