Electronics

Source: Wikimedia Commons

Solar Cell Testing: Understanding the IV Curve

When testing solar cells, one crucial aspect is understanding the current-voltage (IV) curve. This curve can be obtained by adjusting a variable resistor across the cell and measuring the voltage and current at the cell terminals. While this method is straightforward, it can be time-consuming. Therefore, in practical applications, more advanced electronics are typically utilized.

Measuring I_sc and V_oc Separately

To enhance accuracy, the short-circuit current (I_sc) and open-circuit voltage (V_oc) are usually measured separately from the rest of the IV curve. This is achieved by setting the voltage to zero to measure I_sc and setting the current to zero to measure V_oc.

Improving Measurement Accuracy

The IV curve exhibits a varying slope, which can introduce challenges in measurement. One common approach to improve accuracy is to take measurements at equally spaced voltage intervals in two steps. The first step covers the voltage range from 0 to 70% of V_oc with widely spaced points. The second step focuses on the remaining 30% to V_oc with closely spaced points. The region beyond 70% of V_oc contains crucial points such as the maximum power point and the open-circuit voltage, exhibiting a steeper slope.

Challenges in Testing Large Area Cells

With the trend towards larger silicon substrates measuring 15 x 15 cm² and beyond, testing high-current large area cells poses a challenge. These cells can exhibit short-circuit currents surpassing 10 amps, requiring specialized testing equipment capable of sourcing and varying current over several orders of magnitude, from nanoamps to several amps.

Integrated Testing Systems

Modern testing systems are designed to meet the demands of testing large area cells, offering integrated solutions with computer control. These systems can handle the high current requirements and provide the flexibility to specify the cell size for testing purposes.

Source: subcontracteu.com

Feel free to comment your thoughts.