String inverter, microinverter or optimizer: a practical comparison

September 29, 2026 · 5 min read · Danilo Nascimento

Compare the three conversion architectures: how each handles shade, multi-slope roofs, monitoring, cost and expansion. See the difference in the calculator.

Three architectures, one question

Every solar system converts the panels’ direct current into alternating current. The question is where that happens: in a single inverter for the whole string, with extra electronics on each panel, or in a small inverter behind each panel.

String inverter

One inverter for the whole string

String
Inverter
Board

Lowest cost
Few components on the roof
A single device to maintain

Optimizers

DC electronics on each panel

Panel + optimizer
Inverter
Board

Each panel can work at its own best point
Per-panel monitoring
There is still a central inverter

Microinverters

AC conversion on each panel

Panel + micro
Board

No high-voltage DC on the roof
Expansion panel by panel
A faulty panel does not drag the others down

The difference is where the direct current becomes alternating.

What changes with shade and roof shape

In a plain string, all the panels share the same current, and the weakest one drags the others down. Optimizers and microinverters treat each panel independently, so they can reduce losses when there is partial shade or roofs with several orientations; the gain depends on the shade and the architecture. The article on shading explains the bypass diodes and the numbers.

1
Shade is rare or on few panels
A plain string, with bypass, is usually enough. Splitting the roof slopes into separate strings helps.
2
Shade is frequent or on many panels
Optimizers or microinverters recover part of the energy a plain string would lose.
3
Several slopes and orientations
An inverter with several MPPT inputs usually handles many cases. With many small slopes, the microinverter is more flexible.

Compare the shade loss

A string of 10 panels with some of them shaded: see, in this simplified model, how much the plain string loses and how much is recovered with electronics on each panel.

A practical comparison

	String	Optimizer	Microinverter
Upfront cost	Lowest	Medium	Highest
Partial shade	Tends to lose more	Tends to lose less	Tends to lose less
Several orientations	Needs separate MPPTs	Usually handles it	Usually handles it
Per-panel monitoring	String only	Yes	Yes
Parts on the roof	Panels only	One more per panel	One more per panel
Future expansion	Limited by the inverter	Limited by the inverter	Panel by panel

✓ advantage · ◐ depends on the case · ✗ point of attention

How to decide

Is there partial shade you cannot avoid?

Yes → Optimizers or microinvertersThey recover part of the lost energy
Does the roof have many slopes, in different orientations?

Yes → Microinverters or an inverter with several MPPTsEach group works at its own pace
Do you plan to expand the system bit by bit?

Yes → MicroinvertersEach new panel is independent
String inverterSimple, cheap and enough when the roof is clear and uniform

Start with your roof’s case, from top to bottom.

Draw it in Editor Solar

This is Editor Solar itself, already loaded with the diagram from this article. Move the equipment, edit labels, connect new parts and export to PNG, SVG or PDF. It is free and runs right in your browser.

Two architectures on the same board: panels with optimizers feeding a string inverter, and panels with microinverters that deliver AC directly.

Try it: Mark on the diagram which panels get shade and draw an alternative with microinverters: connect their AC outputs to the appropriate AC circuit and remove the string inverter from that path. Compare the two architectures and note which protections each one needs.

Ready-made templates: see all diagram templates

Open this diagram in the full editor ↗

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