What’s the greatest photo voltaic battery general?
We have evaluated many photo voltaic batteries over the course of the 12 months, and the Bluetti EP900 Home Battery Backup is CNET’s choose for one of the best photo voltaic battery general, overtaking the Tesla Powerwall. The EP900 system earned excessive marks for its energy, guarantee, modular design and value transparency. It is vital to notice that we scored our batteries primarily based on a backup energy use case. Batteries aren’t a one-size-fits-all product. The EP900 system is a stable possibility on your dwelling, however it won’t be your “greatest” possibility. One other battery may go well with your house and particular person power wants higher.
Should you’ve bought rooftop solar panels, they might produce more energy than you should utilize. Your utility may pay you for that power by way of net metering, however you can too use it to cost a battery to make use of later. As soon as you have bought a battery full of fresh electrical energy, you should utilize it to keep away from peak fees underneath time-of-use rates, lower your reliance on your utility, use solar energy at night or have a reliable source of energy during a blackout. A current report discovered the top reason for consumers to consider home batteries was to economize on power payments — not for backup energy. The identical report famous that costs are additionally dropping, making dwelling batteries extra inexpensive.
CNET specialists have spent numerous hours digging by battery specification sheets and talking with business specialists to higher perceive how these batteries work and what actually issues for owners who’re purchasing for a house battery. This analysis methodology assumes you are utilizing the battery primarily for dwelling backup functions. Should you’re wanting to make use of your battery for time-of-use offset or virtual power plants, then the “greatest” battery choices now we have listed won’t be proper on your state of affairs. House batteries are a significant family buy and must be handled as such. It is vital to match all of your choices, even ones not featured on this record.
Finest photo voltaic batteries of 2024
Bluetti EP900
Finest general
The EP900 House Battery’s highly effective and modular design offers it a lift over the competitors. The system gives three capability choices and a formidable 9 kW of output at any measurement. The worth is offered on Bluetti’s web site, so there is not any guessing concerned. Nevertheless it’s not probably the most environment friendly.
Tesla Powerwall 3
Finest well-rounded battery
The Tesla Powerwall 3 is a giant enchancment from the Powerwall 2. The Powerwall 3 retains the identical 13.5 kWh capability and guarantee as Powerwall 2, however practically doubles its energy output (11.5 kW). The Powerwall nonetheless falls quick in modularity, value transparency and buyer help. It is solely accessible in a single measurement.
Enphase IQ Battery 5P
Finest decrease capability battery
The IQ Battery 5P is a giant step up from Enphase’s earlier fashions. It is a small 5 kWh battery that packs a whole lot of energy. Enphase additionally gives among the most sturdy buyer help choices that we have seen. However the battery falls a bit quick in value transparency and modularity.
Generac Pwrcell
Finest modular battery
If it is modularity you are after, the Generac Pwrcell is a worthy alternative. The Pwrcell has a battery cupboard that comprises small battery modules. The system’s round-trip effectivity is excessive as properly. Generac additionally gives loads of choices for buyer help. However the Pwrcell’s depth of discharge, guarantee and value transparency might be higher.
SolarEdge House Battery
Finest guarantee
The SolarEdge House Battery could be very well-rounded in its efficiency. However the place it stands out is its limitless cycle guarantee and excessive round-trip effectivity. It falls a bit behind in modularity, value transparency and buyer help choices.
How do photo voltaic batteries work?
A photo voltaic battery’s primary operate is to retailer extra electrical energy generated by your photo voltaic panels. You probably have a photo voltaic battery put in, further electrical energy out of your photo voltaic panels goes into storage so you should utilize that power later. This saved power can be utilized to energy your house in periods of inefficient electrical energy technology, like at night or during cloudy weather.
Batteries additionally present different advantages that you do not even want photo voltaic panels for. You’ll be able to retailer power in your battery to make use of throughout energy outages, or use it to assist offset costly electricity rates.
Professionals and cons of photo voltaic batteries
Similar to solar panels, photo voltaic batteries include their very own set of professionals and cons. A photo voltaic battery may also help you decrease your electrical energy prices, present safety towards energy outages and reduce your reliance on the facility grid. They’re additionally very costly, generally costing as a lot as photo voltaic panels themselves. Relying in your solar system size and what areas of your house you are trying to again up, you may want multiple battery.
