Crossroads Solar Grazing Center
Crossroads Solar I, LLC
Morrow County, Ohio
Communication Systems (AM/FM Radio, TV, LMR, and Communications Towers) Interference Analysis
March 3, 2025
Introduction
Capitol Airspace conducted a communication systems interference analysis for the Crossroads Solar Grazing Center (CSGC) in Morrow County, Ohio. At the time of this analysis, the solar array project area shown in Figure 1 was identified1 . The purpose of this analysis was to identify Amplitude Modulation (AM) and Frequency Modulation (FM) Radio, Television (TV), Land Mobile Radio (LMR) systems, cellular radios, and communications towers that could be affected by the proposed solar array.
AM and FM radio, along with TV stations, are a critical component of the national communications infrastructure. These stations broadcast emergency, news, music, entertainment, and educational content. LMR systems play a critical role in enabling seamless communication among public safety agencies, emergency responders, and transportation services, ensuring swift and coordinated responses to urgent situations and enhancing overall public safety nationwide. Proposed structures that interfere with these systems can degrade the services that they provide.
Solar arrays have the potential to disrupt communication systems through several mechanisms: physical interference with the transmitted signal, as well as electromagnetic interference (EMI) and reflective interference to the receiving equipment. The likelihood of disruption depends on the characteristics of the radio frequency (RF) signal and the proximity of the solar array components to communication system components. Therefore, the proximity of a solar array to a communication facility plays a crucial role in predicting potential interference. This analysis focuses on understanding how the placement of solar arrays relates to the probability of interference.
Methodology
Capitol Airspace studied the proposed project based upon location information provided by Crossroads Solar I, LLC. Using this information, Capitol Airspace used a Geographic Information System (GIS) to determine proximity to communication facilities contained in the Federal Communication Commission (FCC) Universal Licensing System (ULS), Licensing and Management System (LMS), and Antenna Structure Registration (ASR).
This analysis considers the potential impact of the proposed solar project on communication system transmission facilities based on RF signal propagation characteristics, and on RF reception based on Electromagnetic Interference (EMI, or “RF Noise”) from the solar array components, and physical reflections from the solar panels themselves.
AM Radio
Proposed structures located up to ten wavelengths from the transmitter can have an impact on the station. This is based on guidance provided by the FCC via 47 CFR §1.30002.
FM Radio and TV
The location of a proposed structure within an RF signal’s propagation regions can determine the potential for impact (Figure 2). Within the near field, RF signals behave unpredictably and are more susceptible to distortion from obstacles. In the far field, radio waves are more parallel and uniform and are spread over a larger area. Obstacles in the far field are less likely to have an impact on RF transmission. The distance between the antenna and the beginning of the far field is called the “Fraunhofer distance”.
Figure 2: RF signal transition from the near-field to the far-field of a transmitter
LMR and Cellular
The impact from proposed structures like solar arrays is primarily associated with the potential for EMI. As unintentional radiators, Solar arrays have the potential to create EMI in proximity to LMR and cellular transmitters. LMR and cellular frequencies span a wide range, so multiple frequency bands are investigated when studying them. The distance at which EMI may be a concern is based on guidance provided by the FCC via 47 CFR Part 15.
In many cases, antenna locations in the FCC’s databases are inaccurate. When a communication system transmitter’s location was critical, available satellite and aerial imagery were used to refine its coordinates. Available imagery was also used to identify potential receivers in proximity to the defined study area.
In addition to effects of nearby solar arrays on transmission, the effects of EMI emitted from a solar project, and reflections from the solar panels themselves on transmission systems, the same effects on reception were also studied.
Findings
AM Radio
Effects on AM Radio Transmission
Solar arrays located within six kilometers of a transmitting AM facility (dashed purple outline, Figure 3) have the potential to adversely affect AM transmissions.2 This interference could cause the transmitting entity to be out of compliance with its FCC license. There are no AM transmitter facilities located within six kilometers of the study area (the dashed purple outline in Figure 3). As a result, the proposed solar array should not create an adverse effect on the transmission of AM radio signals. The closest AM station to the project is WQCD(AM), which is 20.3 km from the nearest project boundary
2 Six kilometers is a conservative screening distance derived by rounding the worst-case FCC distance of 5.45 kilometers derived from the FCC Rule Section 1.30002(b) directional AM radio station separation criteria, which is based on the distance of ten wavelengths at the lowest possible frequency, 550 kHz. Further, per this same Rule Section, the lowest structure height that may have a potential impact on an AM station within the screening distance is 178.8 feet at 550 kHz, which is well below the proposed height of any proposed solar array structure.
