With the number of utility-scale solar installations and solar farms growing across Australia, it seems inevitable that concerns will be raised as this relatively new technology gains prominence in the country’s energy mix. Like any relatively large development, visual impact is an important consideration in the planning approval process, but there are some who might also ask about noise. Don’t inverters make a lot of noise–especially the larger ones generally used in projects that fall into the 100 kilowatt+ category? This article seeks to lay these concerns to rest.
When noise and renewable energy are mentioned in the same sentence, the first thing that comes to mind for most people is wind turbines. As wind power takes up more of Australia’s (and the world’s) electricity generation pie in Australia, the proverbial din about wind turbine noise has become louder. This makes it a great means of comparison for talking about about noise levels.
Noise, or more specifically ‘sound pressure’, is customarily measured in units called decibels (dB). At the risk of stating the obvious, the decibel level of a given noise source decreases as the distance from it grows–a fact about which few would contest a lack of proof. This is why, for example, wind turbines, airports, and highways are generally legally required to be a certain distance from homes.
Decibels increase on a logarithmic scale, meaning that 20dBis actually 10x louder than 10dB, and 30dB is 100x louder than 10dB. It’s at around 90dB that prolonged exposure could result in hearing loss; 125dB is where the noise becomes painful to listen to, and about 140dB is where hearing loss can happen even with short-term exposure. 140dB is also the recommended upper limit for human ears even with hearing protection.
As the infographic below (created by GE Global Research, a branch of wind turbine & household appliance manufacturer GE) illustrates, conditions at the foot of a windmill would be about as noisy as running a lawnmower without earplugs. Step a few back and it’s comparable to the noise associated with making a smoothie. By 400m, it’s like being in your kitchen with a refrigerator. If you live or work in the city, the noise outside your window during the day is about 50dB; at night, 40dB.
Solar system inverter noise
So where do solar PV system inverters sit on this scale? If you’re talking about a residential solar PV system, noise emission data is readily available on inverter spec sheets–but generally speaking they’re not particularly noisy. SMA‘s popular Sunny Boy inverters, for example, are about 25dB–quieter than a refrigerator, producing more of a ‘hum’ than a noise.
Of course, inverters for larger solar arrays will generate significantly more noise–but only up close. At a distance of 10m, SMA’s multi-kilowatt Sunny Central inverters, for example, have a sound pressure level of about 60dB. This is approximately equivalent to a the amount of noise generated by large air conditioner, but as distance increases it will become less and less audible. Furthermore, because solar panels produce power only when the sun is shining, inverters will be completely silent at night.
The reality is that even during the daytime virtually no one besides those who work at or visit such a plant will ever be in close enough proximity to the inverters to notice the noise that they make. First of all, large developments of this sort are not generally constructed directly adjacent to residences. On top of this, central inverters are usually surrounded on all sides by the vast solar panel arrays whose electricity they manage–further distancing them from anyone who might happen to be nearby. Lastly, mainly for visual reasons, plants are generally required to be hedged to some degree by either walls or greenery. This has the added bonus of acting as a buffer for any noise that might make it past the panel arrays themselves.
In summary, noise produced by inverters is not a serious issue when it comes to solar farms. Close up, they produce a fair amount of noise, but are still significantly quieter than a vacuum cleaner, and distance only reduces the impact further–not to mention the fact that they make no noise whatsoever at night. In addition to all this, they require no fuel, emit no pollutants when generating electricity, and have an extremely low visual profile in terms of height than virtually any other type of power plant.
Solar Choice Commercial: Commercial solar tender management
Solar Choice also develops its own medium- to large-scale solar farms, and has gained considerable experience in all relevant stages of project management, from planning approvals through to Power Purchase Agreement (PPA) negotiations and grid connectivity. We also have a large portfolio of land owners across Australia looking to lease their properties for solar farming. If you would like Solar Choice’s assistance to develop a solar farm from 2MW to 150MW, please contact Angus Gemmell on firstname.lastname@example.org.
© 2013 Solar Choice Pty Ltd
He is now the communications manager for energy technology startup SwitchDin, but remains an occasional contributor to the Solar Choice blog.
James lives in Newcastle in a house with a weird solar system.
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