Why can't solar energy be stored?

25 Mar.,2024

 

Even the most ardent solar evangelists can agree on one limitation solar panels have: they only produce electricity when the sun is shining. But, peak energy use tends to come in the evenings, coinciding with decreased solar generation and causing a supply and demand issue. The thing is, solar panels often pump out more than enough energy during those lower demand hours when the sun is shining to meet peak demand later in the day. This means that efficient solar energy storage can open up a wealth of possibilities for homeowners and businesses alike.

In this blog, we’ll look at solar energy storage in-depth, its benefits, and even tools for modeling it on your solar installs.

Click above to learn more about selling solar under NEM 3.0.

What are the benefits of storing solar energy?

Storing this surplus energy is essential to getting the most out of any solar panel system, and can result in cost-savings, more efficient energy grids, and decreased fossil fuel emissions. Storing solar energy has a few main benefits:

  • Balancing electric loads

    . If electricity isn’t stored, it has to be used at the moment it’s generated. Energy storage allows surplus generation to be banked for peak-use. As far as renewable energy is concerned, storing surplus power allows the lights to stay on when the sun goes down or the wind stops blowing. Simply put, energy storage allows an energy reservoir to be charged when generation is high and demand is low, then released when generation diminishes and demand grows.

  • Filling in the gaps.

    Short-term solar energy storage allows for consistent energy flow during brief disruptions in generators, such as passing clouds or routine maintenance.

  • Energy resilience.

    The energy grid is vulnerable to disruptions and outages due to anything from wildfires to severe weather.

    Solar energy storage creates a protective bubble during disruptive events by decentralizing where we get our energy from.

  • Reducing carbon footprint. With more control over the amount of solar energy you use, battery storage can reduce your property’s carbon footprint in areas with fossil fuel-based utility power. Large solar batteries can also be used to help charge electric vehicles and turn any appliance in your home into a “solar-powered” device.
  • Savings from electric bills.

    If you live in a state that has no solar net energy metering, or policies that don’t fairly compensate you for the solar energy you generate, battery storage can help lower your utility bills while consuming more of your own power. So, while you may not be compensated as much for excess energy sent to the grid, any additional solar power generated and stored throughout the day can be discharged from a battery at night or on cloudy days in the place of utility consumption.

  • California Net Billing Tariff (NEM 3) considerations. One of the big components of NEM 3 is that it has, “notably higher on-peak charges and lower off-peak charges” for electricity. Likewise, the export rate is lowest is the middle of the day, when solar energy is plentiful. Since “peak” hours are from 4pm – 9pm, this means, generally, that customers are exporting power to the grid when the rate they receive is the lowest, and using grid power at peak times, when it’s most expensive. Enter battery storage: Any solar energy that can be stored in a battery during non-peak hours and used during peak times will be much more valuable for the consumer. See Auroroa’s new battery self-consumption features by clicking the “Let’s go!” button in the image below, then learn more details in our blog: Explaining and modeling California’s Net Billing Tariff.

How is solar energy stored?

Solar energy storage can be broken into three general categories: battery, thermal, and mechanical. Let’s take a quick look at each.

What is battery storage?

Batteries are by far the most common way for residential installations to store solar energy. When solar energy is pumped into a battery, a chemical reaction among the battery components stores the energy. The reaction is reversed when the battery is discharged, allowing current to exit the battery. Lithium-ion batteries are most commonly used in solar applications, and new battery technology is expanding rapidly, which promises to yield cheaper, more scalable battery storage solutions. In fact, U.S. energy storage is expected to reach nearly 7.5 GW annually by 2025, a sixfold growth from 2020, representing a market worth $7.3 billion.

What is 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 stored in an insulated tank until the energy is needed, usually to boil water for energy generation.

What is mechanical storage?

Mechanical energy storage takes advantage of the potential energy of an object to generate electricity. Mechanical storage methods convert surplus electrical power into mechanical power, which is converted back into electricity for later use. There are three prominent mechanical energy storage systems:

  • Flywheel.

    This method uses surplus electricity to spin a flywheel, which later generates electricity to supply quick energy during peak demand times.

  • Pumped hydro.

    With pumped hydro, water is pumped uphill to a reservoir located above turbine generators. The water is allowed to flow through turbines and generate electricity when demand is high.

  • Compressed air.

    With this energy storage system, compressed air is pumped into large vessels such as a tank or underground formation. The air is released to generate electricity during peak demand.

Click above to download the Storage Sales Cheat Sheet.

The best way to store solar energy

There’s no silver bullet solution for solar energy storage. Solar energy storage solutions depend on your requirements and available resources. Let’s look at some common solar energy storage options for commercial and home applications. 

