I have solar for back up, I just checked and it looks like the price went down on the solar panels. battery cost went up about 50% along with taxes, utility's, food, fuel, transportation etc.
Some of my panels that are 17 years old and so I have been buying a new deep cycle lead acid battery every 5 or 6 years= low cost. In an emergency I will possibly hook up extra car battery's and run the furnace if the gas is still on. The power was out for two weeks after a storm and when the electricity came back on a TV news person was laughing about the people who still had no power. Its about getting your individual person/persons some heat. Another problem is outdoor light, I have been trying the solar motion detector flood lights but they are not lasting 5 years.