Photo quiz: Gear for green buildings

The answer to the previous question is A. On the left are two flat-panel solar collectors for heating hot water. Tubes are another solar thermal technology. The three panels to the right are solar photovoltaic modules that convert sunlight to electricity.

Next question: What is this device?

A. A tank for a domestic solar hot water system.

B. A Tesla coil for generating high-voltage electricity.

Answer and new question on next page.

Photo by Martin LaMonica/CNET

Caption by Martin LaMonica