Which technology is primarily used to heat water or air rather than directly generating electricity from sunlight?

Which technology is primarily used to heat water or air rather than directly generating electricity from sunlight?

• A. Solar thermal systems (including flat-plate and evacuated tube collectors).
• B. Solar photovoltaic panels.
• C. Wind turbines.
• D. Geothermal heat pumps.

Answer: (A)

This question contrasts technologies that heat using sunlight with those that generate electricity. Solar thermal systems capture sunlight with flat-plate or evacuated-tube collectors to heat a fluid directly. That heated fluid can transfer its heat to domestic hot water tanks or to a space-heating system, providing warm water or heated air without producing electricity. In contrast, solar photovoltaic panels convert sunlight into electricity via semiconductors, wind turbines generate electricity from kinetic energy in the wind, and geothermal heat pumps primarily transfer heat between the ground and a building for heating or cooling (using electricity only to power pumps and compressors, not to produce electricity from sunlight). Thus, solar thermal systems are the ones used mainly to heat water or air directly.

This question contrasts technologies that heat using sunlight with those that generate electricity. Solar thermal systems capture sunlight with flat-plate or evacuated-tube collectors to heat a fluid directly. That heated fluid can transfer its heat to domestic hot water tanks or to a space-heating system, providing warm water or heated air without producing electricity.

In contrast, solar photovoltaic panels convert sunlight into electricity via semiconductors, wind turbines generate electricity from kinetic energy in the wind, and geothermal heat pumps primarily transfer heat between the ground and a building for heating or cooling (using electricity only to power pumps and compressors, not to produce electricity from sunlight). Thus, solar thermal systems are the ones used mainly to heat water or air directly.