Effects of Localized EMI on AM Radio Reception
Due to its lower operating frequency range, AM Radio reception is by far the most susceptible to local EMI of all the radio services.
AM radio reception can be impacted by signals being intentionally or unintentionally emitted by electrical devices and appliances. In the past, some PV subsystems used in residential solar arrays were found to cause localized interference to AM radio reception. Properly designed, installed, and maintained utility scale solar arrays have not been typically found to create localized EMI issues. While it is understood that solar panels are not an intentional RF radiator, it may be possible that some of the components including system interconnection wiring and DC to AC inverters (the inverters in particular) can become “unintentional radiators”.
From the International Electrotechnical Commission’s (IEC) standards document IEC 61000-6, the distance required from the photovoltaic array electronics for unimpaired AM reception for this analysis is 30 meters.3 So long as PV array components are located farther than 30 meters (100 feet) away from roads, homes and businesses with potential AM receivers, there should be no EMI “noise” effects on AM radio with the appropriate IEEE, IEC, and UL codes. Any potential interference effects from professionally and properly installed inverters, control systems, and interconnecting wiring that are in compliance are expected to be minimal and can be further mitigated if needed.4
A list of AM stations that serve the area with a “city grade”2 mV/m signal is provided in Table 1 and Figure 4 should there be concerns about reception in the community.5
3 Up to 43V/m is acceptable @ 550KHz at distance of 30 meters. IEC 61000-6-4:2018 © IEC 2018
4 This statement is made on the assumption that good engineering practices are used following IEC and IEEE standards with regard to installation and grounding.
5 WQCD is not included in Table 1, as while it is closest to the project, it does not have enough signal strength for the city-grade contour to overlap the project area.
Figure 4: AM stations with coverage contours overlapping the CSGC boundary
Effects of Localized Reflection on AM Radio Reception
As mentioned above, local reception of AM Radio stations is normally analyzed based on ground conductivity and “ground wave” propagation. The impact of reflections or blockage at AM frequencies near the solar array should be minimal due to the long wavelength of AM stations and low height of the PV array.
FM Radio
Effects on FM Radio Transmission
Solar arrays located within one kilometer of an FM radio transmitter site have the potential to adversely affect FM transmissions.6 There are no FM transmitter facilities located within one km of the project area (Figure 5). The nearest FM station to the project is WJJE(FM), which is 12.2 km from the project. As a result, the proposed solar array should not create an adverse effect on the transmission of FM radio signals.
Further, the possibility of a solar array inducing near-field effects on an FM transmission is extremely remote since FM transmitting antennas are typically elevated high above the terrain for maximum coverage. It is improbable that a ground-based solar array would be within the main lobe pattern of a high-gain FM transmitting antenna in a way that interacts with the radiated pattern.
Therefore, the CSGC will have no near field impact to the operating characteristics of existing or proposed FM transmission facilities.
6 One kilometer is a conservative screening distance derived by rounding the Fraunhofer distance of 941 meters. The calculated distance of 941 meters is based on the largest typical off-the-shelf 12-element antenna and the lowest possible frequency of 88 MHz
Effects of Localized EMI on FM Radio Reception
As an example of the minimal impact of such installations to the VHF FM band, in the past ten years, more and more airports have allowed photovoltaic (PV) projects to collocate on airport grounds. Several government agencies, including the DoD and the FAA, are concerned with potential interference for safety reasons, as there are several frequencies used at airports which are extremely important to airspace navigation that are very close to the FM radio frequency band (the FAA’s ILS localizer frequencies are directly above the FM band). According to the Renewable Energy Program Office of the DoD,
“The Federal Aviation Administration (FAA) has indicated that EMI from PV installations is usually low risk. PV systems equipment such as step-up transformers and electrical cables are not sources of electromagnetic interference at frequencies above 108 MHz because of their low frequency (60 Hz) of operation and PV panels themselves do not emit EMI. The only components of a PV array that may be capable of emitting EMI are the system interconnection wiring and DC to AC inverters, which convert the solar panel’s low-voltage DC power into a higher voltage AC that can be carried efficiently for longer distances to the solar project’s electrical substation. Inverters may produce low frequency EMI similar to electrical appliances and at a distance of 150 feet from the inverters the EM field is at or below background levels.”7
If the PV array and its components are restricted to a distance of more than 150 feet from houses, businesses and roads, there should be no effects from EMI on FM reception. According to documentation provided by Crossroads Solar I, LLC, there will be a minimum setback of 300 feet between all solar panels and homes, and a minimum setback of 500 feet between inverters and transformers and homes.
