I made a solar powered guitar amp! The goal was to have a guitar amplifier that did not need to be plugged into a power source. It’s so easy to just pick up an acoustic guitar and start making music. I wanted this same experience when playing electric guitar: not worrying about plugging in an amp, or being tethered to a power source. This is an absolute necessity when faced with outdoor situations where there is no AC power source: busking, camping, or jamming in a park with friends.
Rather than start completely from scratch, it was decided to retrofit an existing amplifier, the Vox Mini3. It pumps out around 5 watts of power, which sounds small, but it can get pretty loud. It has 2 inputs, one for guitar, and one for a microphone, along with tone controls and effects like reverb, delay, and compression.
The amp was retrofitted to run off of a rechargeable battery and solar panel. It is interesting to note that the Mini3 already had an existing battery case inside the amp. However, the hassle of installing and removing batteries is less than ideal. An all-in-one solution completely powered by 100% renewable solar energy was the goal.
Several tradeoffs affected the overall system design. A minimum run-time requirement was 3-4 hours to ensure that the amp would last through a performance or rehearsal. A 1.3 Ah sealed lead-acid battery was chosen to provide storage, with the optimum charge capacity vs weight a paramount consideration. Three 2 Watt solar panels were connected in series to provide 18V at 0.33 A of solar power to the battery (6 Watts total).
Finally, a charge controller was installed to allow simultaneous charging of the battery and powering of the amp via the solar panels. The charge controller also ensured the optimum charging currents to the battery, as well as providing protection against overcharging and excess depletion.
The battery and charge controller were both placed inside the amp cabinet, and all wiring tucked neatly inside. A DC jack for the solar panels was mounted to the back panel. The existing DC power jack was left intact, providing an additional means of powering the amp in case the battery was depleted.