Solar powered air conditioning is probably the most logical thing on earth. Homes use air conditioning when it is hot out, and solar power works best when the sun is shining bright. Because air conditioners put the largest load on the power grid, we can save a lot of money and energy by switching to solar powered air conditioners. These air conditioners can also be used when it is not a bright sunny day, because they come equipped with batteries that last 12-24 hours and are charged by the sunlight.

## How do they work?

There are several ways to provide Solar powered air conditioners. One popular method is to use solar panels placed on or around the building being cooled (obviously) that will heat up water and turn it to gas form. The product, water vapor, is then used to take the heat from the air and cool down the ventilation air flowing into the building. The air that is produced is very cool and dry, thus it more efficiently cools down the body.

A second system will use Photovoltaic Solar power to run air conditioners that are powered by photovoltaic panels placed on or around the building being cooled to generate electricity to run a conventional electric air conditioner. Energy can be stored by returning electricity to the grid with a grid inertied inverter, or by battery storage, however about 20% of the energy is lost with batteries due to the chemical in-efficiency of the battery involved.

The third system discussed here would use ammonia and water that are inside sealed steel piping and steel chambers. When these two chemicals where mixed together way back in the 1880's, they created a cooling effect. This is used to chill water, that is pumped into the air handler, to absorb heat from the space to be cooled. With unlimited size tanks of ammonia and water, there would be no need to separate the two chemicals, but to recycle the chemicals, they are heated by 250F hot water, and this will separate the ammonia and water used in the cooling system. Evacuated Tube Solar panels heat up water to 200+F, that is used to separate the ammonia water mixture, then once the two are separated into two streams, they can be re-combined in the evaporator to re-start the water chilling process.

A fourth hybrid way to power the conventional system is with wind energy, that is air heated by the sun will cause wind movements, and this can be collected with a horizontal or vertical axis wind turbine. This energy is stored in batteries or the grid until needed, then used to run a conventional cooling system.

## Any harmful effects?

There are no harmful effects or waste products of a solar powered air conditioner. They use water as a refrigerant instead of some other harmful coolants. Also, because they are solar powered they are independent of the power grid and conserve energy by eliminating heat and friction produced by the wires of a conventional air conditioner.

## How much does it cost?

Cost is the major problem with solar powered air conditioning. The price of a unit made by SolCool can range anywhere from $2,600 to$3,000. As you get into the larger units, the prices can climb to more than \$30,000. But the money you save over time is well worth it. (this needs quantification)

## What climate is best?

These air conditioners work best in sunny, dry climates such as the Southwestern United States or Northern Africa. Because they can also be run on battery power, solar powered AC can also be used in wetter, more cloudy climates but humidity tends to shorten the life of this appliance so areas with large amounts of precipitation are not ideal. Most chinese units are in the market at a fraction of price, you may check the prices and equipments before making a high ticket purchase.

## Discussion

Solar powered air conditioning was discussed some time in the 1980s in Popular Science magazine. A dehumidifierW featuring some kind of desiccant (water absorbing material) removes moisture from the air. The air is then passed by water, which evaporates, cooling the air and restoring moisture. The desiccant is then exposed to the sun, drying it and enabling it to be used again. (For example, it may be in the form of a rotating wheel, half in the air stream, half drying at any one time.)

This assumes that when the moisture is first absorbed by the desiccant, the latent heat of vaporisation is released into the desiccant rather than into the air. The desiccant is also not cooled down afterwards, but actually heated up by drying it in the sun. So the dried desiccant would act as a heat source. Is it possible to surmount these problems? Have such systems been built - or can they be? If so, how cost-effective are they?[expansion needed]