Which statement best defines active solar energy systems?

Which statement best defines active solar energy systems?

• A. Solar energy systems that absorb heat directly from the sun without mechanical devices
• B. Solar energy systems that collect energy through the use of mechanical devices such as photovoltaic cells or flat-plate collectors
• C. Solar energy systems that rely on wind or geothermal sources
• D. Solar energy systems that store heat in thermal reservoirs

Answer: (B)

Active solar energy systems rely on mechanical devices to collect or convert sunlight into usable energy. This means using components like photovoltaic cells that directly convert sunlight to electricity or flat-plate collectors that heat a fluid which is moved by pumps to transfer the heat. This mechanical aspect—having moving parts or devices that capture and move energy—sets active systems apart from passive designs, which rely on building materials and architecture to capture heat without such equipment. The other statements don’t define active collection: absorbing heat directly without devices describes passive solar behavior; involving wind or geothermal isn’t solar energy; and storing heat in a thermal reservoir is about storage, which can be part of an active system but doesn’t define it.

Active solar energy systems rely on mechanical devices to collect or convert sunlight into usable energy. This means using components like photovoltaic cells that directly convert sunlight to electricity or flat-plate collectors that heat a fluid which is moved by pumps to transfer the heat. This mechanical aspect—having moving parts or devices that capture and move energy—sets active systems apart from passive designs, which rely on building materials and architecture to capture heat without such equipment. The other statements don’t define active collection: absorbing heat directly without devices describes passive solar behavior; involving wind or geothermal isn’t solar energy; and storing heat in a thermal reservoir is about storage, which can be part of an active system but doesn’t define it.