dehumidifier is recommended for indoor use. It also cannot compete with the tumble dryer's capacity to dry multiple loads of wet clothing in a single day. Solar clothes dryer The solar dryer is a box-shaped stationary construction which encloses a second compartment where the clothes are held. It uses the sun's heat without direct sunlight reaching the clothes. Alternatively, a solar heating box may be used to heat air that is driven through a conventional tumbler dryer. Microwave dryers Japanese manufacturers have developed highly efficient clothes dryers that use microwave radiation to dry the clothes (though a vast majority of Japanese air dry their laundry). Most of the drying is done using microwaves to evaporate the water, but the final drying is done by convection heating, to avoid problems of arcing with metal pieces in the laundry. There are a number of advantages: shorter drying times (25% less), energy savings (17–25% less), and lower drying temperatures. Some analysts think that the arcing and fabric damage is a factor preventing microwave dryers from being developed for the US market. Ultrasonic dryers Ultrasonic dryers use high-frequency signals to drive piezoelectric actuators in order to mechanically shake the clothes, releasing water in the form of a mist which is then removed from the drum. They have the potential to significantly cut energy consumption while needing only one-third of the time needed by a conventional electric dryer for a given load. They also do not have the same issues related with lint in most other types of dryers. Hybrid dryers Some manufacturers, like LG Electronics and Whirlpool, have introduced hybrid dryers, that offer the user the option of using either a heat pump or a traditional electric heating element for drying the user's clothes. Hybrid dryers can also use a heat pump and a heating element at the same time to dry clothes faster. Static electricity Clothes dryers can cause static cling, through the triboelectric effect. This can be a minor nuisance and is often a symptom of over-drying textiles to an extremely low humidity level. Fabric conditioners and dryer sheets are marketed to correct this condition. History A hand-cranked clothes dryer was created in 1800 by M. Pochon from France. Henry W. Altorfer invented and patented an electric clothes dryer in 1937. J. Ross Moore, an inventor from North Dakota, developed designs for automatic clothes dryers and published his design for an electrically