One of the most abundant and natural sources of energy that we have is solar power. Every day, the sun rises and shines its light on us, offering us heat and electricity.
Even isolated, remote, and rural areas can take advantage of this energy source, given that most areas on this planet get sunlight to some extent. There isn’t even a need for a lot of this inexhaustible source of energy, less than 10% of solar energy is enough to help us meet global energy demands.
As a renewable energy source, it does not create any harmful greenhouse gas emissions while being well-suited to the electricity grid and batteries.
The usage of sunlight isn’t entirely new. Humans were using sunlight as early as the 7th century BC to light fires by reflecting the rays of the sun onto shiny objects.
However, technological advancements have made capturing sunlight to generate electricity and then storing it for later use highly efficient.
Solar technologies capture electromagnetic radiation, which is the light emitted by the sun, and turn it into useful forms of energy. Two main types of solar energy technologies are photovoltaics (PV), utilized in solar panels, and concentrating solar-thermal power (CSP).
Solar panels are currently the most popular means of producing electricity from solar energy. The PV panels have a useful lifespan of 20-25 years, and minimal maintenance is required once they have been installed, apart from some periodic cleaning.
Usually made from a semiconductor material like silicon, when the material is exposed to photons of sunlight, it releases electrons and produces an electric charge. This charge generates an electric current, which is seized by solar panels and then an inverter converts it to alternating current (AC), which is used to power your devices.
The photovoltaic (PV) effect was actually discovered decades ago in 1839 when French physicist Edmond Becquerel was experimenting with a cell made of metal electrodes in a conducting solution and found the cell to be generating more electricity when exposed to light.
Then, in 1954, PV technology was born with the development of the silicon PV cell, which could absorb and convert the sun’s energy into power to run everyday electrical equipment.
Today, solar energy systems are integrated into not just homes and businesses but have become an important mix of renewable energy sources to provide power supply.
Solar energy actually has the potential to significantly reduce electricity, generate backup power by pairing it with storage, contribute to a resilient electrical grid, operate on both small and large scales at similar efficiency, and create jobs and spur economic growth.
Meanwhile, in terms of cost, besides the obvious hardware costs, there are also soft costs such as permitting, financing, and installing solar, along with other operational expenses of such companies, which affect the price of solar energy.
While solar energy has tremendous benefits, the challenge remains in terms of intermittency. The amount of sunlight available, after all, varies by time, location, and season.
For instance, photovoltaics generate energy primarily in the middle of the day when the sun is the brightest. While more efficient and reliable storage systems have allowed us to use this energy source throughout the day, even when the sun has set or it’s cloudy, researchers are even looking at better alternatives.
Back in 2022, researchers from The University of New South Wales (UNSW), made a major breakthrough in this sphere, which allowed them to produce electricity from solar power even during the night-time. This tech is now being taken to space.
Solar Power at Night
So, two years ago, in May, a UNSW team made this major breakthrough in renewable energy technology by producing electricity from solar power at night.
The team of researchers from the School of Photovoltaic and Renewable Energy Engineering (SPREE) produced electricity from heat emitted by Earth as infrared light (IL), much like it cools at night by radiating into space.
For this, the team created a semiconductor device called a thermoradiative diode. A diode is a semiconductor device that allows current to flow in one direction while restricting it in the other. They convert alternating current (AC) into pulsating direct current (DC).
A thermoradiative diode (TRD) meanwhile produces electricity by emitting IL. It can generate power from any warm surface and hence, carries the ability to provide solar power at night. The thermoradiative diode by the team was made up of materials used in night-vision (NV) goggles in order to generate electricity from the emitted infrared light.
As for the power capacity, it was very small, at 100,000 times less than what is supplied by a solar panel. Despite that, the researchers believed that the result could be improved in the future. According to team lead Associate Professor Ned Ekins-Daukes:
“We have made an unambiguous demonstration of electrical power from a thermoradiative diode.”
He explained how by using thermal imaging cameras we can see the amount of radiation at night. However, this is only in the infrared (electromagnetic radiation with wavelengths between 760 nm and 100,000 nm) and not the visible wavelength (which is between 380 and 780 nanometers). So, the team made a device “that can generate electrical power from the emission of infrared thermal radiation.”
