Dec. 02, 2024
After extensively reviewing numerous solar batteries throughout the year, we've found that the Bluetti EP900 Home Battery Backup stands out as the top pick by CNET, surpassing the Tesla Powerwall. The EP900 system excels in power output, warranty, modular design, and clear pricing. However, it’s essential to remember that our evaluations focus on backup power scenarios. While the EP900 is an excellent choice for many homes, it might not be the ideal option for everyone. Some other batteries could be more suitable depending on your unique energy requirements.
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If you have rooftop solar panels, they may generate more electricity than you can consume. Your utility company might offer compensation for the excess energy through net metering, but you can also utilize it to charge a battery for later use. Once your battery is fully charged with clean electricity, you can utilize it to minimize peak charges under time-of-use rates, reduce dependence on your utility, access solar energy during nighttime, or maintain a reliable energy source amid power outages. A recent study indicated that the primary motivation for consumers considering home batteries was to save on energy bills, rather than solely for backup power. The same report highlighted that costs are decreasing, making home batteries more budget-friendly.
CNET professionals have dedicated countless hours sifting through battery specifications and consulting with experts in the field to gain clarity on how these batteries operate and what truly matters for homeowners in the market for a home battery. Our evaluation strategy presumes you're primarily buying the battery for home backup needs. If you're considering the battery for time-of-use offset or participation in virtual power plants, the top battery options we've listed may not be the best fit for your specific situation. Investing in home batteries is a considerable expense, and it is crucial to evaluate all available options, including those not presented in this guide.
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7.5
SCORE
How we score solar panels, products, and services.Evaluating solar equipment and companies hands-on is quite challenging. We scrutinize technical specifications, consult with manufacturers, and review customer feedback to identify the best products available.
Read our methodology pageThe EP900 Home Battery features a powerful and modular design, giving it an edge over its competitors. It offers three capacity choices and an impressive 9 kW of output across all sizes. Pricing is readily available on Bluetti's website, eliminating any guesswork. Nonetheless, it isn't the most efficient battery.
Performance
6 / 10
Warranty
8 / 10
Capacity & Modularity
9 / 10
Pros and Cons
Pros
Cons
The EP900 consists of an inverter stacked above Bluetti's B500 battery units. The capacity varies based on the B500 units installed—approximately 9 kWh with two units, scaling up to 39.6kWh with extra installations. Its power output is impressive—9kW regardless of capacity, or 18 kW with two systems. Backed by a 10-year warranty with an 80% capacity guarantee at the end of the warranty period, this battery offers competitive pricing compared to similar options, and its price details are clearly provided on Bluetti's website. However, it has lower depth of discharge (90%) and round-trip efficiency ratings (85%) compared to competitors.
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7.4
SCORE
How we score solar panels, products, and services.Evaluating solar equipment and companies hands-on is quite challenging. We scrutinize technical specifications, consult with manufacturers, and review customer feedback to identify the best products available.
Read our methodology pageThe Tesla Powerwall 3 brings significant upgrades from the Powerwall 2. Retaining the 13.5 kWh capacity and warranty of its predecessor, it nearly doubles the power output to 11.5 kW. Nevertheless, it still lacks in terms of modularity, transparency in pricing, and customer support, as it is available only in one size.
Performance
8 / 10
Warranty
10 / 10
Capacity & Modularity
6 / 10
Pros and Cons
Pros
Cons
One Powerwall can store 13.5 kWh, which is a great starting point. For larger capacities, additional Powerwalls must be purchased. Tesla maintains that the warranty for the Powerwall 3 mirrors that of the Powerwall 2, which translates to an unlimited cycle warranty. It boasts a continuous power output of 11.5 kW, representing a significant enhancement compared to earlier models. Its round-trip efficiency sits at 89%, a relatively standard rating, though the company’s customer service reputation leaves room for improvement.
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7.3
SCORE
How we score solar panels, products, and services.Evaluating solar equipment and companies hands-on is quite challenging. We scrutinize technical specifications, consult with manufacturers, and review customer feedback to identify the best products available.
Read our methodology pageThe IQ Battery 5P represents a substantial upgrade from its predecessors. This compact 5 kWh battery is impressively powerful. Enphase boasts some of the most comprehensive customer support options available, though it may fall short in terms of pricing transparency and modularity.
