Is Your Roof Partially Shaded?

This article is no longer actively maintained. While it remains accessible for reference, exercise caution as the information within may be outdated. Use it judiciously and consider verifying its content in light of the latest developments.

-----

Are you in doubt about whether to install photovoltaic (PV) solar panels on your roof, because the roof is partially in the shade? You have good reasons for your doubts, but the problem can be solved.

Traditional PV Installation

In a traditional installation, multiple PV panels are connected in series into a so-called string. One installation can contain several such strings, depending on the total power. Special cables connect each string to a central inverter that transforms the generated DC voltage into 230V AC voltage that can be used around the home.

Partial Shadow

Leaves, trees, poles, chimneys and higher neighbouring roofs can all temporarily and partially put PV panels in the shadow. A shaded panel will underperform and, as a result, the entire string will lose performance. Your total energy yield will decrease significantly, extending the payback time of your investment.

Micro-inverters

Micro-inverters offer a solution. Each PV panel can be connected with its proper micro-inverter attached at the back of the panel. The exit voltage of a micro-inverter is 230V AC. The various PV panels are now connected to each other in parallel. A major advantage of this technology is that the shadow on one panel does not affect the performance of the other, non-shaded panels, increasing the total energy yield of your installation.

Micro-inverters are placed at the back of PV panels. (Courtesy of Enphase)

In addition, a central inverter in the garage or the attic is no longer necessary. A small interface enables monitoring over a computer or smartphone. In this way, the user immediately knows which panel is under-performing because leaves, shade or dust have fallen on it.