Solar panels convert sunlight into electricity using solar cells made of silicon wafers. They are used in solar power systems for homes, businesses, and industries. Mono-crystalline solar panels are generally the most efficient, with efficiencies up to 19%, but they are also the most expensive. Poly-crystalline solar panels have a lower efficiency around 15-16% but are more affordable. Proper installation and regular cleaning are important to maximize the performance and lifespan of solar panels.