Project Sol

INSIDE PV SYSTEMS

A simple photovoltaic system What goes on inside a photovoltaic (PV) cell? How can it turn sunlight into electricity?

Find out on this virtual tour of a PV cell. Watch photons, atoms, and electrons interact to produce an electrical current!

Begin your journey

To a silicon sandwich. This is the working part of the PV cell.

The silicon atoms are arranged in a cubic pattern. The top "n-layer" of silicon has electrons to spare. The bottom "p-layer" is missing electrons. It has electron holes.

The cell has a positive side and a negative side, just like a battery. A permanent electrical field called a 'junction' separates the two layers. Electrons can flow through the junction from the p-layer to the n-layer, but not the other way.

When a photon of sunlight hits the n-layer, it knocks an electron free. These electrons stay in the n-layer.

When a photon of sunlight hits an atom in the p-layer, it knocks an electron free. These electrons easily cross into the n-layer. Extra electrons accumulate in the n-layer. A metal wire brings these electrons into a DC electric circuit.

Electrons flow from the negative side of the cell, through the circuit, and reenter the cell at the positive side. As long as sunlight is coming in, the electrical current will keep flowing.

the current delivers electrical energy to a load--for instance, a light bulb we put in the circuit.

If we put a more efficient fluorescent bulb in our circuit, the same amount of power will give us five times as much light.

Any power we don't use can go towards recharging a battery. The battery will push electrons through a circuit after the sun has set. What factors affect the performance of PV systems? Find out in Solar Data.