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SESSION 4

Grid connect Series& Parallel circuits. SESSION 4. Grid connect Series & Parallel circuits. Grid connect Series& Parallel circuits. The path a current follows from one potential to a different potential is called a circuit. SESSION 4.

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SESSION 4

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  1. Grid connect Series& Parallel circuits SESSION 4 Grid connect Series & Parallel circuits DAMON FYSON

  2. Grid connect Series& Parallel circuits • The path a current follows from one potential to a different potential is called a circuit SESSION 4 • When the current passes through all the components of a circuit in succession it is a series circuit. As a result, there is only one path for current to follow and therefore the current will be the same in all parts of the circuit • In the diagram below, resistors R1 and R2 are in series with the battery. DAMON FYSON

  3. Grid connect Series& Parallel circuits For example, if our battery in the series circuit is 12 Volts and R1 = R2, then the voltage across R1 & R2 will be equal at 6 Volts each. R1 = R2 x 2 , then the voltages would be 4 Volts across R2 and 8 Volts across R1. To clarify this, assume R1= 4 Ohm and R2= 2 Ohm and therefore the current, I, would be 12V/(4+2) = 2 Amps. So the voltage across R1 is 2A x 4 Ohm = 8V while for R2 it is 2A x 2 Ohm = 4V SESSION 4 DAMON FYSON

  4. Grid connect Series& Parallel circuits • The diagram belowshows two batteries V1 and V2 connected in series with a resistor R. • In this case, the voltages of the batteries will combine (be added together) to obtain the total voltage VT. • If each battery is 12V, then the potential difference applied to the resistor, R, will become 24V. SESSION 4 DAMON FYSON

  5. Grid connect Series& Parallel circuits SESSION 4 Schematic solar cell module drawing symbol actual solar cell DAMON FYSON

  6. Grid connect Series& Parallel circuits Multiple modules can be wired together to form an array. In general, the larger the area of a module or array, the more electricity that will be produced. Photovoltaic modules and arrays produce direct-current (dc) electricity. They can be connected in both series and parallel electrical arrangements to produce any required voltage and current combination. SESSION 4 Courtesy NASA Science DAMON FYSON

  7. Grid connect Series& Parallel circuits SESSION 4 Solar modules in series A solar module in sunlight is similar to a battery. In the figure above, if the solar modules PV1 and PV2 are nominally 12V each, with a current capability of I1 = I2 = 3.5A, then the output voltage from both modules that appears across resistance R will be the sum of the individual voltages from the PV modules,   but the current IT will be as for one module, i.e. DAMON FYSON

  8. Grid connect Series& Parallel circuits SESSION 4 Solar modules connected in series are called a string. DAMON FYSON

  9. Grid connect Series& Parallel circuits Batteries in opposition SESSION 4 As shown above, the batteries while appearing to be in series, are connected in opposition and assuming they are equal voltages, no current will flow in the circuit. The potential difference across R will be zero. DAMON FYSON

  10. Grid connect Series& Parallel circuits Open circuit SESSION 4 We can see an open circuit condition in a series circuit above. An open circuit may result from a switch being opened or a fuse opening under a fault condition. No current will flow in the circuit and the full supply voltage will be measurable across the open circuit point.  DAMON FYSON

  11. Grid connect Series& Parallel circuits Parallel Circuits When two or more components are connected across one voltage source they form a parallel circuit. Each parallel component forms an individual 'branch', and although each branch will have the same potential difference applied, there is the possibility of a different current flow in each branch. The total current flow, IT, in the circuit below is equal to the sum of the currents (I1 + I2) flowing in the parallel branches, but the potential difference V is the same across all branches. If we provide multiple energy sources in parallel, such as solar modules, and assuming that they are all the same, the potential difference remains constant, but the current capability is equal to the sum of the individual supplies, i.e. SESSION 4 DAMON FYSON

  12. Grid connect Series& Parallel circuits Solar cells in parallel SESSION 4 For example, if the solar modules above are nominally PV1 = PV2 = 12V each and with a current capability of I1 = I2 = 3.5A respectively, then the output voltage of the circuit will be 12V and have a total current of 7AIf we continue to add modules in parallel the voltage will remain constant but the current capability of the complete array will continue to increase DAMON FYSON

