In recent years, solar power has seen rapid growth, as well as promising improvements in technology and price. So far, about 3% of the world’s electricity comes from solar power; and it’s a huge, international industry with $141 billion invested in 2019. But that’s well short of the estimated $794 billion ($27 trillion by 2050) that the International Renewable Energy Agency says is needed annually for renewable energy to meet climate agreement objectives and avoid a global meltdown.
To hit a target like that, experts say, we need to solve a long list of problems. For instance, existing panels are limited in how much sunlight they can convert into electricity. Efficiency has increased over the last 40 years, but only by about 10%. And although advocates would consider residential rooftop installation as a nice way for people to get involved in clean energy, a true solar revolution would likely require large-scale installations.
Here is a list of four things that, researchers say, would help advance solar power – if we can find a solution.
Find a better material for the panels
The disadvantages of traditional silicon panels include high cost and lower efficiency. But with the help of perovskites, a mineral composed of calcium, titanium, and oxygen, solar efficiency is expected to significantly improve: perovskite panels can be manufactured as very thin layers, require less material, and are created from a less energy-intensive process.
After a decade of research and development, efficiency rates of perovskite panels rose from 2% to 25%; that beats the best available silicon ones. But perovskites come with their own set of problems.
“[Perovskite] commercialisation is still very limited,” says Ufuk Alparslan, an electricity and climate data analyst at EMBER, an independent climate and energy think tank based in the UK. According to Alparslan, durability and cost are two contending disadvantages of perovskites, the former issue being related to a lifespan that is “much shorter than regular solar panels.”
At OxfordPV, an Oxford University off-shoot, researchers are attempting to advance perovskites by placing them on top of silicon panels, also known as tandem cells. Henry Snaith, the chief scientific officer at OxfordPV and a professor of physics, says that they have been able to tune the spectrum of sunlight perovskites can absorb with tandem cells.
“We extract a lot more energy out of the visible spectrum,” says Snaith, adding that if perovskites are coated on top of silicon, “it does really well at absorbing the infrared [light]”, making them more efficient. Snaith hopes that tandem cells be will the next step-improvement for mainstream solar. Over the next 10 to 20 years, “the roadmap is to approximately double the efficiency of what modules are today.”
Improving storage and transmission
Other technical challenges for solar include increasing storage capacity. In the US, improvements to expand solar power transmission across large distances, like from southern California where it is sunny to the cloudy Northeast, are also paramount.
“As you get to higher levels of penetration,” says David Feldman, senior financial analyst at National Renewable Energy Laboratory, “flexibility is really helped by storage, particularly depending on how the grid incentivises or pays for the energy. Storage is becoming a very large part of many markets. If we want to get to the levels of deployment that we’ve been talking about, I think storage is going to be a key part of that.”
Additionally, experts believe that it is likely other forms of clean energy will help supplant the weaker areas of solar.
“During very cold winter spells in certain parts of the country, it’s rather difficult to rely on solar and wind alone,” according to Uday Varadarajan of the Rocky Mountain Institute, speaking in a virtual forum hosted by the Environmental and Energy Study Institute. “Efficiency as well as other technologies like hydrogen and carbon sequestration and storage, as well as nuclear, can really help address those difficulties.”
Helping solar stay afloat, literally
One method of expanding solar installation that has not yet been widely implemented is floating the panels on lakes and oceans.
These panels operate in the same way as regular land-based units, but have various advantages: the water keeps panels cooler, increasing performance by 5 to 10%. Installing these panels on water gets around the problem of acquiring land for large scale projects. And floating solar can also use hydropower and become part of the energy grid.
However, floating solar has its own set of unique puzzle pieces. “The thing to consider here is not to cover the water surface much so that it affects the water life,” says Alparslan. “But even 10% coverage of hydropower reservoirs translates into thousands of terawatts of solar power potential in the world.”
But mooring and anchoring the panels in place can prove complicated, as well as more costly than regular, grounded solar.
Getting the right laws and investments
Improvements in manufacturing have made solar more available in the last 20 years. According to EMBER, solar in the EU rose to a record high during June and July 2021, accounting for 10% of total electricity (far above the global average.) But that’s not enough – and the scale of the scale-up challenge is daunting. The possible solutions boil down to money and politics, rather than technology alone.
For instance, in July 2021, as part of its European Green Deal, the European Commission proposed a legislative package to raise renewable energy targets to 40% by 2030. It includes measures to make large-scale solar projects easier to install, exempt rooftop installations from construction permits, invest in the power grid, and require minimum levels of renewable energy in certain buildings.
In the US, the Energy Information Administration noted that shipments of solar panels reached a record increase of 33% in 2019. The Department of Energy released a report outlining how solar could supply nearly half of the nation’s electricity by 2050. Through heavy spending, solar would rise from powering 3% of the nation’s electricity in 2020 to 40% by 2035. President Joe Biden’s proposed, and heavily debated, $3.5 trillion budget plan, if passed – a big if at the moment – initiates solar projects to be built on current or former mining sites.
But a big problem is simply making it easier for people to get their hands on solar panels – in their own homes or industry. Says Daniel Gregory, an emerging energy technologies researcher at Accenture Labs, “Getting the technology available to enough people is more the issue than the technology itself. For someone who is renting a house or apartment, it is not obvious how they would join in on that and use solar for rented houses.”
Despite the challenges remaining, many researchers believe that solar is destined to keep up its momentum and expand across the world. “I think that we’ve reached the tipping point where solar is big business,” says Feldman. “I definitely think that when you look at all the commitments out there, it seems inevitable that we’re moving towards solar and wind.”