Question

Could someone help me with this question please as I am kinda lost as in how to do these type of questions

a What additional physical requirements are necessary for the findings of Bequerel in the 1800's to produce a photovoltaic device capable of producing sustainable electrical energy I5 marks b)What is a major problem for energy harvesting whenusing photovoltaics? Consider the geographical spread of solar irradiance and population density across the [7 marks] c)Draw an V (current-voltage) curve for a photovoltaic cell. On the I-V curve label the Voc, Isc and power point. [5 marks] d) the ill Factor (FF) for a cell is 0.58, the Voc is 0.7 V and Jac 0.0034 Acm2, what is the output power? [5 marks] e) What happens to the I-V curve of a photovoltaic when the temperature quantum efficiency of the device increases? [3 marks]

please explain each step

Answer 1

(a): Edmond Becquerel was probably the first person to demonstrate the photovoltaic effect using different types of light to generate electricity. He was working at the laboratory of his father and he used several methods to generate electricity but the most effective ones were when he used blue or ultraviolet light, also when he coated his electrode with sensitive materials like AgCl or AgBr. He mostly used platinum electrodes and sometimes silver electrodes as well.

In his experiments, he used the acidic solution in a blackened box and dipped the electrodes, one in each chamber separated by a thin membrane. So, to produce a sustainable energy Becquerel needed the following physical requirements:

• Blackened box
• Acidic solution
• Pt electrodes
• Wire
• Sensitive materials to be used as coatings over electrodes

Thin mem bane Pt electrode

(b): Mazor problems in energy harvesting using the photovoltaic effect are as follows:

1. Intermittent availability of the light source poses the biggest problem for the production of energy. It depends on day and night, the weather on a particular day and on seasons.  
2. The storage of energy is also one of the biggest problems we still face. We have yet not developed effective and economical storage devices. Usually, costly material is used and still providing inadequate storage with low power density.
3. Overly complicated process to produce electricity makes it inaccessible for mass to replicate the process and produce the electricity.

(c): I-V curve for the photovoltaic cell:

Se IV cuuve of the solan cell 2 LLJ Pouwen from the Bolon cell VOLTA GE

(d):

Given data:

• Fill factor, FF= 0.58
• V_OC= 0.7 V
• J_SC= 0.0034 A/cm²

To find: Output power of the cell

Analysis: Fill factor is a parameter which determines the maximum power from a solar cell in V_OC and I_SC. It is given by the following formula:

PMP Voc Isc

So, maximum power output can be calculated using the following formula:

$P_{MP}=FF*V_{OC}*I_{SC}$

Here we are given maximum current density at zero voltage, not the current, which means using the given current density we can calculate the maximum power density per unit area as given below:

* VocJso

PM0.58 0.7 0.0034W/cm

PP1.3804 10 W/cm2 1 / C772. cm

PMP 13.804W/m2

(e):

• The number of carriers collected by the solar cell to the total number of the photons of a given energy incident upon a solar cell is known as quantum efficiency.
• When all photons belonging to a certain wavelength are absorbed, the quantum efficiency at that certain wavelength is unity.
• If the photons have the energy below the band gap, their quantum efficiency is zero.
• When at a certain wavelength the quantum efficiency increases, that means the total number of photons being absorbed is increased which is equivalent to increase in the intensity of the light at that wavelength, hence it results in an increase in current density and a marginal increase in voltage. In the same manner, I_SC in the IV graph increases.