Solar panels convert sunlight into electricity through the photovoltaic effect. Sunlight knocks electrons loose in the panel's silicon cells, creating direct current (DC). An inverter then converts that DC into the alternating current (AC) your home uses. Surplus power flows to a battery or back to the grid.

A string inverter converts the combined DC output of many panels at one central point, so shade on one panel reduces the whole string. A microinverter sits on each panel and converts DC to AC individually, so each panel works independently. String inverters cost less; microinverters offer panel-level monitoring and longer warranties.

A grid-tied solar system without a battery shuts down automatically when the grid loses power. This is a code-required safety feature called anti-islanding protection, which prevents the system from feeding electricity into lines that utility workers may be repairing. Battery storage with an automatic transfer switch keeps power on during an outage.

Four factors drive real-world solar production: panel direction, roof angle and tilt, season and climate, and shading. South-facing panels produce the most in the northern hemisphere. Winter output can fall 30 to 60 percent below summer, and very hot days also reduce output because panels are tested at 25 degrees Celsius.

For most homes, whole-home backup is not realistic from a single battery. A typical 10 to 13.5 kWh residential battery powers essential loads, such as a refrigerator, lights, and medical devices, for 8 to 24 hours. Critical-load backup, which prioritizes the most important circuits, is the practical approach for most homeowners.

Net metering is a utility billing arrangement where excess solar electricity exported to the grid earns credits that offset future consumption charges. Programs vary by state and utility, and the credit structure directly affects a solar system's return on investment.