Home Solar Energy Storage
Residential solar has myriad benefits, including resiliency, cost savings, and decentralization of electrical production . 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 tostore solar energy.
Lithium-ion batteries are the go-to for home solar energy storage. Theyre relatively cheap , 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 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.
Reducing Your Carbon Footprint
Many utility companies in the U.S. still create most of their power using dirty fossil fuels. This means that for every kilowatt-hour of electricity you use from your utility, youre probably contributing to the burning of fossil fuels.
With solar energy storage systems, however, you use all of the electricity your solar energy system produces, maximizing the amount of renewable energy your home runs on. Using a clean energy source like solar cuts back on carbon emissions and makes for a happier and healthier planet.
How Energy Storage Works
A common example of energy storage is a lithium-ion battery the same batteries that power your phone or power bank. They use reversible chemical reactions to store electricity. Allowing them to absorb power and discharge it later.
One other thing to note is that storage and retrieval of energy arent 100% efficient.
Some amount of energy is always lost in the process. But still, energy storage provides you the flexibility to use energy whenever you want to.
Two important concepts used with energy storage technologies are:
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Can You Store Solar Power
Yes, you can store solar power. All you need is a home battery.
In 2016, 2% of the United Statesâ electricity generation came from solar power⦠but it could have been a lot, lot more. In fact, it could have been ALL OF IT. In about an hour and a half, the sunlight that touches the surface of the planet could power all of the Earthâs electrical demand for an entire year. Yeah, you heard that right. Every single day, the sun dishes out free, clean energy. The problem isnât that there isnât enough solar power⦠itâs that weâre not capturing it all.
Weâre definitely generating more electricity from solar power than we ever have before. The growth of new solar power installation in both the commercial and residential sectors has been exponential the last few years. Homeowners and businesses have been soaking up the sun to power everything from refrigerators to computers⦠during the day, that is. Everything changes when the sun goes down.
Everyone, especially the owners of rooftop solar, is familiar with the sunâs routine. At the end of the day, the sun is going to go down, whether itâs in charge of keeping your lights on or not. Many solar households are pretty frustrated by the sunâs intermittency⦠but they donât have to be. Thereâs a way to keep the sun working for you, and providing electricity for your home, even in the middle of the night. Sounds awesome, right? Itâs called Energy Storage.
Solar Power The Environmentally Friendly Power Option
Solar power has come a long way in the last several decades.
Before it used to be incredibly inefficient and expensive, but now solar panels have gotten so much better. In fact, people worldwide in homes big and small have started going solar because theyve realized that they can spend less money on powering their homes while replacing renewable sources of energy with clean, green energy.
And while solar energy technology has improved so much, theres still more we can do to improve our solar energy systems and the power that they produce.
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Storing Solar Energy At Home
Having a solar storage system at home comes with multiple perks, such as decentralization of electrical generation, savings on electricity expenses and resiliency.
As a result of solar battery storage, countless homeowners can now delight in efficient and economical means to store solar energy.
As of today, lithium-ion batteries are the most common option for residential solar energy storage. These batteries are comparatively low profile, inexpensive and suitable for an array or requirements. Other options for home batteries usually include lead-acid and saltwater batteries.
You Should Use Only Half Of Your Lead
To maximize the life of lead-acid batteries, short discharge cycles are best, and deep discharges should always be avoided. Even a single dischange of more than 50% can permanently reduce the capacity of the battery.
You can maximize the life of your lead-acid battery by maintaining a high charge level, keeping it at least 80% full in typical day-to-day usage.
This is a pretty serious drawback if you are buying lead-acid batteries for daily usage, such as trying to maximize your solar electricity usage under a net billing scheme.
Deep cycle lead acid batteries will have depth-of-discharge rating for a given percentage. For example, a battery with a 50% DoD rating of 1,000 cycles means that the battery will tolerate 1,000 discharge cycles where the battery is depleted by half.
Deep cycle lead-acid batteries marketed for solar applications will have 50% DoD ratings around 1,000 to 3,000. While this may be fine for light usage, such as battery backup, itâs less desirable if youâre using your batteries on a daily basis. It means that you really need to buy twice as much battery capacity as you actually need, because you can never discharge your batteries completely or else youâll end up ruining them.