Professionals:
- Backup energy throughout outages
- Offset excessive electrical energy prices
- Much less reliant on the facility grid
- Simpler monitoring of your power consumption
Cons:
- Very costly
- You may want to purchase a number of batteries
How to decide on one of the best photo voltaic battery on your dwelling
Your funds is probably going the largest issue at play when selecting a battery, however there’s far more to search for in a battery past its price ticket. You may desire a battery that may match your household’s energy usage and has enough output to help {the electrical} masses in your house that you simply need to again up throughout an outage. Take into accout what precisely you propose to make use of your battery for. Some batteries are higher for backup purposes and others are higher for electrical energy offset and virtual power plant participation.
It’s best to think about modular batteries. These battery designs make it simpler to improve your power storage capability afterward, they usually are typically simpler to put in. Since photo voltaic batteries are costly, you must also evaluate battery warranties. A lithium-ion-based photo voltaic battery’s lifespan is usually wherever from 10 to fifteen years. Most producers supply a 10-year guarantee with their batteries, however there are some outliers.
Selecting a battery is not straightforward, and it is not a call that must be made on impulse. Take your time evaluating all of your choices. Native installers are going to be your greatest supply of knowledge on what sort of battery is greatest on your family’s power wants and targets. They’re going to additionally have the ability to give you quotes on how a lot issues are going to value.
The distinction between AC and DC coupling
When your installer goes to wire every thing up, your battery might be both AC-coupled or DC-coupled. The massive distinction between the 2 is the trail the electrical energy travels between your photo voltaic panels, battery and residential, in addition to the variety of instances that electrical energy is transformed.
DC means direct present, through which electrical energy flows just one means. AC is an alternating present, through which the present is able to altering route. The vital factor to notice is that your photo voltaic panels generate DC electrical energy, however your home (and the facility grid) runs on AC electrical energy. Then there’s your battery, which might solely retailer DC electrical energy.
That is the place a key piece of kit often called an inverter comes into play. The inverter acts as a form of translator between your photo voltaic gear and your home, changing the DC electrical energy out of your panels and battery into AC electrical energy that your house can use.
In an AC-coupled system, electrical energy out of your battery will must be transformed 3 times earlier than it reaches your house. Your photo voltaic panels generate DC electrical energy after which are despatched to your primary photo voltaic inverter the place the DC electrical energy is transformed into AC electrical energy. From there, this AC electrical energy can both go straight to energy your house or be despatched to the battery for storage. If it goes to the battery, that AC electrical energy will must be transformed again to DC first. That is the place a separate inverter for the battery turns into mandatory.
The AC electrical energy is transformed to DC by way of the battery inverter and is then saved within the battery. Once you’re prepared to tug power from the battery to ship to your house, it goes by the battery inverter as soon as final time (from DC to AC). For sure, it is a fairly inefficient course of.
In a DC-coupled system, issues are a lot easier. There’s much less gear concerned and you may solely must convert electrical energy as soon as. The DC electrical energy generated out of your photo voltaic panels will both go into the battery with no conversion mandatory, or it goes to the primary photo voltaic inverter to be transformed to AC electrical energy. As soon as that conversion occurs, the AC electrical energy is distributed to energy your house.
Time-of-use offset
Photo voltaic batteries aren’t simply good for offering backup energy. A battery may also help you get monetary savings in your electrical energy invoice, particularly in case your utility fees time-of-use rates. The very best half is you do not even want photo voltaic panels for this to work.
Some utilities cost extra money for electrical energy use throughout hours of the day when the demand for electrical energy is excessive, like mornings and evenings. Charges throughout these particular hours can generally be double the conventional electrical energy price or greater.
A battery may also help you keep away from these excessive time-of-use charges through the use of the saved power out of your battery to energy your house throughout these peak hours. Your photo voltaic panels may also help recharge the battery. Throughout hours of regular electrical energy charges, you’ll be able to cost up your battery utilizing energy from the grid as properly.
Power storage capability
A battery’s capacity is the quantity of power it could retailer expressed as a unit of energy over time, known as kilowatt-hours. The bigger the kWh capability, the extra power your battery can retailer. Other than value, a battery’s power storage capability must be one among your greatest issues when battery procuring. Your battery must be sized primarily based in your family’s power utilization and which home equipment or areas in your house you need to hold powered up throughout an outage. Relying in your backup energy targets, you may want a number of batteries to realize what you are in search of.
