Solar Inverter Types Explained

The inverter converts the DC electricity your solar panels generate into the AC electricity your home uses. It is not the most glamorous part of a solar installation, but the choice of inverter type has real consequences — particularly if you are thinking about adding battery storage later, have a shaded roof, or panels facing more than one direction.

String inverters: the straightforward option

A string inverter connects all your panels in a series string (or a few strings) and converts the combined DC output to AC in one unit. It is the most common configuration for UK residential installs, typically sits in the loft or garage, and is generally the lowest-cost approach. String inverters from reputable manufacturers (SolarEdge, SMA, Growatt, Solis) are reliable and well-understood by installers.

The main limitation: a string inverter treats all panels on a string as a single electrical unit. If one panel is partially shaded, its output constrains the whole string — a well-known effect often called the "Christmas lights problem". On a fully unshaded south-facing roof this is not a concern. On a roof with chimneys, dormer windows, or tree shadow, it matters.

Hybrid inverters: the battery-ready option

A hybrid inverter does everything a string inverter does, but also includes a DC-coupled battery connection. This means you can add a compatible battery system later without replacing the inverter. If there is any realistic chance you will want battery storage in the next few years, a hybrid inverter is worth considering from the outset — the cost difference over a standard string inverter is often £200–£400, which is far less than replacing the inverter later.

Hybrid inverters also typically include more sophisticated energy management — monitoring self-consumption, grid export, and battery state in one system. The main consideration is compatibility: hybrid inverters are designed to work with specific battery brands (Huawei inverter + LUNA battery, SolarEdge + SolarEdge battery, Solis + Solis battery, etc.). Check the compatibility list carefully before specifying. Browse battery storage systems alongside inverters to check what pairs with what.

MPPT trackers and multi-orientation roofs

Most string and hybrid inverters have two or more MPPT (Maximum Power Point Tracking) inputs. Each MPPT input can handle a separate string of panels independently, which means you can connect panels on different roof orientations — say, south-facing and east-facing sections — without them dragging each other down. If you have an east-west split roof and want panels on both sides, an inverter with two MPPT inputs is essential. Check the spec sheet for the number of MPPTs and the maximum input power per MPPT before specifying the layout.

Micro-inverters: panel-level conversion

Micro-inverters fit to each panel individually and convert DC to AC at the panel rather than centrally. This eliminates the string shading problem entirely and provides panel-level monitoring. They are typically more expensive in total cost (more units, more installation labour) and can be harder to service if one fails. The main use case for micro-inverters in the UK is a heavily shaded or awkward roof where a string approach would incur significant losses.

Optimisers: a middle path

Power optimisers (Tigo, SolarEdge P-series) fit to individual panels and condition the DC output before it reaches the central inverter. They largely solve the shading problem without requiring a full micro-inverter system. SolarEdge in particular has built its UK residential proposition around an optimiser-plus-inverter combination. Worth considering for roofs with partial shading where micro-inverters feel like overkill.

Single vs three-phase

Most UK homes are single-phase, which limits the maximum inverter output to around 3.68kW per phase without a G99 application. For systems above 3.68kW on a single-phase supply, you will need multiple strings or a G98/G99 grid connection agreement — your installer will handle this, but it is worth knowing why some quotes specify a particular inverter size. Three-phase properties (less common in residential, more common in new-builds and converted commercial premises) can support larger systems more straightforwardly.

To compare inverters currently available, browse inverters on SmartSolarHomes.