String, micro or hybrid inverter: which suits your roof?

Solar panels produce direct current (DC); your home and the grid run on alternating current (AC). The inverter does the conversion. Which type you choose affects how your system copes with shade, how easily you can add a battery later and how your DNO connection works. Here are the four options side by side, with figures from the 86 inverters in our inverter database.

The four options at a glance

String inverters: the default

Most rooftop systems use a single string inverter in the loft, garage or utility room. In our database 83 of 86 models are string or hybrid inverters. 76 have two MPPTs (maximum power point trackers) and seven have three. Each MPPT manages its own string, so an east and a west roof can each run at their best.

The drawback: panels in the same string share one current. When a chimney or dormer shades one panel, the whole string produces less. Bypass diodes in the panels reduce the loss but do not remove it.

Larger string inverters also tend to be more efficient: in our data the median European efficiency rises from 97.0% (1–4 kW) to 98.0% (above 6 kW). See inverter efficiency explained.

Microinverters: one per panel

With microinverters every panel works independently. The three microinverters in our database deliver 325 to 380 W AC each, weigh 1.1 kg and are rated IP67. Their European efficiency of 96.6–96.8% is a little below the median for all models (97.35%). On an unshaded south roof that is a small penalty; with shifting shade the extra yield usually more than makes up for it.

Microinverters are also at the heart of plug-in solar, which became legal to buy and use in Great Britain from 27 August 2026 ¹. Under the interim product specification, kits are supplied complete with PV module(s), a microinverter and the manufacturer’s cables and connectors ². The government has limited output to 800 W per device, allows one device per circuit protected by a circuit breaker at the consumer unit, and requires devices to be registered on the ENA Type Test Register before they are placed on the market ².

Optimisers: the middle way

An optimiser sits behind each panel and adjusts its current and voltage; a central inverter still does the conversion. You get most of the shade tolerance and panel-level monitoring of microinverters, with one central box that is easy to reach if it fails. Optimisers usually only work with an inverter from the same maker. Our database does not (yet) include optimisers.

Hybrid inverters: battery-ready

A hybrid inverter adds a battery input. Of the 58 models in our database where we have this data, 34 are hybrid.

Whether that matters depends on your plans. With the Smart Export Guarantee, exported power earns whatever tariff your supplier offers, so many households add a battery to use more of their own solar — see Smart Export Guarantee and VAT. You do not need a hybrid inverter for that: an AC-coupled battery can sit next to an ordinary inverter. The differences are explained in AC vs DC-coupled batteries.

One UK-specific catch: G98 covers installations up to 16 A per phase, which the installer can connect first and notify within 28 days; above that, G99 requires the DNO’s permission before installation ³. Adding a battery can tip a system over that line. More in grid connection: G98, G99 and the ENA register.

Lifespan

The Energy Saving Trust says an inverter needs replacing after around 12 years, while panels should last 25 years or more ⁴. With a string system that usually means one replacement over the life of the panels. See inverter lifespan, warranty and monitoring.

How to choose

1. No shade, one or two roof faces: a string inverter with two MPPTs is usually simplest and cheapest.
2. Shade, several small roof faces: consider microinverters or optimisers.
3. Battery planned: a hybrid inverter, or keep an AC-coupled battery as an option — and check G98 vs G99.
4. Plug-in solar: a complete kit with microinverter, up to 800 W, listed on the ENA register ².
5. Check the sizing: power, voltage window and input current must match your panels. See sizing a solar inverter.

Compare models on efficiency, MPPTs and power in our inverter comparison.