Explain why solar cells and tidal barrages are both classified as renewable energy resources, and describe one key difference in how each produces electricity.

OCR GCSE Physics A: Gateway Science (J249) — P6.2 Producing electricity · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

A town council is considering replacing its ageing coal-fired power station with either a solar farm or a tidal barrage. Both options have been described as renewable energy resources.

Model answer (4 marks)

Solar cells and tidal barrages are both renewable because their energy sources – sunlight and tidal movement – are continually replenished and will not be exhausted. Solar cells (photovoltaic cells) convert sunlight directly into electricity by the photovoltaic effect, so no turbine is required. A tidal barrage uses the kinetic energy of moving water to turn turbines, which then generate electricity.

Examiner tips

Use the definition of renewable – ‘continually replenished’ – to gain the first two marks.
Mention the specific source for each (sunlight, tidal movement).
Explain the key difference: solar cells generate electricity directly, while tidal barrages use turbines.
Keep the answer concise and use the exact terminology from the mark scheme.

Common mistakes

Confusing solar cells with solar thermal panels – both are renewable but the question asks about photovoltaic cells.
Saying that solar cells use a turbine – they do not.
Failing to state that tidal energy is produced by turning turbines – missing the key difference.

Mark scheme (4 marks)

A renewable energy resource can be replenished whilst it is being used (accept: is not used up / is not finite).
Both solar and tidal qualify because their energy source (sunlight / tidal movement) is continuously restored / will not run out.
Solar cells (photovoltaic cells) directly produce electricity from the Sun's energy (no turbine required).
A tidal barrage uses the wave / tidal action of water to directly turn turbines, which generate electricity (whereas solar cells require no turbine).

Key terms in this question

renewable energy resource · solar cells · tidal barrage