Performance
7.5 / 10
Warranty
7 / 10
Capacity & Modularity
6.5 / 10
Pros and Cons
Pros
Cons
The Enphase IQ Battery 5P has a 5 kWh capacity that offers substantial power, with a peak power of 7.68 kW and 3.84 kW of continuous power per battery. This battery has a round-trip efficiency of 90% and depth of discharge rating of 98%. Enphase provides numerous customer support options, including live chat available 24/7. The warranty lasts for 15 years, but it does not feature a modular design, meaning you'll need to purchase additional 5 kWh batteries to increase capacity.
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7.2
SCORE
How we score solar panels, products, and services.Evaluating solar equipment and companies hands-on is quite challenging. We scrutinize technical specifications, consult with manufacturers, and review customer feedback to identify the best products available.
Read our methodology pageFor those seeking modularity, the Generac Pwrcell is an excellent pick. This battery features a cabinet housing small battery modules, resulting in a high round-trip efficiency. Generac also provides ample customer support options, though it could improve in areas such as depth of discharge, warranty offerings, and pricing transparency.
Performance
6 / 10
Warranty
5 / 10
Capacity & Modularity
9.5 / 10
Pros and Cons
Pros
Cons
The Pwrcell battery is designed as a cabinet containing individual battery modules that can increase capacity incrementally. One cabinet provides between 9 and 18 kWh, with capacity expandable in 3 kWh increments, making upgrades straightforward. You can install up to two cabinets for a total capacity of 36 kWh. The Pwrcell exhibits high round-trip efficiency (96.5%) but has a low depth of discharge (84%). Generac also offers ample customer support options, featuring 24-hour accessibility. The warranty is somewhat basic, and pricing details aren't publicly available, requiring reliance on estimates from installers.
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7.1
SCORE
How we score solar panels, products, and services.Evaluating solar equipment and companies hands-on is quite challenging. We scrutinize technical specifications, consult with manufacturers, and review customer feedback to identify the best products available.
Read our methodology pageThe SolarEdge Home Battery combines commendable performance with an unlimited cycle warranty and exceptional round-trip efficiency. However, it lacks in areas such as modularity and customer support options.
Performance
7.5 / 10
Warranty
10 / 10
Capacity & Modularity
4 / 10
Pros and Cons
Pros
Cons
The SolarEdge Home Battery offers a usable capacity of 9.7 kWh, displaying impressive performance. Its unlimited cycle warranty along with high round-trip efficiency (94.5%) and full depth of discharge (100%) make it stand out. The power capabilities are standard, with a peak output of 7.5 kW and continuous power of 5 kW. However, the battery lacks modularity, requiring another 9.7 kWh unit for any capacity increase. Information on pricing is limited, and support options appear to be lacking.
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The primary role of a solar battery is to store surplus electricity generated by your solar panels. If a solar battery is in place, excess electricity from the panels is saved, allowing you to utilize that energy later. This stored energy can power your home when solar generation is low, such as at night or during overcast days.
Batteries also offer various benefits, even without solar panels. You can store energy in your battery for times of power outages or mitigate the impact of high electricity rates.
Similar to solar panels, solar batteries have distinct advantages and disadvantages. A solar battery can lower your electricity expenses, offer backup during power outages, and reduce reliance on the grid. However, they can be quite costly, sometimes priced similarly to solar panels themselves. Depending on your home's energy needs, you may need multiple batteries.
Pros:
Cons:
Your budget will significantly influence your choice, but several other factors matter as well. Look for a battery compatible with your household energy consumption and capable of supporting the appliances you want to back up during an outage. Consider what you plan to use the battery for; some are more suitable for backup, while others excel in time-of-use offset or virtual power plant activities.
Modular batteries should be part of your consideration. These designs facilitate easy capacity upgrades and often simplify installation. Additionally, monitoring the health of individual battery modules is easier, making it possible to replace smaller parts instead of the entire battery. Given the high cost of solar batteries, warranty comparisons are also crucial. Typically, the lifespan of a lithium-ion solar battery ranges from 10 to 15 years, with many manufacturers offering a 10-year warranty, although some may surpass this.
Choosing a battery isn’t a snap decision. Take your time exploring your options, and local installers can significantly assist, with insights on the best battery for your home and cost estimates.
