Whether you're an engineer or not, chances are you've encountered two main types of batteries: The small ones in devices like watches and alarms, and the larger rechargeable ones found in cars, trucks, or motorcycles. Thanks to the Italian physicist Alessandro Volta, this groundbreaking discovery and explanation of the battery in 1800 sparked a major revolution in science and technology.
From energizing toys and tools, to driving electric vehicles, the importance of batteries goes beyond their traditional role in powering everyday devices; and it becomes especially pronounced in the context of utilizing solar energy. Despite its renewable and environmentally friendly nature, solar power faces interruptions due to factors like weather conditions and the time of day. To address these interruptions and ensure a consistent power supply, the concept of solar battery storage has become crucial. Because this stored energy proves invaluable during periods of low power generation or for running devices not consistently connected to the mains. But the catch is – not all batteries are suitable for solar energy backup!
That being said, join us on a virtual battery tour. In the next section, you will find the 8 interesting types of batteries and the technology behind their working principles, with some interesting daily applications. By the end of this reading, you'll have a clear idea of the top four solar batteries for both optimal energy storage and efficiency, as well as the least preferred options with reasons.
All battery forms can be divided into 2 sections: Primary Cell or Primary battery and Secondary Cell or Secondary battery. Primary cells are non-rechargeable batteries. They are designed for one-time usage. While secondary cells are rechargeable. So, they provide multiple cycles of charge and discharge for sustainable use. Now, here are the main battery types in each category;
Zinc-carbon batteries (Zn-MnO2), classified as primary cells, generate electric current through the chemical reaction of zinc and manganese dioxide. Featuring a zinc anode, a cathode (carbon rod enveloped in a compound with higher standard electrode potential), and an electrolyte of ammonium or zinc chloride dissolved in water, they pioneered commercial dry cells. While carbon enhances conductivity and moisture retention in the cathode, the primary reaction involves manganese dioxide, not carbon. So, these batteries cannot be efficiently recharged, making it impractical to store solar-generated electricity over multiple cycles. Moreover, their lower voltage (1.5V) and specific design characteristics make them unfit for the requirements of solar panel systems. Most importantly, these batteries require appropriate disposal, and it is crucial to apply protective wax or oil treatments to prevent environmental impact and maintain efficiency.
Nickel-metal Hydride (NiMH) are rechargeable batteries. They work by storing electrical energy in a chemical form that can be later released to power various devices. One of their key characteristics is that NiMH batteries can be recharged multiple times, making them a cost-effective and eco-friendly choice. The working principle involves the movement of hydrogen ions between the positive and negative electrodes during charging and discharging. This movement of such ions enables the storage and release of electrical energy, allowing NiMH batteries to power a wide range of devices efficiently, namely remote controls, digital cameras, MP3 players, etc. But these batteries can be quite expensive and bulky. Yet, NiMH batteries are a practical and environmentally conscious choice for storing solar energy.
Lithium-ion (Li-ion) batteries are advanced rechargeable cells that convert chemicals into electricity. These batteries facilitate the movement of lithium ions, generating an electric current, like a “rocking chair.” These batteries comprise of the cathode (typically lithium cobalt oxide), anode (graphite), separator (microporous membrane preventing contact), and electrolyte (a conduit for electricity). Li-ion batteries streamline the power flow. They enter the cathode when charging and get released from the cathode and absorbed by the anode during discharge. As a safety factor, a separator prevents electrode contact. Damage to the separator can cause heat buildup and a potential fire. Yet with these considerations, Li-ion batteries have a range of applications across electronics, DSLRs, EVs, laptops, and medical devices owing to their lightweight, efficiency, and portability. These are also a few reasons why Lithium-ion batteries are the top choice for residential solar energy storage – the Tesla solar battery serves as a classic example.
Alkaline batteries are designed with a fundamental structure that incorporates an alkaline electrolyte, typically potassium or sodium hydroxide. This structure includes a zinc-based anode, a manganese-based cathode, and an ion-conducting separator soaked in alkaline electrolyte. Housed in a metallic case, these batteries feature a positive terminal connected to a collector pin at the negative terminal, all insulated by a gasket. They come in various sizes such as D, C, AA, AAA, AAAA, N, and 9V, including button cells. Known for their extended shelf life, alkaline batteries are widely used in devices like remote controls, toys, cameras, radios, and flashlights. They also offer a steady voltage, higher energy density, and resistance to leakage. However, alkaline batteries are not solar-compatible, as they can be sensitive to temperature changes and have lower efficiency compared to the ones that are optimized for solar applications.
