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Solar 101

How solar works

How a PV cell makes electricity

Under the sun, a photovoltaic cell acts as a photosensitive diode that instantaneously converts light – but not heat – into electricity.

Cell Layers

A top, phosphorus-diffused silicon layer carries free electrons – un-anchored particles with negative charges. A thicker, boron doped bottom layer contains holes, or absences of electrons, that also can move freely. In effect, precise manufacturing has instilled an electronic imbalance between the two layers.

Sun Activation

  1. Photons bombard and penetrate the cell.
  2. They activate electrons, knocking them loose in both silicon layers. Some electrons in the bottom layer sling-shot to the top of the cell.
  3. These electrons flow into metal contacts as electricity, moving into a circuit throughout a 60-cell module.
  4. Electrons flow back into the cell via a solid contact layer at the bottom, creating a closed loop or circuit.

Powering Homes and Businesses with Solar

Current leaving a module, or array of modules, passes through a wire conduit leading to an inverter. This device, about the shape of a waffle iron, inverts direct current, which flows with a fixed current and voltage, into alternating current, which flows with oscillating current and voltage. Appliances worldwide operate on AC.

From the inverter, the solar-generated power feeds into circuitry of a household, business or power plant and onto the region’s electrical grid. A remote, or independent, power system also can form a self-contained circuit without connecting to the grid. The off-grid system, however, requires batteries to store power for times, such as night, when modules do not capture enough light energy from the sun.