Solar thermal power plants designed for solar-only generation are ideally matched to summer noon peak loads in prosperous areas with significant cooling demands, such as Spain. Using thermal energy storage systems, solar thermal operating periods can even be extended to meet base-load needs. For example, the 50-MWe AndaSol solar trough power plants are designed with six to twelve hours of thermal storage, which increases annual availability by some 1,000 to 2,500 hours.