Ultimately, the process is still harnessing solar power, said Professor Ekins-Daukes. During the day, sunlight hits our planet, warming it up. This very same energy radiates back into the expansive, cold outer space at night in the form of infrared light. The concept of a radiative diode takes advantage of this process, which the team has proven to generate electricity.
“Whenever there is a flow of energy, we can convert it between different forms.”
– Team lead Professor Ekins-Daukes
As we developed the artificial process of photovoltaics for the direct conversion of sunlight into electricity, similarly, with the thermo-radiative process, the energy flowing in the infrared from a warm Earth has been diverted into the cold universe.
Also, much like how a solar cell can produce electricity by absorbing sunlight, the thermoradiative diode produces electricity by emitting infrared light into a colder environment.
“In both cases, the temperature difference is what lets us generate electricity.”
– The co-author of the paper, Dr. Phoebe Pearce
What was previously a theoretical process was practically accomplished by the team to confirm that specialized and far more efficient devices can be made in the future to capture the energy at a much larger scale.
Prof. Ekins-Daukes likened the new research to that of Bell Labs’ engineers when they showed the first practical silicon solar cell, which was only about 2% efficient. We have come a long way since then, now being able to convert about 23% of the sun’s light into electricity.
According to co-author Dr. Michael Nielsen:
“Even if the commercialization of these technologies is still a way down the road, being at the very beginning of an evolving idea is such an exciting place to be as a researcher.”
This new technology, as per the researchers, can find many applications in the future including powering bionic devices like artificial hearts which currently use batteries that need to be replaced regularly. So, their novel tech can potentially remove the need for batteries in certain devices or help to recharge them.
So far, though, the term radiative diode was able to generate “relatively very low power.” It has been a challenge to detect the power, and there’s still about a decade of university research work to be done before the industry picks it up. But in theory, it’s possible for the technology to “ultimately produce about 1/10th of the power of a solar cell.”
After the ‘unambiguous demonstration of electrical power,’ the team started working with a new material that is easier to manufacture, in turn, to scale.
At the same time, the team is working on applying their technology to spacecraft like satellites. Solar-powered satellites aren’t a new thing, it was actually first demonstrated in 1958.
Powered by solar cells, these spacecraft rely on batteries during eclipse conditions. So, the UNSW researchers are now applying the technology to generate power for satellites as they orbit in darkness.
The technology, which was first used in space, has now been used to produce huge amounts of electricity from solar power for our homes, and in a similar way, Prof. Ekins-Daukes intends “to fly the term radiative diode in space within the next two years.”
Click here to learn why increasing usage of solar energy marks the start of the solar age.
The Shift to Clean & Abundant Solar Power
Due to solar panels needing sunlight to generate power and as such unable to work at night, a lot of research and developments have been working on finding solutions to this problem.
One of the ways it has been addressed is battery storage, which is used to store excess energy production. This stored energy can then be used whenever one wants, at night and on cloudy days. The likes of Tesla Powerwall or Generac PWRcell offer an alternative to this. These battery banks act as off-grid electricity sources during power outages.
Another way is net metering. Here, having access to a solar buyback program allows you to use the local power grid as your battery. In order to power bill credits, you have to send the excess energy generated by your solar panels during the day back to the grid. Your earned credits will be applied to your power bill to cover your nighttime power consumption.
Researchers have even created solar panels that harvest electricity from the night sky. For instance, anti-solar cells work in reverse to solar panels during the day. Then, there are friction-powered panels that convert motion into energy and harness the power of radiation off warm surfaces.
Recently, Stanford University scientists designed a new type of solar panel to produce electricity at night. For this, they integrated a thermoelectric generator in the conventional sun power solar cells. Not only can it offer continuous power generation, but it also improves efficiency during the day.
Then there’s California-based startup Reflect Orbital, which has shared its plan to sell sunlight at night. To achieve this, it plans to use a constellation of satellites equipped with mylar mirrors, which will orbit 370 miles above the surface. They will reflect sunlight onto solar panels on Earth’s surface.
“We think sunlight is the new oil, and space is ready to support energy infrastructure.”
