Microinverters and Power Optimisers

The problem they address

In a conventional string, panels are wired in series, so a shaded or underperforming panel drags on the rest of its string. On a simple unshaded roof that never matters. On a broken-up or shaded roof it can matter a great deal.

Optimisers and microinverters

Optimisers sit behind each panel and condition its output before it joins the string, with a conventional inverter still doing the DC-to-AC conversion. Microinverters do the conversion at each panel and dispense with the string inverter entirely.

Both give panel-level monitoring, which makes fault finding far easier years later.

What they do not do

Neither removes shading losses. A shaded panel still produces less; what changes is that it no longer holds back its neighbours. Any claim that optimisers eliminate the effect of shading is overstated.

Cost

Both add cost and add components on the roof. On a clean south-facing slope with no shading, that money usually buys you very little.