Huawei 450W DC solar panel optimiser.

If you want to maximise the output of your solar installation, year after year, then consider these little black boxes called 'optimisers' on some or all of your panels.
The most common use for them is to reduce power losses from shade. Shade comes from obvious things like trees, but also from less obvious ones like flues, TV antennas, evaporative air-con units, neighbours roofs.

Here's an image of partial shading on one panel.

That shaded panel will reduce in output while it is shaded and at the same time will bring down the output of the other 12 panels on the roof. An optimiser on that panel and perhaps on a couple more would protect the other panels from dropping in output. Of course, they could chop the top of the tree too, but sometimes shade comes from obstacles that can't be cut back.

Another feature of optimisers is to allow panels on more than two roof orientations. For example, you might have space for ten panels facing North, six facing West but no space for the remaining 2 panels unless you put them on the East roof. Fit those two panels with optimisers and it will all work just fine.

A popular feature of optimsed systems is the ability to view the individual output of each panel.

In the picture below we can see a 6.6kW system using 17 x 390W panels.

...and here is what that fully optimised system looks like at 2pm in the reports.
You can see that the ten West facing panels have each made a bit over a 1kWh, but the North facing ones, having had more sunlight so far in the day are higher at about 1.69kWh each.