This is the question every solar customer asks, and the honest answer is: it depends. String inverters: cheapest per watt, longest track record, single point of failure, limited monitoring, and require a dedicated rapid shutdown solution. Best for: simple south-facing roofs with no shading, cost-sensitive customers, commercial projects with large uniform arrays.
Power optimizers (SolarEdge): each panel has a DC optimizer that does panel-level MPPT and passes a DC voltage to the string inverter. Benefits: shade tolerance, panel-level monitoring, built-in rapid shutdown compliance. The inverter is still a single point of failure. SolarEdge inverters are not interchangeable with other brands - you’re locked into their ecosystem.
Microinverters (Enphase): each panel has its own inverter. Full panel-level monitoring, maximum shade tolerance, no single point of failure (one fails, 95% of the system keeps running), inherent rapid shutdown compliance. More expensive per watt than string inverters. Enphase’s Ensemble system also supports battery backup without a separate inverter. Best for: complex roofs, customers who care about reliability, homes with batteries.