Lead-acid batteries were invented in 1859 by physicist Gaston Planté. They operate via a double sulfate chemical reaction involving lead and lead dioxide on the battery's plates. The batteries use sulfuric acid in the electrolyte to form lead sulfate, generating electricity. Despite having a relatively low energy density, these batteries excel in supplying high surge currents, making them ideal for motor vehicles; especially for engine starters. Beyond their role in vehicles, they serve diverse applications such as backup power for renewable energy storage. Indeed, Lead-acid batteries are widely available, and the technology is familiar to technicians and installers. This availability and familiarity contribute to their continued use in solar applications. Despite the advantages of cost-effectiveness and the ability to deliver short, powerful bursts of energy, lead-acid batteries face limitations, from the standpoint of prolonged device powering. This is primarily due to their inherent self-discharge characteristics (i.e., loss of stored energy over time even when not in use).
Silver Oxide batteries, known as button cells or coin cells, generate electricity through the interaction of silver oxide (Ag2O) and zinc. In this simplified process, silver oxide acts as the positive electrode (cathode), and zinc serves as the negative electrode (anode). During discharge, silver oxide undergoes reduction, releasing silver ions and electrons, creating an electric current. At the anode, zinc reacts with the silver ions, completing the electrochemical cycle. Owing to their characteristics, silver oxide batteries maintain a stable voltage output throughout their lifespan, ensuring steady and reliable performance. Widely used in watches, modern cameras, calculators, hearing aids, and even in NASA and the Military, these batteries are safer. One of its popular specs, the Silver Oxide Battery 357, is an essential power source for laser pointers, LED (Light Emitting Diode) flashlights, and more. Yet being non-rechargeable and tailored for small, low-power electronics, these batteries prove unsuitable for solar applications.
The sodium nickel chloride (Na-NiCl2) battery stands as a formidable competitor to the widely used lithium-ion battery, offering distinct advantages. Also known as ZEBRA batteries, this energy storage solution is widely recognized for its safety and reliability due to its unique chemistry - molten sodium as the anode and a Nickel Chloride cathode, uniquely placed in the middle of a cylindrical cell. The dual electrolyte system includes beta alumina ceramic for sodium ion conduction and molten Tetrachloroaluminate for efficient electrochemical reactions. So, these devices run efficiently even with elevated temperatures, within the typical range of 270°C–350°C. Additionally, sodium-nickel chloride batteries are fully recyclable, as they contain no hazardous or toxic chemicals. However, certain drawbacks exist. They have a limited lifespan of around 3,000 cycles and only an 80% depth of discharge; it means that up to 20% of the stored power cannot be used. Still, Na-NiCl2 batteries find their best use in commercial solar installations, particularly in solar off-grid systems and emergency power backup setups.
Solid-state batteries represent an advanced technology free from liquid or gel electrolytes, employing solid materials for energy storage. Unlike the liquid electrolytes used in conventional ones, solid-state batteries feature ceramics or polymers for the anode, cathode, and electrolyte, ensuring a conductive medium. Facilitating ease of ion movement through a solid electrolyte, these batteries offer enhanced safety, reduced leakage risk, and the potential for higher energy density. As of now, solid-state batteries are more commonly applied in electric vehicles, smartphones, laptops, and energy storage systems, with potential future applications. However, their usage in solar panels is still in the initial stages of exploration, pending further research and development.
As we conclude the exploration of various battery types and technologies, it is evident that these energy storage devices are the backbone of everyday applications. From Alessandro Volta's contributions to modern solid-state battery advancements, each type plays a crucial role in various industry needs. While solar batteries drive progress in portable electronics and renewable energy, making informed choices becomes paramount when integrating them into EV Charging Station Design (EVCS) to support your sustainable energy initiatives.
If in doubt, you can always reach out to Illumine-i. Assisting global EPCs, our in-house professional engineers specialize in selecting the right and best solar batteries and fine-tuning plans for peak performance. A consultation not only ensures maximum energy efficiency, but also turns your investment cost-effective in the evolving landscape of sustainability!
The ideal solar battery depends on factors like capacity, efficiency, cycle life, and compatibility with your solar system. Look for batteries that offer a balance between these aspects for optimal performance.
Yes, Lithium-ion batteries are best for solar power storage, owing to their high energy density, longer cycle life, and efficiency. However, other types like lead-acid and nickel-metal hydride might suit specific setups better based on size, cost, and infrastructure.
You can determine the right capacity for the best solar battery by estimating your daily energy usage and considering the duration of backup needed during cloudy days.
Charge/discharge rate, temperature, depth of discharge, and maintenance significantly impact the performance and longevity of a solar battery.
Solar design services, provided by well-established firms like Illumine-i, include a thorough electrical and structural analysis by professional engineers. They assess your energy consumption patterns, site conditions, and local regulations to optimize the placement and capacity of both solar panels and batteries. This meticulous planning gives maximum efficiency and performance, in terms of both energy generation and storage.