A string inverter is a device used in solar power systems to convert direct current (DC) electricity generated by solar panels into alternating current (AC) electricity, which can be used in homes and businesses. It connects multiple solar panels in a series, or "string," allowing them to work together efficiently. String inverters are popular for residential installations due to their simplicity and cost-effectiveness. They are typically installed on a wall near the solar panels and can be monitored for performance. However, their efficiency can be affected by shading or differences in panel performance, which may require additional solutions like microinverters for optimal energy production.