Out of all the solar panels we install the sunpowers are currently my favorite, especially now they have realsed the new all black panels.  The cells of the panels have been mounted onto a black background instead of the typical white and the wires are on the back of the panels instead of the front.  Personally I think all well designed systems look aesthetically pleasing but if the traditional looking solar panels aren’t for you then Sunpower could be the answer.

One of the aspects that makes them so aesthetically please is also the reason for the exceptional performance and high efficiency of the panels.  The seemingly simple idea of  placing the wiring on the back of the panels instead of the front it increases the available surface area of the panel and eliminates any shading caused by the wiring.

The E20 series have whopping 22.1% efficiency, making them the most efficient panels on the market at the moment.

The increased efficiency of the panels also makes them a perfect solution for smaller roof spaces, meaning the same kWp can be achieved in a smaller area.

Shading can have a big impact on the efficiency of a solar PV system, even minor shading can result in a significant loss of output. This is because the panels are wired together in series, so the panel with the most shading will determine the current at which the whole string of panel will operate. If there is shading on any of the panels in the array, this will not only bring down the output of these panels, but will bring the rest of the panels in the array down to the lower output. Even if only one panel is affected by shading the system will perform as if all panels were shaded.

Common sources of shading come from trees and chimneys, your installer should make note of any potential shading issues on the site survey and provide you with a system design showing the impact of any shading hazards on the output of the system.

Potential Solutions

The ideal solution would be to design a system that is not affected by shading, although systems which are affected by a small amount of shading can still be viable. The system can be designed to minimise the effect of the shading, limiting it to early morning or late afternoon in winter, leaving the system shade free for the majority of the day. For larger systems an inverter with an multiple power point tracker could be used – dividing the system into strings so only one area of the array would be affected.

So in conclusion if you have a good sized south facing roof there is the potential for a viable PV system, even with a bit of shading – but it is important to go with an installer who will design the system taking into account any shading hazards and will make you aware of the effect of these hazards on the output of the system.