Solar Power for the Amateur Station
This section covers the practical task of running an amateur station from photovoltaic panels and battery storage. It focuses on matching array and battery capacity to the station's actual transmit duty cycle and on controlling the radio-frequency interference that solar hardware itself produces on the HF and VHF bands.
Energy Calculation for Transmit Duty Cycle
Transmit duty cycle determines average current draw. CW and SSB voice produce low average power because the transmitter is active only during key-down or speech peaks, while modes such as RTTY or certain digital protocols keep the final stage conducting for longer intervals. The battery must therefore supply the full peak current during those intervals and still retain enough reserve for overnight or multi-day periods of low insolation. Panel area is sized to return the total daily energy removed from the battery, accounting for conversion losses in the charge controller and wiring voltage drop. MPPT controllers track the panel's maximum-power point more effectively than PWM units when cell temperature rises or when partial shading occurs, but both types switch at frequencies that can couple into receiver front ends.
Interference from Solar Hardware
Switching elements inside charge controllers and DC-DC converters generate broadband noise that travels along DC wiring and radiates from the panels themselves. This noise appears most strongly on the lower HF bands and can mask weak signals during digital-mode operation. Pure-sine-wave inverters reduce some conducted noise compared with modified-sine units, yet their internal switching still requires common-mode chokes on both positive and negative leads and careful single-point grounding to avoid creating loops with the station's RF ground. Physical separation between the array and the antenna feed point, combined with ferrite suppression at the controller output, is the most direct mitigation when the noise source cannot be relocated.
Points of Practical Disagreement
Operators differ on how much headroom to build into battery depth-of-discharge limits and whether to treat the solar system as the sole source or as a supplement that can draw from other power when insolation is poor. Placement of the array relative to towers and feed lines also produces ongoing discussion: closer mounting reduces cable loss but increases the chance that panel wiring will act as an unintended receiving antenna for the station's own transmitted signal. Choice between sealed lead-acid and lithium-iron-phosphate banks turns on cycle-life expectations versus the need for active balancing circuitry that can itself become another noise source.
Readers arriving here will find concrete descriptions of panel tilt effects, battery-discharge curves under pulsed loads, and measured RF spectra from common controller topologies. Subsequent pages address step-by-step measurement of station current draw by mode and the layout of filtered DC distribution that keeps solar-generated noise below the receiver noise floor.
Where to go next
Further reading