Solar panel inverter: which one fits your roof?

Solar panels produce direct current (DC). Your sockets and the grid run on alternating current (AC). The inverter sits in between and turns DC into AC. That makes it the heart of your system.

Most inverters also track your output. Through an app or display you see how much your panels generate each day, and you spot problems quickly. Estimate how much you can generate annually on our page about solar panel output.

A string inverter is usually mounted indoors, in the attic, garage or a utility room. Micro-inverters sit behind each panel on the roof. Outdoor inverters exist too; they withstand weather but need good ventilation.

At full load an inverter can give a soft hum. So do not mount it right next to a bedroom. Heat and airflow affect how long it lasts: a cool, dry spot is ideal.

A string inverter connects several panels to one central unit. Micro-inverters sit on each panel and work well with shade or multiple roof sections. A hybrid inverter can also work with a home battery, so you store surplus instead of feeding it back.

The inverter must match the power of your panels. In practice the installer chooses an AC rating slightly below the total DC rating on your roof. That is the DC/AC ratio: the inverter runs efficiently without unnecessary oversizing.

Too small and you leave output on the table on sunny days. Too large and you pay for capacity you rarely need. At SolarFast we calculate this in the quote based on your roof, orientation and any shading. Deliberately no fixed price or brand ranking here: that depends too much on your situation.

An inverter usually lasts less long than the panels themselves. In practice expect around 10 to 15 years, depending on type, environment and use. During the life of your system you usually replace the inverter once.

With solar panels you often get different warranties per component. Panels have a longer expected lifespan than the inverter, so warranty terms differ. Always ask exactly what is covered, as the ACM advises for home upgrades.

Factory warranty is what the supplier or manufacturer promises on paper; it often runs longer than statutory warranty, depending on brand and component. Statutory warranty also applies: with normal use you can expect an inverter to last several years even if factory warranty is shorter. For expensive appliances the ACM says statutory warranty can be six to ten years or longer. Ask which warranty applies per component, as the ACM advises for home upgrades. See the ACM on warranty.

Sometimes your inverter temporarily limits output, for example when the local grid is full. That is not a fault: when many nearby systems feed in at once, grid voltage rises, and above roughly 253 volts the inverter switches itself off through its mandatory voltage protection. No signal from the grid operator is involved. Once the voltage drops it switches back on by itself and your panels carry on as normal.

Grid operators and the homeowners' association have tips on these situations. See the publication on curtailing inverters with solar panels. Unsure whether your output really drops? Check your app first; if low output persists ask us.

At the survey we look at your roof, shading, fuse box and whether you want a battery later. Then we choose string, micro or hybrid and the right power rating. The quote states which type fits and whether your system is battery-ready.

Read more about the buying process in our guide buying solar panels. Ready for a concrete proposal? See solar panels and request a quote.