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How To Store Your Solar Energy
Most homeowners choose to store their solar energy by using a solar battery. Technically, you can store solar energy through mechanical or thermal energy storage, like pumped hydro systems or molten salt energy storage technologies, but these storage options require a lot of space, materials, and moving parts. Overall, not the most practical way to store energy for a home.
Solar batteries, on the other hand, are a great way to store residential solar energy. The most common type of battery used for solar energy storage are lithium ion batteries. Lithium ion batteries last longer, require less maintenance, and take up less space than other solar energy storage solutions on the market, like lead-acid batteries.
Lithium ion batteries are able to store solar energy through a series of chemical reactions, where lithium ions are moved through an electrolyte solution within the battery. So, when solar panels send electricity to the battery storage system a chemical reaction occurs that moves lithium ions and releases electrons in an electrolyte solution within the battery, which stores the energy.
When you need to use electricity from the battery, the electrons flow backward and the electricity is discharged from the battery. This process can be repeated over and over again, making the battery rechargeable.
Energy Storage Is Developing Rapidly And Within Striking Distance Of Transformative Costs
There are two key characteristics of a storage technology: power capacity and energy capacity. Roughly speaking, power capacity refers to how fast you can get energy out of it, measured in kW energy capacity refers to how much energy you can store in it, measured in kWh. Each is priced separately, power capacity costs and energy capacity costs. The latter is the number weve been using for targets .
Remember how the study divides storage technologies into two tiers? Tier one technologies were modeled with high power capacity costs and low energy capacity costs . They include things like pumped hydro, compressed-air storage , and some proposed flow batteries, which use cheap and abundant elements dissolved in large volumes of water to store energy. They tend to have lower energy density than tier two technologies, but because of their low energy capacity costs, they are good for long-term grid storage.
Tier two technologies were modeled with relatively lower power capacity costs and higher energy capacity costs . They include things like further advanced lithium-ion batteries, other battery chemistries, flywheels, and supercapacitors that are more suited to short-duration, high-power applications like, say, vehicles or appliances.
Can storage out-compete them?
A 2017 report from the International Renewable Energy Agency contains some intriguing projections.
And there is furious work going on around a number of promising new technologies.
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Storing Sunlight As Heat
Other renewable energy storage solutions cost less than batteries in some cases. For example, concentrated solar power plants use mirrors to concentrate sunlight, which heats up hundreds or thousands of tons of salt until it melts. This molten salt then is used to drive an electric generator, much as coal or nuclear power is used to heat steam and drive a generator in traditional plants.
These heated materials can also be stored to produce electricity when it is cloudy, or even at night. This approach allows concentrated solar power to work around the clock.
This idea could be adapted for use with nonsolar power generation technologies. For example, electricity made with wind power could be used to heat salt for use later when it isnt windy.
Concentrating solar power is still relatively expensive. To compete with other forms of energy generation and storage, it needs to become more efficient. One way to achieve this is to increase the temperature the salt is heated to, enabling more efficient electricity production. Unfortunately, the salts currently in use arent stable at high temperatures. Researchers are working to develop new salts or other materials that can withstand temperatures as high as 1,300 degrees Fahrenheit .
Tip : Determine The Battery Capacity
The most efficient way to size the battery system is to size it based on the daily energy demand. For example, if the daily energy demand is 20 kWh, it is advisable to install a 20 kWh battery system.
Alternatively, estimate the excess solar production that you will generate during the daytime and size the battery bank for this excess solar production.
It will be difficult to get this number right and the worst-case scenario is an undersized battery system.
Remember: yes, a battery system is pricey, but having a slightly larger battery bank will save you money in the long run.
The charge-discharge cycles and depth of discharge determine the life of the battery. If you have a larger battery bank, the daily depth of discharge will be shorter and in principle, this will increase the life of the batteries.
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Is Solar Energy Storage Right For Your Home
If you live somewhere that experiences frequent electric grid power outages, or if your utility uses Time-of-Use rates, then solar battery storage will be a worthwhile investment for you. Otherwise, solar batteries are still pretty expensive, so they wont pan out financially for most homeowners.
While there are plenty of solar battery benefits, you need to consider if those benefits outweigh the costs. What we mean is, solar energy storage isnt something you need to install, its more of a luxury.
