For my particular experience, that still wouldn't have helped. First, the storms that knocked out power mostly occurred at night and had 100% cloud cover, so we're talking about total darkness. There was also really heavy rain or snow, which I'm sure makes the panels less effective even when there's light hitting them.
10% or less power wouldn't be enough, I think. The goal would be to keep the refrigerator and some lights running, and during the winter my heating system needed power for the electric ignition on the gas-burning boiler. (Why those things don't have a backup manual spark ignitor, like a gas barbecue, is beyond me.) During the storm this would all be without power, though I guess solar would help during the day once the storm passed, so long as the panels weren't covered with snow.
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.
10% or less power wouldn't be enough, I think. The goal would be to keep the refrigerator and some lights running, and during the winter my heating system needed power for the electric ignition on the gas-burning boiler. (Why those things don't have a backup manual spark ignitor, like a gas barbecue, is beyond me.) During the storm this would all be without power, though I guess solar would help during the day once the storm passed, so long as the panels weren't covered with snow.