Common solar panels catch the light and produce energy at the front side while the back side is covered  with a non-transparent white or black backsheet. That is okay if the panel is mounted on a pitched roof. 
Bifacial modules can harvest energy from the front and back side simultaneously. 
If the panels can be mounted on a ground with a well reflecting surface (snow in winter or bright stones/concrete in summer), the energy yield can increase by up to 25%.
If the front side is covered with snow in winter, it takes some time before the snow is melting and slides off. The back side of a tilted panel is in contrast never covered with snow. Here energy is produced earlier than at the snow covered front. In addition heat gets produced that clears snow faster than at monofacial panels. Look at the study: Monofacial vs Bifacial Solar Photovoltaic Systems in Snowy Environments showing results from Michigan.
We are planning to measure the difference of snow clearing time and energy yield between monofacial and bifacial panels in Kirkenes.

Recently vertical mounted bifacial solar panels became enormously popular. These harvest sun ligt that is reflected both from clouds and the ground. During winter much snow on the ground enhances the efficiency. 
During summer we have 2 month with midnight sun, but a panel mounted against south doesn´t produce energy while the sun is shining from west or east. In this case vertical west/east mounted bifacial solar panels can help to produce energy also at early morning or late evening.