- Renewable & Alternative Energy
How are Solar Panels and Photocells used to make Energy
Advantages Of Solar Energy
- Not dependent on fossil fuels
- Available in most areas and compatible to most houses
- You are not dependent on the National Grid
- Environmentally friendly
- Free energy
Disadvantages of Solar Panels
- Expensive to set up
- It takes along time to repay back your investment
- Not useful during night or when cloudy
- Solar Panel are quite big and unattractive
- The technology is not very advanced
- Doesn't create that much electricity
The Sun is the source of energy for the Earth
Without solar energy there would be no life on Earth
- Light from the Sun allows plants to photosynthesise
- Heat from the Sun provides the warmth for living things to survive.
Photocells and Solar Cells
A photocell changes light into electricity. A solar cell uses light from the Sun. The larger the area of a photocell, the more electricity is produced.
Photocells can be used in places where mains electricity is not easily available.
The large area of the photocells on the International Space Station provides a direct current (dc) supply to run the spacecraft.
Electricity From Light
The direct current from a photocell is similar to the current from a battery. It is in one direction.
Photocells have many advantages over other electrical systems.
- They are very robust and need little maintenance.
- No fuel or lengthy power cables are needed.
- They do not contribute any pollution to the atmosphere in the form of dust or greenhouse gases.
- They use a renewable energy source.
The only disadvantage is that they do not produce electricity when it is dark such as during the night or when it is cloudy.
A Photocell consists of two layers of silicon. One layer negatively charged and the other positively charged.
The place where the silicon meet is called the p-n junction. An electric field is created between the two layers.
Silicon is a neutrally charged substance. To make it negatively charged you add phosphorus. To make it positive you add boron. When light falls on the p-n junction it supplies energy. This energy makes the charge (positive and negative) and a current is produced in the circuit.
Sunlight is made up of tiny packets of energy called photons. When photons are absorbed the energy causes electrons to become free. They move to the negative layer and leave the junction to flow in an external circuit