 |  | |
|---|---|---|
| Model | Powerwall | LG Chem RESU |
| Capacity | 13.5 kWH | 9.8 kWh |
| Warranty | 10 years | 25 years |
Compare our top 3 solar battery picks
Lead-acid batteries are the oldest and cheapest option, but they can’t store as much energy as the others — and they have a shorter life span. Nickel cadmium batteries tend to fit commercial or big-business needs because they’re resilient against extreme high heat, but they’re also extremely toxic and even illegal in some countries.
Newer to the field and popular among homeowners, lithium batteries are convenient and lightweight. They also have a longer life span than the alternatives and require less maintenance. Flow batteries, another recent innovation, are nontoxic and use 100% of their stored energy — but they can be expensive.
All our top picks are lithium batteries.
- Model
- Powerwall
- Capacity
- 13.5 kWh
- Warranty/guarantees
- 10 years
- Model
- LG Chem RESU
- Capacity
- 9.8 kWh
- Warranty/guarantees
- 25 years
What is a solar battery?
A solar battery is an energy storage option for those with solar panel systems. With the increased use of solar power, solar batteries are more popular with homeowners who want to offset electricity costs and those living or camping off-grid.
Solar generators and portable solar chargers are types of solar battery storage systems. While solar generators are typically affixed to their location — usually houses, campers or boats — a portable solar charger is a smaller, often hand-held device typically used to charge phones or other electronics. Some solar generators are available as all-in-one kits, but you can buy components separately as well.
According to Asim Hafeez, the president of renewable energy company Empower Energy Solutions, solar batteries can be beneficial when your solar panels struggle to get sunlight. “If your roof does not get enough sunlight,” he said, “then solar batteries are a good option.”
Types of solar batteries
There are multiple battery types to consider when choosing solar batteries. Which type is best varies based on your needs and whether you prioritize cost efficiency, safety or environmental impact.
» READ MORE: Types of solar panels
Deep-cycle battery
Lithium-ion battery
Lithium batteries have the added advantage that their voltage stays relatively constant as it discharges. In a lead-acid battery, the voltage decreases as the battery discharges. So, in order for a lead-acid battery to maintain its output, the current draw increases as the voltage drops. This, in turn, discharges the lead-acid battery more quickly. Lithium batteries do not have this drawback.
Lithium-polymer battery
Flooded lead-acid battery
Sealed lead-acid battery
Nickel-cadmium battery
Saltwater battery
Solar gel battery
How do solar batteries work?
Solar batteries can be installed alongside your solar panel system to store the excess energy it produces. When the panels don't produce power at night, you can use the stored energy instead. Many solar battery storage options come with an inverter to convert the stored DC power to the AC power you need, but some require you to buy the inverter separately.
You can then use it as a solar battery generator to power electricity needs. This helps people looking to mitigate electricity costs, prepare for disasters or be completely off-grid. Homes still on the electrical grid can offset their consumption with backup energy and run on battery power until the storage is depleted.
The amount of electricity a solar battery can deliver at once is measured in kilowatts (kW). Kilowatt-hours (kWh) refers to the total amount of energy utilized over an hour. The U.S. Energy Information Administration (EIA) states the average American home consumes 901 kWh per month, or 30 kWh a day. With a battery that provides 2.5 kWh, you would need 12 batteries for sufficient daily power.
Since solar batteries self-discharge, the stored solar energy depletes over time. The rate of self-discharge depends on the type and age of the battery. Newer batteries typically deplete at a rate of 1% to 2% per month, whereas older batteries could deplete by as much as 2% per week.
Residential solar panel arrays don’t usually require solar batteries. Still, solar panel battery storage lowers your utility bills, protects you from power outages and reduces your carbon footprint. If you already have solar panels, solar batteries work to store energy for the future. However, most popular solar batteries like Tesla Powerwall and LG Chem RESU aren’t designed to go completely off the grid.
» READ MORE: How long do solar panels last?
Pros and cons of solar batteries
Solar batteries are an investment that offer notable pros and cons. Before purchasing a solar battery, here’s what you should keep in mind.
Pros
- Reduce carbon footprint and enhance sustainability efforts
- Save on electric bills
- Have relatively long life span of up to 15 years
- Energy independence due to stored energy
Cons
- High initial upfront cost
- Certain solar batteries need timely maintenance
- Can occupy a large area of space
- Improper installation or maintenance can end up posing serious safety hazards
How much do solar batteries cost?
Solar batteries are known for their significant cost. Small solar batteries run between $200 and $2,000. However, a quality battery for residential solar energy storage can cost up to $7,000 or more. When comparing solar battery prices, you should also consider the cost of battery storage per kilowatt-hour (kWh), which ranges from $400 per kWh to $750 per kWh.
As solar batteries become more popular and have been manufactured more their prices have gone down remarkably. That’s why, based on your budget and how many batteries your system requires, they can potentially be an affordable option.
Factors like the battery capacity, what’s included with the battery, installation costs, the manufacturer and chemistry all play a role in the cost of a solar battery. Although solar batteries can have a high cost, tax programs and bundling solar batteries or stored energy are potential ways to save.
FAQ
How many solar batteries are needed to power a house?
Most homeowners need between two and five solar batteries to effectively power a house. Depending on your energy needs, you can connect several batteries in a series or parallel battery bank with interconnecting cables. Solar batteries are stackable, meaning that you can install multiple batteries with your solar storage system to reach the right capacity for you.
Why are solar batteries so expensive?
Solar panels are expensive because of the materials required to produce them. Prices are expected to drop as solar technology advances.
How long do solar batteries last?
Generally, fully charged solar batteries should power your home for 12 to 24 hours. Variables like your household energy consumption, the capacity of your batteries and whether you’re connected to an electrical grid determine exactly how your long solar batteries last. A solar battery’s lifespan can be anywhere between five and 15 years. You can extend a battery’s life with proper maintenance and by protecting it from extreme temperatures.
What is a battery bank?
A battery bank is a collection of batteries that are connected. A battery bank allows for more power storage than you get from a single battery.
Are solar batteries worth it?
Solar batteries are an energy-efficient way to generate backup power. However, for those who just want to go off the grid, diesel generators might be cheaper in the short term. Solar batteries make a lot of sense if you live in an area where utilities are unreliable or if you want to go off the grid while using renewable energy. Solar batteries store excess energy produced by your solar energy system so that you can tap into it whenever your panels don’t produce enough electricity.
» READ MORE: Are solar panels worth it?