When installers wire everything together, your battery will be either AC-coupled or DC-coupled. The primary distinction is the route electricity takes between your solar panels, battery, and home, as well as how many times it is converted.
DC stands for direct current, where electricity flows in a single direction, while AC is alternating current—electricity that can change direction. Importantly, solar panels produce DC electricity, while homes and the power grid use AC. Meanwhile, your battery can only store DC electricity.
This is where an inverter becomes vital, acting as a translator between your solar equipment and home, converting DC electricity from the panels and battery into AC that your home can use.
In an AC-coupled setup, electricity from the battery undergoes three conversions before it reaches your house. The solar panels create DC electricity running through the main solar inverter, converting it to AC. This AC electricity either goes directly to your home or is stored in the battery. Should it go to the battery, another inverter is required to change the AC back to DC for storage. Lastly, when extracting energy from the battery to the house, the inverter converts the DC electricity back into AC once more. This process is relatively inefficient.
An AC-coupled system.
In a DC-coupled system, operations are streamlined, requiring less equipment and only one conversion. The DC electricity produced by the panels heads straight into the battery or can go to the main solar inverter, which converts it to AC for household use.
A DC-coupled system.
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Related links:Solar batteries serve more than just as backup energy sources. They can also cut electricity costs, particularly for those on time-of-use rates. Incredibly, you don’t even need solar panels for this to work.
Certain utility companies charge more during peak hours—often mornings and evenings—when electricity demand surges. Rates during these periods can even double. Utilizing stored battery energy to power your home during these high-rate periods allows you to bypass those expensive time-of-use charges. Your solar panels can recharge the battery throughout lower-cost hours, and you can also recharge it from the grid when rates are favorable.
A battery's capacity refers to the energy it can store, measured in kilowatt-hours (kWh). The larger the kWh capacity, the more energy your battery can hold. Aside from cost, storage capacity is an essential consideration when shopping for batteries. The battery must align with your household energy usage and address the appliances or areas you'd like to power during an outage. Depending on how much backup power you want, you may need more than one battery. If you consume lots of energy, a higher capacity will be necessary.
Higher storage capacity generally translates to higher expenses. It’s impractical to keep everything powered during blackouts. Instead, focus on critical appliances like your refrigerator, router, TV, microwave, and lights to maintain comfort without depleting battery power within the first hour or two. It's advisable to prioritize essential rooms over powering the whole house.
Your installer can help you size a suitable battery system based on your needs. Ensure clarity between you and the installer about battery expectations and what will remain operational during an emergency to avoid surprises.
Many of today's batteries feature a modular design. These modular batteries consist of smaller units connected within one or more enclosures. Rather than relying on a massive 15 kWh battery weighing 300 pounds, you can have three smaller 5 kWh modules stacked in a battery cabinet. Such a design benefits both users and installers.
Modular batteries offer a greater degree of control over capacity and enable quick upgrades without the need for an entirely new battery. These units tend to be lighter, which simplifies and increases safety during installation. Generally, fewer installers are necessary, potentially reducing labor costs. Many modular systems can monitor each battery module separately, promoting faster diagnostics and maintenance; should a module fail, simply replace the individual unit without needing to replace the complete battery.
Round-trip efficiency measures how effectively a battery stores energy. This efficiency percentage indicates how much energy isn't lost, notably to heat, during storage. The higher this efficiency, the less energy you lose. If a battery has an 80% round-trip efficiency, it means 20% of the energy sent to it isn’t stored.
Numerous solar batteries exhibit round-trip efficiency ratings around 90%.
This term denotes the proportion of energy usable from the battery concerning its maximum capacity—quantified as a percentage. It reflects the safe energy usage threshold without damaging the battery, sometimes disclosed by manufacturers. A depth of discharge nearing 100% is more favorable.
If manufacturers don’t disclose this figure, you can estimate it by comparing the maximum and usable capacities. A typical battery clearly indicates both these figures. The maximum capacity signifies the total energy allowed for storage, while the usable capacity defines the amount accessible for use. For instance, a battery with a maximum capacity of 10 kWh and a usable capacity of 9 kWh results in a depth of discharge of 90%.
Even though some batteries can be drained to zero, this is typically discouraged as it shortens their lifespan and hampers their ability to retain a charge over time. Optimal battery longevity will arise from moderate usage patterns. Some manufacturers reserve a minority of storage for regenerative purposes if the battery runs completely out of charge.
