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Solar Panel Energy Storage: What It Is And How It Works For Homeowners


Solar power is one of the fastest-growing ways to generate renewable clean energy. But the main problem with just having a field of solar panels is that, by definition, the sun only shines during the day. If you use power during the night, like most people do, you will need to have a storage solution that can store solar energy for the nighttime as well as on cloudy days where you don't get sufficient power from the sun.

In this article, we’ll discuss some of the technological innovations that allow homeowners to use a hybrid solar system to efficiently store solar power to be used later. We will look at the different energy storage systems, battery technologies and how to run a cost-benefit analysis to decide what type of renewable energy storage system is right for you.

What Is Solar Energy Storage?

Solar energy storage is a way to store any excess solar energy for use when demand exceeds the supply from your solar system. With a solar-based system, this typically happens during the night, but can also be effective during cloudy periods when the energy you get from the sun is not optimal.

Imagine a solar panel system that generates 7 kilowatt-hours (kWh) when exposed to direct sunlight. This will likely be enough power to more than satisfy the electrical demand of most households during the day. But once the sun goes down, the electricity generation also ends. Without a form of battery storage, there will be no power available from your panels until sunrise.

There are a variety of technologies and innovations that make it possible for residential solar customers to have batteries at home. This battery storage is crucial for anyone relying on producing enough power throughout the day to cover all their electrical needs. This is especially important for people who are completely off-grid, but it is useful even if you are connected to the electrical grid.

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How Do Solar Batteries Work?

At their most basic level, solar batteries work just like any other type of rechargeable batteries. They can store energy and be charged from a power source like solar installations. Then, when there is no solar power coming in, the solar batteries can continue to provide backup power to the house. This allows you to continue to use electricity even when your solar panels are not producing energy from sunlight.

Here are a few key terms that you'll want to be aware of when trying to understand how solar batteries work:

  • Kilowatt hours: Kilowatt hours (kWh) are a unit of measurement commonly used in energy metering. A watt is a unit of measurement produced by 1 amp and 1 volt. A kilowatt is equal to 1000 watts, so if a 10-watt LED light bulb is running for 100 hours, it produces 1 kilowatt hour of energy.
  • Inverters: An inverter takes the direct current (DC) produced by solar panels and transforms it into the alternating current (AC) used by most homes. If you have a solar system generating energy for your house, you will almost certainly need some sort of inverter.
  • Storage capacity: The storage capacity of your solar battery system represents how much electricity it can store. You'll need to have sufficient battery energy storage to provide electricity during the times when you aren't producing solar power.
  • Time-of-use charges: Many utilities get most of their energy from power plants and other fossil fuel sources. Because the peak demand for energy happens during the day and afternoon, these utilities will charge a higher rate for power use during these periods of peak energy demands. Having a sufficient battery storage system allows you to use your stored solar energy during peak demand periods instead of pulling from the grid. It makes sense to also save energy-intensive items like charging your Tesla or other electric vehicles for nighttime when electricity rates are lower.

Different Types Of Solar Energy Storage And Batteries

There are several different energy storage technologies to consider when looking to purchase a battery storage system for your solar array. Here are a few of the most common battery types:

  • Lead-acid batteries: This is the oldest type of solar battery storage solution. They have the cheapest upfront cost but also require the most maintenance. They are often used for solar-powered tiny homes.

  • Lithium-ion batteries: Lithium-ion batteries are a newer form of solar energy technology. They cost more than lead-acid batteries but also last longer and are more durable.
  • Lithium-iron-phosphate batteries: Lithium-iron-phosphate batteries are the newest form of solar battery technology. They are the most expensive but have a longer shelf life and can also withstand higher temperatures.
  • Solar charge controller: An off-grid home powered by solar panels needs a PWM or MPPT solar charge controller to ensure your batteries get the correct voltage and remain at the correct state of charge.

What Are The Benefits Of Solar Storage?

Here are a few of the different benefits of solar storage for homeowners:

  • Greater grid independence: Having solar battery storage allows you to have greater independence from the electric grid. That makes you less susceptible to potential power outages.
  • Lower utility bills: The less energy you have to use from the power company, the lower your utility bills will be. That will help you save money and keep yourself in budget.
  • Faster ROI of your solar system: The more money that you save from lower utility bills, the greater return on investment your solar energy system will have. That means a shorter period of time to pay off your initial investment.
  • Getting a tax credit: There are several tax incentives for increasing energy generation or reducing energy use. Check to see if your solar energy storage system qualifies for a tax credit.
  • Tracking and efficiency of energy usage: Being able to track and monitor your total energy usage can help you reduce your overall energy use, saving you money.
  • Avoiding peak electricity usage: With a battery, your home can use stored energy during peak electricity hours. This can save you money if your utility uses net metering, while also reducing strain on the grid.

  • Solving The Duck Curve Problem: Excess electricity generated by home, commercial and utility solar creates an issue called the duck curve. Energy storage could be the solution to helping utility companies manage the need to cycle their power plants on and off throughout the day.

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How Much Does It Cost To Install A Solar Battery?

The average cost to install a solar battery system will depend on how big of a system you are looking to install. While you will need to pay an installation cost, the major cost will be the purchase of the batteries themselves. Some smaller battery installations may only cost a few hundred dollars, but it's more common for a sufficiently large solar battery system to cost thousands if not tens of thousands of dollars.

Other Solar Energy Storage FAQs

Here are a few frequently asked questions about solar energy storage:

How Do I Know If I Need Solar Storage?

Nearly all solar energy systems will need some sort of solar storage since the sun does not shine constantly. It is possible to build a solar system without any sort of battery storage if you are connected to the electrical grid, but most systems do include some sort of battery storage component.

How Long Do Solar Batteries Last And How Often Do I Need To Replace Them?

The battery systems that go with most household solar energy systems will last 5 – 15 years. As solar batteries age, they will hold less and less of a charge, decreasing the overall efficiency of your system. The solar panels themselves usually have a warranty life of 20 – 30 years, so you can count on replacing your solar batteries at least once during the life of your solar panels.

Can I Store Solar Energy Indefinitely?

No, solar batteries will not hold solar energy indefinitely. How long solar batteries hold their charge will vary greatly depending on the type of solar battery that you have. Most solar batteries will hold their charge for 1 – 5 days. That should be more than enough for most common household scenarios.

How Many Batteries Do I Need?

Calculating how many batteries you need for your solar system will depend on a variety of factors, most importantly your average daily energy usage. You'll also want to consider the efficiency of the type of batteries that you're planning on getting. Finally, make sure to round up in your calculations to help account for batteries aging and becoming less efficient.

Solar Energy Storage Could Be Right For Your Household

If you are looking to set up a home-based clean energy system, you have several different options. While hydro power or natural gas may not be cost-effective in your area, solar projects could make a lot of sense for your household. Deciding on the right size of solar storage will depend mostly on how much energy your household generates. It's important to correlate the number of solar panels you have (and therefore the energy that they generate) with a corresponding amount of battery storage. That will make sure you never run out of electricity.

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