Shade cloth is a woven material that blocks most sunlight while letting some through. It is rated by the amount of light blocked, so 90% shade cloth blocks 90% of the light. Shadecloth is one option for passive cooling to help keep direct sun off those who need to park in full sun to make solar power.
Compared to tarps and awnings, a shade cloth:
- can be lighter weight
- is less affected by wind because some can pass through
- allows more breeze
- is quieter
- is generally more expensive
- is somewhat more bulky due to woven material
For additional temperature reduction, reflective aluminum shade cloth reflects a lot of sunlight back up to the sky while still allowing light through. If you don't have things on your roof like solar panels or vents, you can simply lay the cloth over your entire vehicle while parked to significantly reduce the temperature inside. Aluminet is one brand name that may be higher quality.