Not afraid of rainy days Solar photosynthesis

Traditional Solar Energy is Costly and Limited

It's a strange paradox: the Earth receives more energy from the sun in just one hour than the entire world uses in an entire year. Despite being free, clean, and endless, solar energy accounts for less than 1% of global energy production. Why? Because early solar cells were developed for space missions in the 1950s—expensive, inefficient, and only effective under direct sunlight. In most parts of the world, they’re not practical. Even when there is enough light, you need vast areas to make them economically viable. That’s why solar energy has often been called “Cinderella” in the renewable energy sector—beautiful but overlooked.

Solar energy has huge potential to become a cheap, clean, and dominant energy source. No one disputes that. It’s easy to access, simple to develop, and can last billions of years. According to calculations, if just 1% of the Earth’s surface were covered with traditional solar panels, it would be enough to power the entire planet. But the problem is that 1% is equivalent to the size of Spain—and covering that much area with solar panels would cost tens of trillions of dollars.

However, this calculation assumes that solar technology will remain the same forever. In reality, photovoltaic (PV) cells have evolved over time. They look like dark slabs and are commonly seen on top of chargers or high-tech buildings. PV cells use materials like silicon, which release electrons when exposed to sunlight, creating an electric current.

New Technology Mimics Plant Photosynthesis, Works on Cloudy Days and Indoors

Now, a new wave of solar technology is emerging. This breakthrough involves simulating how nature uses light energy—something plants have done for millions of years through photosynthesis. At first glance, photosynthesis doesn't seem like a promising energy source. After all, its main purpose is to convert carbon dioxide and water into carbohydrates. But during this process, plants use sunlight to split water molecules and release electrons, which then create an electric current.

Scientists have long tried to replicate this natural process to generate electricity. Recently, researchers made a breakthrough and created commercially viable prototypes. One of the most exciting developments is the "dye-sensitized solar cell" (DSC), also known as the "Gretzel battery," named after its inventor, Professor Michael Grätzel from the Swiss Federal Institute of Technology in Lausanne.

Grätzel and his team began experimenting with chlorophyll and titanium dioxide in the 1970s. Early results were disappointing, with conversion efficiencies as low as 0.01%. But in the late 1980s, they replaced chlorophyll with a more efficient dye and used a different form of titanium dioxide, boosting efficiency by hundreds of times. This opened up new possibilities beyond traditional silicon-based solar cells.

Since then, DSC batteries have shown great promise. Their efficiency has reached around 10%, and their low cost and ease of manufacturing make them competitive. Even better, they can work in cloudy conditions and indoors, unlike traditional solar panels that require strong sunlight. DSC batteries can also be transparent or colored, making them ideal for windows that generate electricity. In 2010, the scientific community recognized the potential of DSC technology, and Grätzel was awarded the Millennium Technology Prize.

Electrolyte Shortages Hinder Large-Scale Production

So why haven’t DSC batteries replaced traditional solar panels on buildings or phone chargers? While some test sites have been set up and prototypes are already in use, there are still challenges. The main issue is the electrolyte. DSC cells rely on an electrolyte to function, and currently, the supply is limited. According to Oxford University chemist Henry Snaith, this shortage is slowing down mass production and limiting the impact of DSC technology on the energy market.

"We need to produce hundreds of square kilometers of DSC panels every day," he said. "That's about the same scale as paving roads." The current liquid electrolytes in DSC batteries have a lifespan of only a few years, while buildings require decades of reliable performance. To solve this, Snaith and his team are developing solid electrolytes that are easier to produce and more durable. This research has received funding from the UK Technology Strategy Board, and they believe mass production using standard printing techniques is now within reach.

Organic Photovoltaic Technology Uses Polymers to Generate Power

While DSC batteries are gaining attention, another promising technology is also advancing: organic photovoltaic (OPV) cells. These use a thin layer of polymer-like material to absorb light and generate electricity. Like DSC batteries, OPV cells work well in low-light conditions and can be made transparent or in various colors. Their flexible nature allows them to be produced using traditional printing methods, making them highly scalable.

However, OPV cells have slightly lower efficiency compared to DSC batteries—usually a few percentage points less. Some researchers are also concerned about their durability, as the polymer degrades over time. Despite these challenges, scientists like Professor Leach are working to improve their performance. He believes that increasing efficiency from 10% to 12% is achievable and that OPV technology could be commercialized within five years.