Best Solar Battery 2021

Choose the best solar battery for your home

Finding the best solar battery is a smart investment for homeowners with solar systems. Solar batteries allow consumers to save energy generated from solar panels to use later. By investing in solar batteries, you can increase your energy independence, lower your monthly electricity costs, and improve the efficiency of your solar panel system.

As home solar has grown in popularity, so have solar batteries. According to the SEIA, about 25 percent of solar systems will be connected to battery storage by 2025 – compared to six percent in 2020. What’s more, a study by the Lawrence Berkeley National Lab concluded solar projects are almost six times more likely to be paired with batteries than other fuel sources such as wind and natural gas.

Are you interested in finding the best solar battery for your home? This guide will walk you through the best solar batteries in 2021 and how to choose the right option for your energy needs.

What are the best solar batteries?

According to the Energy Information Administration (EIA), the average residential customer uses about 877 kWh per month. This equals approximately 30 kWh of energy each day. When searching for the best solar battery for your home, check the battery capacity to ensure it will meet your energy needs.

Following are the best solar batteries of 2021:

Tesla Powerwall

The Tesla Powerwall is one of the most popular solar batteries on the market and costs $8,500, before installation costs. This solar battery offers a capacity of 13.5 kWh – almost half of the average amount of energy consumed in a household each day – and a DoD of 100 percent. In terms of round trip efficiency, the Tesla Powerwall sits at 90 percent and includes a warranty of 70 percent for 10 years.

Generac PWRcell

The Generac PWRcell battery offers up to 9kWh of continuous backup power when paired with a solar panel system. Including installation, a Generac PWRcell costs about $20,000 and comes with a 10-year limited warranty.

Delta BX6.3

The Delta BX6.3 battery comes with a total capacity of 6.3kWh and 80 percent DoD. Before factoring in installation, the Delta BX6.3 solar battery costs about $7,4,00. It also offers a 10 year warranty with a guaranteed 60 percent battery capacity.

Sonnen ECO

The Sonnen ECO solar battery is an interesting option for consumers because it is sold in 2.5kWh modules at 90 percent DoD. This means homeowners can invest in the right amount of these smaller solar batteries as is needed for their home. Battery capacity begins at 5kWh (two batteries) and can reach up to 20kWh. For a 5kWh system, the Sonnen ECO would cost about $6,100 before installation costs.


The LG RESU solar battery comes in a variety of sizes, including 6.5kWh, 9.8kWh, 13kWh, and 16kWh options. The DoD for these batteries is 90 percent, they include a warranty of 10 years, and a cycle life of up to 4,000 cycles. The price for LG RESU batteries ranges based on the capacity, but typically sits between $6,400 and $7,200 before installation costs.

How to find the right solar battery

There are several factors to consider when shopping for the best solar battery. A few things to keep in mind include:

  • Battery capacity: Your battery’s capacity is how much energy – measured in kilowatt-hours (kWh) – it can store at once. A normal solar battery has a capacity of about 10 kWh.
  • Depth of discharge: The depth of discharge (DoD) is the amount of energy you can draw from a battery before impacting its lifespan. If you draw 100 percent of a battery’s charge, it will shorten the battery’s lifespan. The average home solar battery is 10 kWh. If that battery has a DoD of 80 percent, you wouldn’t want to consume more than 8kWh from the battery without allowing it to recharge. The higher the DoD, the more power you can pull from the battery at one time without causing harm.
  • Battery duration: This measures how many hours a solar battery can run without recharging. Battery duration depends on the type of battery being used. On average, a utility-scale lithium-ion battery can run for up to 4 hours. Battery duration will increase with battery banks – or a collection of batteries working together. Keep in mind the less energy you consume, the longer a solar battery will power your home.
  • Round-trip efficiency: This measures how efficiently a battery can run during one cycle. Like many items in your home, batteries need energy to run. This means they will consume some of the energy that they store. Round-trip efficiency is the percentage of electricity you can get back from the battery after it consumes the energy it needs. If the average 10kWh battery only lets you draw out 8kWh, that means it has an 80 percent round-trip efficiency. 
  • Battery lifespan & warranty options: A battery’s cycle is made up of one charge and one discharge. Once a battery has been through multiple cycles, its ability to hold a charge will decrease. Warranties provide a guarantee that a battery will last a certain amount of cycles or years, often at a guaranteed capacity. For example, a solar battery distributor may offer you a battery with a warranty of 10 years or 5,000 cycles, and guaranteed to retain an 80 percent battery capacity during that amount of time or cycles.
  • Battery types: There are several different types of solar batteries, which can impact the efficiency of your solar panels. Read on to learn more about the best types of solar batteries available.

