Microinverter vs String Inverter — Which Is Better?

Microinverters — panel-level AC

Each module gets its own inverter. Partial shade on one panel does not drag an entire string to the weakest cell’s current. Monitoring is granular, module swaps are surgical, and rapid-shutdown compliance is usually straightforward.

Cost: plan roughly +$0.20–$0.40/W versus a basic string design. You are paying for more electronics on a hot roof — failure modes become many small units instead of one big box.

• Best for complex roofs, dormers, chimneys, or tree shade
• Per-panel monitoring and easier expansion later
• 25-year product warranties common on premium micros

String inverters (+ optimizers)

A single (or dual) inverter on the wall is cheaper on clean, south-facing rectangles. DC optimizers recover much of the shade penalty while keeping central conversion. The tradeoff: the inverter is a single mid-life replacement item (~10–15 years for many models), and string design needs careful shading analysis.

• Lower upfront $/W on open roofs
• One visible equipment pad / garage wall unit
• Optimizer hybrids for mixed shade without full micro premium

How MySunROI would choose on a quote desk

If the site survey shows >10% annual shade loss on a string model, micros or optimizers usually win the NPV even at a higher $/W. If the roof is a clean plane with no obstructions, a quality string bid at $0.30/W less often wins. Demand the shade report either way — topology talk without irradiance math is theater.