This project can be used with a CirKits solar circuit kit.
Measured Current: 0-10 Amps DC, can be increased by changing the resistors. Circuit Voltage: Will work with DC circuits at any practical voltage. Accuracy: approximately 2% with a high quality meter movement.
The 500 ohm variable resistor is used to adjust the meter's full scale reading. The 50 ohm resistor limits the maximum current through the meter. The series resistance of the meter, the 500 ohm (or less) variable resistor and 50 ohm resistor should total 1000 ohms. Different meters may require a different variable resistor to achieve the 1000 ohm value.
A PV panel is naturally current-limited and would also work well for alignment of this meter. Just wire the panel and two meters in a series loop and adjust the calibration potentiometer for the same reading.
Note that the wiring in a PV system is slightly resistive and will have a measurable voltage drop. You can take advantage of that by using the system's wiring in place of the 0.01 ohm resistor. Just connect a small signal-wire to two places on either the positive or negative side of your PV system's feed wiring and send that to the meter and its two series resistors. Typical connection points would be at the PV panel's negative terminal on one side and where the PV's negative line connects to the charge controller on the other side.
The voltage drop across the PV wiring will vary with the wire gauge, the wire length and the maximum PV current. It may be necessary to adjust the value of the two series resistances and possibly the meter rating depending on the current to be measured.
1x 100 microamp DC meter 1x 0.01 ohm 5 W resistor 1x 50 ohm 1/4 W resistor 1x 500 ohm 10 turn variable resistor 2x banana plugs or a 2 pin screw type terminal block. 1x metal box
Newark Electronics eBay for new and surplus meters