How to Measure Milliamps in a Solar Panel

Solar panels convert sunlight into electricity.

Solar panels are an environmentally sound method of generating small quantities of electricity. Light falls on the panel cells and is directly converted into electrical power, but the quantity of power depends on the efficiency of the cells, the number of cells and the intensity of the light. Mathematically determining the current produced by the panel requires that the voltage and resistance of the entire circuit are known. Direct measurement is a more realistic approach to calculating the milliamps produced by a panel.

Things You'll Need

• Multimeter

Instructions

1. Ensure that the panel is exposed to sunlight and is directly connected to a storage battery. If the test is to determine the current under specific conditions, ensure that those conditions exist. Output varies according to the load and the light conditions. For example, ensure that the right conditions exist if the test is to measure current under bright sun conditions, or when the panel feeds power to a fully charged storage battery.

2. Break the circuit at a convenient point between the solar panel and the battery. Existing terminals and wire junctions are ideal locations at which to break the circuit. Connect the multimeter leads, one to either side of the broken circuit, so the meter becomes part of the circuit.

3. Set the multimeter to measure milliamps. If the multimeter is not auto-ranging, selecting the highest range available. Switch on the meter and observe the digital display. The display shows the current flowing between the solar panel and the battery.

Tips & Warnings

• If the reading is very low and the meter is not auto-ranging, select a display range intended to use with lower values.

• Unless you are certain that the current is less than an amp, do not start measuring in milliamps. Start by assuming a much higher current, and adjust the meter scale once you know the actual current.

• Current varies according to the load or resistance applied to the circuit.

References

• University of Southern California; Solar Cell Experiments; Jerry Loomer
• Science Buddies; How Does Solar Cell Output Vary with Incident Light Intensity?; Andrew Olson, Ph.D. ; March 2009
• Electronics And Radio Today: How To Measure Current
• Southern Methodist University Department of Physics; Digital Multimeter; Randall J. Scalise Ph.D

Resources

• Read this Article in Spanish