Effects of Localized Reflections on FM Radio Reception
Obstructions such as mountains, hills, tall buildings, or similar high structures reflect VHF (both FM and VHF television) broadcast waves. This “multipath” impact on FM reception can become significant when cancellation of desired signal occurs within the area of reception
The effects of reflection are extremely local, likely occurring only within a short distance (150 feet or less) of the panels themselves. For listeners of the FM radio stations nearby, mitigation of signal distortion or loss to stationary receivers such as tabletop or portable radios is achieved by re-orienting the attached antenna on the receiver or moving the radio receiver slightly. Temporary, local, in-car, reception distortion may also be present, known as the “stop light effect”, where drivers listening to an FM station may lose the signal while sitting at a traffic signal, only to regain it when they move the vehicle 5-10 feet. The impaired FM signal will be regained as soon as the vehicle changes position. Any short-term multipath created by the solar panels in motion on FM radio reception will be short-lived and can be mitigated.
Television Effects on TV Transmission
Solar arrays located within two kilometers of a transmitting TV facility (dashed red outline, Figure 6) have the potential to adversely affect TV transmissions.8 However, no transmitting TV facilities are located within two kilometers of the study area. The nearest television facility is WOCB-CD, which is 19.3 km from the solar array boundary. Therefore, the CSGC will have no adverse effect on TV transmitter facilities.
Further, the possibility of a solar array interacting with the near field of VHF and UHF television transmission is extremely remote since television transmitting antennas are typically elevated high above ground level to achieve maximum coverage. It is improbable that a ground-based solar array would be within the main lobe pattern of a high-gain TV transmitting antenna in a way that interacts with the radiated pattern.
8 Two kilometers is a conservative screening distance derived by rounding the Fraunhofer distance of 1,772 meters. The calculated distance of 1,772 meters is based on the largest off-the-shelf 36-element antenna on Channel 14 (the lowest TV channel in the UHF band).
Effects of Localized EMI on TV Reception
If the PV array is located more than 150 feet distant from houses, businesses and roads, there should be no effects from EMI on TV reception. VHF Television signals behave much like FM signals and can be treated in the same fashion. UHF TV signals are higher frequency and more “line of sight”. Their transmission technology is similar to AM Radio and can be treated in the same way as AM radio signals. According to documentation provided by Crossroads Solar I, LLC, there will be a minimum setback of 300 feet between all solar panels and homes, so should have no effect on nearby in-home reception.
Effects of Localized Reflection on TV Reception
Stationary or slow-moving PV arrays will have a negligible effect on nearby TV reception due to signal reflections. From a practical standpoint, the amount of signal that is reflected by these low-height PV panels is reduced significantly when they are installed on flat ground because they intercept and reflect less of the direct TV signal. The effects of reflection are extremely local, likely occurring only within a short distance of the panels themselves. If PV array components are located farther than 150 feet away from homes and businesses, there should be little or no reflection impact to TV reception. For over-theair TV viewers nearby, mitigation of signal distortion or loss of signal (blockiness or black picture) is achieved either by re-orienting the antenna on the receiver for fixed TVs or moving a portable device a few inches or feet. According to documentation provided by Crossroads Solar I, LLC, there will be a minimum setback of 300 feet between all solar panels and homes, so there should be no effect on inhome TV reception.
Further, regarding EMI and reflection interference, a list of TV stations that serve the area is provided in Table 2 and Figure 7 should there be concerns about reception in the community. Given the complexity of predicting such interference, an evaluation was conducted on TV facilities located within 175 kilometers of the project boundary to determine the TV station contours which might provide service to the project area9 There are 14 TV signal contours that overlap the project boundary. If the planned solar project does result in TV reception interference, resolutions are usually addressed on a case-by-case basis. Common mitigation measures include adjusting the orientation or placement of the receiving antenna. Alternatively, solutions might involve offering another means of TV viewing, such as cable, satellite, or internet-based subscriptions.
Note that any EMI or reflections from solar farm components do not affect cable television or satellitedelivered television services.
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9 Coverage contours are calculated using “dipole correction”, so that the efficiency of the receiving antenna is considered across a very wide spectrum of TV frequencies.
