One kilowatt is about what it takes to heat up some leftovers in a microwave — or to power the largest and most technically advanced telescope ever built. Thanks to its solar array, NASA’s James Webb Space Telescope will stay energy-efficient more than 1 million miles (1.5 million kilometers) from Earth.

American engineers at Bell Labs unveiled the first photovoltaic solar cell in 1954. Four years later, the National Aeronautics and Space Administration (NASA) launched solar panels into space.

NASA launched the James Webb Space Telescope, the most powerful telescope ever built, on Christmas Day 2021. Today, solar panels power the James Webb Space Telescope, which offered the world the most detailed look into the most remote reaches of the universe to date.


Webb’s 20-foot (6-meter) solar array is attached to the main observatory of the craft. The “powerhouse” of the telescope, the array will supply energy to all of the telescope’s scientific instruments and communication and propulsion systems. While Webb will only use 1 kilowatt of power, the solar array is capable of generating nearly double that amount to factor in the gradual wear and tear of a harsh space environment.

The array consists of five panels that are connected by hinges for folding into the launch vehicle, the Ariane 5 rocket. The telescope’s onboard battery was designed to only last a few hours, so the unfolding and activation of the array were considered one of the most critical early steps of the telescope’s voyage. A video of the deployment of the fold-out array can be viewed below.

Solar panels power the James Webb telescope

The James Webb telescope is not the only NASA project that relies on photovoltaics to power its systems. Last June, Astronauts Shane Kimbrough of NASA and Thomas Pesquet of the European Space Agency (ESA) completed their spacewalk upgrade of the international space station, installing the iROSA roll-out solar arrays.

It cost about $100 million to install the six arrays. The arrays are expected to add more than 120kW in capacity, which will increase the station’s power generation by 20% to 30%. The solar panels that were replaced were designed for 15-year service life but had been continually operating since December 2000. Although they were functioning well, the older arrays were showing signs of degradation, as expected. 

Last December, NASA announced it is testing solar-powered electric propulsion systems for asteroid defense. The Double Asteroid Redirection Test (DART) mission will employ roll-out solar arrays and a 6.9 kW gridded ion electric propulsion system to redirect Earthbound asteroids by smashing the small craft into the asteroid.

NASA is also using two large cross-shaped PV arrays to power its Psyche mission, which will bring a craft 1.5 billion miles away from Earth to the asteroid Psyche. The mission is to explore a large, metal-rich asteroid with the remote-operated craft.

On Earth, the solar array can generate about 21 kW of electricity, but far away from the sun alongside Psyche, they will only produce 2 kW, about the same energy demand as a hair dryer. Despite this low amount of energy, it will be sufficient to power the planned three-and-a-half-year journey to the asteroid, and the two years of orbiting and observation of the body.

“Even in the beginning, when we were first designing the mission in 2012, we were talking about solar electric propulsion as part of the plan. Without it, we wouldn’t have the Psyche mission,” said Arizona State University’s Lindy Elkins-Tanton, who, as principal investigator, leads the mission. “And it’s become part of the character of the mission. It takes a specialized team to calculate trajectories and orbits using solar electric propulsion.”

The launch is planned for this August, and the Psyche spacecraft may make first contact with the Psyche asteroid in 2026.

Unfortunately, NASA’s James Webb Space Telescope has been damaged after the space telescope was hit earlier this year by at least 19 small space rocks, also called micrometeoroids. One of the rocks has reportedly left noticeable damage on one of the telescopes’ 18 gold-plated mirrors.