The extra power you employ, the bigger your battery capability will must be. Batteries with extra storage capability are typically dearer, and powering every thing in your house throughout an outage is a bit unrealistic. Due to this, we suggest selecting a number of necessities to ship backup energy to. Issues like your fridge, router, TV, microwave and lights are good decisions to maintain you snug and be sure that the battery will not run out of juice inside the first hour or two. Simply choose a number of rooms to maintain powered up as an alternative of the whole home.
Your installer ought to have the ability to measurement an applicable battery system on your dwelling primarily based in your power wants. Just remember to’re each on the identical web page concerning the expectations of the battery and precisely what is going on to have energy throughout an emergency. You do not need any surprises.
Modularity
Many batteries on right now’s market function a modular design. Modular batteries are primarily a number of small battery modules linked collectively inside one or a number of enclosures. So as an alternative of 1 large 15 kWh battery that weighs 300 kilos, you may need three small 5 kWh battery modules that sit on high of one another in a form of “battery cupboard” or enclosure. Any such battery design usually advantages you and the installer.
Modular batteries give you a bit extra management over your battery’s capability, permitting you to extra simply discover a measurement that is “excellent” on your power wants. The largest profit is the power to improve your power storage capability with out having to purchase one other large battery, so long as there’s room contained in the battery enclosure. Should you’re at most capability, you will have to purchase one other battery enclosure.
Modular batteries additionally are typically simpler for installers. The battery modules are likely to weigh lower than 60 kilos, making them a lot simpler and safer to hold. Some batteries may solely require one or two installers. This might prevent some cash on labor prices. In some batteries, every battery module is monitored individually, so if one thing goes improper and also you want upkeep, your installer can establish precisely which module is failing extra rapidly. If a module must be changed, it is often so simple as pulling the useless module out after which sliding a brand new one in. You will not must undergo the trouble of changing the whole battery.
Spherical-trip effectivity
A battery’s round-trip efficiency is precisely what it feels like; how environment friendly the battery is at storing power. Spherical-trip effectivity is the share of power despatched to the battery that truly makes it into storage with out getting misplaced, usually to warmth.
The upper a battery’s round-trip effectivity, the much less power you are shedding. In case your battery’s round-trip effectivity is 80%, this implies 20% of the electrical energy despatched to the battery is misplaced on its option to storage. You may discover most photo voltaic batteries have a round-trip effectivity of round 90%.
Depth of discharge
Depth of discharge is the quantity of power you should utilize (discharge) from the battery relative to its most capability. This quantity represents the quantity of power (in share kind) you’ll be able to safely use out of your battery with out damaging the battery, in response to the producer. Most producers will disclose this determine, however some do not. The nearer the battery will get to 100%, the higher.
If the depth of discharge isn’t disclosed, you may get an thought of what it could be by yourself so long as you recognize the battery’s most and usable capacities. Most may have a specified most (general) capability and a usable capability.
- Most capability: The overall quantity of power the battery lets you retailer.
- Usable capability: The quantity of power within the battery that you should utilize.
These capability numbers can be utilized to calculate the depth of discharge by dividing the usable capability by the utmost capability after which multiplying the reply by 100. For instance, if a battery has a most capability of 10kWh and a usable capability of 9kWh, then its depth of discharge is 90%.
Even should you can drain your battery to zero, It is not really useful. This may shorten its lifespan and make it tougher on your battery to carry a cost over time. You may get extra cycle life out of your battery through the use of as little power out of your battery as you’ll be able to at a time. Some producers have slightly power storage capability put aside within the battery for use to revive it if the battery runs out of cost.
Energy output
All batteries may have peak and steady power output ratings, measured in kilowatts. Some producers solely disclose the continual score. These scores primarily let you know how a lot energy the battery can deal with in sure conditions.
Peak energy represents how a lot energy the battery can put out with out risking harm. A battery can solely “peak” for therefore lengthy; this surge of energy often lasts for lower than a minute. Form of like when your air conditioner or fridge kicks on. Steady energy is the quantity of energy the battery can help at any given second.
