How solar works
A rooftop solar system is simpler than it looks. Sunlight hits the panels, gets converted into electricity your home can use, and anything you don't use can flow back to the grid. Here's the whole chain.
1. Panels make DC electricity
Solar panels are made of photovoltaic (PV) cells — usually silicon. When sunlight hits them, it knocks electrons loose and creates a flow of direct current (DC) electricity. More sunlight (and cooler, clear conditions) means more output. Panels are rated in watts; a typical home system is a collection of panels totaling somewhere around 5–12 kilowatts (kW).
2. An inverter converts it to AC
Your home runs on alternating current (AC), so the DC from the panels passes through an inverter that converts it. There are two common designs:
- String inverters — one central unit for the whole array. Cost-effective, but shading on one panel can drag down the string.
- Microinverters / power optimizers — one per panel, so each panel performs independently. Better for roofs with shading or multiple angles.
3. Your home uses it first
The AC electricity feeds your home's electrical panel and powers whatever is running right now — lights, appliances, the AC. Solar is used on-site first because that's the cheapest electricity you'll ever have.
4. Extra power goes to the grid (net metering)
When your panels make more than you're using (a sunny afternoon), the surplus flows back onto the utility grid. Under net metering, your meter effectively runs backward and you earn credits you can use later — at night, or on cloudy days, when you pull power from the grid as normal. Net-metering rules vary by state and utility, and they have a big effect on your savings.
What about night and cloudy days?
Standard grid-tied systems simply pull from the grid when the sun isn't out — the net-metering credits you banked earlier offset that. If you want power during outages, you'll need a battery; a normal grid-tied system shuts off during a blackout for safety unless it has battery backup.
The main system components
- Panels — capture sunlight
- Inverter — DC to AC
- Racking/mounting — secures panels to roof or ground
- Monitoring — an app showing production
- Battery (optional) — stores power for night use or backup