Research & Resources

You are here

Solar Cooling

Presentation
File(s): 
Download PDF

Solar electric panels can connect to an air conditioner. The solar heating panels can power an air conditioner as well. Electricity powers an air conditioner, but in reality, any source of energy can power it, which is why the energy gathered by solar heating panels can power it too.

The Importance of Solar Dehumidification

They say “It’s not the heat, it’s the humidity.” Air conditioning cools indoor air by lowering its temperature AND by removing humidity from the air. Solar dehumidification uses solar generated heat to power a dehumidifier to remove the humidity from indoor air. This reduces the amount of grid-supplied electricity needed for air conditioning.

How Solar Powered Dehumidification Works

Warm air holds more humidity than cool air, for example, a hair dryer uses heat to dry and "dehumidify" your hair.

 

Brief Introduction to Thermodynamics

  • The First Law, applied to air conditioning:

- Energy can be neither created nor destroyed. It can only change forms.

- An air conditioner doesn’t just produce “cooling,” it moves heat energy from cooler indoors to warmer outdoors

  • The Second Law, applied to air conditioning:

- Heat energy flows from a hotter object to a colder object

- An air conditioner requires energy to move heat from cooler indoors to warmer outdoors

 

How do we move the "heat ball" uphill?

It's like gravity, energy is required to move the ball up the hill. Moving heat from a cool room to the warmer outdoors is like rolling a "heat ball" uphill-it takes energy. In order to do this, we take advantage of how a liquid absorbs heat when it changes into a gas, and releases heat when it changes back to a liquid.

A can of compressed air works similarly to an air conditioner. The “air” inside is actually a liquid, when you spray air out the pressure in the can drops and some liquid evaporates into a gas. Releasing the air absorbs heat, making the can colder. This is how the evaporator in an air conditioner works.

A bike pump gets hot as you pump up a bike tire. As air is compressed, it gets hotter and its pressure gets higher. This compression requires energy, if the air were pumped to high enough pressure, and then allowed to release heat and cool off, some of the air condenses into a liquid.

We take advantage of how a liquid absorbs heat when it changes into a gas, and releases heat when it changes back to a liquid. Now we can put both processes together.

Air conditioners use mechanical energy to move the "heat ball" uphill. The expansion valve causes the warm liquid to change into a mix of cool gas and liquid by reducing the pressure of the warm liquid.

In order to power the air conditioner with solar we replace the compressor with an absorber and a heater:

The absorber is like a “liquid sponge” that absorbs gas – the solar heater “boils” the gas out of the liquid similarly to how a warm soda goes flat quickly.

The compressor is replaced by the absorber/heater, which uses heat energy.

Solar Cooling Benefits

Solar cooling, when integrated into a solar water heating system, provides both efficient hot water and air conditioning. Solar dehumidification can help reduce the load on electrical air conditioners and solar energy is available during times of peak air conditioning demand.

Sign up for the latest alerts

Get emails from SEIA and be the first to know about solar news and issues in your state.

Or, sign up for our press list.