Despite the world’s continuing reliance on oil, coal and gas, the overwhelming trend in energy production has, for the past few decades, been in the direction of renewables. According to BP’s Statistical Review of Global Energy, the world produced almost six petawatt-hours from renewable sources in 2016. This is an increase of more than 500% since the mid-60s. Hydropower accounts for a majority of this output, with wind coming in a distant second.
Solar’s global contribution stands at just 330 terawatt-hours – around a twentieth of global renewable output. Given that the sun bombards the planet constantly with more energy than we could conceivably consume, this figure might not seem terribly impressive. The solar industry, clearly, has yet to fulfil its considerable promise.
Governments across the world are helping to support the growth of this technology. In the US, tax incentives have been offered to homeowners and businesses which adopt solar panel technology. Since this credit was implemented in 2006, the solar industry in the US has enjoyed a hundred-fold growth. Even oil-rich states like the United Arab Emirates are pushing the technology.
As welcome as these steps might be, solar panels themselves will need to change if they are to be widely adopted. As things stand, they are too expensive, cumbersome, and the energy they produce is difficult to store. A solution to many of these challenges comes in the form of perovskites: a radical and relatively new form of photovoltaic material that’s being developed at prestigious universities across the globe.
Perovskites have been gathering considerable hype in recent years. The term refers to a family of materials, each of which consists of a thin film made from readily-available salts. It began life in 2009, as an alternative to the dye found in some silicon-based solar cells. Only a few years later was the material’s potential as a semiconductor realised. The solar cells of the future might therefore dispense with silicon entirely, and consist instead of layers of hyper-thin perovskites. This simpler design has the potential to vastly exceed traditional photovoltaic cells in terms of efficiency.
This material is exciting for reasons other than efficiency, too. Given that perovskite is flexible and lightweight, it can be easily transported from place to place and installed at low cost. Moreover, it can be stylised to fit the shape of an existing building, or the cells might even form the inspiration for the buildings of the future. Given that the ugliness of a solar panel is a considerable impediment to widespread adoption, this advantage may help domestic solar panels to finally go mainstream.
In the near-term, perovskites are seen not as an alternative to silicon, but as a complementary technology. By augmenting a conventional PV panel with a layer of perovskite, researchers in MIT, Oxford and Eindhoven are confident of reaching energy-efficiencies in the high thirty-percent bracket.
There are other obstacles to overcome, however, before we can feel comfortable hailing perovskites as a successor to traditional silicon panels. For one thing, we don’t know how long a perovskite panel will last in the real world. Silicon panels have been around for decades, and their longevity is proven. Perovskites, on the other hand, are not. Given the urgent need for action on climate change, however, rushing the technology to market might be judged a worthwhile risk.