1. Series/Parallel Circuits Section 3.1-3.4

2. Concepts Studied So Far Ohms Law: Victory Is Rare Power: P=IV KCL KVL

3. Outline Resistors in Series Req Resistors in Parallel Req Voltage Divider Circuits Voltage divider formula Current Divider Circuits Current divider formula

4. Resistors Connected in Series Series-connected circuit elements carry the same current

5. Equivalent Resistor R eq =R 1 +R 2 +R 3 ….

6. Exercise Identify the resistors connected in series

7. Resistors in Parallel Parallel-connected circuit elements have the same voltage across their terminals

8. Equivalent Parallel Resistor 1/R eq =1/R 1 +1/R 2 +1/R 3 +1/R 4

9. Series Parallel Simplification

10. P3.5 Find R ab

11. P3.7 Find R ab

12. The Voltage-Divider Circuit Function: to develop more than one voltage level from a single voltage supply

13. A Voltage Divider Connected to a Load

14. The Current Divider Circuit

15. Example 3.3 Calculate power dissipated in the 6 Ohm resistor

16. Problem 3.14 v o (no load)=4 V v o (load)=3 V Find R L

17. 3.15 Assume that only 0.5 W resistors are available The no-load voltage is to be the same as in the schematic. Specify the smallest values of R 1 and R 2

18. Application: Photovoltaic System Solar Cell – I-V Characteristics Equation – Series construction – Parallel construction

19. I-V Characteristics of a Solar Cell Open Circuit Voltage (V oc ) Short Circuit Current I(I sc ) I-V Characteristics shows all the possible operating point for the solar panel

20. Open Circuit Voltage Measurement Observation: there is no current at V oc.

21. Short Circuit Current Measurement

22. Why is OK to short circuit a solar cell? It is possible to produce short circuit a solar panel because The current comes from the electrons produced by the solar cell. Only some of the photons striking the solar cell are converted into current. The current produced by the solar cell is finite.

23. Power Produced by Solar Cell P=IV Observation: No power is produced at V oc and I sc. Why?

24. Example If Vmp is 15 V and Imp is 3A, what resistance is required in order to operate the solar cell at its maximum power? Answer: A 5 Ohm load.

25. Rule of Thumb Solar cells are generally connected in series to achieve a desired voltage. The serial connected solar cells are connected in parallel to build current and power. Cells are connected to form modules and modules are connected to form array.

26. Connect Cells/Modules in Series Individual cells are connected in series by soldering the metal strip from top surface (- terminal) of one cell to the back surface (+ terminal) of the next

27. Use Series Connection to Increase Voltage You want to use cells of matching current capacity!

28. Use Parallel Construction to Increase Current (Acquire proper voltage)

29. Increase Current Capacity by Connecting Cells in Paralell