Solar panels turn sunlight into direct current (DC) electricity, an inverter converts that into the alternating current (AC) your home runs on, and your breaker panel sends it to whatever is switched on. Anything you don't use is stored in a battery or sent to the grid. That's the whole system. Here's each step in a little more detail.
A solar panel is a grid of photovoltaic cells: thin wafers of silicon treated so that incoming light knocks electrons loose, while a built-in electric field pushes them all in one direction. Electrons flowing in one direction is direct current. There are no moving parts, no fuel, and no noise.
A typical home panel today is rated between 350 and 450 watts and converts about 20% of the sunlight that hits it into electricity. The rating assumes full, direct sun, so real output rises and falls through the day with the sun's height, the weather, and the angle your panels sit at. The panels themselves bolt onto rails on your roof or a ground mount, held down by mid and end clamps.
Your appliances run on alternating current, so the DC output from the panels passes through an inverter that converts it to AC at your grid's voltage and frequency (120V and 60Hz in the US). Most home systems use either one string inverter for the whole array or a microinverter under each panel. Microinverters cost more, but a shaded or dirty panel only drags down its own output instead of the whole string's.
The AC power feeds into your breaker panel, the same box your grid connection uses, and flows to whatever is drawing power. Your home always uses the solar power first and pulls from the grid only when the panels can't keep up.
On a sunny afternoon your panels usually make more than you're using. A battery can store that surplus for the evening. Without one, it flows out to the grid, and in most US states net metering credits it against the electricity you buy back at night. Some utilities pay cash for surplus power instead, usually at a lower rate than the one they charge you.
Panels generate the most electricity when they sit perpendicular to the sun, and the sun's path through your sky depends on your latitude. So the best fixed tilt is close to your latitude, a little flatter the further you are from the equator, facing south in the northern hemisphere and north in the southern. Getting the tilt and direction right is the cheapest upgrade a system can get: the hardware is identical, only the mounting changes.
We've worked out the exact angle for every city on Earth:
Yes, at reduced output. Clouds scatter sunlight rather than block it, so panels keep producing from the diffuse light that gets through, typically 10 to 25% of their rated output under heavy cloud and more under a thin overcast.
No. Photovoltaic cells need light, so production stops at night. Your home switches to a battery if you have one, or draws from the grid, which is where net metering credits earn their keep.
A 400W panel in reasonable sun produces roughly 1.5 to 2 kWh a day, which works out to 550 to 750 kWh a year. The average US home uses about 10,500 kWh a year, so most rooftop systems pair 15 to 25 panels with the household's actual usage.
Most panels are warrantied for 25 to 30 years and lose about 0.5% of their output per year, so a panel installed today should still produce close to 90% of its original power after two decades. Inverters wear out sooner; expect to replace a string inverter after 10 to 15 years.