A solar inverter converts the direct current (DC) electricity that solar panels generate into alternating current (AC), the form of electricity that household appliances use and the national grid carries. Without an inverter, a home could not use or export the power its panels produce.
How it works
Solar cells produce DC, which flows in one direction. The inverter switches this current rapidly to create AC that matches the voltage and frequency of the grid. It also adjusts how much current it draws from the panels to get the most power from them as light levels change, and it shuts down if the grid goes off, so that it does not feed power into lines that engineers may be working on. Most inverters also record how much electricity the system has generated.
Main types
| Type | Where it sits | Main points |
|---|---|---|
| String inverter | One unit, often in the loft or garage, serving a whole row (“string”) of panels | Lowest cost; shade on one panel can reduce the output of the whole string |
| Micro-inverter | A small unit behind each panel | Each panel works independently, which helps on shaded or split roofs; higher cost |
| Hybrid inverter | One unit that also connects to a home battery | Manages solar, battery charging and grid supply in one box |
Some systems pair a string inverter with power optimisers on each panel, which reduces the effect of shading while keeping a single central inverter.
Lifespan
The inverter usually wears out before the panels. The Energy Saving Trust says solar panels should last 25 years or more, but the inverter typically needs replacing after around 12 years. Inverter warranties are usually shorter than panel warranties, so a replacement is worth allowing for when weighing up the long-term cost of a solar system. This is general information, not advice.
Read more: Solar panels for your home in the UK: costs, savings and how they work.