Solar battery storage in 2021

In the solar market, there are many different kinds of batteries that pair with solar panels to store excess energy. The most common battery types for residential solar systems are lead-acid or lithium-ion batteries.

Lead-acid solar batteries

Lead-acid batteries tend to cost less than other types and are older technology. They also tend to have larger dimensions than newer types of batteries. Lead-acid batteries normally have a lower DoD and need to be recharged often. These types of batteries aren’t common for homeowners who want to power their homes with solar energy every day, but can work well as a backup solution in the event of a power outage.

There are two varieties of lead-acid batteries, including:

  • Flooded lead-acid battery – These need proper maintenance every one to three months because the battery needs to be regularly monitored and refilled with water.
  • Sealed lead-acid battery – These do not require maintenance or regular upkeep. One thing to note is that sealed lead-acid batteries never fully charge in order to avoid water depletion and gas dispersal.

Lithium-ion battery

Lithium-ion batteries are newer than lead-acid and are normally smaller and lighter. They also tend to have a longer DoD and a minimum lifespan of 10 years. Another plus of lithium-ion batteries is that they are lower-maintenance than many of the alternatives.

Other solar battery types

  • Lithium-polymer battery: These are similar to lithium-ion batteries, but tend to be more expensive and have a shorter lifespan. The plus side is that they are protected against overcharging or leakage.
  • Deep-cycle battery: These solar batteries are best for keeping a consistent stream of power over a longer period of time.
  • Saltwater battery: These solar batteries use saltwater as an electrolyte, making them a more natural and environmentally-friendly option. Saltwater batteries are also maintenance free and normally have a long lifespan.
  • Solar gel battery: For solar owners who move around a lot, solar gel batteries are a good option. These batteries don’t have to remain upright, meaning they handle moving around well and are an ideal battery for owners of RVs or people who want to travel with a solar battery.

How do solar batteries work?

Solar batteries store the extra energy generated by a solar panel system. The majority of homeowners consume the most electricity in the mornings and the evenings as they wake up or get home from work. But solar panels often generate the most energy in the middle of the day when the sun is shining the most. With a solar battery installed, solar panels can continue to produce electricity and store it for later use, even when you are away from home.

By pairing your solar panel system with a battery, you can increase your energy independence, lower your total electric costs, improve the reliability of your solar panels, and prepare for times of high demand when the supply of electricity runs low.

Solar battery FAQs

How much do solar batteries cost in 2021?

Solar batteries normally cost between $5,000 to $9,000 in 2021. These prices do not include  the cost of installation. However, sometimes batteries are included in the cost of buying a solar panel system. The federal tax credit can help lower the total cost of a solar panel system.

How many solar batteries do I need for my home?

Most homes use between two and five solar batteries. This depends on your energy needs and how reliable your solar panels are. The average home consumes about 30kWh of electricity every day, so you should research each battery’s total capacity to decide how many batteries you would need to power your home.

What is the lifespan of a solar battery?

Solar batteries can last between 5 and 15 years. The lifespan of a solar battery will be longer if you maintain it and protect it from extreme weather conditions. A battery’s total lifespan is also impacted by the DoD. If you draw more energy out of the battery than is recommended, you may end up affecting your battery’s efficiency.

Are solar batteries worth it?

For owners of solar panels, solar batteries are normally a worthwhile investment. Of course, this depends on the amount of energy your panels generate and how much power your household consumes each day. If your panels are generating more power than you can use, batteries are definitely worth the cost. In addition, solar batteries can help to cut down on electric costs, increase your home’s energy independence, and can even allow you to live off the grid completely.

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