Sharon Santhosh, energy storage applications engineer at Wärtsilä, talks all things BESS noise, including enclosure design, the various mitigating measures engineers can implement, and implications of BESS technology developments further down the line.
Energy-Storage.news has previously covered the topic of noise emissions from battery energy storage system (BESS) projects, one of growing importance as projects begin to be deployed closer to where people live.
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The main sources of noise from BESS technology can be grouped into electrical sources, which covers inverters and transformers, and mechanical noises, covering cooling fans and HVAC systems from the BESS itself.
Consultancy Acentech wrote a guest piece on noise and how to mitigate against it when configuring a site last year, while our interview with Wärtsilä Energy Storage & Optimisation’s (ES&O) Sharon Santhosh delves more into the technology developments from the BESS manufacturers’ side.
ES&O is the BESS system integrator arm of marine and power technology firm Wärtsilä, which yesterday announced it would be keeping full ownership of ES&O following an 18-month long strategic review.
Enclosure design will affect noise
Santhosh stared by explaining that the quality and nature of a BESS enclosure design could well have implications for how much noise it emits.
“Many times, the enclosure itself might be well-designed, but all these components which are situated on the base of the enclosure might lead to ‘translated’ noise, because the equipment might not be sitting properly,” she said.
“That can end up vibrating, and that gets translated onto the rest of the enclosure causing it to vibrate further. Bases not being bolted properly or any air gaps could act as exit points for the noise to leak. So a lot of the time we put heavy emphasis on the enclosure design.”
“You could also get retrofit issues. Sometimes we might not necessarily have full control over all the equipment or the components that are coming inside the enclosure. Conversely, you could also retrofit the enclosure with anti-vibration pads such as foam. It’s a multi-faceted approach.”
In response to our question, Shanthosh said that there are many anti-vibration and anti-noise materials for padding which are also fire-resistant.
Repeating what her divisional director Darrell Furlong told us last year at the Energy Storage Summit USA 2024, she said that “…almost 100% of projects have noise criteria – it can be make or break on whether we have a next discussion or not, and almost all stakeholders are interested in the noise question.”
On average, the company sees projects requiring night-time noise limits for the nearest dwellings of 30-40db. That is the noise measured at a specific distance from the units, while BESS units typically emit peaks of 70-90db measured at the unit itself.
We’ve previously heard that as BESS units are getting more energy-dense, they are potentially getting more noisy. “They could be, but everyone is focusing on noise and actively implementing mitigating measures and people are designing quieter solutions,” says Santhosh.
How do you mitigate against noise in BESS design?
Santhosh gave a presentation on the topic at the Energy Storage Summit EU 2025 in London in February, which you can watch below, in which she discussed smart ventilation controls as one way to reduce the noise emissions from a BESS unit. We asked her to explain more about what that meant.
“Generally, when we talk about smart ventilation control, we are essentially taking into account the software parameters, the entire SCADA systems, maybe even the individual equipment operation interface, the software interface that helps control the operation of the units,” she said.
“From a site level perspective, we do not necessarily need all the units to operate at full capacity all the time. To take advantage of that, we need to do a lot of software-based studies and a lot of software logic needs to be implemented. It’s smart in the sense that it takes into account what exactly the operating profile would look like.”
“In the daytime, we would have a different requirement compared to evening or nighttime operational profiles or operational loads. So we take into account the customer requirements, and we also take into account the capabilities that our equipment has, and essentially combine them together, into an active noise control approach.”
Active noise cancellation (ANC) technology
Santhosh also said that the firm is exploring using active noise cancellation (ANC) tech, the same used in noise-cancelling headphones, to mitigate BESS noise.
For now, it is still just under development. There is a challenge in that noise from a BESS site can propagate in varied and unpredictable ways, based on changes in the atmosphere and environment. ANC can cancel out specific frequencies but it is very directional, so noise that goes all over the place is more of a challenge.
“But there’s a lot of research and development into this in the acoustics industry,” Santhosh said.
Newer BESS technologies and noise: AC blocks, non-lithium chemistries
Next, we asked Santhosh how noise emissions might differ between a BESS project using DC blocks with large, central inverters, versus one with AC blocks which have inverters integrated into the BESS unit.
She said that the AC block project would in theory be simpler to address with mitigating measures at the site-level because it reduces the points within the project that emit noise. However, she cautioned that it would not necessarily mean that there was less to deal with.
“The individual level of noise propagation would then depend on the design of the individual systems itself. Even if we move to an AC block, the string inverters that are being used should be also designed in a way that we keep noise as the priority as the focal point in the design phase. I would say again, even if it does help to an extent, we cannot concretely say that it’s going to be the solution,” she said.
Note that Wärtsilä launched an AC block product in September 2024, which also saw it fall in line with the rest of the industry on energy density (with 5MWh per 20-foot container).
And what about BESS that uses newer battery chemistries, like sodium-ion and zinc that might need less cooling because of their lower fire risk? Santhosh said that this might be the case, but by that point noise rules might be even stricter, meaning a need to focus on noise mitigation as a priority might not go away.
