How Is Solar Energy Stored? | Energy Storage and Solar Panels Explained

The Importance of Solar Energy Storage

Even for the most ardent solar enthusiasts, the limitation of solar panels is clear – they only produce electricity when the sun is shining. However, peak energy use often comes in the evenings, coinciding with decreased solar generation and causing a supply and demand imbalance.

The good news is that solar panels frequently generate more energy during those lower demand hours when the sun is shining than is needed to meet peak demand later in the day. This surplus energy can be harnessed through efficient solar energy storage, opening up a wealth of possibilities for homeowners and businesses alike.

Storing this excess solar energy is essential to getting the most out of any solar panel system. It can result in significant cost-savings, more efficient energy grids, and decreased fossil fuel emissions. In this comprehensive article, we’ll explore the various ways solar energy can be stored, the benefits of doing so, and the latest advancements in solar energy storage technology.

Key Benefits of Solar Energy Storage

Solar energy storage offers several important advantages, including:

Increased Self-Consumption and Energy Independence: By storing surplus solar energy, homeowners and businesses can use more of the renewable electricity they generate, reducing reliance on the grid.
Cost Savings: Storing solar energy allows users to avoid purchasing grid electricity during peak demand periods when rates are highest, resulting in lower utility bills.
Improved Grid Stability and Resiliency: Large-scale solar energy storage can help stabilize the electrical grid by smoothing out fluctuations in solar generation and providing backup power during outages.
Reduced Emissions: Greater use of stored solar energy means less reliance on fossil-fuel-based electricity, leading to lower greenhouse gas emissions and a cleaner environment.

Types of Solar Energy Storage

Solar energy storage can be broadly categorized into three main types: battery, thermal, and mechanical. Let’s take a closer look at each:

Battery Storage

By far the most common method for residential solar installations, battery storage involves using a chemical reaction to store the surplus solar energy. When solar energy is fed into a battery, it causes a chemical reaction that stores the energy. This reaction is reversed when the battery is discharged, allowing the current to flow out.

Lithium-ion batteries are the most commonly used battery technology in solar applications, but other options like lead-acid and saltwater batteries are also available. As battery technology continues to advance, we can expect to see even cheaper, more scalable battery storage solutions in the coming years. In fact, U.S. energy storage capacity is projected to reach nearly 7.5 GW annually by 2025, a sixfold increase from 2020, representing a $7.3 billion market.

Thermal Storage

Thermal energy storage uses various mediums, such as water or molten salt, to absorb and retain heat from the sun. This heated medium is then stored in an insulated tank until the energy is needed, usually to boil water for electricity generation.

Mechanical Storage

Mechanical energy storage takes advantage of the potential energy of an object to generate electricity. These systems convert surplus electrical power into mechanical power, which is then converted back into electricity for later use. Some examples include:

Pumped Hydropower: Using electrical energy to pump water uphill into a reservoir, then releasing the water to turn turbines and generate electricity when needed.
Compressed Air Energy Storage: Compressing air into a storage vessel, then releasing it to drive a turbine and generate electricity.
Flywheels: Spinning a heavy wheel to store kinetic energy, then using that motion to power a generator.

While these mechanical storage methods can be effective for large-scale, utility-level applications, they tend to be more costly and complex, making them less suitable for most residential solar installations.

Solar Energy Storage Solutions for Homes and Businesses

The choice of solar energy storage solution depends on the specific requirements and resources available. Let’s explore some common options for both commercial and residential applications.

Commercial and Utility-Scale Solar Energy Storage

Utility companies and other businesses generally have larger budgets than individual households, making mechanical and thermal storage viable options. While the costs for these storage methods can be high, they help utilities keep up with peak energy demand.

Residential Solar Energy Storage

For the average homeowner, battery storage is typically the most cost-effective and efficient way to store solar energy. Lithium-ion batteries are the go-to choice, offering a relatively low profile, cost-effective, and versatile solution.

Other battery types, such as saltwater and lead-acid, are also available for residential use. Regardless of the battery chemistry, home backup batteries allow homeowners to save energy during high production, low demand periods (e.g., during the workday) for use during high demand periods when generation diminishes.

The benefits of home solar energy storage mirror those of large-scale storage, including improved resiliency, uninterrupted energy, and cost savings – all directly benefiting the homeowner.

Designing Solar Energy Storage Systems

Designing a storage system alongside a solar installation used to be a labor-intensive process involving a fair amount of guesswork. However, the latest software tools like Aurora’s have made the process much more streamlined and intuitive.

Using Aurora’s battery storage functionality, solar installers can analyze load offset, calculate projected project pricing, and provide smart battery sizing recommendations based on customer priorities. This allows installers to present customers with interactive, easy-to-understand models of performance and savings.

The Future of Solar Energy Storage

The sun offers a limitless supply of clean power, but harnessing it can be a challenge. Fortunately, several proven solutions for storing solar energy are available, and emerging technologies are being developed daily.

For commercial and utility-scale applications, mechanical storage options provide effective ways to harness solar energy when it’s needed most, and grid-scale battery storage will likely become more prevalent. For residential solar, battery storage is the best option, with a variety of affordable units on the market.

Together, these storage solutions provide a compelling portfolio for maximizing the benefits of solar energy in both commercial and residential settings. As research and development continue, we can expect to see even more innovative and cost-effective solar energy storage technologies emerge in the years to come.

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