PV Array

What photovoltaic means

Photovoltaic comes from “photo” (light) and “voltaic” (producing voltage). The photovoltaic effect - discovered by French physicist Edmond Becquerel in 1839 - is the generation of voltage and current in a material when exposed to light.

In a silicon solar cell, photons from sunlight knock electrons loose from their silicon atoms. These free electrons flow through an external circuit, creating current. The cell structure and electrical contacts direct this flow to produce useful DC power.

Array vs panel vs system

The terminology can be confused in casual use:

• Cell: The fundamental unit - a wafer of silicon generating a fraction of a volt at low current
• Module (panel): Multiple cells wired together and encapsulated in glass and polymer, producing 400–550W
• String: Multiple panels wired in series, producing higher voltage
• Array: The complete collection of panels installed - one or multiple strings - producing the system’s total DC output
• System: The array plus the inverter, wiring, mounting, monitoring, and connections to the home and grid

When someone says “my solar array” they typically mean all the panels on their roof.

Array configuration decisions

Orientation. In Australia, north-facing maximises annual energy yield. East-facing produces more in the morning, west-facing more in the afternoon. East-west split arrays are increasingly installed to spread generation more evenly across the day and reduce lunchtime export.

Tilt. Optimal tilt equals roughly the site’s latitude minus 5–10°. Sydney (latitude 34°S) ideally tilts panels at 24–29°. Most roof pitches in Australia (15–25°) are close enough to optimal that tilt isn’t a major issue.

Shading. Even partial shading of one panel affects the string it’s in with a standard string inverter. Array layout should be designed to keep shading off the panels, or panel-level electronics should be specified for shaded roofs.

Ground-mounted arrays

Not all arrays are roof-mounted. Ground-mount systems on larger properties allow optimal orientation and tilt, easier cleaning, and better cooling (panels perform better when air can circulate underneath). They require significantly more racking and civil work and are more common on rural properties with available land and no suitable roof orientation.