10% is generally the extreme low end and not something your going to see repeated for several days.
If you want days of off grid use your going to have battery's anyway. If your willing to cut back on energy that much then you might not need to even clear the snow from your panels. But, there is a wide range of easy solutions to that from manual clearing with a long pole, heating elements, or even just a steep mounting angle.
One major upside is the system should be automatic so you can leave your house unattended through a major storm. However, from a cost perspective solar hot water systems are generally worth it long before solar panels in the north.
If you want days of off grid use your going to have battery's anyway. If your willing to cut back on energy that much then you might not need to even clear the snow from your panels. But, there is a wide range of easy solutions to that from manual clearing with a long pole, heating elements, or even just a steep mounting angle.
One major upside is the system should be automatic so you can leave your house unattended through a major storm. However, from a cost perspective solar hot water systems are generally worth it long before solar panels in the north.