Inverters

String inverters

A single inverter sits in the house and is wired to all the panels in series. They are the cheapest option, well understood, and the right answer for a roof with one orientation, light or no shading, and no immediate plan to add a battery.

The main limitation is that one shaded or underperforming panel can drag the output of the entire string. Workarounds include adding panel-level power optimisers (small DC-DC converters bolted to the back of each panel) which mitigate this without the cost of full microinverters.

Hybrid inverters

A hybrid inverter is a string inverter with an integrated battery interface and grid management firmware. Adding storage later is then a question of buying the battery and wiring it in, rather than installing a second inverter.

If a battery is in your plans within two to three years, paying the modest premium for a hybrid inverter at install time is usually cheaper than retrofitting later. If it isn't, a standard string inverter is fine.

Microinverters

One inverter per panel, mounted on the back. Each panel operates independently, which means shading or differences in orientation no longer drag down the rest. The downside is cost (typically 20-40% more than a string system at the same kWp), and the inverters sit outdoors on the roof, where any future fault means going back up to fix it.

Microinverters make sense for complex roofs with multiple orientations, persistent shading, or installations where future expansion onto a different roof plane is likely.

Decision tree

In short:

• One roof orientation, no shading: string inverter.
• One orientation, light shading: string inverter with power optimisers on affected panels.
• Battery within two to three years: hybrid inverter.
• Two or more roof orientations, or heavy shading: microinverters.
• Plans to add panels on a different roof plane later: microinverters.