Commercial solar energy storage

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

  • Grid energy storage with next-generation batteries. 2020 was a record year for new energy storage in the United States. In the third quarter alone, the nation

    deployed

    476 MW of new storage, a 240% increase from the record-breaking previous quarter. Most of the new deployments are one-hour front-of-the-meter (FTM) storage solutions, but nonetheless offer a promising look into the future of commercial solar energy storage.

  • Compressed air

    . The most

    recent government estimates calculate compressed air

    costs at $105/kWh, making it the most cost-effective mechanical storage option for large-scale applications.

  • Pumped hydro.

    Surplus solar energy can be used to pump water uphill, creating a massive amount of potential energy.

    Current pumped hydro costs

    are around $165/kWh, making it the second-best option for mechanical energy storage at scale. It’s only available in certain areas, however, as new pumped hydro involves high upfront costs and significant regulatory hurdles.

Home solar energy storage

Residential solar has myriad benefits, including resiliency, cost savings, and decentralization of electrical production (otherwise known as “virtual power plants”). But the commercial energy storage methods we discussed above are likely cost-prohibitive for the average homeowner. Thankfully, battery storage can now offer homeowners a cost-effective and efficient way to store solar energy.

Lithium-ion batteries are the go-to for home solar energy storage. They’re relatively cheap (and getting cheaper), low profile, and suited for a range of needs. Other batteries commonly available for residential use include saltwater batteries and lead-acid batteries.

Regardless of the battery type, home backup batteries allow homeowners to save energy during high production, low demand times (i.e. during the workday) for use during high demand periods when generation diminishes. Home solar energy storage inherits the same benefits of large-scale solar energy storage, translating into resiliency, uninterrupted energy, and cost savings. And these benefits go directly to the homeowner.

Technology to help design solar battery storage

Designing a storage system along with a solar installation used to be labor-intensive and include a fair amount of guesswork. Now, software like Aurora‘s includes battery storage as part of its offerings.

Using Aurora Solar’s Battery Storage Tool, solar installers can analyze load off-set, calculate the projected price of a project, forecast smart battery sizing recommendations based on customer priorities, and present it to the customer in a compelling, easy-to-understand way.

Aurora has also introduced battery self-consumption modeling. You can learn more here.

So, while the technology used to store solar energy may seem complicated or overwhelming to some customers, Aurora can help you break down the complexities for customers with interactive and easy-to-understand models of performance and savings. 

Click above to learn more about modeling battery storage for self consumption in Aurora.

How to Store Solar Energy: FAQ

Click here to learn more about Aurora’s battery self-consumption modeling capabilities.

Conclusion

The sun offers a limitless supply of clean power, but harnessing it can be a challenge. Thankfully, several options for commercial and residential storage offer proven solutions for storing solar energy, and emerging technologies are being developed daily. For commercial applications, mechanical storage options provide effective solutions to harnessing solar energy when it’s needed most, and grid-scale battery storage will likely become available soon. For residential solar, battery storage is the best option, with a variety of affordable units on the market. Together, these solutions provide an effective portfolio for storing solar energy and provide a compelling argument for further solar deployment in commercial and residential settings. 

To learn more, visit these resources:

To see battery self-consumption modeling in action, schedule a quick demo.

As the world continues to shift towards renewable energy sources, solar power has emerged as one of the most promising options. However, one of the biggest challenges of solar energy is its intermittent nature. The sun doesn’t always shine, and when it does, the energy produced needs to be used immediately or it is lost. This has led many people to ask the question: can solar energy be stored? The good news is that the answer is yes. In recent years, significant advancements have been made in solar energy storage technology, allowing us to store excess solar power for use when the sun isn’t shining. From batteries to thermal storage systems, there are now multiple options available for storing solar energy. In this article, we’ll explore some of the most promising solar energy storage solutions and their potential to revolutionize the way we power our homes and businesses.

It’s Not Constantly Produced

One of the most significant downsides of solar power is that it can’t be produced all the time. Since peak power hours, and therefore the most expensive, tend to be when the strength of the sun is beginning to wane, it would make sense to be able to store solar energy for when it’s most needed. 

Lowering Power Bills

Solar power can offset energy bills during peak hours. Every energy provider increases their energy costs, usually in the evening between 4-9. Of course, this is when you’re cooking a meal, throwing in a load of laundry, and the kids are watching TV—the perfect time to harness stored solar energy instead of using expensive grid power.

Using solar storage can help reduce your carbon footprint. Using a portable power station as storage, for example, can be used in any room in the house or taken on camping trips to power your essential (and, honestly, non-essential) appliances.

Power Resilience

Power outages can happen almost anywhere, and solar batteries can help bridge the gap when the grid goes down. Storing solar energy can protect us from the adverse effects of blackouts by allowing us to decentralize our power.