Should you stay in a big dwelling or have a whole lot of massive power-hungry home equipment that you simply plan on backing up, you are going to need greater energy output scores. Bigger home equipment like your HVAC, fridge, pool pump and EV charger are going to require extra energy to run. The battery in an EV is usually a number of instances bigger than the typical dwelling battery you employ to energy your home, so it’s going to doubtless eat up your saved power so much quicker. A good installer will have the ability to present suggestions on your dwelling primarily based in your power utilization and energy wants.
Guarantee
Photo voltaic batteries are an costly funding, so you have to be anticipating a superb guarantee. Most battery warranties will cowl as much as a sure variety of years, cycles or throughput and supply an end-of-warranty capability assure.
Years: You’ll be able to count on most battery guarantee intervals to final a minimum of 10 years. We have seen loads of producers providing 12-year warranties as properly. Something above 12 years is fairly unusual, however some batteries available on the market supply 15-year warranties. Simply needless to say as soon as your battery hits a sure cycle depend or delivers a specific amount of power throughout its lifetime, your guarantee will expire, no matter what number of years you have got left.
Cycles: Any time you drain your battery, it must recharge. This course of known as a cycle. Like most batteries, your battery will slowly lose its means to carry a full cost over time. Many producers will usually cowl a sure variety of cycles within the guarantee settlement. The common guarantee often ensures someplace between 4,000 and eight,000 cycles.
There are outliers available on the market that may cowl 10,000 cycles or extra. Some batteries, just like the Tesla Powerwall and the SolarEdge Home Battery, supply limitless cycle warranties.
Throughput: Some battery warranties embody a throughput clause. The battery’s throughput is the overall quantity of power (usually measured in megawatt-hours) that the battery is anticipated to ship throughout its total lifetime. This implies your guarantee is legitimate till your battery hits its throughput. Typically, should you handle to hit your throughput earlier than your guarantee interval ends, your guarantee will expire.
Finish-of-warranty capability: Your battery’s usable capability will lower over time. A battery’s end-of-warranty capability is the producer’s assure that your battery will have the ability to retailer as much as a sure share of power by the point your guarantee is up. Most producers will assure that your battery will nonetheless have the ability to maintain a minimum of 70% of its authentic capability by the point your guarantee ends. This implies should you purchase a battery with a usable capability of 15kWh, your battery ought to have the ability to retailer a minimum of 9kWh of power earlier than your guarantee expires.
How a lot does a photo voltaic battery value?
A photo voltaic battery might run your photo voltaic estimate up fairly a bit. In some instances, the battery will value virtually as a lot as your photo voltaic panels. Photo voltaic batteries can value wherever from $12,000 to $22,000, in response to the US Department of Energy. You’ll be able to often discover smaller batteries (8kWh or much less) for lower than $10,000 earlier than set up.
The bigger your house, the extra money you will spend on photo voltaic. As a normal rule of thumb, you’ll be able to often count on to pay between $1,000 and $2,000 per kWh of power storage. Photo voltaic battery set up charges are usually round $3,000 or extra.
As a result of most battery producers do not ship these merchandise on to you, they are typically very nontransparent about value. To a level, that is comprehensible. The producer does not know your power consumption or wants, they usually cannot predict how a lot cash each installer goes to cost for set up and labor. Some producers, like Bluetti and EcoFlow will ship their batteries on to you. When it is shipped to you, you will get to see precisely how a lot the product prices. It is as much as you to seek out an installer or rent an electrician to get every thing linked to your house.
Producers ought to know a minimum of the minimal quantity that their battery sells for, no matter upcharges from third events. Some producers will show a “beginning at” value or some type of ballpark estimate on their web site, however that is very unusual. This lack of simple pricing info could make procuring round for batteries irritating and tedious.
Need one thing smaller than a whole-home photo voltaic system? See our picks for the best portable solar panels and solar generators.
Different batteries we reviewed
Franklin House Energy: The Franklin Home Power battery is a stable possibility, receiving a mean rating in practically each class. The standouts for this battery are its 12-year guarantee and the truth that you’ll be able to set up as much as 15 batteries on one system for a complete power storage capability of 204 kWh. It is a good battery should you’re in search of a well-rounded battery for including massive capability expansions. Franklin House Energy can also be dearer than comparable batteries available on the market.
