Generally, Solar Power System works when sunlight carries energy down to the Earth. In off-grid system system, solar panels are mounted on the roof or exposed in the sunlight outside on ground. They convert sunlight into DC electricity and flows into PWM or MPPT solar charge controller, and then charge different types of batteries (Deep cycle, Gel or Lithium battery), and then inverters convert DC power to AC grid electricity for AC home appliances use. But in Grid-tie system, DC electricity flows to inverters directly, then creates AC electricity. Your houses can use it, on the other hand, if there is surplus electricity, it can be faded into Grid for a credit or selling by Net-meter. Except for regular solar power systems, there are other types available, such as Solar hybrid system, Solar dc home kit system or solar lighting system, etc.