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The Effects of Shading on Solar Photovoltaic Panels


The Problems of Shading on Solar Photovoltaic Panels


Shading can have a huge impact on the performance of your solar photovoltaic panels. It is obvious that the best solution is to avoid shading altogether, but what many people don’t realise is that even if a small section of the solar photovoltaic panel is in shade, the performance of the whole solar photovoltaic panel will significantly reduce. This is because solar photovoltaic panels actually consist of a number of solar photovoltaic cells that are wired together into a series circuit. This means that when the power output of a single cell is significantly reduced, the power output for the whole series is reduced to the level of current passing through the weakest cell. Therefore, a small amount of shading can significantly reduce the performance of your entire solar photovoltaic panels system.

Another problem that can occur in solar photovoltaic panels due to partial shading is that, because one cell (or group of cells) is generating a significantly smaller amount of power than the rest of the cells in the series, the weaker cell can suffer from thermal stress (i.e. over heating) and thereby reduce the power output of the solar photovoltaic panel even further.

How to overcome the effect of shading on solar photovoltaic panels


Whilst, where possible, it is best to avoid any shading at all on your solar photovoltaic panels, it is possible to change the wiring configuration of solar photovoltaic panels to lessen the negative effects. The most common method of lessening the effect on solar photovoltaic panels is to connect bypass diodes in parallel to the solar cells in the panel. When the solar photovoltaic panel is not shaded, the diode is ‘blocked’. However, when the solar photovoltaic panels become shaded, the change in voltage in the weaker cells causes the diode to conduct the current instead, thereby bypassing the weaker cells altogether. This has the advantage of restricting the loss in power output to the shaded cells, but still results in a slightly reduced power output for your solar photovoltaic panels.

If you do use bypass diodes in your solar photovoltaic panels to minimise the effects of shading, you should also be aware that your inverter will need to be able to cope with the range of currents the solar photovoltaic panels will produce. This is to ensure that you do not lose additional power in the conversion from DC to AC in your inverter.

An experienced solar photovoltaic panels installer will be able to provide you with individual advice and information. To find out more, feel free to contact us on 0116 2987467.

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