The Voltage-Divider Circuit Function: to develop more than one voltage level from a single voltage supply
A Voltage Divider Connected to a Load
The Current Divider Circuit
Example 3.3 Calculate power dissipated in the 6 Ohm resistor
Problem 3.14 v o (no load)=4 V v o (load)=3 V Find R L
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
Application: Photovoltaic System Solar Cell – I-V Characteristics Equation – Series construction – Parallel construction
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
Open Circuit Voltage Measurement Observation: there is no current at V oc.
Short Circuit Current Measurement
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.
Power Produced by Solar Cell P=IV Observation: No power is produced at V oc and I sc. Why?
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.
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.
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
Use Series Connection to Increase Voltage You want to use cells of matching current capacity!
Use Parallel Construction to Increase Current (Acquire proper voltage)
Increase Current Capacity by Connecting Cells in Paralell