Organic solar is (finally) efficient enough to compete

Organic solar cell sounds like a euphemism for “plant”. But it actually means a solar cell made using carbon, rather than silicon or other materials. That offers several great advantages over current photovoltaics. Where traditional solar panels are thick, rigid, and expensive, organics are thin, flexible, and cheap. They can be made into long rolls that are faster to manufacture. Unfortunately, the low cost has come at the expense of efficiency: they’re bad at converting sunlight into electricity.

But researchers at the University of Michigan have found a way to capture over a third more solar energy using organics, pulling them within reach of more expensive panels on the market now. This may herald a new wave of cheaper and less intrusive solar power.

Efficiency vs. Economics: The most efficient technology isn’t always the most cost effective. Some experimental solar systems can convert nearly 50% of available sunlight into electricity, but they’re crazy expensive and hard to manufacture. Right now, most photovoltaics on the market average 15-17% efficiency, with high-end systems hovering around 20%. For years, organic solar has lagged well behind, stuck around 10-11%—meaning you might need twice as much space to get the same amount of electricity. Even if it was cheap, you might like having a yard covered in grass, rather than solar panels, no matter how thin and flexible they are.

The Breakthrough: Researchers at Michigan have discovered a way to dramatically boost the efficiency of organics. Their new process stacks organic cells in thin, interconnected layers, allowing them to reach 15% efficiency—right in the range of what’s commercially available now, at significantly lower cost. Using their materials and design, the researchers estimate these organic solar cells could produce electricity at less than 7 cents per kilowatt-hour, over their lifetime. That’s less than half the cost of current residential solar electricity, and neck and neck with utility-scale solar power plants. And they’re pretty confident they can get the current design up to 18% efficiency in the near future, without increasing the cost.

Competitor, Not Gamechanger: The most important fact about solar power is that it’s out of our control: we can’t just turn on the sun (or turn it up) when we want more, and storing electricity in batteries is really expensive and inefficient, so we still need nuclear or fossil fuels to smooth out the supply and pick up the slack on cloudy days. But solar is getting so cheap that it could make up for that: the cost of large-scale solar power has come down 30% in the last year, and residential is down 6%, before subsidies. If storage systems like Tesla’s Powerwall (or even your water heater!) can meet innovations like organic solar halfway, reliable power straight from the sun looks more achievable than ever.

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