How to Hook a Multimeter to a Solar Cell to Measure Amps

Unlike current, voltage is measured by connecting the meter in parallel with the circuit rather than in series with the circuit.

Amperage is the rate of flow of electricity through a circuit. A circuit's amperage is dependent upon the voltage applied and the resistance of the circuit. An equation for determining amperage is E/R = I, where "E" represents volts applied, "R" represents resistance in ohms and "I" represents current in amperes. Solar cells are designed with a maximum amperage rating; however, the actual working amperage of a solar cell depends on the voltage supplied and the resistance of the circuit. To measure a solar cell's amperage, a digital multimeter is connected in series with the solar cell in a circuit.

Things You'll Need

• 3-volt, 100 milliampere solar cell with leads
• 5 mm red LED
• Digital multimeter
• Red and black multimeter leads
• Alligator clip leads

Instructions

1. Insert the red digital multimeter lead into the (+)Volt-Ohm-Ammeter jack. Insert the black digital multimeter lead into the (-) Com jack.

2. Connect the positive (red) lead of the digital multimeter to one end of an alligator clip lead. Connect the remaining end of the alligator lead to the long lead of a red LED. The long lead of an LED is the positive (anode) lead. The red LED is used to show that a circuit is connected correctly and working.

3. Connect one end of a second alligator clip to the short lead of the red LED. The short lead is the negative (cathode) lead. Connect the remaining end of the alligator lead to the positive lead of a 3-volt, 100 milliampere solar cell.

4. Connect one end of a third alligator clip to the negative lead of the solar cell. Connect the remaining end of the alligator lead to the negative lead of the digital multimeter. The solar circuit is now complete.

5. Turn the digital multimeter selector knob to its highest ampere setting. Expose the solar cell to direct sunlight. Note whether the LED shines. If the LED does not light then check the circuit connections. An LED in the wrong orientation will not allow current to flow through a circuit.

6. Observe the multimeter display for the amperage reading. If the reading is off-scale, turn the selector knob to a lower ampere setting until a whole number is displayed.This is the amperage of the solar cell in milliamperes.

Tips & Warnings

• Try adding two or more additional LEDs to the circuit and note the change in the amperage reading. More devices will cause an increase in the current draw from the solar cell.

References

• Science Buddies; How Does Solar Cell Output Vary With Incident Light Intensity?; 2009
• The Electronics Club; Light Emitting Diodes (LEDs); John Hewes; 2011
• Science Buddies; Electronics Primer: Using a Multimeter