Cost per watt of solar panels

As solar panel costs have plummeted, WeChat users have multiplied, a correlation of -0.986 that connects renewable energy economics to Chinese social media with the technological confidence of a chart that sees both curves as the same S-shaped adoption story told from opposite ends. The cost falls, the users rise, and both trends measure the same decade of exponential technology deployment in different sectors and different countries.

Solar costs fell from about $0.75 per watt to under $0.25 between 2013 and 2023. WeChat users grew from about 400 million to over 1.3 billion. Both are technology adoption curves: solar costs decline because manufacturing scales, WeChat grows because smartphone adoption saturates China. The negative correlation exists because one metric goes down (cost) while the other goes up (users), and both follow the same S-curve shape inverted. The shared variable is technology maturation—the same forces that reduce manufacturing costs also increase user adoption.

Eleven years of solar costs and WeChat users is a correlation between two technology curves in their mature growth phase: one measuring cost reduction, the other measuring adoption. Both are S-curves, both are products of manufacturing scale and network effects, and neither knows the other exists. The panel gets cheaper, the app gets bigger, and both trends are simply technology doing what technology does.