Will Flexible Solar Panels Become the Next Gold Standard
Solar panels, the workhorses of the renewable energy world, have traditionally relied on silicon as their light-absorbing material.
Conventional silicon photovoltaic (PV) cells supply more than 95% of the world’s solar electricity. But they contain brittle crystalline silicon wafers that are heavy and bulky, making it hard to attach them to structures.
Alternatives to Rigid Silicon Solar Panels
Thin film solar cells have been in use for over 30 years, but the ability to produce cheap silicon panels sidelines them. If you are as old as me you probably remember your watch or solar powered calculator. Today, there are a few materials that are being used to make flexible solar panels.
Cadmium Telluride is the most commonly used material in thin film production accounting for almost half of all flexible solar panels. Recently, the solar efficiency of these cells has risen, and is almost equal to silicon panels. It’s also cheaper and can reduce the payback period- making it the best of all the solar technologies, with the average in good areas being around eight months return on investment. These panels are stable and can withstand high temperatures and radiation.
The lightweight and portable nature of flexible solar panels makes transportation, handling, and installation substantially easier compared to heavy glass-encased rigid panels.
Flexible solar panels increase opportunities for mounting beyond farm fields, homes, and parking lots. They can be vertically mounting on building facades, carports, advertising displays, or anywhere with exposure to direct or indirect sunlight throughout the day.
Organic solar cells are another option because of their flexibility, high throughput large-area printing, light weight, and low cost. They also work in special cases such as portable devices for indoor building-integrated solar and automotive-integrated solar.
Other innovations have explored integrating solar generation into our urban environments, including solar windows. Using a transparent solar technology that absorbs ultra-violet and infrared light and turns them into renewable power, these windows could transform skyscrapers into solar farms and have been installed in buildings including in the US and Europe.
One commercial example is Merlin Solar Technologies, a Silicon Valley startup. They have redesigned the flexible solar panel so with thin, peel-and-stick panels that can be installed nearly everywhere, including buildings, homes, recreational vehicles, boats, and drones. Merlin Solar claims its panels are 80% lighter than traditional glass panels and produce 20% more energy in real-world situations. They show their panels on top of trucks and other vehicles, such as RVs and boats.
Challenges to Overcome
The lower solar conversion efficiency of flexible panels poses a disadvantage relative to the higher efficiencies achievable with rigid silicon solar panels. Most commercial flexible panels currently max out at around 15-18% efficiency, while premium rigid silicon panels push 20-22% efficiency, converting more of the sun's rays into useful energy.
Lifespans for quality flexible panels average 20-30 years, but material deterioration inevitability occurs. Conversely, glass-encased rigid panels resist environmental degradation for 25-30 years or longer, keeping their water-tight seal intact.
Perovskite: A New Solution to Flexible Solar Panels
Perovskites were discovered in 1839 and named after Russian mineralist Lev Perovski. They are now the most promising alternative to silicon solar panels. Perovskite solar cells have shown remarkable progress in recent years with rapid increases in efficiency, from reports of about 3% in 2009 to over 26% today on small area devices, and recent advances reaching efficiencies of almost 34%.
They can be formulated into inks and printed on widely available industrial printers into rolls which are easy to transport, saving energy costs and use during transportation. They could be printed onto any object, as well as formed into threads to be woven into fabric, bags or building materials.Their advantages go beyond their lower weight and include higher efficiency, ease of manufacturing at lower temperatures and lower materials costs.
The flexibility of perovskite solar panels means they can be applied almost anywhere including roofs that cannot support the weight of standard panels, curved surfaces, and even capture energy from indoor lighting.
Another advantage of perovskite solar panels is that they can be produced without rare and expensive materials such as indium, which is commonly used in conventional photovoltaic devices. At a time when there is a race for access to critical minerals, this is an important distinction.
One challenge is that perovskite solar panels are susceptible to the effects of water, heat, and oxygen which results in low durability. They can decompose when they react with moisture and oxygen or when they spend extended time exposed to light, heat, or applied voltage.
A number of companies are pushing forward with getting more perovskite solar panels to market. Sekisui Chemical implemented the first film-type perovskite solar cell building material panel in Japan in its Osaka headquarters building in October 2023 and began operating it in July 2024.
Anglo-German company Oxford PV has set up the world’s first series production line for perovskite silicon tandem cells in Brandenburg an der Havel, Germany.
The Chinese government has included 50 MW or larger perovskite and tandem solar cells and other next-generation solar cell technologies in a national renewable energy model project starting in September 2023, with a focus on solving durability issues. Chinese startup Auner plans to launch a 100 MW pilot production line producing 166 mm cells. Other companies in China with plans for large facilities include GCL Group, Utmolight, and Mellow Energy.
Cracking the Waste Problem
One big issue with solar panels is the waste they generate. Typically solar panels last 25 years, and since solar power installation began to take off in 2014, we will see a significant increase in waste in the next decade. With the amount of solar panels being installed today, it’s possible that the world will be handling 78 million tons of solar panel waste by 2050. Many solar panels end up in landfills today.
The good news is that the materials in solar panels have value. According to the International Renewable Energy Agency, by 2030, the cumulative value of recoverable raw materials from end-of-life panels globally will be about $450 million, which is equivalent to the cost of raw materials currently needed to produce about 60 million new panels.
A recent publication in the journal Nature demonstrates recycling of perovskites that retains 96.6 of the original materials and reduces human toxicity (carcinogenic) impacts by 68.8% versus sending them to the landfill. On top of this, by recycling perovskite panels, the costs decrease by 18.8% for utility-scale systems and by 20.9% for residential systems.
In terms of environmental impacts, the question will be whether perovskite panels can use less materials and become easier to recycle than silicone panels. If so, they will likely become the next gold standard.
