People decide to buy solar systems for a variety of reasons. For example, some people buy solar systems to conserve fossil fuel resources and to reduce air pollution. Others prefer to invest in order to pay less for electricity. Some people need independence or energy security to protect themselves against future increases in electricity prices. If the system is designed correctly, it may be able to provide power in the event of a utility power outage, thereby increasing the reliability of the power supply. Some live in places where the cost of expanding power lines is higher than buying a solar system.