Do solar panels store energy?

Solar panels don’t store energy. They simply collect the sun’s rays, which then get turned into electricity using an inverter. Without any solar storage, the excess power just goes back into the grid, which means in the event of a power outage during the night, a photovoltaic solar system is little help. 

How is solar energy stored? 

Solar Batteries

There are several ways to store solar energy, depending on the amount and industry. Solar batteries are the most common way to keep solar domestically. They’re affordable, resilient, and an excellent way of decentralizing power. 

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Thermal Storage

Thermal energy requires various mediums, such as molten salt or water, to absorb the heat. It’s then stored in an insulated tank until the energy is needed.

Mechanical Energy Storage

Mechanical solar energy storage uses potential energy to generate electricity on a commercial level. This can be done in three main ways: flywheel, pumped hydro, and compressed air. For example, with pumped hydro storage, water is first pumped uphill and stored in a reservoir. To generate electricity, the water is released downwards through a turbine.

How do solar batteries work?

Put simply, solar batteries work through a series of chemical reactions that store solar energy captured using solar panels and then release energy as electricity. 

The solar panels convert sunlight into DC electricity, which then passes through a charge controller and is stored in the battery. The charge controller regulates the flow of electricity from the solar panels to the battery, ensuring that the battery doesn’t become overcharged or undercharged. 

Types of solar batteries 

The batteries used in solar energy systems are typically made of lithium-ion, lead-acid, or flow chemistry. 

LiFePO4

Lithium-ion batteries, known as LFP, are the most popular choice due to their high energy density, long life, and low maintenance requirements. One of the biggest advantages of LFP batteries is their high energy density. They can store more energy per unit volume or weight than other types of batteries. This means that LFP batteries can provide more power for longer periods of time, making them ideal for use in electric vehicles and other high-power applications.

Another key advantage of LFP batteries is their long cycle life. They can withstand thousands of charge and discharge cycles without losing their capacity, which means they can last for many years. This makes them a cost-effective option for applications that require a long-lasting power source.

Lead-Acid

Lead-acid batteries are a more affordable but have a shorter lifespan and require more maintenance. One of the key advantages of lead-acid batteries is their low cost. They are relatively inexpensive to manufacture and are widely available. They also have a decent lifespan, with many batteries lasting for several years before needing to be replaced. Lead-acid batteries, however, tend to be heavy and bulky, which can make them difficult to transport and install. They also require regular maintenance to ensure they are functioning properly and are not very environmentally friendly, as they contain toxic lead and sulfuric acid, which can harm the environment if not properly disposed of.

Flow Chemistry

Flow chemistry batteries are still in the experimental phase and are not yet widely used. They utilize the principles of flow chemistry, where reactions take place in a continuous flow, to create a more efficient and reliable battery. They offer a more efficient, reliable, and cost-effective alternative to traditional batteries, and have the potential to revolutionize the way we think about energy storage. 

Solar backup power for home

Having solar panels producing electricity for your home is a real selling point. You’re not only saving money but reducing your carbon footprint, too. But, without solar batteries to collect the energy, you still rely on the grid at night or on cloudy days. Portable solar batteries can act as a solar panel backup to store energy for your home. They’re also great for on-the-go, camping, RV-ing, or even electric vehicle charging. EcoFlow LFP batteries can be used daily for at least 10 years and come in a range of capacities and output power to fit a whole host of energy needs.

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FAQ

How long does a fully charged solar battery last?

This will depend on several factors: what you’re powering, the size of the battery, and the age of the battery. If you’re running a full-size fridge using a 1kWh battery, this will drain it pretty quickly. However, if you’re only powering lights or charging smartphones, a 1kWh battery may last a day or more.

Read more:
– https://blog.ecoflow.com/us/how-long-does-home-backup-battery-last/ 
– https://blog.ecoflow.com/us/how-long-can-battery-powered-generator-last/ 

How long can batteries store solar energy?

It depends on the battery type, how well it’s maintained, and how often it’s used. LFP batteries are capable of storing energy for at least 10 years. 

How much solar battery storage do I need

It depends on the situation. If you’re using solar energy to power your home without much or any assistance from the grid, you may need several solar batteries. However, if your solar battery storage is only for short-term home backup, camping, or recreation, one battery will probably suffice. 

Read more:
– https://blog.ecoflow.com/us/what-size-backup-generator-to-power-home/

How much do solar batteries cost?

For the most part, it depends on the battery capacity and chemistry.
You can pick up a small solar battery for around $200, and this will do perfectly for using outdoors or preparing for blackouts. However, for whole-home backup or to become completely energy independent, you could be looking at around $25000 batteries and inverters that fit your needs.

Why can't solar energy be stored?

Can Solar Energy be Stored?

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