In 2022, solar power provided 4.4% (13GW) of the UK's electricity generation mix. In the same year, a record 4GW of additional solar capacity was approved across the UK.

With the Government's net zero target date of 2050, numbers are set to increase with renewable energy set to contribute a greater portion of the country's electricity mix.

An increase in solar farms bring inevitable exposure risk to noise sensitive receptor locations with potential impacts and loss of amenity due to visual impacts, habitat loss and other environmental considerations. But is noise a material factor for solar farms?

Are Solar Farms Noisy?

The Sun is loud! If it weren't for the vacuum of space, Sun generated noise on Earth would be around 125dB(A). Fortunately, we have 150 million kilometres of empty space to protect us so we can enjoy its warming rays and utilise its light without being deafened in the process.

So, are solar farms noisy? In absolute terms; not really. However, the answer is more nuanced and other important factors need to be considered when assessing the potential for noise impacts.

A commercial scale solar farm is likely to include several panels feeding into inverters, which in turn, feed into power transformers which facilitate connection to the local and National Grid. The panels are effectively silent during operation¹; however, other elements of the power chain can generate some levels of noise. For instance, a typical string inverter can generate a sound pressure level of around 74dB at 1m. This, in itself, is not particularly noisy; however, a larger solar farm my include more than 100 string inverters, arrayed across the site. This, coupled with the transformer units can give rise to a significant level of noise.

However, as indicated previously, the answer is more nuanced and the actual impact of the noise generated is related other factors inherent in the design and setting of the solar farm.

Site Context

Factors to consider when assessing the potential noise impact of a solar farm include:

• The nature of the area/setting;

• The existing noise climate in the area;

• The character of the noise generated; and,

• The level of noise generated.

For instance, a commercial scale solar farm may be located on farmland, in a tranquil, rural setting, away from transport or industrial infrastructure. On this premise, the site is likely to be exposed to a rural soundscape including noise from livestock; seasonal farming activities; bird song, etc. In these instances, sensitive receptor locations are likely to be exposed to relatively low background noise levels and a generally tranquil soundscape.

Against this context, noise from unnatural sources may stand out. Any hums or tones associated with the electrical plant while not subjectively ‘loud', are likely to be more readily identifiable, giving rise to impacts virtually irrespective of the absolute level of the noise generated.

Design Considerations

Consideration of noise during the early design stages of a solar farm is important. It is generally more cost-effective to ameliorate potential impacts through design than to retrospectively include noise mitigation measures.

In this regard, the following basic principles can inform the design process:

1) Location of noise sources is key;
a. In principle, keep noise sources away from sensitive receptors to maximise attenuation afforded by distance;

b. Utilise existing sources of noise to provide masking, i.e., locate noise sources closer to existing roads, etc;

c. Utilise natural screening, i.e. the existing landform: hills and bunds etc;

2) Try to ameliorate any noise emissions and specific characteristics;
a. Review the manufacturer's specification sheet and obtain robust noise source information;

b. Consider the number of plant items, i.e., a smaller number of ‘louder' sources may be a better solution than a large number of quieter sources;

c. Identify any plant specific mitigation measures, i.e., alternate operating modes, product specific enclosures, etc;

3) A baseline noise survey is a benefit, though not always essential. It will help to better inform the overall assessment.

Conclusion

Noise from solar farms is unlikely to be a showstopper though is a salient point to consider in the design process. Through consideration of noise and potential noise impacts, it is possible to ameliorate impacts through the design process, facilitating a more favourable assessment outcome and minimising impacts, and in the wider picture, helping to achieve the Government's net zero target.

For any noise assessment needs, please do not hesitate to get in touch at acoustics@enzygo.com

For further information on the acoustic services we offer, please visit our website - Noise Services - Enzygo

¹Tracking solar panels which follow the sun during the day can generate very low levels of noise but the actual panel element is still, effectively silent.