Solar Cell and Photovoltaic Operation
A solar cell is a large-area p-n junction operated in photovoltaic mode. Its terminal power is VI, and conversion efficiency is electrical output power divided by incident optical power.
Why this shows up in the exam
Photovoltaic energy conversion · Comparing photodiodes and solar cells · Calculating output power and efficiency
Learn the idea
A solar cell uses junction-generated carriers to deliver electrical power without an external bias. Light creates electron-hole pairs, and the built-in junction field separates them. Connected to a load, the cell supplies current and converts part of the incident optical energy into electrical energy.
🧠 Memory hook: Solar cell supplies power with no external bias.
Get this one clearly and it pays off every single time it shows up in the paper. 🎯
Formulas & facts to keep ready
- P_out = V I — electrical output power at an operating point
- eta = P_out / P_in — solar-cell energy conversion efficiency
How to approach it
- 1Look for photovoltaic or no-external-bias operation
- 2Compute incident power from intensity times area when needed
- 3Use the stated operating voltage and current for output power
Common slip-ups that cost marks
- •Saying a solar cell needs forward bias to work
- •Confusing maximum current with maximum-power operation
- •Ignoring illuminated junction area in incident power
🌟 That's the whole idea — you've got this. Try the practice set below; every question you attempt makes it stick a little harder.
Original chapter practice
Original questions for this chapter, not past-paper questions or an exact mapping to this individual concept.
A transistor has common-emitter current gain beta = 50. If base current is 20 microA, find collector current.
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