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A solar cell's route from light to electricity

Shining sunlight onto a piece of silicon is only the first step in making solar power. When incoming photons knock electrons loose inside the semiconductor, an internal electric field built into the solar cell's layers must separate those charges and guide them into an external circuit before they simply recombine.

4–5 min

Questions you could explore

  • What happens between absorbing light and delivering current?
  • Why does absorbing more light not automatically mean collecting all its energy?

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How can a heat pump deliver more heat than its electricity input?

Energy4–5 minA heating device seems to promise something impossible when its heat output exceeds the electricity it uses. A heat pump's energy account includes another input: heat moved from its surroundings.

How does a wind turbine turn moving air into electricity?

Energy3–5 minA turbine's blades are only the visible beginning of the journey from wind to electricity. Their rotation drives a generator, though the machinery connecting those parts differs between turbine designs.

Energy

Why would an electricity system pump water uphill?

Water raised to an upper reservoir stores energy that can later be recovered through a turbine and generator. Pumped storage shifts electricity use across time, with losses between charging and discharge.

4–6 min

Why would an electricity system pump water uphill?

Energy4–6 minWater raised to an upper reservoir stores energy that can later be recovered through a turbine and generator. Pumped storage shifts electricity use across time, with losses between charging and discharge.

A solar cell's route from light to electricity | Speech Topic | speaking.app