Solar 101: how a rooftop system actually works

Before comparing quotes or credits, it helps to know what a rooftop system actually is: four hardware stages and three billing effects. This guide walks the whole chain in plain English — no jargon required.

The four hardware stages

Panels convert sunlight into direct current (DC) electricity. A residential module is typically rated 350–450 W DC; panels are wired in strings or as individual optimizers.
Racking holds the panels to the roof — usually aluminum rails flashed at the attachments so the roof stays sealed. Ground-mounts and carports use steel posts instead.
Inverters convert DC into the alternating current (AC) your house and the grid use. Options: one string inverter (whole array), microinverters (per panel), or power optimizers paired with a central inverter.
Meter and interconnection — the utility installs or programs a bidirectional meter so home consumption and exported solar power are tracked separately.

The three billing effects

Self-consumption — solar generation used in the house at the moment it is produced replaces grid power at your full retail rate. This is the most valuable kWh your system makes.
Export credits — generation not used at the moment either flows to the grid (credited) or is stored in a battery for later. How much the credit is worth depends on your state's export rule — the difference between net metering and net billing.
Fixed charges — most homes still pay a delivery or customer charge each month; solar reduces the energy portion of the bill, not the fixed portion.

The practical consequence: a system sized near ~100% of your annual usage is the usual planning target, because export credit timing and rates are what the meter really decides. Each state guide documents the export rule you will actually get, and the estimator runs the bill math.

Sources

U.S. DOE, Office of Energy Efficiency & Renewable Energy — solar rooftop technology explainer (components and interconnection) — accessed 2026-08-08.
U.S. EIA — solar explained: photovoltaic systems and net metering — accessed 2026-08-08.