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Phase 5 - Powering Up

Teacher Backgrounder

The International Space Station requires an astronomical amount of energy to generate electricity for life support systems, daily operations and scientific equipments onboard. Orbiting at an elevation of 400 km above the Earth, the ISS revolves around the Earth every 92 minutes. In a 24 hour period, the ISS will experience 16 sunrises and 16 sunsets.

In order for the Station to use solar energy effectively and efficiently, a system was developed that compensates for the fact that direct sunlight is obstructed by the Earth from reaching the Station for as much as 36 minutes during each orbit. Therefore, up to 40% of each orbit is in the shade.

Solar energy is captured and transformed into electricity through the use of four sets of huge solar panels plus rechargeable nickel hydrogen batteries installed on the ISS. These solar panels represent the largest solar power system ever built in space.

Solar panels refer to a source of power for satellites and other devices, made up of many individual solar cells. These devices transform the energy of sunlight into electricity.

The batteries store electricity generated by the silicon cells during the sunlit portion of each orbit. While in the shade, they release electrical energy.

Each set of solar arrays consists of two panels. Each panel measures 34 metres in length by 12 metres in width and extends like wings from the sides of the Station. Each panel contains 32,400 silicon cells, each about the size of a computer diskette. The purpose of these silicon cells is to absorb as much of the Sun's energy as possible and change it directly to electricity in a process known as "photovoltaic".

Click here to learn more about the installation of these solar panels during Marc Garneau's STS-97 mission.