Every battery is equipped with peak and continuous power output ratings, which are measured in kilowatts. Certain manufacturers only provide continuous ratings while others may share both. These designations clarify the power readiness of the battery during varied scenarios.
Peak power represents the maximum surge of energy the battery can produce momentarily, while continuous power reflects the ongoing power the battery can sustain. For homes with many appliances needing substantial power, higher output ratings are essential. Appliances such as HVAC systems, refrigerators, pool pumps, and EV chargers demand significant energy and can quickly deplete stored capacity. A qualified installer can recommend ideal solutions based on your specific energy needs and consumption.
Your home battery's power output determines how many loads it can support.
When investing in solar batteries—typically a substantial expenditure—a reliable warranty is essential. Most battery warranties cover a specific number of years, cycles, or energy throughput, along with an end-of-warranty capacity guarantee.
Years: Battery warranties often last at least 10 years, with some companies extending warranties to 12 years or even 15 years in rare cases. Exceeding 12 years is uncommon, but some products do offer extended durations. Keep in mind, though, that warranties can expire once battery cycles or total throughput reach certain limits.
Cycles: Each time the battery is used and subsequently recharged is classified as a cycle. Gradually, the battery’s capability to maintain a full charge declines. Typical warranty coverage ranges between 4,000 and 8,000 cycles, but some models include coverage for 10,000 cycles or more. High-profile models like the Tesla Powerwall and SolarEdge Home Battery offer unlimited cycle warranties.
Throughput: A battery's warranty may encompass a throughput clause dictating its total expected energy output throughout its life span, often referenced in megawatt-hours. If throughput exceeds during the warranty period, it may void the warranty.
End-of-warranty capacity: As the usable capacity diminishes over time, most manufacturers ensure that by the end of the warranty period, a battery still retains up to 70% of its original capacity. For example, a battery with a usable capacity of 15 kWh should still collect at least 9 kWh of energy by the expiry of its warranty.
A solar battery can significantly raise your solar system's overall costs. In some instances, the battery's cost can closely match that of the solar panels. According to the US Department of Energy, you might expect to spend between $12,000 and $22,000 on solar batteries. Smaller models (8 kWh or less) can typically be found for under $10,000, not factoring in installation costs.
As your home's energy efficiency increases, expenses will climb. Generally, battery costs range from $1,000 to $2,000 per kWh, not including installation fees that tend to start from $3,000.
Most manufacturers do not sell directly to customers, leading to limited pricing transparency. This is somewhat understandable as energy consumption varies, and pricing from installers can differ. Manufacturers like Bluetti and EcoFlow ship batteries straight to consumers, allowing you to see exact pricing. You’ll need to hire an installer or electrician to complete the connection.
Looking for smaller solutions than a full solar system? Check out our recommendations for the best portable solar panels and solar generators.
Solar batteries are a considerable investment.
Franklin Home Power: The Franklin Home Power battery is a noteworthy option, scoring evenly across various parameters. Its standout feature is its 12-year warranty and capacity for up to 15 batteries for a total energy storage capacity of 204 kWh. It's an excellent choice for users looking for an adaptable battery with the potential for extensive capacity. However, it does carry a higher price tag than comparable batteries.
Panasonic Evervolt Home Battery: While not featured in our top five, the Panasonic Evervolt Home Battery remains a solid option for those wanting modularity without sacrificing performance. It offers 9, 13.5, and 18 kWh capacities, which can be expanded in 4.5 kWh increments. With a robust 12-year warranty and strong continuous power output (7.6 kW), it still falls short regarding AC round-trip efficiency and depth of discharge.
Emporia PowerStation: If modularity is important to you, Emporia's PowerStation presents reasonable capabilities. Available in 9, 13.5, and 18 kWh sizes, up to four units can be installed for an impressive total capacity of 72 kWh. Its notable features include a 12-year warranty and a 7.6 kW continuous power rating; however, other modular options outperform it.
SunPower SunVault: The SunPower SunVault offers reliability, backed by an established solar company known for efficiency. Suitable for clients that prefer SunPower as their solar installer, the SunVault comes in both single (13 or 19.5 kWh) and double-unit (26 or 39 kWh) options. It lacks efficiency, power, and modularity compared to competitors, while support options are limited.
