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

### Work Task and Measurement Procedure

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

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

3. Determine the values of the electric voltage Ue (no-load voltage) and the 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) – Theory.

5. Find the value of the maximum power (at a given illumination) 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 used solar cell from the knowledge of the electric voltage and current of the 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 gradually increase the current through the solar cell circuit by changing the size of the rheostat at the set illumination value. We save in the table individual pairs of experimental values (voltage, current) of experimental values on the control panel of the remote task.

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

5. We can save the data to the computer after measuring the required number of relevant data for the given illumination, then we can set another illumination of the cell and repeat the measurement in a similar way for the next illumination 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 illumination.

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

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 dependence of the electric power on the consumed current in a graph.

9. We determine all necessary points on the graphs – i.e. 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 power and power 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.