Thursday, April 22, 2021

Solar cell design by using Photonic Simulation software

 

Basic solar cell design includes P-N junction with thin N layer being at top and bulk P layer at bottom. It is designed without the ARC coating. But since bare silicon is oxidised due to reaction of oxygen so top and bottom side of solar cell is thin silica oxide layer.


Dimensions of solar cell- 

Overall dimension of cell=14 x 10 x 6 um (considered for simulation)

N – type layer at top of cell diffused doping surface concentration = 10^19 /cm3 and reference concentration = 10^10/cm3, With thickness of 1 um and junction width of 0.4 um.

Remaining material is p-type doped with density 10^16/cm3.

At upper and lower surfaces 1 um thick silicon oxide layer.

At top emitter side the silver current collector wire of  2 um breadth and 0.5um thickness.

At bottom base side aluminium current collector of 1 um thickness.


The picture of lumerical simulation model is given below-






To do the simulation in device first of all we need generation curve(wavelength range 0.3 – 1.1 um) which is obtained from the FDTD. Generation curve gives the variotion of electon hole pair generation with the solar cell depth.

After that we imported the generation rate data in the device applied  biasing across the solar cell to get the following I-V curve.



This curve shows the variation of current density of solar cell with respect to the voltage.

The short circuit current is maximum current of solar cell obtained at zero voltage, and open circuit voltage is maximum voltage obtained at open circuit i.e. zero current. It is showing that the current is nearly constant up to certain voltage after that it falls very fast.


The above curve shows the power density variation with respect to voltage. We can get the maximum value of power from the above curve so that we can find the efficiency.


 Efficiency η % =( Pmax / solar irradiance at 1.5  AM) * 100.


Results.=

Voc = 562.222 mV

Jsc = 12.37 mA/cm^2

Pmax = 5.76976 mW/cm^2

η % = 5.76976%

Sunday, April 18, 2021

Voltage and current waveform of various type of loads- Simulations

In this post, I have plotted volatage and current wavefrom under various loads such as resistive, capacitive, inductive and thier combination under sinusoidal input through simulation softwares.

1. With Resistive Load- RESISTOR 10 ohm

2. With Inductive load- 10mH



3. Capacitive load- 10 mF (10 mili Farad)




4. With Resistive and Capacitive ( RC ) Load R- 10ohm & C- 10 mF 




5. With Resistive and Capacitive ( RC ) Load R- 10ohm & C- 1mF 




Comparison with C= 10mF & 1 mF


6. With Resistive and Inductive ( RL ) Load R- 10ohm & L- 10mH



7. With Resistive and Inductive ( RL ) Load R- 10ohm & L- 1mH


Comparison between with 10 mH & 1 mH

8. With Resistive, Capacitive and Inductive ( RL ) Load R- 10ohm, C- 10mF & L- 1mH



There are many simulation software such as Multisim, Matlab, proteus available for simulation trial version may be downloaded for beginning. It will help you in understand the theory in good way.

Friday, April 16, 2021

Calculation of the theoretical heat generated in the Proton Exchange Membrane fuel cell & Electrical potential Difference

Calculation of the theoretical heat generated in the fuel cell.

Basic reaction at fuel cell electrodes-

                 At the anode:       H2 →  2H+ + 2e-                                                                                                   

                 At the cathode:    ½ O+ 2H+ + 2e- →  H2O                                            

                 Overall:               H2 + ½ O2 →  H2O                                                                      

The overall reaction is same as the hydrogen combustion. Since combustion is exothermic process so heat will be released -

                                  H2 + ½ O2 →  H2O + heat

Standard enthalpy of reaction can be calculated by difference of heat of formation of products and reactant.

       ΔH= (hf)H2O(l)- (hf)H2- (hf)0.5O2

Heat of formation of liquid water is -

(hf)H2O = -286 kJmol-1 (at 25°C)

Heat of formation of reactant gases 

(hf)H2= (hf)0.5O2 =0 kJ/mol

So,                                                  ΔH= -286-0-0= -286 kJ/mol.

-ve sign indicates that reaction is exothermic.

But if products H2O is not cooled enough to become liquid, and it remains as vapour then the enthalpy of reaction reduced by enthalpy of vaporisation of water ie. 44 kJ/mol

     ΔH= (hf)H2O(g)- (hf)H2- (hf)0.5O2

              = -286+44 -0-0= -242 kJ/mol.

All the generated energy cannot be converted into electricity due the reaction entropy. The portion of the reaction enthalpy (or hydrogen's higher heating value) that can be converted to electricity in a fuel cell corresponds to Gibbs free energy and is given by the following equation:

                                                       DG = DH- TDS    .

So Gibbs free energy in the liquid water conversion at 250 C

                                                      DG= -286-(25+273)*(-0.1663)= -237 kJ/mol.

Heat produced theoretically in the reaction is = -237-(-286)= 49 kJ/mol

And Gibbs free energy in the vapour water conversion at 250 C

                                                     DG= -242- (25+273)*(-0.0444) = -229 kJ/mol.

Heat produced theoretically in the reaction is = -229- (-242)= 13kJ/mol.

Electrical work:                           W el= nFE,       

 n= no of electrons per mole. E= electric potential

Maximum amount of electrical energy generated in a fuel cell corresponds to Gibbs free energy, DG:                                              

Wel = - DG =nFE

So theoretical electrical potential   E= = - DG/ nF

                                                            =- (-237*1000)/ (2*96500) = 1.23 V 


Fore more details on fuel cell, please commment, I can share more details of fuel cell. 