Savant Power Storage 20: For a solid battery choice in the smart home ecosystem, the Savant Power Storage 20 is ideal. Designed for intelligent energy management within your home, it offers extensive control over energy use and backup capabilities but rated lower in some scoring categories. With a peak power output of 12.5 kW, its efficiency and warranty stand out but fall short in terms of depth of discharge, modularity, and customer support.
Sonnen Ecolinx: The Sonnen Ecolinx caters to those seeking involvement in a virtual power plant. Designed primarily for VPP application with backup capabilities, it offers an impressive 15-year warranty covering 15,000 cycles, plus modularity for 12 kWh - 20 kWh, expandable in 2 kWh increments. Nevertheless, it suffers from lower efficiency (81.6%) and higher costs, alongside limited customer support.
LG ESS Home 8: LG benefits from strong brand recognition, but the Home 8 doesn’t distinguish itself significantly against competitors. Still, its warranty and price competitiveness offer some reassurance.
LGES 10H & 16H Prime: These batteries are straightforward, focusing on providing a standard solution. They tend to be older, leading to performance discrepancies and reduced modularity capabilities. Only one additional unit may be connected, limiting expansion possibilities, and support options are less comprehensive.
Sonnen Core Plus: This option is remarkable mainly for its warranty and depth of discharge rating, but with less merit in terms of efficiency and performance. The 10-year or 10,000 cycle warranty offers substantial coverage compared to many alternatives, though performance may lag.
Sonnen Evo: Similar pros and cons align with the Core Plus, giving it a 10-year or 10,000 cycle warranty along with full depth of discharge. Performance metrics including efficiency, power, and modularity rank lower compared to competitors.
Tigo EI Battery: The Tigo EI Battery generally scores average across categories, showing better pricing and efficiency than many, but lacks standout features.
Considering a home battery? It's worth it if you're worried about power outages, whether or not you have solar panels. They can provide backup power during outages, running your home for hours or days. If you reside in areas prone to these outages, it’s a valuable investment.
Data from the U.S. Energy Information Administration supports insights on how many power outages customers face annually. We also offer a visualization of counties and states to show average outage durations. States along the East Coast and Southeast generally experience more frequent outages.
A home battery delivers backup energy, although it's not the only option. Portable power stations can provide more limited backup power, as can fuel-powered generators.
It’s important to clarify that not every battery suits every home; solar is a site-specific decision, making it difficult to pinpoint the absolute "best" option without an on-site consultation.
It’s worth noting that hands-on testing was absent when scoring the batteries. Our analysis assumes that you're primarily acquiring the battery for energy backup; if your goal is mainly electricity offset or virtual power plant participation, different batteries may serve you better. For tailored insights on your household energy requirements and system needs, we highly encourage doing further research and consulting local installers.
We've employed specific criteria for evaluating and comparing these batteries, which helped us create the top solar batteries list. Here's a breakdown of our assessment foundation.
Initially, we identified categories relevant for assessing battery performance, capacity, and value, also weighing each category based on significance to everyday users.
By reviewing more than 15 significantly available batteries, we compiled data within each category to better compare their features. Each battery received a tiered rating (from 1-5) assessing above-average, average, or below-average performance within our evaluated list.
Do solar batteries qualify for the federal tax credit?
The federal solar tax credit covers 30% of the total cost of your solar system in tax credits. Solar batteries qualify for the federal solar tax credit as long as your battery can hold at least 3 kWh of energy and is installed in 2022 or later.
How long do solar batteries last?
A solar battery typically lasts between 10 to 15 years. Factors like weather conditions (if it's outdoors), battery type, depth of discharge (using less energy at one time benefits longevity), installation, and consumption patterns can influence this lifespan.
How many solar batteries do I need to go off-grid?
Going off-grid is unique for every homeowner due to the varying nature of solar. Most households will require several batteries to achieve complete independence. The pairings of your energy usage and solar system size considerably dictate necessary battery counts.
Will a solar battery power my house during an outage?
Absolutely. Protection from power outages is a major reason homeowners opt for batteries. If you have solar panels, a battery allows you to retain excess energy generated for use even during grid outages.
Which type of battery is best for a residential solar panel system?
Lithium-ion batteries dominate residential solar applications due to durability and low maintenance requirements. They also boast higher energy density and depth of discharge ratings.
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