I designed the Solar Panel Testing Shunt Regulator to function as a variable voltage shunt regulator for measuring the power output of small solar panels.
I wanted to be able to load the output of a solar panel with a variable load to obtain various output voltage levels and measure the corresponding current flow. Repeating current measurements at various voltage levels to characterize a solar panel without having the output voltage level drift.
The shunt regulator has a two position range switch. A high range where the shunt regulator starts to conduct at about 28 volts at the minimum shunt setting and a low range that the shunt regulator starts to conduct at about 15 volts with the minimum shunt setting.
Both ranges can shunt the solar panel to less than about 1 volt at the maximum shunt setting but the low range has a finer voltage adjustment.
Here are the measured voltage levels at full shunt and the corresponding current levels for this unit.
.25 volt @ 500 ma.
.44 volt @ 1055 ma.
.74 volt @ 1750 ma.
Solar Panel Testing Shunt Regulator
Schematic, Board Drawing and Parts List.