In Australia, we are spoilt with good weather. All year-round, the sun shines, and the temperature never drops below ideal surfing conditions. Because of this, we are ideally suited to solar energy production, with few things affecting optimal production. However, the Photovoltaic effect that produces electricity from the sun has one weakness: no ideal weather and investment can completely solve; shading. Whether it is from overhead cloud cover or a large tree in the backyard, shading prevents sunlight from hitting the panel with the concentration required for optimal performance. This means different things depending on the type of system you have invested in, but it will reduce production in all cases.
Traditional string systems are most heavily affected by shading as panels operate in a string, meaning that if one panel is shaded, it involves a whole string’s production. While a single panel being partially shaded will not shut off the string, it will provide an obstacle for the current being produced by the rest of the string. Suppose a string system is consistently shaded on the same panel. In that case, it can overload the bypass diode, which is responsible for cutting a panel out of a circuit when it is not performing correctly, allowing the panel to overheat, potentially causing hotspots depending on the severity of the situation. For this reason, string systems should not be installed on a roof with permanent shading from trees or neighbouring roofs, as even a partially shaded system can put your home at risk. Many companies also refuse to validate warranties caused by this fault, meaning that you may not be able to replace the solar system you have installed on top of everything else.
Optimised systems allow each panel to operate independently, meaning that if one panel has been partially shaded, then the rest can perform at their average level. This circumvents the chance of developing the issues associated with bypass diodes on string systems. The inclusion of optimisers also allows for much more flexibility in the design of a system, meaning that if you have multiple smaller faces on your house that are better positioned for solar than a larger surface, the panels can be designed in a way to maximise production. If your roof is shaded on the area where you intend to install a system or your roof layout necessitates multiple faces to be utilised, optimisers are necessary.
Microinverters are inverters placed on the back of panels and convert DC power to AC power on the panel level. These inverters have a higher cost per unit than the above optimisers but function without the usual central inverter attached to systems. These systems function almost identically to the above optimisers but tend to have a higher failure rate than the above, which is why we prefer installing optimisers on our systems.
In the United States, optimised and microinverter systems hold a significant majority of the market share, both due to the way they can handle shade and their advanced safety features and stricter safety regulations on a government level. However, in Australia, a lower price point has historically been the most critical factor for consumers. It has taken a while for companies such as Solaredge and Enphase to meet the lower price points demanded by the Australian market. In 2021, the additional investment required to install optimisers is almost negligible compared to the extra performance offered by their addition, especially in shaded areas. If your property is shaded but you are still looking for a solar solution that works, get in touch with one of our experienced designers today!
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