Messing around with FUJI FWAVE solar panels
Rollable, 92W, ~$50, discontinued — and producing 420 volts open circuit. A working solution for making FUJI FWAVE solar panels actually usable.
The FUJI FWAVE FPV1096SLN is a rollable solar panel rated at 92W peak output, historically available for around $50. No longer manufactured, but interesting for off-grid and experimental power applications — if you can deal with the output.
The problem: the cells are wired in series, yielding approximately 420 volts open circuit. Maximum power output occurs at 320V — which conveniently aligns with rectified European mains voltage (~325V). This opens up possibilities for driving switchmode power supplies directly, without a step-down converter.
Working through the practical considerations: which loads work (switchmode only), which don't (resistive loads, transformer-based supplies), and what to do about the dangerously high open-circuit voltage. The implemented solution uses a shunt regulator built from an N-channel MOSFET, three 100V zener diodes in series, and resistors — dissipating excess voltage as heat. End result: a Macbook Air and a 12V Chinese power supply, running off a rolled-up solar panel.
A note on safety: 400V is lethal. Even a face-down panel in overcast conditions will generate over 200V. Handle accordingly.