– Reflect Orbital Co-founder Ben Nowack on X (previously Twitter)
If we look at numbers, among clean energy sources, solar is certainly leading. 2023 was actually a record year for this energy source as the world deployed 447 GW of new solar capacity, a whopping 78% of the entire new renewable capacity addition. By recording an increase of 87% from the year before that, the global solar market recorded a growth rate that hasn’t been seen since 2010.
Most of this growth was driven by China, which is the world’s largest solar market. It added 253 GW of new solar PV capacity, a surge of 167%, and was responsible for 57% of global installed capacity last year.
This “unforeseen growth” in total solar energy, according to the Global Market Outlook for Solar Power 2024-2028, was due to a massive price collapse of about 50% for modules. This drop has been due to a substantial increase in global PV manufacturing capacities which resulted in overcapacities.
Besides orders from previous years being finally installed in 2023, individuals, businesses, and governments have been turning to solar power as a reliable and cost-effective solution to high energy prices.
On the back of further product availability, cost improvements, and the many benefits the tech provides, the report anticipates “substantial demand growth for solar PV power in the coming years.”
Companies Advancing the Solar Energy Sector
Now, let’s take a look at a few prominent names that have been taking alternative routes to generate energy.
Clearway Energy (CWEN -2.17%) is one such company that operates wind farms and solar power plants to provide clean, renewable energy, while Ormat Technologies (ORA -0.31%) focuses on geothermal power generation. Heliogen (HLGN -5%) is yet another name in this space, and it uses AI and advanced mirror technology to concentrate sunlight and generate electricity. Enphase Energy (ENPH -1.88%) and Piedmont Lithium (PLL -7.2%) meanwhile lead the energy storage field.
#1. Bloom Energy (BE -0.58%)
This company is using solid oxide fuel cell technology to generate reliable and efficient electricity. By using their energy servers for on-site generation, Bloom Energy provides a cleaner alternative to traditional power generation and reduces dependence on the grid.
Bloom Energy Corporation (BE -0.58%)
As of writing, BE shares are trading at $10.80, down 26.82% year-to-date, with its market cap at $2.465 bln. Bloom Energy has an EPS (TTM) of -1.30 and a P/E (TTM) of -8.31. For Q2 2024, the company reported $335.8 million in revenue, which is an increase of 11.5% year-over-year. The gross margin for the quarter was 20.4%, while its operating loss came in at $23.1 million. Bloom Energy also issued 3% convertible green notes during that time to strengthen its balance sheet.
Additionally, the company partnered with AI leader CoreWeave to power Chirisa Technology Parks-owned high-performance data center. Bloom fuel cells will also power Silicon Valley Power’s 20 MW of AWS data centers. According to Bloom’s CEO KR sridhar:
“It is now widely understood that demand for electricity is expected to far exceed available supply through the grid. It is presenting Bloom with a huge opportunity. We are seeing high levels of commercial interest in our products and solutions. We continue to execute well, advance our technology, and build out our team for future growth.”
#2. NextEra Energy (NEE +0.66%)
With a focus on solar, wind, and battery storage, NextEra has become one of the largest producers of renewable energy. The electric power and energy infrastructure company’s shares are currently trading at $83.85, up 38.05% YTD, which has NextEra’s market cap at $172.27bln. Its EPS (TTM) is 3.67 and P/E (TTM) is 22.85.
NextEra Energy, Inc. (NEE +0.66%)
For 2Q24, the company reported a GAAP net income of $1.622 billion while adding over 3,000 MW of new renewable and storage projects to its backlog. A couple of months ago, meanwhile, its subsidiary NextEra Energy Resources, along with Entergy, announced a joint development agreement to accelerate the creation of up to 4.5 GW of new solar generation and energy storage projects.
Conclusion
Sun is an inexhaustible resource of energy and when combined with efficient and advanced technologies, it offers great potential to meet the fast-rising global energy demand and address the issue of climate change.
As the rising leader of the ongoing global clean energy transition, the solar industry has seen a lot of investment, exceeding all other generation technologies combined last year and development. All of this has led to many breakthroughs in solar technology, such as sun-tracking solar cells, printable solar cells, photovoltaic windows, and, of course, night-time solar energy generation, which can help push solar energy toward becoming the long-term energy solution for future generations.
Click here for a list of top solar stocks to invest in.