Microinverter Calculator

Microinverters or string inverter — which is right for your roof? Enter your setup and shading — get the comparison.

Your solar system

Number of panels?

panels

Panel wattage?

Shading level?

Peak sun hours?

hrs/day

Microinverter vs string inverter comparison

8.0 kW system

Microinverter equipment + install premium$4,400

String inverter equipment + install$2,700

Microinverter cost premium$1,700

Annual production — microinverter11,074 kWh

Annual production — string inverter10,170 kWh

Annual production gain904 kWh (+$136/yr value)

Premium payback period12.5 years

Shading: Moderate shading — microinverters recover ~8% more production

Recommendation: Moderate shading is the sweet spot for microinverters. The production gain justifies the cost premium over the system lifetime, plus you get panel-level monitoring.

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How to Use This Calculator

Enter your system details

Start with the number of panels and their wattage. These determine your system size and the total number of microinverter units needed (one per panel). Enter your location's peak sun hours to get accurate annual production estimates for both inverter types.

Set the shading level

The shading level is the key variable in this comparison. Shading is the primary reason to choose microinverters over string inverters. Select the option that best describes your installation — none, light (edge shading at certain times), moderate (chimney, dormer, or nearby tree), or heavy (significant cover). The production comparison updates based on how shading affects each inverter type differently.

Understand the comparison

The result shows equipment + installation cost for each option, annual production difference, the annual dollar value of extra production, and how many years the production gain takes to offset the microinverter premium.

The Formula

Annual production = System kW × Peak sun hours × 0.86 × 365 Microinverter production = Annual production × (1 - micro shading loss %) String inverter production = Annual production × (1 - string shading loss %) Production gain = Microinverter production - String production Annual value = Production gain × electricity rate Payback = Cost premium ÷ Annual value gain

The critical difference: in a string inverter system, all panels in a string operate at the current of the weakest (most shaded) panel. One shaded panel can reduce the entire string's output by 30-50%. Microinverters decouple each panel — a shaded panel at 20% output doesn't affect neighboring panels. This is called the "Christmas light" problem of string inverters.

Example

Complex roof with chimney — 20 panels in Denver

A Denver homeowner has a 20-panel, 8 kW system. A chimney creates moderate shading on 3 panels for 2-3 hours each afternoon. Denver gets 5.0 peak sun hours.

System size20 × 400W = 8 kW

ShadingModerate (chimney)

Peak sun hours5.0 hrs/day

Results

Microinverter cost premium~$4,400

String: annual production11,270 kWh

Micro: annual production12,155 kWh

Annual production gain885 kWh (+$133/yr)

Premium payback~33 years

The math suggests the premium takes too long to pay back via production gain alone. However, microinverters have additional value beyond production: panel-level monitoring to detect failures, no single point of failure, easier system expansion, and 25-year warranties vs 10-year for string inverters. Many homeowners with moderate shading choose power optimizers (SolarEdge) as a cost-effective middle ground — near microinverter production with near-string-inverter pricing.

FAQ

When are microinverters worth the extra cost? ▼

Microinverters are clearly worth it when: panels face multiple roof directions (east/west/south mix), heavy shading is unavoidable, you want panel-level monitoring, or you're installing on a complex roof shape. For a simple south-facing roof with no shading, the economics rarely justify the 15-25% cost premium. Many installers recommend microinverters for any system with moderate or greater shading, or where future expansion is planned.

What is the difference between microinverters and power optimizers? ▼

Microinverters convert DC to AC at each panel — no central inverter needed. Power optimizers (like SolarEdge) optimize the DC output of each panel individually but feed into a central string inverter for the AC conversion. Both solve the shading/mismatch problem, but power optimizers typically cost 10-15% less than a full microinverter system while providing most of the production benefits. The tradeoff: power optimizers still have a central inverter that can fail.

Do microinverters really last 25 years? ▼

Enphase and other major brands offer 25-year warranties, which is 2.5× longer than typical 10-year string inverter warranties. Whether they achieve the warranty period in practice is debated — Enphase's IQ series has strong reliability data. The distributed architecture also means a single failure only affects one panel (not the whole system). Replacing one microinverter costs $150-250 versus replacing a central string inverter at $1,500-3,000.

Can I mix microinverters with a string inverter? ▼

Yes — this is a practical approach for roofs with mixed shading. Put the shaded panels on microinverters and the unshaded panels on a string inverter. The AC outputs connect to the same service panel. This optimizes cost: you only pay the microinverter premium where shading actually exists. However, confirm with your installer that your utility's interconnection rules allow mixed inverter types on one system.