What is the core difference between the two?

A microinverter converts the output of a single panel at the panel itself. A string inverter is one central unit that converts the combined output of several panels wired together in a series 'string'. Both turn DC into mains-compatible AC; the difference is where that conversion happens.

Which copes better with shade?

Microinverters generally cope better. Because each panel is converted on its own, shade on one panel mainly affects that panel. With a simple string inverter, a shaded or underperforming panel can pull down the output of the whole string it shares.

Why do plug-in solar kits use microinverters?

A plug-in system is usually just one or two panels feeding your home through a single connection. A small microinverter, built into or attached to the panel, produces mains-synchronised AC directly, which suits that simple, movable design far better than a separate central inverter wired to a string.

Does this change whether plug-in solar is legal?

No. The inverter type does not affect the legal position. Plug-in solar is not currently legal to sell, supply or use in the UK, and a Government consultation is open until 30 June 2026.

Guide

Microinverter vs string inverter

A focused comparison of the two ways to convert solar electricity — per-panel and central — and why small plug-in systems use microinverters.

Written and edited by Christopher Panteli

Last reviewed 19 June 2026

Christopher is the founder and editor of MyPlugInSolar. He oversees the site’s research standards, data tools and editorial process. He is not an electrician or solar installer, and specialist technical claims are sourced from official documentation or reviewed by appropriately qualified professionals.

A solar panel produces direct current (DC), but your home runs on alternating current (AC). Something has to convert one to the other, and there are two common approaches: a microinverter at each panel, or a single string inverter for a group of panels. This guide compares the two head to head and explains why small plug-in systems use microinverters. For a fuller introduction to microinverters on their own, see the broader microinverters guide.

One point first: plug-in solar cannot currently be legally sold, supplied or used in the UK, whatever inverter it uses. A Government consultation that could change this is open until 30 June 2026. We cover the detail on the UK legal status page.

Per-panel conversion versus a central inverter

With microinverters, each panel has its own small inverter, often built into or fixed to the panel. Conversion happens independently, panel by panel. With a string inverter, several panels are wired together in series — a “string” — and their combined DC output runs to one central unit that does all the conversion in a single place.

Neither is simply better than the other; they suit different situations. The practical differences come from where the conversion sits and how many panels share it.

How they compare

A general comparison — exact behaviour depends on the specific equipment and design.
Aspect	Microinverter	String inverter
Where conversion happens	At each individual panel	One central unit for a string of panels
Shading tolerance	Shade on one panel mainly affects that panel	A weak panel can reduce the whole string
Monitoring	Often available per panel	Usually reported per string, not per panel
Scalability	Add panels one at a time, each self-contained	Sized around a string; changes can mean re-planning
Cost	More units, often higher cost per watt at small scale	One larger unit, often lower cost per watt at larger scale
Failure mode	A fault tends to affect one panel only	A central fault can stop the whole array
Typical use	Small plug-in and per-panel systems	Larger fixed rooftop arrays

Shading, monitoring, scalability

Because a microinverter works on one panel at a time, partial shade — from a chimney, a tree or a neighbouring building — mainly affects the shaded panel rather than its neighbours. A simple string inverter converts panels as a group, so an underperforming panel in the string can hold back the others. Microinverters also make per-panel data more accessible, while string inverters typically report at the level of the whole string. For adding capacity, microinverters let you extend a panel at a time, whereas a string is usually planned as a set.

Cost and failure modes

At larger scale a single string inverter can be lower cost per watt, because one unit serves many panels. Microinverters add a converter to every panel, which can cost more per watt on small systems but spreads the points of conversion out. That spreading matters for resilience: if a microinverter fails, it tends to take only its own panel offline, whereas a fault in a central string inverter can stop the whole array until it is fixed.

Why small plug-in systems use microinverters

A plug-in system is usually just one or two panels feeding your home through a single connection. A small microinverter, attached to or built into the panel, produces mains-synchronised AC right there — so a single lead can carry usable electricity to a socket, with no separate central inverter and no series DC string to design around. That simplicity, and the fact the kit can be moved, is why plug-in solar takes the microinverter approach.

Not yet legal — consultation open

The DESNZ consultation opened on 16 June 2026 and closes on 30 June 2026, with a response expected by 22 July 2026. See the legal status for the full picture and sources.

In short

Microinverters suit

Small systems of one or two panels
Sites with partial shading on some panels
Per-panel monitoring and gradual expansion
Simple, movable plug-in designs

String inverters suit

Larger fixed rooftop arrays
Mostly unshaded, uniform panel layouts
Lower cost per watt at scale
A single central conversion point

Safety and compliance

Any inverter interacts with your mains supply, so any installation must follow current UK wiring regulations such as BS 7671 and the manufacturer's instructions, with fixed-wiring work carried out by a qualified, registered electrician. Because the UK framework for plug-in solar is unsettled, do not buy a system expecting to use it legally today.

Frequently asked questions

What is the core difference between the two?: A microinverter converts the output of a single panel at the panel itself. A string inverter is one central unit that converts the combined output of several panels wired together in a series 'string'. Both turn DC into mains-compatible AC; the difference is where that conversion happens.
Which copes better with shade?: Microinverters generally cope better. Because each panel is converted on its own, shade on one panel mainly affects that panel. With a simple string inverter, a shaded or underperforming panel can pull down the output of the whole string it shares.
Why do plug-in solar kits use microinverters?: A plug-in system is usually just one or two panels feeding your home through a single connection. A small microinverter, built into or attached to the panel, produces mains-synchronised AC directly, which suits that simple, movable design far better than a separate central inverter wired to a string.
Does this change whether plug-in solar is legal?: No. The inverter type does not affect the legal position. Plug-in solar is not currently legal to sell, supply or use in the UK, and a Government consultation is open until 30 June 2026.

Sources

1. BS 7671 Wiring Regulations — Institution of Engineering and Technology
2. Connecting generation to the network (G98 / G99) — Energy Networks Association

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