Dirty solar panels?

Fast read

A solar panel system's performance and efficiency can be significantly impacted by dirt and shading. In addition, the system's total ability to produce energy can be affected considerably when a section of the solar array is damaged.

Even if shade that happens outside of the peak energy production times, typically from 9 to 3 p.m., it may still have an effect. It is still crucial to minimise shading. Shading can negatively influence solar panels connected in a string through a string inverter because when one panel's output is diminished, it affects the efficiency of the entire array.

To avoid these issues, it is essential to have a thorough site inspection to identify any potential shading obstacles. This includes nearby buildings or trees, and consider using micro-inverters or power optimisers instead of string inverters. Proper panel placement and regular cleaning can also help reduce the impact of shading and dirt.

Is dirt and shade on my panels affecting electricity generation and performance?

Regarding efficient energy production from your solar system, dirt and shading are your biggest enemies.

Even if only a tiny portion of your solar array is affected. The effect on your system’s overall energy production can be considerable.

In saying this, for shading specifically, if it occurs outside of your significant energy production hours. Usually 9 am – 3 pm, the effect is considered less. But, as in the early or late hours of the day, solar production from your system will be reduced. Nevertheless, the alternative argument is that when your solar output is reduced, you would not want to lose more electricity due to shade. 

The main issue with shading and dirt on your panels arises when your solar system includes a string inverter. String inverters, as the name suggests, will see several solar panels. Typically 6 to 12 in a residential system are all connected in one string and then enter the string inverter via the MPPT.

In this technology, the output of one panel is reduced due to debris or shade. The efficiency of the whole array is affected as the panels need to all run on the same voltage. One of the main ways to avoid this problem is to split your collection into multiple strings or have microinverters or optimisers on each panel instead. This can be explored in our FAQ of string inverters vs microinverters

Shading and Dirt

Since shading and dirt are prominent threats to your solar system’s energy production, they become vital to the design process. This means one will work hard to avoid them. For example, if one has a large enough roof to put the panels on various aspects. One would choose the roof location less likely affected by shade. 

residential solar system
Panel shading dramatically decreases your electricity generation

During your site inspection, your solar installer must perform a shading analysis to evaluate potential obstacles, such as more significant neighbouring buildings or trees. Regarding trees, it’s not just the current status quo but also the likely situation in 5 or 10 years. For example, a small palm tree might have matured.

Below we have listed the different types of shading that can occur on a solar panel, including shade due to dirt pile-up. 

  • Temporary shading – this is the shading that is caused by dirt, bird poo, or fallen leaves, which can be removed via panel cleaning or heavy rain; 
  • Self-shading – this can be caused by the tilt of your panels on a flat roof. Where one decided to install a tilted panel set, which is not well designed, and the front row of tilted panels overshadows the row behind;
  • Shading via the location – this is the shading caused by the panels’ location. For example, the shade could come from a nearby antenna, trees, satellite dish, ventilation pipe, or chimney.  
  • Shading from buildings is shading caused by nearby structures or your residence and is known as direct shading.

How to avoid shading and dirt issues?

There are several ways to avoid these problems and ensure that your system produces the most renewable energy output possible. 

Firstly, hire a local quality installer who cares about your outcome. Not a fast and furious solar sales company that will try to catch you on price alone.

A sound installation company will be able to assess your shading risk. This means they can design the most efficient solar system considering your surrounding environment if solar mapping is considered. As a result, the effects of solar shading can be reduced dramatically. 

Secondly, when shading issues are likely, you should consider installing microinverters or optimiser technology. This can solve the problem of shading. When string inverters are used, shading can affect the production of a whole solar array; however, microinverters or power optimisers are used. Then, shading affects just the panels being shaded while the ones sitting in the sun power away as usual. 

So can I still get solar?

Finally, ensure you have quality solar panels installed on your roof. Quality solar panels perform better in low light. So even with shade, you get a better outcome than the bargain basement panels. Quality panels also offer a higher efficiency per panel. This means the physical footprint of the solar array can be reduced. Therefore hopefully, avoiding the shade risk spots on your roof. 

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