7: TV station coverage contours overlapping the CSGC boundary
Effects of Localized EMI on Land Mobile Base Stations
The discussion in the FM and TV sections above for the potential effects of inverter EMI on FM Radio reception also applies to LMR reception, as LMR technology utilizes both VHF and UHF frequencies. There is only one Land Mobile fixed base station located within the study area (Table 3 and Figure 7), but it is not within the project area. All other LMR licenses in the county are mobile-only.
To reduce the possibility of Electromagnetic Interference (EMI), PV array components should be sited at least 150 meters from LMR base station locations. As is shown in Figure 8, the 150-meter exclusion zone around the LMR base station does not overlap the project area, so the PV array is not of concern to this LMR base station. As the FCC-licensed coordinates of LMR base stations are often in error, the coordinates are verified against aerial imagery and corrected if needed.
Coordinates have been corrected utilizing aerial imagery.
Figure 8: LMR base station “exclusion zone” (dark blue area) to be avoided when siting PV arrays
Effects of Localized Reflection on Land Mobile Reception
Land Mobile radios are in the VHF and UHF frequency bands (such as FM radio and TV). Obstructions such as mountains, hills, tall buildings, or similar high structures reflect VHF radio waves. This “multipath” impact on reception can become significant when cancellation of desired signal occurs within the area of reception
The effects of reflection on VHF LMR radios are extremely local, likely occurring only within a short distance (150 feet or less) of the panels themselves. For operators of mobile or handheld LMR radios, temporary, local, in-car, reception distortion may also be present, but the operator will regain it as soon as the vehicle changes position. Any potential short-term multipath created by the solar panels in motion on VHF LMR 2-way radio reception will be short-lived
Stationary or slow-moving PV arrays will have a negligible effect on nearby UHF LMR reception due to signal reflections. From a practical standpoint, the amount of signal that is reflected by these low-height PV panels is reduced significantly when they are installed on flat ground because they intercept and reflect little of the UHF LMR signal. The effects of reflection are extremely local, likely occurring only within a short distance of the panels themselves. If PV array components are located farther than 150 feet away from roads and businesses, there should be little or no reflection impact to UHF LMR reception. According to documentation provided by Crossroads Solar I, LLC, there will be a minimum setback of 150 feet between all solar panels and public roads, and a minimum setback of 300 feet between solar panels and homes and businesses.
Effects of Localized EMI on Land Mobile and Cellular Reception
For users of land mobile and cellular/mobile telephone services, temporary, local, reception issues are possible but should be unlikely and short-term in nature. See the discussion in the TV section above for the potential effects of photovoltaic inverter EMI on TV reception, which also applies to UHF land mobile and cellular reception, as these systems utilize frequencies that are smaller-wavelength, and line-of-sight. Any transitory signal impairment would be regained as soon as the person or vehicle changes position. If the PV array is located more than 150 feet distant from houses, businesses and roads, there should be no effects from EMI on Land Mobile reception. According to documentation provided by Crossroads Solar I, LLC, there will be a minimum setback of 150 feet between all solar panels and public roads, and a minimum setback of 300 feet between solar panels and homes and businesses.
Effects of Localized EMI on Other Communications Towers and Cellular Service
The primary concern with antenna towers not identified in the sections above is the potential for interference to cellular service. See the discussion in the FM and TV sections above for the potential effects of photovoltaic inverter EMI on FM Radio reception, which also applies to cellular reception, as cellular radio technology utilizes frequencies that are above the TV band that are smaller-wavelength and line-of-sight. There is one communications tower with registration number 1219886 where cellular licenses KNKN840 and KNKN955 are located 790 meters outside the study area (Table 4 and Figure 9).
To reduce the possibility of Electromagnetic Interference (EMI), PV array components, including inverters, should be sited at least 150 meters from communications tower locations. As is shown in Figure 10, the 150-meter exclusion zone around the tower does not overlap the project area, so the PV array is not of concern to the tower or the cellular radios on it.
Figure 10: Tower “exclusion zone” (orange area) to be avoided when siting PV arrays
Effects of Localized EMI on Wired and Wireless Internet Reception
Properly designed, installed, and maintained utility scale solar arrays have not been typically found to create localized EMI issues with any kind of wired communications reception, including wired internet.
Wireless internet is delivered in several ways:
• Via licensed microwave backbone + licensed wireless point-to-multipont distribution. This methodology is covered under the “land mobile radio” section of this report and the microwave path report.
