Reducing RF Interference from Solar Panels: How to Mitigate Noise on Your Beam Antenna

With the rise of renewable energy, more ham radio operators are encountering an unexpected challenge: increased radio frequency interference (RFI) from nearby solar panel installations. While solar panels themselves do not generate noise, their associated electronics—such as inverters, power optimizers, and charge controllers—can significantly raise the noise floor, impacting HF reception. This article explores why this happens and how RF.Guru’s common-mode chokes and other strategies can help mitigate the problem.

Understanding Solar Panel RFI

How Solar Installations Generate Noise

Inverter Switching Noise

  • Solar inverters rapidly switch DC to AC, creating harmonics that can extend from 100 kHz to 30 MHz.
  • Poor filtering or substandard inverter designs may lead to significant wideband noise.

Wiring as a Radiating Antenna

  • Long unshielded DC and AC power cables can act as antennas, radiating unwanted RF energy.
  • Even in well-installed systems, small inconsistencies—such as loose connectors, aging insulation, or imbalanced currents—can contribute to interference.

Power Line Conduction

  • The noise from the inverter can travel through household and utility power lines, re-radiating across the neighborhood.

Sunlight Variability Affects Noise Levels

  • Because sunlight isn’t constant (e.g., passing clouds, shading, and angle changes), inverters dynamically adjust their operation, modulating their switching frequencies and generating variable noise spikes.

Can RF.Guru Chokes Help?

Common-mode chokes can be effective if the noise is entering your station via common-mode currents on your coaxial feedline. However, if the noise is primarily airborne and directly radiated from solar wiring or inverters, additional mitigation steps will be required.

Effective Strategies for Reducing Solar RFI

1. Use Common-Mode Chokes on the Coaxial Feedline

2. Reduce Noise at the Source

  • If possible, work with the solar panel owner to install ferrite chokes on the DC and AC lines near the inverter.
  • Encourage the use of proper grounding and shielding.
  • If upgrading is an option, look for solar inverters with EMI filtering and certifications for low RF emissions.

3. Optimize Antenna Placement and Beam Direction

  • Rotating the beam can help determine if the noise is directional. If so, you may find a null in the noise pattern.
  • Raising or lowering the antenna temporarily can help determine if the noise is ground-based or coming from the surrounding air.

4. Use a Noise-Canceling Antenna

  • Consider a phased noise-canceling system using an auxiliary receive antenna, such as a small magnetic loop or an active E-probe antenna like the RF.Guru EchoTracer.
  • These antennas can pick up the noise and, via a phasing device, create an adjustable null to significantly reduce or cancel out the interference before it reaches the receiver.

Final Thoughts

While solar RFI is becoming more common, it can be managed with the right combination of chokes, filtering, and antenna adjustments. RF.Guru’s high-performance ferrite chokes can help reduce common-mode interference, while additional steps such as noise-canceling antennas and better inverter filtering can further enhance your HF reception.

For more details on selecting the right chokes for your setup, visit RF.Guru’s website or reach out for personalized recommendations!

Written by Joeri Van Dooren, ON6URE – RF, electronics and software engineer, complex platform and antenna designer. Founder of RF.Guru. An expert in active and passive antennas, high-power RF transformers, and custom RF solutions, he has also engineered telecom and broadcast hardware, including set-top boxes, transcoders, and E1/T1 switchboards. His expertise spans high-power RF, embedded systems, digital signal processing, and complex software platforms, driving innovation in both amateur and professional communications industries.