While solar energy storage might not provide you with additional financial savings, solar panels almost certainly will. Solar panels are cheaper than ever and will start saving you on your electric bills from Day 1. You can see if solar panels are right for your specific home using our solar savings cost and savings calculator.
Batteries Provide Backup Power
Even though youll still be connected to the grid, you can operate off-grid since pairing solar plus storage will create a little energy island at your home. So in the event of an outage, either due to extreme weather or a utility shutoff, youll still be able to keep your lights on.
Two things to note about backup power. First, if you just have a solar panel system without a battery, you will not have power in the event of an outage, even if its a sunny day. This is because your solar panel system will shut down in the event of a power outage so that it doesnt send electricity onto transmission lines while utility workers are attempting to fix them, which would pose a safety risk.
Second, most batteries only provide backup power for part, not all, of your home. Unless you also install a smart electrical panel with your battery , most battery installations will require you to select what parts of your home you want to back up with the battery, and pull those loads onto a critical load panel. However, many batteries can be stacked, meaning you can keep adding additional batteries until you have the storage capacity you want. So while it might be possible to achieve whole-home backup, it can be cost prohibitive to purchase enough batteries to provide that level of backup.
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Hybrid Solar Storage Systems
A hybrid energy system is one whereby a combination of two or more energy systems is used for energy production. This could be a combination of solar technology and wind turbine for energy production.
The hybrid solar storage system can be a combination of solar storage batteries and the public utility grid. When this type of solar storage system is used, solar energy generated is stored up in batteries while the customer makes use of the public utility. When the energy in the batteries is used up, you can comfortably switch to the utility grid. On the other hand, when there is a power outage from the public utility grid, you can also switch to your batteries.
About Solar Energy Storage Systems
Generally, energy storage systems are put in place to capture electricity, store it as chemical, mechanical or thermal energy and release it back as electrical energy when needed. Energy storage saves up excess energy generated during peak periods for future use.
Different types of solar energy storage systems can be adopted to have backup power when the grid goes down and to reduce the amount of money spent on electricity bills.
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How Much Storage Do I Need
Every homes energy needs are unique. The same way you would size your solar panel energy system to meet energy requirements battery storage capacity should also be matched with your energy requirement. It also takes into account the duration of time you need your battery storage to provide you with power.
The Best Option: Lead Acid Batteries
But none of these types has better performance and is as cost-effective as the lead acid batteries . Lead acid batteries have an electrode filled with lead oxide and the other electrode is filled with pure lead . The electrolyte used in this type of battery is the sulfuric acid.
Lead acid batteries can be divided into two main groups:
- Vented Lead Acid Batteries
These batteries have small holes that are closed by removable plugs. They allow you to verify the level and specific gravity of the electrolyte as well as refill distilled water lost during chemical reactions.
These batteries generate gases produced by the internal chemical reactions, and release them into the atmosphere, this is why they require periodic maintenance and continuous refilling of distilled water. They must be always placed in the correct angle to avoid any fluid spills.
Due to these reasons, these batteries are not the most commonly used for solar applications, although some designers use these batteries for their lower costs.
VLA batteries can be divided into three main categories:
- Vented Regulated Lead Acid Batteries
A great advantage of these batteries is that they recombine oxygen and hydrogen through the electrochemical process that allows them to recover lost water in the energy conversion. This process is 99 percent efficient, which is why it is generally assumed that there are no water losses, and therefore, no maintenance is needed from your side.
They can be divided into two main groups:
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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 nationdeployed 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 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. Its only available in certain areas, however, as new pumped hydro involves high upfront costs and significant regulatory hurdles.
Can I Use A Solar Powered Battery Pack Instead Of A Generator
Power outages due to extreme weather events are increasingly common across New England.
The increased frequency of extreme weather events in New England , together with our increasing reliance on electronics in the home has led many New England homeowners to install fossil fuel powered backup generators to provide assured power in the case of a grid outage.
Many homeowners also are concerned about the threats of cyber attacks or terrorism on grid infrastructure . Hundreds of thousands of generators are sold across the United States each year, the majority of them dirty, inefficient, gas-burning portable backup generators sold at big box stores.
For the homeowner seriously considering a propane or gas powered standby generator, the economics and power properties of a solar-powered storage solution can be quite attractive. While a generator can provide power for everything, for a limited period of time, a solar + battery solution can provide power for the essentials, for a near unlimited period of time.
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