The first week of 2025 saw solar stocks experiencing a nice rally as Tesla (TSLA +0.15%) announced its record energy storage deployments.
In 2024, the electric car company, whose energy storage division produces residential and commercial batteries to store solar energy, deployed 31.5 gigawatt hours of energy storage products, while almost 35% of it (11GWh) was distributed in just Q4 of 2024.
Chinese battery manufacturer company Contemporary Amperex Technology Co., Limited (CATL), which supplies Tesla with battery cells, also released its own mass-producible energy storage system called TENER last year. The system has a 6.25 MWh capacity and energy density of 430 Wh/L while achieving five-year zero degradation.
These big developments in the energy storage space are of critical importance due to the rising demand for energy. This demand is driven by the rising world population, urbanization, economic growth, and technological advancements. Global electricity demand, according to IEA, is actually expected to rise at a faster rate over the next three years. It will grow by an average of 3.4% annually through 2026.
Here, energy storage systems can help meet the rising demand by supporting grid electrical supply, transmission, and distribution systems. By switching to storage mechanisms, grid system operators ensure grid resiliency and reliability. It further eliminates the reliance on higher greenhouse gas (GHG) footprint options.
So, what exactly is energy storage? Well, it is what it says: storing energy. The way it is done is that energy produced is first captured and then stored for use at a later time so that the demand and supply can be better matched.
Now, energy comes in various forms: electrical, thermal, kinetic, chemical, radiation, and gravitational. This means that in order to store energy, it must first be converted into a form that can actually be stored until it can be converted back to electrical energy.
A rechargeable battery is a common energy storage device. It’s in your phone. These batteries store chemical energy that quickly converts into electricity. Another popular and valuable example is the hydroelectric dam. They harness the energy of flowing water, generate electricity, and store it in a reservoir.
Fossil fuels are also energy storage. They hold chemical energy from sunlight, trapped in plants and animals that decomposed millions of years ago.
Innovation in Energy Storage
Energy is the cornerstone of the modern industrial economy. After all, it provides an essential ingredient for almost all human activities, from cooking, heating, lighting, health, education, and transportation to food production, industrial production, and mineral extraction. Given how critical energy is for human civilization, there is a lot of focus on energy storage.
Thermal energy storage (TES) is a type that includes solid-state, liquid-air, and molten-salt storage. The unique benefit of this technology is the decoupling of heating and cooling demand from immediate power production and supply availability.
Compressed air energy storage is another way to store energy; air is compressed into storage tanks when electricity demand is low and released when demand is high.
Hydrogen storage, meanwhile, is an emerging energy storage technology. Most recently, China connected its largest integrated photovoltaic (PV)-hydrogen-storage project in Jiangsu Province to the grid and started power generation. This offshore facility combines hydrogen production, PV power generation, refueling, and energy storage. It is expected to reduce CO2 emissions by about 309,400 tonnes annually, 1,125.3 tonnes of nitrogen dioxide, and 562.6 tonnes of sulfur dioxide.
Batteries are transforming energy storage. They’re leading the shift to a sustainable energy system. Fastest-growing in their field, they dominate the power sector. And thanks to continuous innovation, they’re getting smarter, better, and cheaper.
In groundbreaking research from a few years ago, which has been in the works for close to a decade, scientists from the Chalmers University of Technology and KTH Royal Institute of Technology in Sweden made a structural battery 10x better than in any previous experiment. A structural battery is an energy storage device that can bear weight as part of a structure.
For their battery, scientists layered a buffer glass ‘fabric’ between a positive and negative electrode, packed it with a space-age polymer electrolyte, and then cured it in the oven, resulting in a tough, flat battery cell having an energy density of 24 Wh/kg, stiffness of 25 GPa, and holding up to tensile tests in all directions. This “massless” structural battery has its main use case in electric cars but can also be used in e-bikes, satellites, laptops, and aircraft.
Currently, researchers are focused on further enhancing the battery, though commercialization has yet to be realized.
In order to create better solutions, researchers are now looking into self-charging power systems. These systems harvest energy and store it, making them highly beneficial in the next technology era, which will be marked by 5G technology, the Internet of Things (IoT), and artificial intelligence (AI).
These self-charging energy storage devices can provide stable, autonomous, and sustainable power for the next industrial revolution.
So far, many attempts have been made to integrate different energy harvesting technologies with energy storage devices. This includes solar cells, thermoelectric generators, triboelectric nanogenerators (TENGs), and piezoelectric nanogenerators (PENGs).