Panasonic Evervolt House Battery: The Panasonic Evervolt Home Battery did not make our high 5, however it’s nonetheless an important possibility for these wanting a modular battery with out sacrificing energy. It is accessible in 9, 13.5 and 18kWh capability sizes, and is expandable in 4.5kWh increments. The Evervolt House Battery comes with a powerful 12-year guarantee and a stable steady energy output (7.6kW). In our scoring, the battery falls barely quick in its AC round-trip effectivity and depth of discharge.
Emporia PowerStation: Emporia’s PowerStation is not a nasty possibility should you’re in search of a modular battery. We discovered different modular choices available on the market to be a bit higher. The PowerStation is offered in 9, 13.5 and 18 kWh capability sizes and you may set up as much as 4 models for a complete capability of 72 kWh. Its greatest options are its 12-year guarantee and seven.6 kW of steady energy. We additionally discovered Emporia to be some of the price-transparent producers. You can get a fast quote on-line with out giving freely any private info. There are cheaper choices available on the market and among the PowerStation’s efficiency specs fall behind the competitors.
SunPower SunVault: The SunPower SunVault is a stable battery, with an important guarantee. It is also backed by a photo voltaic firm with a confirmed monitor file and the most efficient solar panels available on the market. Should you’re already contemplating SunPower as your photo voltaic installer, the SunVault is an efficient alternative for a battery. The largest standouts with the SunVault are its massive capability choices and limitless cycle guarantee. The SunVault is offered as both a single unit (13 or 19.5kWh) or a double unit (26 or 39kWh). It falls quick in effectivity, energy and modularity. We additionally discovered fewer choices for buyer help compared to different battery producers.
Savant Energy Storage 20: Should you’re in search of a battery to combine together with your ever-expanding good dwelling ecosystem, the Savant Power Storage 20 is probably going one among your greatest choices. It is designed as an clever good power system, designed to offer you extra management over your house’s power use on the circuit degree, in addition to present backup energy throughout an outage. Based mostly on the classes we use to attain batteries, it did not make the lower. The Energy Storage 20 has a really spectacular 12.5 kW steady energy output, and its effectivity and guarantee aren’t too shabby both. It falls quick within the depth of discharge, modularity and buyer help choices. It is also one of many dearer batteries available on the market.
Sonnen Ecolinx: The Sonnen Ecolinx is a stable possibility if you wish to take part in a digital energy plant. Most of Sonnen’s batteries are designed with VPP performance in thoughts first and backup energy second. The Ecolinx has a superb 15-year guarantee, masking 15,000 cycles. It additionally contains a modular design. You’ll be able to set up between 12 kWh – 20 kWh, expandable in increments of two kWh. Compared to different batteries, the Ecolinx has poor effectivity (81.6%) and could be very costly. We additionally did not see many choices for buyer help on Sonnen’s web site.
LG ESS House 8: LG has the advantage of being a family identify, and also you may already produce other LG home equipment in your house. The Home 8 is not essentially a nasty battery alternative, however it lags behind the competitors in nearly each class we rating for. We did discover its guarantee and value to be a bit aggressive.
LGES 10H & 16H Prime: Each the 10H and 16H Prime batteries are fairly barebones when it comes to cool options, however should you’re after a reasonably normal battery with a regular guarantee, then one among these could be for you. These batteries are a bit older, so the efficiency specs and general design are beginning to present their age a bit. In addition they are typically a bit cheaper than different choices. The LGES 10H and 16H Prime aren’t modular batteries, and you may solely set up as much as one different unit, making capability upgrades harder. Buyer help choices are missing as properly.
Sonnen Core Plus: The SonnenCore Plus falls a bit quick in nearly each class aside from its guarantee and depth of discharge. The guarantee is sweet for 10 years or 10,000 cycles, which is fairly substantial compared to different battery warranties, notably the cycle life. Like most Sonnen batteries, the Core Plus falls quick in effectivity, energy and buyer help choices.
Sonnen Evo: Sonnen’s Evo battery mannequin shares the identical professionals and cons because the Core Plus. The Evo’s guarantee can also be 10 years or 10,000 cycles and has a 100% depth of discharge. It falls quick in nearly each different class, notably effectivity, energy, modularity and choices for buyer help on Sonnen’s web site.
Tigo EI Battery: The Tigo EI Battery landed a mean rating in most classes and has only a few standouts. We discovered its value and effectivity to be higher than different batteries. It lags behind the competitors a bit in each different class.
