Solar Farm Noise Study

A proposed 162 MW solar project to be built on 611 acres of a privately owned property in Central Michigan is estimated to generate enough energy to power over 25,000 homes. Since many of these existing homes are adjacent to the proposed new solar farm, noise generated by its equipment was of concern. While solar panels themselves are silent, certain pieces of equipment on a solar farm do produce sound. For example, inverters and transformers generate low-frequency sound, with acoustic frequencies of 120 hertz and harmonics (240, 360 Hz). This equipment produces a typical “hum” you might hear when around electrical equipment.

Acentech consulted with development team to conduct a background sound survey, perform a noise evaluation, and provide recommended noise controls for the planned farm. Using Cadna/A software, we developed an acoustic model of the proposed solar farm and the surrounding neighborhood. The model estimated noise impacts from equipment at the proposed solar farm, which will include 64 inverters, 2 substation transformers, 2 POI transformers, and approximately 6,500 tracker motors. During normal nighttime operation, the inverters and tracker motors would remain inactive, but the transformers would remain energized and continue to produce noise.

Our study confirmed that the project would comply with the EPA’s typical noise guidelines for Day-Night Average Sound Level. To aid in this compliance, we recommended the inclusion of noise mitigation for receivers with predicted increases over ambient sound greater than 5 dB. Sound mitigation of the inverters was as simple as relocating the inverters further from residences. For the project site itself and the POI transformers, we suggested a noise barrier. Acentech offered noise consulting services for the detailed design phase as well, which furnishes continued community support for the duration of the project.