Insulating the house and using energy efficient products would be more cost effective than investing in solar panels. The energy investing pictures explains the process for most effective cost savings.

This are Solar Panels and Wind Turbines that are on sale through retailers.  The Solar Panels are 200 watt panels for about $200 dollars which is about average for the industry.  The Wind Turbine is 3000 watts for about $3000.  The average home would need about 10,000 to 15,000 watts the major appliances which is the more expensive option.

Below is a table of home appliances usage add the watts of the appliances you will run at the same time of an emergency.  That is the system of backup wattage that you will need.