From sunlight to your outlet
Solar panels are made of photovoltaic (PV) cells, usually silicon, that convert light directly into electricity. When photons strike the cell they knock electrons loose, creating direct current (DC) power. Your home and the grid run on alternating current (AC), so every system includes an inverter that makes the conversion. That is the whole trick: light in, DC out, inverter to AC, power to your panel.
Everything else about residential solar, sizing, batteries, net metering, payback, is bookkeeping around that simple flow: how much the roof produces, how much of it you use yourself, and what the grid pays for the rest.
The parts of a system
- Panels (modules): Most residential panels sold today are in the 400 watt range. More efficient panels produce more per square foot of roof, which matters on tight roofs.
- Inverter: String inverters convert power for the whole array centrally; microinverters convert at each panel, which helps when some panels are shaded. The inverter is also the safety brain of the system.
- Racking and wiring: The unglamorous parts that determine whether the install survives 25 years of weather; workmanship warranties cover these.
- Meter: Your utility's meter tracks power flowing both directions, which is how exports get credited under your utility's policy.
- Battery (optional): Stores surplus daytime production for evening use or outages. A system works fine without one; whether it pays depends on your rates and reliability needs.
How your home and the grid share the load
A grid-tied home uses solar power first, automatically. When the panels produce more than the house is using, the surplus flows out to the grid; when the house needs more than the panels are making, the difference flows in. You never notice the switching, only the meter does.
What the grid pays for your exports is the single most misunderstood number in solar. In some territories exports earn close to the retail rate; in many others they earn a small fraction of it. That gap decides whether oversizing a system makes sense and how fast it pays for itself. Our net metering guide explains the policy landscape, and our utility pages list what 17 major utilities actually pay.
What determines how much a system produces
- Sunlight where you live: The same panel produces roughly 1,000 to 1,300 kWh per installed kW per year in cloudier regions and 1,500 to 1,900 in the Southwest. NREL's free PVWatts tool models your exact address.
- Orientation and tilt: South-facing roofs produce the most in the U.S.; east and west faces produce meaningfully less but are often still viable.
- Shading: Trees, chimneys, and neighboring buildings cost real production; a good installer quantifies this in the site survey rather than hand-waving it.
- Degradation: Panels lose roughly 0.5 to 0.8 percent of output per year. Honest 25 year projections build that in rather than assuming year-one output forever.
Put together, that is why two identical houses can need different systems. Our system size calculator turns your actual annual usage into a system size and panel count, and the payback calculator turns that into the money math with your utility's real export rate.
Nights, clouds, and outages
Panels produce nothing at night and less under clouds; the grid fills those gaps automatically, which is why annual production is the number that matters rather than any single day's. A battery can shift midday surplus into the evening, which matters most where exports earn little.
Outages surprise people: a standard grid-tied system shuts itself off when the grid goes down. That is a deliberate safety requirement so solar homes cannot energize lines that utility crews are repairing. Backup power requires specific equipment chosen up front; our guide on whether solar works during an outage covers exactly what it takes, and the battery guide covers the storage decision.
Next steps
- Pull 12 months of kWh from your utility account and run the size calculator.
- Check what your utility pays for exports on our utility pages, then run the payback math.
- Read how to choose an installer before collecting quotes, and get every quote on the same system size.
- Check incentives that actually apply to you in the incentives guide; rules changed substantially for 2026.
FAQ
How do solar panels generate electricity?
Photovoltaic cells convert sunlight into DC electricity, and an inverter converts it to the AC your home uses. Your home consumes solar first; the meter tracks whatever flows to or from the grid.
Do panels work on cloudy days?
They produce less, not nothing, and the grid fills the gap automatically. Annual production across all weather is the figure that determines the economics.
Do solar panels work in a blackout?
Standard grid-tied systems shut off during outages by design, a safety requirement protecting line workers. Backup requires a battery system with islanding capability or a limited daytime-only inverter feature.
How long do panels last?
Production warranties typically run 25 years, with output declining gradually, roughly half a percent to eight tenths of a percent per year. Inverters often need replacement sooner than panels.