Enphase IQ Battery 3/3T & 10/10T: Each of those batteries scored on the decrease finish in virtually each class. The largest spotlight for the IQ Battery 3/3T and 10/10T is their value, which often tends to be cheaper than different batteries on this record. Enphase additionally has a plethora of choices for buyer help, together with stay chat and 24-hour availability. Most producers solely have a help e mail and cellphone quantity.
House batteries may also help you thru a blackout
Whether or not you have got photo voltaic panels or not, you may need to think about getting a house battery should you’re nervous about energy outages. Batteries can run your house for hours and even days when the facility goes out, and should you stay in an space the place that occurs continuously, it could be a superb funding.
We checked out information from the US Power Data Administration to place collectively a map of what number of energy outages per 12 months, on common, the typical utility buyer in every state had from 2018-2022 (utilizing all reporting strategies). We additionally put collectively a map exhibiting the typical complete length of outages per 12 months, in hours. Typically, states alongside the coast and people within the Southeast had probably the most and longest outages.
A house battery is a method to offer backup energy, however it is not the one factor. You should use a portable power station for a smaller, extra restricted backup resolution. A fuel-powered generator can also be a chance.
How we evaluated one of the best photo voltaic batteries
In the beginning, it is vital to level out that not each photo voltaic battery is correct for each dwelling. Photo voltaic is a really site-specific and customized choice course of, so it is slightly tough to pinpoint precisely which photo voltaic battery is the “greatest” battery on your dwelling’s power wants with out doing an on-site session.
It must also be mentioned that we did not have any type of hands-on testing with any of the batteries we scored. This record additionally assumes you are buying a battery for the primary function of utilizing it for power backup. Should you primarily plan to make use of your battery for power offset or digital energy plant functions, there are doubtless higher choices than what now we have featured on this record. We strongly encourage you to do your individual impartial analysis, in addition to communicate with installers in your space. An installer will have the ability to get a greater understanding of your house’s power use and what kind of system you may want.
We used a number of methods to guage and evaluate these batteries to seek out the stand-outs. Here’s how we developed our list of top solar batteries.
First, we decided which classes can be used to guage every battery’s efficiency, capability and worth. We additionally weighted every class. The load of every class displays the significance we felt was related to the typical client.
- Modularity: 20%
- Guarantee: 20%
- Spherical-trip effectivity: 15%
- Energy output: 15%
- Depth of discharge: 10%
- Worth: 5%
- Worth transparency: 5%
- Buyer help choices: 10%
We checked out greater than 15 of probably the most broadly accessible batteries available on the market and picked up the information for every class to match the numbers. Every class (for each battery) was given a tier-style score (from 1 to five) to guage which facets of every battery have been above common (amongst our record), simply common or under common.
Photo voltaic battery FAQs
Do photo voltaic batteries qualify for the federal tax credit score?
The federal solar tax credit covers 30% of the overall value of your photo voltaic system in tax credit. Photo voltaic batteries qualify for the federal photo voltaic tax credit score so long as your battery can maintain at least 3kWh of energy and is put in in 2024 or later.
How lengthy do photo voltaic batteries final?
A photo voltaic battery’s lifespan is usually between 10 and 15 years. Components affecting the lifespan of your battery embody climate situations (if outside), sort of battery, depth of discharge (the much less power you employ at one time, the higher), set up and utilization.
What number of photo voltaic batteries do I must go off-grid?
As a result of photo voltaic is so site-dependent, there isn’t any definitive reply for the variety of batteries it takes to go off-grid. It may be completely different for everyone. Most householders are going to want a number of batteries to go utterly off-grid. Your property’s power utilization and the dimensions of your photo voltaic system are two of the largest elements figuring out what number of batteries you will must go off-grid.
Will a photo voltaic battery energy my home throughout an outage?
Sure. Safety from energy outages is without doubt one of the primary the reason why owners select to have a house battery put in. You probably have photo voltaic panels, putting in a photo voltaic battery will permit you to retailer extra electrical energy generated by your photo voltaic panels. This saved electrical energy can be utilized at any time, even throughout a grid outage.
Which sort of battery is greatest for a residential photo voltaic panel system?
Lithium-ion batteries are the most well-liked sort of photo voltaic battery for residential photo voltaic purposes. These batteries are sturdy and require little to no upkeep. In addition they include a better power density and depth of discharge.