This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Switching to modern silicon solar cells could cut the cost of powering satellites by as much as 90% based on beginning-of-life (BOL) performance, according to a review led by the University of Surrey. The switch to silicon cells could also halve the weight of the solar cells needed on a spacecraft, freeing mass for fuel or instruments or cutting launch costs.
Silicon was the industry-standard solar cell material for spacecraft from 1958 until 1977, when gallium arsenide cells displaced it, offering better efficiency and radiation resistance. Triple-junction cells built from gallium, indium and germanium have been the standard ever since. Today, silicon heterostructure cells hold a record efficiency of 27.8%, and perovskite/silicon tandem cells hold a record of 34.85%.
In a review published in Acta Astronautica, researchers from Surrey show that triple-junction space cells cost between $250 and $450 per watt, whereas silicon costs tens of cents. As of November 2025, the three main silicon designs (PERC, TOPCon and heterojunction) averaged $0.275, $0.285 and $0.39 per watt, respectively. The raw materials are cheaper, too: Silicon costs a few dollars per kilogram, while gallium and germanium cost thousands per kilogram.
To make this more tangible for real-world use, the Surrey team modeled two formats—one face of a 3U CubeSat (a satellite roughly the size of a large loaf) and a Micro Sat built by Surrey Satellite Technology Limited (SSTL), which co-funds the lead author's Ph.D. and supplied the spacecraft data used in the study. Including the space-qualified glass that protects the cells, the savings were as large as 85% to 90%. Coverglass, not the cell, dominates the cost of a silicon array.
"The interesting finding for us was not that silicon is cheaper but where the remaining cost sits. Once you put silicon cells behind space-qualified glass, the glass is what you are paying for. "That changes what we should be working on.
If we can make the cell itself tougher against radiation, we can use thinner glass or substrates, and we cut cost and weight at the same time. It reframes the problem from a materials contest into an engineering one we know how to attack," said Tommy Richards, a Ph.D. student in future space solar cell technology and first author of the review. The researchers found that silicon heterojunction cells delivered roughly twice the specific power of the triple-junction option, at around 920 to 1,000 watts per kilogram, compared with 455 to 505.
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