Solar Inverters: Types, Pros, and Cons

What is a solar inverter?

Solar panels produce direct current (DC) electricity. Homes and the grid use alternating current (AC). A solar inverter converts DC → AC so your home can use the power and (for most systems) export to the grid. (U.S. DOE, U.S. EIA)

Solar inverter types (3 common options)

1) String inverter [blocked] (central inverter)

How it works

• Multiple panels are wired into one or more “strings.”
• The string(s) feed a single, centralized inverter that converts DC → AC.

Best fit

• Simple roofs (one main plane)
• Minimal shade
• Most panels face the same direction

Pros

• Lowest equipment cost
• Fewer electronics on the roof (simpler hardware layout)

Cons

• Shade or underperformance on one panel can reduce output for the whole string
• Typically less granular monitoring than module-level options

(Background on central vs module-level conversion: NREL)

2) Microinverters (one per panel)

• Each panel has its own microinverter [blocked].
• DC → AC conversion happens at the panel, so each module operates more independently. (NREL)
• Roofs with multiple orientations (east/west faces)
• Partial shade, complex roof geometry
• Homeowners who want panel-level monitoring
• Shade on one panel has less impact on others
• Easier to identify underperforming panels (panel-level visibility)
• Expansion is often simpler (add panels + microinverters)
• Higher upfront cost than a basic string inverter
• More electronics on the roof (more components overall)

(Plain-language comparison of microinverters vs string systems: EnergySage)

3) Power optimizers + string inverter (hybrid approach)

• Each panel has a DC optimizer (DC-DC electronics).
• Optimizers condition/optimize the DC, then send it to one central inverter for DC → AC conversion. (EnergySage, NREL)
• Some shade / mixed orientations
• Want module-level monitoring, but prefer a central inverter architecture
• Typically better shade tolerance than basic string inverters
• Often lower cost than full microinverter setups
• Module-level monitoring is usually available
• Still relies on a central inverter (single main conversion point)
• More components than a basic string system

What to look for when choosing an inverter

Performance and sizing

• Inverter power rating (kW AC): must match your system design.
• MPPT count and range: more MPPT channels can help when arrays face different directions.
• Commonly, PV arrays are sized so DC is greater than inverter AC (e.g., ILR > 1).
• This can increase annual energy yield, but too much oversizing increases clipping (lost power during peak conditions). (NREL ILR & clipping, PVWatts technical reference)

Efficiency (don’t look at “peak” only)

• Peak efficiency = best-case conversion.
• Weighted efficiency (often CEC or European efficiency) better reflects real operation across different power levels. (Sandia PV Performance Modeling, PVsyst explanation)

Grid-interconnection and certification (important for permits)

Look for inverters tested/certified to the standards your market expects:

• UL 1741 (safety and interconnection equipment testing for DER inverters) (UL DER testing, UL program overview)
• IEEE 1547-2018 (technical requirements for interconnecting DER with the electric power system) (IEEE)

If you’re selling into California or referencing “smart inverter” functions, the CEC Grid Support Inverter list is a practical checkpoint. (California Energy Commission)

Safety features (code-driven)

Many rooftop PV systems in the U.S. must meet rapid shutdown requirements for firefighter/electrical safety. The details depend on the code version and local authority, but it can influence inverter and MLPE choices. (NREL firefighter best practices)

Warranty and serviceability

• String inverters: often around 10–12 years
• (Always confirm the specific model terms.) (EnergySage warranty overview, Consumer Reports)

Key terms (quick definitions)

• MPP (Maximum Power Point): the operating point where a PV module/string produces its highest power for given conditions.
• MPPT (Maximum Power Point Tracking): inverter control that continuously adjusts to stay near MPP as sun/temperature change.
• Clipping: when the PV array can produce more DC power than the inverter can convert to AC at that moment, so output is limited. (NREL on ILR/clipping)
• ILR / DC:AC ratio: DC nameplate capacity divided by inverter AC rating; used to balance yield vs clipping. (PVWatts technical reference)

Practical selection shortcut

• Choose string inverter if: simple roof + little shade + lowest cost priority.
• Choose microinverters if: mixed roof faces, shade, or you want the strongest module-level independence/visibility. (NREL)
• Choose optimizers + string if: you want module-level monitoring and shade tolerance, but prefer a central inverter approach. (EnergySage)