In a new research, scientists built a high-performance self-charging energy storage device that can efficiently store solar energy.
The new device dramatically improves the performance of existing supercapacitor devices by making use of electrode materials that are based on transition metal. The researchers further created a new energy storage technology by combining supercapacitors with solar cells to accomplish high performance.
Click here to learn about the future of energy storage.
Self-charging Energy Storage Devices
To meet the demand for next-generation high-capacity energy devices that address increasing global energy consumption and the growing dependence on portable and smart electronic devices, self-charging devices have emerged as a sustainable and standalone power supply solution.
One such device that harvests and stores solar energy is the photo-supercapacitor, which combines solar cells and supercapacitors. Silicon solar cells convert solar energy into electrical energy, and a supercapacitor stores this energy.
In the latest study, which was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) and by the DGIST R&D Program, researchers showed a new self-charging energy storage device that merges silicon solar cells and binary transition metal supercapacitors.
Crystalline silicon photovoltaic (PV) technology, which is the most widely used PV tech, is actually a promising renewable energy storage tool, according to ITRPV, which reported the tech accounting for as much as 95% of the total 135 GW installed in 2022.
Meanwhile, among solar energy devices, silicon-based ones are gaining a lot of traction as a dominant power source for the future. This is because of their high power conversion efficiency, extended stability, abundant materials, non-toxicity, and established production technology that helps with scalability.
As for supercapacitors, they are being utilized as promising candidates to power high-performance devices thanks to their high reliability, high power density, long cycling life, and short charging time.
As the study noted, self-charging capacitors are necessary due to the rapid increase in the use of portable electronic devices. This has created a need for a system that can be charged quickly at any time and anywhere.
Then, there’s the growing dependence on renewable energy sources in order to protect the environment and promote sustainable development. By using solar energy, self-charging systems reduce the need for battery replacement while enabling efficient energy supply even in areas with limited access to power grids.
Yet another driving factor of self-charging capacitors is the fast charging and discharging attribute of supercapacitors, which makes them really useful in emergency situations or scenarios where there is a need for high power consumption.
A High-Performance Self-charging Supercapacitor
Given the need for self-charging capacitors and their many benefits, the latest research, published in the journal Energy last month, fabricated a self-charging device by combining a supercapacitor with a Si solar cell.
To design the electrodes for the same, the research team used nickel (Ni)-based carbonate and hydroxide composite material. Then, the team added transition metal ions like Manganese (Mn), Cobalt (Co), Copper (Cu), Iron (Fe), and Zinc (Zn) to maximize the conductivity and stability of the electrodes.
These transition metal ions allow the team to address the conductivity reduction problem that emerges due to using only Ni ions. Introducing these metal ions enabled them to create binary compounds as electrode material, which offered high electrical conductivity, reversible capacity, and structural stability.
Doing this has improved the performance of the electrode substantially, showing significant advancements in energy and power density and stability in charging and discharging.
When it comes to energy storage per unit weight, the study achieved 35.5 Wh kg⁻¹, which surpasses the values (5-20 Wh kg⁻¹) recorded in previous studies. As for the amount of energy flow per unit, it is 2555.6 W kg⁻¹, which is again far higher than what previous studies have accomplished at 1000 W kg⁻¹.
With much higher energy density and power density, the latest study demonstrates the ability to release higher power rapidly. In this way, the asymmetric supercapacitor device can enable an immediate energy supply, even for high-power devices.
This isn’t even all; this high performance had minimal degradation when put through repeated charge and discharge cycles, making it suitable for the long term as well.
The team then combined this device with silicon solar cells, which allows for the storage of solar energy and its utilization in real-time. This combination attained an energy storage efficiency as high as 63% while the general efficiency of the device was 5.17%, validating its potential for commercialization and contributing significantly to the advancement of energy storage technology.
“This study is a significant achievement, as it marks the development of Korea’s first self-charging energy storage device combining supercapacitors with solar cells.”
– Jeongmin Kim, Senior Researcher at the Nanotechnology Division of DGIST
Kim further noted that by making use of transition metal-based composite materials, they have been able to get past the restrictions of energy storage devices and create a sustainable energy solution.
But that isn’t the end of the study, as Damin Lee, a researcher at the RLRC of Kyungpook National University, stated:
“We will continue to conduct follow-up research to further improve the efficiency of the self-charging device and enhance its potential for commercialization.”
Companies Engaged in Related Fields
Now, let’s take a look at a couple of companies that are providing and advancing energy storage solutions.
