NOTICE:
We disagree with the exclusion of Newton's laws, Ohm's law and the energy conservation law from physics of primary schools in the Czech Republic!

## Load characteristics of the Solar cell

### Work task and measurement procedure

1. Measure (point by point) the load characteristic of the solar cell under different lighting.

2. Plot the dependence of the cell voltage on the current drawn by the load and the total power on the current taken for different illuminations of the cell. Compare the shapes of the obtained dependencies with the theoretical form of these dependencies.

3. Determine the values of electric voltage Ue (no-load voltage) and electric current Ik (short-circuit current) for individual cases of different cell illumination.

4. Read from the graph the values of the electric current IMP (current at maximum power) and the corresponding electric voltage UMP (voltage at maximum power) – see Theory.

5. Find the value of the maximum power (at a given lighting) and the value of the theoretical power. From the obtained values, determine the so-called filling factor of the given solar cell.

6. Estimate the power of the incident light and thus the efficiency of the solar cell used from the knowledge of the electrical voltage and current on the light bulb and its approximate efficiency of 3 %

#### Measurement procedure:

1. We run a remote experiment DEVIL (Solar cell load characteristics).

2. We will choose one of the four prepared values of solar cell illumination.

3. We increase the current through the solar cell circuit gradually by changing the size of the rheostat at a set exposure value. We save to the table individual pairs of experimental values (voltage, current) of experimental values on the control panel of the remote task.

4. We can verify the correctness of the obtained values of the given dependence by previewing the graph directly in the control panel of the task.

5. We can save the data to the computer after measuring the required number of relevant data for the given lighting, then we can set another lighting of the cell and repeat the measurement similarly for the next lighting value.

6. We can leave the remote task and continue processing the data in the spreadsheet after obtaining several series of experimental values for the given lighting.

7. We will open a file with the data of the selected lighting. We can use any spreadsheet (MS Excel, OO Calc…) that can load a CSV file. (CAUTION: data separated by semicolons!)

8. We create a column of generated electrical power from voltage and current values. We plot both the dependence of the electric voltage on the electric current and the electric power on the consumed current in a graph.

9. We determine all the necessary points in the graphs – ie Ue (no-load voltage), Ik (short-circuit current), UMP (voltage at maximum power) and IMP (current at maximum power).

10. We calculate the values of theoretical performance and performance factor according to valid formulas.

11. We determine the approximate power of the light source from the power supply parameters of the source and its estimated efficiency (about 3 %).

12. We will try to estimate the overall efficiency of a given solar cell as a ratio of maximum power and incident light power.