How a Photovoltaic Cell Turns Sunlight into Electricity

Sunlight is made of photons

Sunlight is made up of photons, or particles of solar energy. Photons contain various amounts of energy, corresponding to the different wavelengths of the solar spectrum. That spread of energies is why a solar cell responds differently to different light conditions — it is not one uniform input.

Only absorbed photons do work

When photons strike a PV cell they may be reflected, absorbed, or pass right through. Only the absorbed photons generate electricity. This is why cell quality, glass and lamination matter: low iron tempered glass and EVA lamination exist to get as many photons as possible into the cell rather than bouncing them back off the surface.

Energy transfers to an electron

When a photon is absorbed, its energy is transferred to an electron in an atom of the PV cell — which is a semiconductor. That transfer is the whole mechanism. Everything else in a module is packaging designed to keep that process running for twenty-five years.

What this means when you specify a module

The figures on our datasheets follow from this. Module efficiency, quoted from 6.5 % on the 5 W panel to 13.10 % on the 45 W BSM045P, is the fraction of incident energy the module converts. Operating temperature range, −40 °C to +85 °C across the range, tells you where the cell still behaves predictably. And the air gap our mounts hold under a panel exists because a hot cell converts less.