1. Tesla (TSLA +0.15%)
This electric vehicle maker is also heavily involved in the energy storage market. Its energy products include the Powerwall and Megapack, which integrate advanced energy storage solutions.
With a market cap of $1.318 trillion, Tesla is the world’s 8th largest company, while its CEO Elon Musk, who is also involved in X (previously Twitter), SpaceX, Neuralink, and The Boring Company, is the richest man in the world with a net worth of $437 billion.
As of this writing, Tesla’s stock is trading at $412.82, which is up 1.63% this year. This green start of 2025 for the company stocks comes after a stellar 2024, during which its shares surged about 67% in value.
Tesla, Inc. (TSLA +0.15%)
Interestingly, much of Tesla’s gains have been in the last two months of the year, with its price increasing 75% on the back of President-elect Donald Trump winning the 2025 US presidential race. Musk was actually the largest donor of the election cycle, spending at least $277 million to back Trump and other Republican candidates.
With Trump coming into office later this month, there certainly will be positive developments ahead for Tesla. Even before that, the company reported producing about 459,000 vehicles and delivering over 495,000 units in Q4 2024. With this, Tesla’s total production for 2024 stands at 1,773,443 vehicles, while deliveries reached 1,789,226 units. However, it faced increased competition from Chinese giant BYD and US legacy automakers like Ford.
The complete Q4 2024 financial results, including net income and cash flow, will be announced by Tesla on January 29, 2025. In the previous quarter, the company reported $25.18 billion in revenue and $2.17 billion in net income. During this period, Tesla’s automotive revenue rose 2% to $20 billion compared to Q3 2023, while its energy generation and storage revenue surged 52% to $2.38 billion.
Its energy storage deployments in Q4, meanwhile, have made a new record at 11.0 GWh and an unprecedented 31.4 GWh for the entire year. In comparison, Tesla deployed 14.7 GWh of energy storage in the year before that, which was double the 2022 numbers. Also, in 2020, Tesla’s energy storage deployments were merely 3.0 GWh, which points to a 10x increase in the company’s storage capacity in just four years.
These figures came as Tesla’s gigafactory in Shanghai began trial production this week, with mass production expected early this year.
2. Enphase Energy (ENPH -1.07%)
The global energy technology company, which is actively expanding its market reach domestically and internationally, specializes in solar energy solutions. This includes microinverters, which convert solar energy into electricity, and energy storage systems for residential and commercial applications.
With a market cap of $9.74 billion, ENPH shares are currently trading at $72.15, up over 5% already this year. These gains follow a disappointing 2024, during which its stocks dropped more than 46%. Meanwhile, ENPH’s peak was in Dec. 2022, when its stock price hit $339. Enphase Energy has an EPS (TTM) of 0.44 and a P/E (TTM) of 164.01.
Enphase Energy, Inc. (ENPH -1.07%)
For Q3 2024, the company reported a revenue of $380.9 million. Region-wise, revenue in the US rose 43% compared to the previous quarter as inventory returned to normal levels, while revenue in Europe decreased 15% due to further softening in demand. Enphase shipped a total of 1,731,768 microinverters in this quarter, which represents 730 megawatts DC and 172.9 megawatt hours of IQ® Batteries.
For Q4, Enphase Energy estimates its revenue to be within the range of $360 million to $400 million and shipments of 140 to 160 MWh of IQ Batteries. The net IRA benefit, meanwhile, is expected to be between $38-$41 million.
The Inflation Reduction Act (IRA) was introduced under the Biden administration with bipartisan support. The $369 billion package, which was signed into law in 2022, provided incentives for renewable energy via tax credits, grants, and investments. This has been a game-changer for the renewable energy sector.
At the end of Q3, Enphase Energy had $1.77 billion in cash, cash equivalents, and marketable securities, while free cash flow was $161.6 million. The company meanwhile generated $170.1 million in cash flow from operations.
During this time, it also launched AI-based software to improve its consumers’ understanding of energy usage and help them maximize their savings in the increasingly complex energy rate market by integrating solar and consumption estimation with electricity tariffs.
Conclusion
With global energy demand continuing to rise significantly, at a rate faster than ever before, due to intense heat waves, robust economic growth, and, of course, the increasing adoption of technologies like EVs and AI, there is a need for energy storage solutions that can help satisfy this demand.
Here, the development of high-performance self-charging energy storage devices represents a major step in the advancement of energy storage technology and meeting the global energy demand. While yet to be commercialized, innovations like these can help ensure a stable and reliable energy supply and unlock vast potential in renewable energy integration!
Click here for a list of top battery stocks.
