Skip to 0 minutes and 6 secondsSo what is a solar cell? So we learned last week is that the sun can deliver enough energy in one and a half seconds to power the earth for a whole year. So what is the device, the electrical device, that can convert this enormous amount of energy into useful electrical power? This device is called a solar cell. A solar cell is therefore able to absorb the photon energy from the sun and deliver electrical power. Electrical power is current and voltage. And to better illustrate, you have to think about the camera in your phone, which is also sensitive to photons and captures images, but it doesn't deliver power. It only delivers current.

Skip to 0 minutes and 49 secondsSo the key requirement of a solar cell is that it is able to deliver both current and the voltage, and therefore provides electrical power.

What is a solar cell?

What is a solar cell and how does it work?

A solar cell is able to absorb the photon energy from the sun and deliver electrical power. Electrical power is current and voltage.

Electrons are a vehicle for electrical energy, the current is the flow of electrons from one place to another. When electrons build-up on an object but cannot flow further they are called an electrical charge. This charge can be released as static electricity if touched by another object that can conduct electricity.

Solar cells are made of the same kinds of semiconductor materials, such as silicon, used in the microelectronics industry. For solar cells, a thin semiconductor wafer is specially treated to form an electric field, positive on one side and negative on the other. When light energy strikes the solar cell, electrons are knocked loose from the atoms in the semiconductor material. If electrical conductors are attached to the positive and negative sides, forming an electrical circuit, the electrons can be captured in the form of an electric current – that is, electricity. (1)

So when everything is in place and light energy hits a solar cell an electrical circuit is formed.

At present, solar photovoltaic energy provides 1% of all electricity usage globally. On average, one square metre of land receives the equivalent energy per year as a barrel of oil or 200 kg of coal. (2)

We know that the sun provides us with enormous energy, but how do we convert that into usable electricity to power our homes, cars and devices?

We use solar panels. Solar panels are comprised of dozens of solar cells, wired together to generate a large enough electrical output.

By the time you have combined hundreds, thousands, if not millions of solar panels together, you end up with complexes large enough to meet the electricity needs of a million or more people, like in the Pavagada solar park in India.

Conversation Starter

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References

  1. How do Photovoltaics Work? Science Mission Directorate [Internet]. Science.nasa.gov. 2019 [cited 10 May 2019]. Web link

  2. Solar [Internet]. Worldenergy.org. 2019 [cited 10 May 2019]. Web link

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How to Survive on Earth: Energy Materials for a Sustainable Future

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