Happy birthday, solar power! I had no idea that the first solar cells were invented by scientists from Oregon’s sunny Willamette Valley.

Even though solar panels are now 50 years old, the technology is still in its infancy. As Seattle-based power engineer and amateur historian Larry Clifton recently explained to me, power generation has taken myriad forms over the millenia, but there are still only 3 core power technologies: muscle power (both animals and people); fluids (including wind, water, and steam); and now, solar. The first two have their origins in antiquity: even the modern nuclear plant is simply a variant of combustion-powered steam turbines, which themselves derive from windmills and water mills used for at least three thousand years.

The history of power technology suggests that shifts between different technologies can be surprisingly rapid, given a sound technology and favorable economics. Small windmills proliferated throughout Europe in the late middle ages, once the technology proved profitable and reliable. The same could be true of solar: once the cost comes down just a bit more (it’s already dropped from $1,700 per watt to $3)—or, in the alternative, once other fuels become more costly—we could reach a tipping point where solar power and other alternative energy sources, from wind to conservation, really start to take off. And given the Northwest’s high rate of energy consumption, it’s not a moment too soon.