Sunday, April 11, 2021

School project for Kids- Solar powered fan in a Cap

 

Aim- To make familiar with solar panel and its electrical output by running a small DC fan with the solar panel.

Components required-

1.       Solar panel (6V, 200mA)

2.       Diode (1N4007)

3.       Small DC Fan (5V, 200mA)

Theory-

The solar panel generates electrical power when it is placed under the sun light. The output depends on the solar panel dimensions and solar radiation available to solar panel. The diode is unidirectional device. It conducts the current in one direction and blocks in the opposite directions. Due to this property diode is used to stop the reverse power flow toward the solar panel. The fan will work as load and will take electrical power generated from the solar panel to blow the air.

Steps-

1.      Take the solar panel and put in the opposite way.

2.    Find the + (plus) and – (minus) symbol on back side.

3.       To the +side connect the black side of diode.

4.       To the silver side of diode connect the fan + terminal (red wire).

5.       Connect the –ve terminal (black wire) of Fan to the –ve side of solar panel.

6.       Now take the solar panel in the sun light and put front side up. The fan will start running.

7.       Now just put solar panel in different sun lights intensity and see the variation in the fan speed.

Connection Diagram-



Follwing type product can be made using above-

sample design.

More innovative design can be made. Your ideas may please  be shared in the comment section. 



Design aspect of Solar panel operated ventilation system or Airconditioner for avoiding Heat-stroke in Car using

 

Heatstroke-

 Heatstroke (or sunstroke) is a heat illness defined as a body temperature of greater than 40.6 °c (105.1 °F) due to environmental heat exposure with lack of thermoregulation.

It happens due to lack of water in body so that body temperature becomes more than the 40.60c.

Fact and Causes of Heatstroke-

When car is parked in 25°C ambient condition under normal sunlight and car inside temperature is 22°C, within 15 minute the inside temperature rises to 48°C even when window is partially open.

This is due to greenhouse effect of interior of Car. The glasses passes the visible light(sun light) but does not allow to IR radiation(heat waves) to come out. Due to which temperature increases very fast inside the car.

The human body wants to stay at 98.6 degrees F(370 C). The only way to stay at 98.6 is to sweat. By putting moisture on the skin and letting it evaporate, our body can cool itself very effectively and keep its temperature in the proper range.

At 48-50 0C the rate of sweating becomes very much so human body needs lots of water. Due to unavailability of water body temperature increases very fast and leads to heat stroke.

Effect of heatstroke-

Sometimes parents leaves their child in the car and goes for shopping or other purposes. The heatstroke in car leads to death of the child inside. Many cases have been reported in this regard.

Due to high temperature of the car seat and inside air, if the persons comes to drive the car, he has to run the A. C. at very high cooling rate for few minute which leads to more fuel consumption.

Also sometimes, Car driver stays inside the car and run the car engine to cool it, which leads to much more fuel consumption.


Following are few designs-

Design-1

Targeted for lower end customer and less stylish design-

·         A solar vehicle ventilator also called solar car vent or solar car fan

·         Sun's energy converted  into the low-voltage electricity required to drive a small fan

·         The fan blows stale, hot air out of your vehicle and draws fresher air in.



Features -

1) Auto cool solar powered car fan

2) Auto cool is the revolutionary solar powered ventilation system to keep it up to 30 C cooler than it would normally be

(3) Being compact, it fits in any car window and does not need batteries

Specification -

 Colour: Same as car

 Item size: 14.5x 11 x 6cm

 Solar panel size: 10x7 cm

 Cost: $ 10

 Package item: 342 g

Design-2

Design for upper end customer and good looking design

      Solar panel on the top of CAR will be placed.

      Can give enough power to run a fan for good Ventilation

      With use of high efficiency panel Air-condition Also can be run.

·         Area available= 3m2

·         Power available by panel= 3*150= 450 Wp

·         Panel cost(for m-c Si )= 23,000 INR

·         Ventilation system cost= 5,000 INR

·         Installation cost= 4,000 INR

·         Total cost= 32,000 INR

·         Can maintain temperature near to the ambient condition


Design-3

Design for long cars and more cooling requirement design

  • Foldable panel design
  • Can give large area to absorb irradiance
  • Air-conditioning system can be used  cool the car
  • Panel will give continuously energy at low power, it will be stored in the battery, battery will give power to charge super-capacitor at low power for more time. To run AC Super-capacitor will give high power for short time.


  • On long Car available total area available is= 7 m2
  • So panel can be give power= 7x150= 1050 Wp

      This Panel will cost= 50,000 INR

      Super capacitor cost= 10,000 INR

      BLDC motor cost= 3,000 INR

      Installation cost= 5,000 INR

  • Total cost= 68,000INR
  • Can maintain temperature ~ 220C


Prototype design result-

we designed a solar panel driven Thermo- electric based cooler in a closed box of around 1ft x1ft x 0.5 ft and measured the test data as follwing. 


Conclusion-

      This is good idea to solve current problems of sunstroke in Cars by using solar power.

      By using this idea we can able to reduce AC operating cost. 

      It will reduces fuel consumption so it will cut carbon footprint.

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