The most common domestic application of solar heating is to provide hot water for sanitary use, normally at a temperature of 45º. The new legislation coming into effect in Spain is designed to provide 60-75% of domestic hot water requirements using solar energy. The solar panels for this type of system are heated by the sun's rays and use a fluid to remove the heat from the collector surface and transport it to a “heat store”. The heat can then be used throughout the day to meet the needs of the system users.