How to Test the Efficiency of a Photovoltaic Cell?
Grade Level: 6th - 8th; Type: Physical Science/Mathematics
The performance of a photovoltaic cell (solar cell) is measured in terms of its efficiency at turning sunlight into electricity. Much of the light energy is reflected or absorbed by the material that makes up the cell. Because of this, a typical commercial photovoltaic cell has an efficiency of 15% or about one-sixth of the sunlight striking the cell generates electricity. The research aspect of this science fair project is to determine how much of the energy from the Sun that reaches a photovoltaic cell is converted into electric power.
A photovoltaic or solar cell will be exposed to sunlight at different angles to find which position will allow the greatest amount of sunlight to reach the cell. In the second part of the investigation a determination will be made of how much of the sunlight that has reached the cell is converted into electric power. Based on the results of these investigations data tables will be prepared and the efficiency of the photovoltaic cell calculated. A real world correlation of this project is to make aware to the investigator that low efficiencies mean that larger arrays of cells are needed in order to generate electricity, and that means higher cost. Improving photoelectric cell efficiencies while holding down the cost per cell is an important goal of the photovoltaic cell industry.
- What is the project about?
- What are the goals?
- How does changing the angle of the photovoltaic cell affect the speed of the fan?
- At which angle is the fan’s speed the fastest?
- Why does the angle of the photovoltaic cell affect the speed of the fan?
- Why would the season of the year possibly affect the efficiency of the photovoltaic cell?
- Besides angle, what other factors will affect the energy output of the photovoltaic cell?
- Based on the results of this investigation would the power output of the photovoltaic cell be greater or less just beyond Earth’s atmosphere?
The sun produces 3.9 x 1026 watts of energy every second. Of that amount, 1,386 watts fall on a square meter of Earth’s atmosphere and is known as the solar constant. The amount of this energy that reaches the Earth’s surface on a sunny day varies according to the time of year, from about 1000 watts/meter2 on a sunny summer day to less than 700 watts/meter2 on a sunny winter day. A watt is a unit used to measure power. This energy can be used to generate electricity by a device called a photovoltaic cell.
Photovoltaic or solar cell convert sunlight directly into electricity. These cells are often used to power calculators and watches. They are made of semiconducting materials similar to those used in computer chips. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce electricity. This process of converting light (photons) to electricity (voltage) is called the photovoltaic (PV) effect.
The performance of a photoelectric cell is measured in terms of its efficiency at turning sunlight into electricity. Much of the light energy is reflected or absorbed by the material that makes up the cell. Because of this, a typical commercial photovoltaic cell has efficiency between a low of 5% to a high of 20%. On average only about one-sixth of the sunlight striking a photovoltaic or solar cell generates electricity.
- Any required diagrams/pictures (Pictures speak a thousand words!)
Digital photos can be taken during the investigation process also the following sites offer down loadable images that can be used on the display board.