Even the most enthusiastic solar evangelist will agree with one limitation of solar panels: they only generate electricity when the sun is shining. However, energy usage peaks often occur at night, which coincides with the reduction in solar power generation and leading to supply and demand problems. The problem is that during sunny low-demand periods, solar panels usually output enough energy to meet the peak demand later in the day. This means that efficient solar energy storage can provide a wealth of possibilities for home owners and businesses.
In this blog, we will delve into solar storage, including its advantages, working principles, and how to help.
What are the benefits of storing solar energy?
Storing this excess energy is essential to make the most of any solar panel system, and can save costs, improve grid efficiency, and reduce fossil fuel emissions. There are several main benefits of storing solar energy:
1. Balance the electrical load. If electricity is not stored, it must be used at the moment it is generated. Energy storage allows the remaining power generation to be stored for peak use. As far as renewable energy is concerned, storing excess electricity can keep the lights on when the sun goes down or the wind stops. In short, energy storage allows the accumulator to be charged when power generation is high and demand is low, and then released when power generation decreases and demand increases.
2. Fill in the blanks. Short-term solar storage allows for a consistent flow of energy during brief outages of the generator, such as traversing clouds or routine maintenance.
3. Energy resilience. For any reason, from wildfires to severe weather, the power grid is susceptible to interference and interruption. Solar storage creates protective foam during destructive events by distracting where we get energy from.

How is solar energy stored?
Solar energy storage can be divided into three categories: thermal energy, batteries and machinery. Let's take a quick look.
What is heat storage?
Thermal energy storage uses various media (such as water or molten salt) to absorb and retain heat from the sun. This heated medium is stored in an insulated tank until energy is needed, usually by boiling water to generate energy.

What is battery storage?
Solar energy can also be stored in electrochemical cells. When solar energy is pumped into the battery, the chemical reactions between the battery components store energy. When the battery is discharged, the reaction is reversed, allowing current to flow out of the battery. Lithium-ion batteries are most commonly used in solar applications, and new battery technologies are developing rapidly, which are expected to provide cheaper and more scalable battery storage solutions.
What is mechanical storage?
Mechanical energy storage uses the potential energy of objects to generate electricity. The mechanical storage method converts excess electrical energy into mechanical energy, which is converted back to electrical energy for later use. There are three main types of mechanical energy storage systems:

1. Flywheel. This method uses excess electricity to spin the flywheel, which then generates electricity during peak demand times to provide fast energy.
2. Pumping. For pumped storage, water is pumped uphill to a reservoir located above the turbine generator. When demand is high, water is allowed to flow through the turbine and generate electricity.
3. Compressed air. Through this energy storage system, compressed air is pumped into large containers, such as storage tanks or underground formations. Release air to generate electricity during peak demand periods.
The best way to store solar energy
There is no silver bullet for solar storage. Solar storage solutions depend on your requirements and available resources. Let's take a look at some common solar storage options for commercial and household applications.
Commercial solar storage
Utility companies and other businesses usually have more budgets than individual households, which makes mechanical and thermal storage viable options. Although these storage methods can be costly, they help utilities keep up with peak energy demand.
1. Grid energy storage using next-generation batteries. 2020 is a record year for new energy storage in the United States. In the third quarter alone, the United States deployed 476 MW of new energy storage, a record increase of 240% over the previous quarter. Most new deployments are one-hour front-to-meter (FTM) storage solutions, but they still provide a promising prospect for the future of commercial solar storage.
2. Compressed air. The latest government estimates calculate the cost of compressed air at $105/kWh, making it the most cost-effective mechanical storage option for large-scale applications.
3. Pumping. Excess solar energy can be used to pump water up the mountain, thereby generating a lot of potential energy. The current cost of pumped storage is about US$165/kWh, making it the second best choice for large-scale mechanical energy storage. However, it is only available in certain areas because the new pumped storage involves high upfront costs and major regulatory obstacles.
Home solar storage
Residential solar has countless benefits, including resilience, cost savings, and decentralization of electricity production (also known as "virtual power plants"). But the commercial energy storage methods we discussed above may be too costly for ordinary homeowners. Fortunately, battery storage can now provide homeowners with a cost-effective way to store solar energy.
Lithium-ion batteries are the first choice for home solar storage. They are relatively cheap (and getting cheaper), low-key and suitable for a variety of needs. Other batteries commonly available for residential use include salt water batteries and lead-acid batteries.
Regardless of the type of battery, home backup batteries can allow homeowners to save energy during high-volume, low-demand hours (ie, working days), so that they can be used during periods of high demand when power generation is reduced. Home solar storage inherits the same advantages of large-scale solar storage, which translates into flexibility, uninterrupted energy and cost savings. These benefits go directly to the homeowner.

How to store solar energy: frequently asked questions
1. What is the cheapest solar cell? Lead-acid batteries are currently the cheapest option for solar storage, but they have a short lifespan and are not as efficient as other options. Lithium-ion batteries provide the best value in terms of cost, performance, longevity, and availability.
2. How long is solar energy stored? In theory, as long as the potential energy is maintained, the mechanically stored solar energy can be sustained. Any energy transfer will have energy loss, and in the case of mechanical storage, leakage will always occur during storage and release. The same applies to batteries. Generally, standard solar cells can be charged for 1-5 days.
3. How long can solar cells last? Standard solar cells can last 15-30 years, depending on the type.
4. How many solar cells do I need? Storage capacity varies greatly depending on your specific needs, and takes into account factors such as your required storage capacity, backup load, and backup duration. Aurora Solar's battery storage tools can help you eliminate guesswork when calculating these storage requirements.
5. Is solar energy worth it to me? Yes. Solar energy became cheaper than coal in 2019 at an average of US$0.068 per kWh (while the average price of residential electricity in the United States in the same year was US$0.13, mainly fossil energy). In addition to economic benefits, solar energy can also reduce carbon emissions and increase flexibility.
6. How can I see the best solar efficiency? Good question, this is the importance of solar panel placement. We recommend using solar panel design software to inform your installation and create the best efficiency. See how Aurora Solar works.
in conclusion
The sun provides an unlimited supply of clean energy, but using it can be a challenge. Fortunately, the multiple options for commercial and residential storage provide effective solutions for storing solar energy, and emerging technologies are being developed every day. For commercial applications, the mechanical storage option provides an effective solution for using solar energy when it is most needed, and grid-scale battery storage may soon be available. For residential solar energy, battery storage is the best choice, and there are various reasonably priced units on the market. Together, these solutions provide an effective combination for storing solar energy and provide a convincing argument for the further deployment of solar energy in commercial and residential environments.