• Via unlicensed microwave backbone + unlicensed wireless point-to-multipoint distribution. Typical distribution systems of this nature utilize Wi-Fi frequencies. Wi-Fi is not licensed with the FCC, so there is no method by which it is discoverable using publicly available databases, and Capitol Airspace is unable to identify unlicensed facilities
• Via satellite distribution directly to the premise (VSAT). While the satellite uplink facilities that carry internet facilities are licensed, the home satellite receivers are not. If the PV components, including inverters, are sited at least 150 feet from houses and businesses (as in Land Mobile and cellular reception), there should be no interference to VSAT receivers.
Conclusion
Capitol Airspace conducted a communication systems interference analysis for the CSGC. This analysis assessed the potential for impact on various systems:
AM Radio
There are no AM transmission facilities in proximity to the study area that would be affected by the proposed solar array. Further, the proposed solar project should not interfere with AM radio reception from an EMI standpoint, as the proposed solar array is far enough away from potential AM receivers as to not impact AM reception.
FM Radio
There are no FM transmission facilities in proximity to the study area that would be affected by the proposed solar project. Any EMI from the solar project has negligible impact on FM reception, and if the PV array is restricted to more than 150 feet distant from houses, businesses and roads, there should be no effects from EMI on FM receivers According to documentation provided by Crossroads Solar I, LLC, there will be a minimum setback of 150 feet between all solar panels and public roads, and a minimum setback of 300 feet between solar panels and homes and businesses.
Any reflections that the solar project might produce to affect cellular reception are negligible due to the height difference between FM radio transmit antenna mounted on a tower and the solar panels installed in the project. Further, they are temporary in nature and can be easily mitigated. As a result, FM radio reception should not be affected by the proposed project.
Television
There are no TV transmission facilities in proximity to the study area that would be affected by the proposed solar project. Any EMI from the solar project has negligible impact on TV reception, and if the PV array is restricted to more than 150 feet distant from houses, businesses and roads, there should be no effects from EMI on TV reception. According to documentation provided by Crossroads Solar I, LLC, there will be a minimum setback of 150 feet between all solar panels and public roads, and a minimum setback of 300 feet between solar panels and homes and businesses.
Any reflections that the solar project might produce to affect TV reception are negligible due to the height difference between a TV transmit antenna mounted on a tower and the solar panels installed in the project. As a result, TV reception should not be affected by the proposed project.
Mitigation options include simple changes to the placement of the receiving antenna or providing alternate means of viewing TV such as cable, satellite, or internet TV subscriptions.
Land Mobile Radio
There are no LMR base stations located within the project boundary, and nearby LMR licenses are located farther than 150 feet from any proposed solar panels. Any EMI from the solar project has negligible impact on LMR base stations, and aerial imagery does not indicate the possibility of potential LMR receivers within 150 feet of the proposed solar array. Any reflections that the solar project might produce to affect LMR reception are temporary in nature and can be easily mitigated. As a result, Land Mobile reception should not be affected by the proposed project.
Other Communications Towers and Cellular Service
Outside of the communication systems identified above, the primary concern associated with other communications towers is cellular service. There are no communications towers within the study area that would be affected by the proposed solar project. Any EMI from the solar project has negligible impact on cellular reception. Any reflections which the solar project might produce to affect cellular reception are negligible due to the height difference between a cellular radio antenna mounted on a tower and the solar panels installed in the project. As a result, cellular reception should not be affected by the proposed project.
Wired and Wireless Internet Reception
Properly designed, installed, and maintained utility scale solar arrays have not been typically found to create localized EMI issues with any kind of wired communications reception, including wired internet. The minimum setbacks in the CSGC permit application are a minimum of 300 feet between panels and homes and a minimum of 500 feet between inverters and homes. As a result, wireless internet should not be affected by the proposed project.
In summary, the analysis indicates that so long as the proposed CSGC PV arrays and individual components are professionally installed according to IEEE and IEC standards and are placed at least 150 feet from roads, buildings and individual licenses, they are not expected to cause interference to nearby communication systems. Comprehensive evaluations of AM and FM Radio, TV, Land Mobile Radio services, and nearby communication towers suggest that any potential impacts can be managed through prudent mitigation strategies and awareness of the specific system dynamics.
Based on the studies contained in this analysis, the CSGC should not cause any harmful effects to radio or television station transmission or reception, or Wi-Fi reception, either by EMI or by signal reflection, so long as the electrical components, especially DC to AC inverters, have been installed according to current codes and correct industrial installation procedures.
Further, as discussed in the analysis, if there are any effects on radio, television, land mobile, or cellular reception from the solar project, they are relatively easily mitigated.
If you have any questions regarding the findings of this study, please contact Travis Harrison or Cindy Cavell at (703) 256-2485.