Are microinverters better than a string inverter?

On shaded roofs or arrays spread across several roof faces, usually yes. On a single unshaded plane, a string inverter performs about as well and puts the main electronics in one box at ground level.

How long does a string inverter last?

The Department of Energy says string inverters usually last 10 to 15 years, so plan on replacing one during the life of the panels.

Do string inverters meet the rapid shutdown rule?

Yes, when paired with module-level shutdown devices, DC optimizers, or a listed PV hazard control system installed to its listing.

What are power optimizers?

DC devices mounted under each panel that manage that panel's output and handle rapid shutdown, feeding a central string inverter. They give panel-level monitoring and shade tolerance with a single inverter.

Inverters compared

Microinverters vs String Inverters

Name: AJ Long Electric
Address: 2724 Dorr Ave, Suite 102, Fairfax, VA, 22031, US
Telephone: (571) 444-6886

Microinverters convert power at each panel. A string inverter converts a whole series of panels in one box on the wall. Microinverters suit shaded or chopped-up roofs, and a string inverter suits one clean, unshaded roof plane, especially when a battery is planned on the DC side.

Get a roof study Call (571) 444-6886

Reviewed 2026-09-24

Two text-free solar scope binders comparing array, roof attachment, electrical service, and equipment photographs

Google reviews

1,463 across four profiles

Family-owned

Since 1996

Licensed and insured

VA 2705031092

Answer first

The short answer

Neither is better everywhere. The right inverter depends on shade, how many roof planes the array uses, how you want to monitor it, and whether a battery is in the plan. A third option, a string inverter with DC optimizers on each panel, sits between the two.

Shade or several roof directions: module-level electronics (microinverters or optimizers) keep one weak panel from pulling down the rest.
One unshaded plane facing south or west: a string inverter handles it well with one serviceable box at ground level.
Rapid shutdown: both can meet the National Electrical Code. String systems need added rooftop devices or a listed hazard control system to do it.
Service life: DOE says string inverters usually last 10 to 15 years, while microinverters tend to last about as long as the panels.

How each one works

Solar panels produce direct current. Your home and the grid run on alternating current. The inverter does the conversion, and where it happens is the whole difference.

String inverter: panels are wired in series into strings, and the strings run as DC to one inverter, usually mounted near the meter or in the garage. The Department of Energy describes it as one inverter converting the power produced by the entire string.
Microinverter: a small inverter under each panel converts that panel's output to AC on the roof. Rooftop wiring is AC branch circuits.
String inverter with optimizers: a DC optimizer under each panel manages that panel's output and handles rapid shutdown, while a central inverter still does the conversion.

Side by side

This table compares how the two designs behave. It says nothing about brands, and prices vary too much by roof and equipment to compare fairly in a table.

Microinverters vs string inverters
	Microinverters	String inverter
Where DC becomes AC	At each panel, on the roof	In one box, usually on an exterior wall or in the garage
Shade on one panel	Only that panel produces less	Output of the whole string can drop
Mixed roof directions	Each panel works on its own	Planes are split into separate strings or inputs
Rapid shutdown	Met at the module	Needs rooftop shutdown devices, optimizers, or a listed hazard control system
Monitoring	Panel by panel	Whole system or per string; panel level only with optimizers
Typical service life	Similar to the panels (DOE)	10 to 15 years (DOE)
Where a failure is fixed	On the roof, one unit at a time	At ground level, one box
Battery pairing	AC-coupled battery	AC-coupled, or DC-coupled with a hybrid inverter

Service life figures are from the Department of Energy's consumer guide. Individual units vary.

Shade and roof shape decide most cases

In a series string, current is limited by the weakest panels in the string. DOE notes that a string setup loses production on the whole string when one panel has a problem such as shading, while a microinverter keeps shade or damage on one panel from affecting the others.

On a Northern Virginia roof with a tree line to the east, a chimney, or panels spread across south, east, and west faces, that difference adds up across a year. On a single south-facing plane with open sky, it barely matters, and the string inverter's single serviceable box is an advantage.

Rapid shutdown under the electrical code

Section 690.12 of the National Electrical Code requires rooftop PV circuits on buildings to include a rapid shutdown function so firefighters can de-energize them. Conductors outside the array boundary, one foot from the array, must drop to 30 volts within 30 seconds. Inside the boundary, voltage must drop to 80 volts within 30 seconds, or the system must use a listed PV hazard control system.

Microinverters meet the inside-the-boundary limit because each unit stops producing when shutdown is initiated. A string system meets it with a shutdown device or optimizer under each panel, or with a listed hazard control system. Either path passes inspection when installed to its listing. What changes is how much equipment ends up on the roof.

Service life and repairs

DOE's consumer guide says string inverters usually last 10 to 15 years and may need replacement during the life of the panels, while microinverters tend to have lifetimes similar to the panels. Plan for one string inverter replacement over the life of a string system.

Repairs look different too. A failed string inverter takes the whole array offline, but the fix happens at ground level. A failed microinverter takes one panel offline, and the fix requires getting to that panel on the roof. Panel-level monitoring tells you which one.

If a battery is in the plan

Microinverter systems pair with AC-coupled batteries, which have their own inverter and connect on the AC side. String systems can do the same, or use a hybrid inverter that charges a battery directly from the panels' DC output. Both approaches can provide outage backup when the right transfer equipment is installed. The better choice depends on whether the array already exists and how much of the home you want to back up.

What we install

This guide is neutral on purpose. For what AJ Long Electric puts on most Northern Virginia roofs and why, see our microinverters page. Your written proposal names the inverter we recommend for your roof and explains the choice.

Straight answers

Questions

Are microinverters better than a string inverter?: On shaded roofs or arrays spread across several roof faces, usually yes. On a single unshaded plane, a string inverter performs about as well and puts the main electronics in one box at ground level.
How long does a string inverter last?: The Department of Energy says string inverters usually last 10 to 15 years, so plan on replacing one during the life of the panels.
Do string inverters meet the rapid shutdown rule?: Yes, when paired with module-level shutdown devices, DC optimizers, or a listed PV hazard control system installed to its listing.
What are power optimizers?: DC devices mounted under each panel that manage that panel's output and handle rapid shutdown, feeding a central string inverter. They give panel-level monitoring and shade tolerance with a single inverter.

Sources

Next step

Ask which inverter fits your roof

A free roof study looks at shade, roof planes, and your panel, and the proposal explains the inverter choice in writing.