String inverters are the most common inverter type for commercial solar PV installations. Panels are wired in series strings, with each string connected to one or more MPPT (Maximum Power Point Tracker) inputs on the inverter. String inverters are cost-effective, well-proven in commercial service, and straightforward to maintain.
The performance of a string inverter is sensitive to shading and mismatch: if one panel in a string is shaded, the output of the entire string reduces to the level of the shaded panel. For roofs with significant shading or complex orientations, module-level power electronics such as optimisers or microinverters may be preferred to mitigate mismatch losses.