What is a solar panel?

Panels bolt to aluminum racking anchored through the roof deck into rafters, with flashed penetrations that should outlive the shingles beneath them. South-facing at a 15 to 40 degree tilt is the strongest orientation in the U.S.; a west-facing array gives up some annual production but delivers it during expensive late-afternoon hours. Conduit carries the DC down to the inverter and back into the house through a dedicated breaker in the main panel. Each panel also carries a rapid shutdown device that drops roof voltage to a safe level when the system is switched off.

Output falls slowly and predictably, roughly 0.5% a year, which is why 25 year performance warranties commonly guarantee 80 to 90% of original output at the end of the term. Panels rarely die; they get held back. Shade is the biggest thief, and one branch across a single panel can drag down an entire string. Soiling comes next: dust, pollen, pine sap, and bird droppings can cost 5–20% of production in a region that goes months without rain, and that adds up in unbilled kilowatt hours. Real hardware failures are rarer, mostly hail cracks, delamination at the edge seal, or a burned-out bypass diode in a junction box, which shows up as one panel reading dead in the app.

Rinse the array once or twice a year with a hose and a soft brush on a cool overcast morning, more often under trees or near farmland and highways; the cleaning interval covers the regional differences. Never pressure wash, never put hot water on cold glass, and never step on a panel. Trim branches before they throw a shadow at 3 p.m. in July, and check flashing and racking bolts each spring along with the rest of the solar maintenance checklist. Kept that way, panels reach 25–30 years and usually keep producing past the warranty.