  13. Grid connect Series& Parallel circuits Formative questions SESSION 4 DAMON FYSON

  14. Grid connect Series& Parallel circuits SESSION 4 DAMON FYSON

  15. Grid connect Series& Parallel circuits SESSION 4 DAMON FYSON

  16. If a customer uses the following appliances, how much energy would they have consumed? • 3 x 60W light globes for 30 minutes each • 1 x 110W television for 2.5 hours You answered 365Wh The light globes use 3 x 60W x 0.5h = 90Wh total The television uses 1 x 110W x 2.5h = 275Wh Therefore the sum of these is 90 + 275 = 365Wh So the customer uses 365Wh with these appliances. Grid connect Series& Parallel circuits SESSION 4 DAMON FYSON

  17. Grid connect Series& Parallel circuits SESSION 4 Combination Series/Parallel Circuits By combining the features of both series and parallel circuits we can arrange solar modules or batteries in any voltage or current configuration that we desire. When there is a combination of solar modules connected in series and/or parallel the combination is called an array. DAMON FYSON

  18. Grid connect Series& Parallel circuits Series/parallel SESSION 4 Below is an array of 2 parallel strings of 2 modules in series. Assuming the same values as in previous examples, this solar array has an output voltage of: output current of : DAMON FYSON

  19. Grid connect Series& Parallel circuits • SUMMARY • When solar modules are in series, the voltages add together while the current remains constant. • The current is equal to the minimum current provided by the smallest (in watts) solar module that is in series. • When solar modules are in parallel, the voltage is the same and is equal to the average output of the parallel modules. • The current in the circuit connected to the parallel modules is the sum of the output currents of the parallel modules. SESSION 4 DAMON FYSON

  20. Grid connect Series& Parallel circuits Apparent PowerWhat is the apparent power of a 250W appliance with a power factor of 0.85? Round answer to one decimal place. Is this value in W or VA? Your Answer: 294.1 VA Current Through ResistorHow many Amps would be flowing through a 1.2kΩ resistor that had a voltage of 96V across it? Answer to two decimal places (in Amps). Your Answer: 0.08A SESSION 4 DAMON FYSON

  21. Grid connect Series& Parallel circuits Parallel Circuits 2In the circuit below, assume that the battery has a voltage of 24V and R1 = 100Ω; and R2 = 240Ω, as shown. What are the values of the currents IR1, IR2 and IT? Show your workings for full marks SESSION 4 Your Answer: IR1 = Vs/R1 24/100 = 0.24A IR2 = Vs/R2 24/240 = 0.1A It = 0.24 + 0.1 = 0.34A DAMON FYSON

  22. Grid connect Series& Parallel circuits SESSION 4 Series Circuits 2A module has a maximum power point voltage of 35V and an output current of 4.8A. If 10 of these modules are connected in series, what is the output current and voltage?Your Answer: 4.8A @ 350V DAMON FYSON

  23. Grid connect Series& Parallel circuits Take home question continued…. 5) If the four modules below are identical, each with an output of 6A @ 34V, what is the voltage (VT) and current (IT) of the output? SESSION 4 What is the overall power rating of the array?Your Answer: Vt = 68v It =12A DAMON FYSON

  24. Grid connect Series& Parallel circuits Take home questions Define the terms Series circuit Parallel cct Series parallel circuit 2) If three solar modules of nominal voltage 24v/3.6A output are connected in series, what will be the combined voltage and current available? 3) If the three modules , mentioned in Q2 are now connected in parallel, what will be the combined voltage and current available? 4) What voltage would be possibly measured across the contacts of a fuse holder if the fuse is removed? Assume a system voltage of 48V and circuit resistance 24Ωs SESSION 4 DAMON FYSON

  25. Grid connect Series& Parallel circuits Parallel Circuits 2In the circuit below, assume that the battery has a voltage of 48V and R1 = 100Ω; and R2 = 240Ω, as shown. What are the values of the currents IR1, IR2 and IT? Show your workings for full marks SESSION 4 DAMON FYSON

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