String inverter vs micro-inverter

The inverter is the heart of your installation: it converts the direct current from your panels into alternating current for your home. Which type fits depends mostly on your roof. Below we compare string and micro on how they work, shade, cost and lifespan. What an inverter does exactly is covered in our inverter explainer.

With a string inverter your panels are wired in series, like a string of fairy lights: the current runs through all panels in a row to one central unit. Micro-inverters flip that around. Each panel gets its own small inverter on the roof and works independently.

That series wiring is also the string's weak spot. If one panel underperforms, it slows down the whole row. Panels have built-in bypass diodes that temporarily skip a shaded section, but each time that switches off a sizeable part of the system. That is why shade deserves serious attention before you pick an inverter.

Think of a chimney casting a long winter shadow across three panels, a dormer blocking the morning sun, or the neighbours' tree. With a string inverter such a spot drags down the output of the whole string; with micro-inverters only the shaded panel loses output. Milieu Centraal (Dutch) also lists micro-inverters as the solution when shade is unavoidable.

There is a middle ground: power optimizers. These are small boxes per panel that optimise the balance between current and voltage, while a central inverter still does the conversion. They recover most shade losses and are usually cheaper than micro-inverters. For a roof with one awkward spot, that is often the smartest compromise.

During the roof survey we check where shade falls and when: chimney, dormer, trees, or a taller neighbouring building. If that shade structurally hits part of the panels, or if your panels are split across east and west, we recommend micro-inverters or optimizers. If your roof is shade-free with a single section, a string inverter is usually the sober choice.

Thinking about a home battery, now or later? We factor that in: storage combines most easily with a central (hybrid) inverter. To estimate what your installation delivers, see our page on the yield of solar panels. Not sure what fits your roof? Put your situation to us and we will look at it with you.

On an unshaded roof with one section, a string inverter is often fine and the cheapest option. With shade, dormers or panels facing multiple directions, micro-inverters or optimizers quickly earn back their premium. We settle the advice during the roof survey, not upfront from a brochure.