Best Home Battery Storage Options: 2021 Guide

Be wary of marketing statements about how many days of power the battery offers, as that is entirely dependent on how much energy your home requires so that it can vary widely. The key to sizing is understanding how much power you will be using/drawing from the battery. Some homeowners see batteries to get off the grid, but that’s an unlikely scenario, at least with lithium batteries. These batteries typically only hold enough energy to power an average American home for hours, not days.

Connecting to the grid, however, isn’t always the best option either. Your solar panels will be giving back to the grid during the daylight hours when most of us are at work. In addition, many electric companies charge premium prices during peak hours, usually during the daytime and early evening. This means that the electricity from the grid that you do use overnight will most likely be charged to you at a lower rate if you have a time of use billing.

Tesla’s Powerwall 2

Each Tesla Powerwall 2.0 lithium-ion battery provides 13.5 kWh of electricity and costs $6,700 each, plus $1,100 for supporting hardware. So, that equates to $578 per kWh. In addition, the Tesla website has a tool that lets you properly size your system based on your home's size. The tool even accounts for the critical energy-intensive appliances you choose to support.

Tesla Powerwall 2 Specs

• 7kW peak / 5kW continuous
• Floor or wall-mounted rechargeable lithium-ion battery options with liquid thermal control
• Dimensions: 45.3" x 29.6" x 5.75"
• Weight: 114kg
• Recommending Operating Temperature: -4°F to 122°F / -20°C to 50°C
• Scale up to 10 Powerwall's
• Sleek, wall-mounted design installed indoors or out
• 10 Year Warranty
• Cloud-based web and mobile control and monitoring

Pika Energy Harbor

Pika Energy designs a wide variety of batteries; the Harbor pairs directly with the inverter, is a smart lithium-ion battery, and ranges in size from 10.1 to 20.3 kWh. The 10.1 kWh system costs $13,500, coming in at $1,336 per kWh.

Pike Energy Harbor Specs

• Total capacity, Harbor 3 = 10.1kWh up to Harbor 6 20.3kWh
• Up to 10kW of instantaneous power
• DC Current: Input/Output: 24A
• The DC-coupled design eliminates lossy power conversions
• Recommending Operating Temperature: 54-86°F
• 10 Year Warranty

Sonnen Eco

The Sonnen Eco Batterie, based in Germany, is a lithium ferrous phosphate battery; its smallest size starts at 4 kWh and costs $9,950—coming in at almost $2,500 per kWh. If you size it up to 10 kWh, the price tag is $16,750, which drops the per kWh price to $1,675 per kWh—still quite a premium over the competition. Why? It includes an inverter and smart energy management software, differentiating itself as a more fully integrated system.

Sonnen Eco Specs

• Complete storage system, everything included and ready to connect
• Sonnen eco output: 2.5 – 3.3 kW
• 5 kWh – 15 kWh storage capacity
• Expandable in steps of 2.5 kWh
• 10,000 charge cycles
• 10 Year Warranty

Panasonic 11.4 kWh EverVolt

The Panasonic EverVolt enables seamless installation with new and existing solar panel systems or generators. The EverVolt app allows you to manage consumption, backup power, net metering, charge/discharger, and more in real-time. EverVolt's pre-programmed Time-Of-Use (TOU) helps you manage energy use and costs. EverVolt can is available in several sizes ranging from 5.7 kWh for $12,705 to 17.1 kWh for $19,055. The Panasonic EverVolt is the mid-tier offering from Panasonic that costs $15,880.00. The warranty guarantees at least 60% minimum capacity at the end of the warranty period.

Panasonic 11.4 kWh EverVolt Specs

• 13.5 kWh total energy
• 11.4 kWh usable energy
• 4.8 kW continuous battery output power
• 5.5 kW maximum continuous power
• 84% / 89% round-trip efficiency
• 6 hours of backup capability
• Recommending Operating Temperature (charge): 41°F to 131°F [5°C to 55°C]
• UL certified
• 10 Year Warranty

Nissan XStorage

The auto manufacturing giant Nissan has a solar backup battery option called the Nissan XStorage. This battery comes in three different sizes. The 4.2 kWh system costs $3,700, while the broadest choice of 9.6 kWh costs just under $10,000. Many of these battery options are factory refurbished electrical vehicle batteries giving a useful second life to the millions of EV batteries produced in the coming years. 

Nissan XStorage Specs

• Power range from 3.6 kW to 6 kW
• Nominal capacity from 4.2 kWh to 10.08 kWh
• Can be wall or floor mounted
• 5 to 10-year warranty depending on model
• Stocks both grid and renewable energy during the day

Enphase Encharge 10

The Enphase Enchage is an all-in-one AC-coupled storage system, a Lithium iron phosphate (LFP) costing $10,649.97 without installation. Enphase offers a smaller Encharge 3 for $3,979.97, which may be adequate depending on your needs. The Encharge 10 offers output (AC) at 240 VAC, 3.84 kVA AC continuous power, and is rated for 16 A of output current. Its touted benefit is that it works seamlessly with Enphase micro-inverters; because of its small size, it’s not intended to help homeowners go off-grid.

Enphase Encharge 10 Specs

• 10.08 kWh total usable energy capacity
• Twelve embedded grid-forming microinverters with 3.84 kW Ten-year limited warranty
• Grid-forming capability for backup operation
• Mobile app-based monitoring and control
• Passive cooling (no moving parts/fans)
• Lithium iron phosphate (LFP) chemistry for maximum safety and longevity
• Ten-year limited warranty

Solar Rebates and Incentives

Incentives exist for homeowners who want to invest in battery technology, often in conjunction with solar installations. A 26 percent tax credit exists for solar battery buyers, too, though to get the entire credit, the energy stored must come entirely from the sun—and the system must be in place by the end of 2020. According to EnergySage, the average solar shopper saves at least $5,000 thanks to the solar tax credit. In 2021, the tax credit drops to 22% before expiring in 2022.

As the federal government’s incentive expires, some states consider tax credits for batteries, among them California, Maryland, and Massachusetts. Keep your eye on your local state legislature as a new tax credit for solar storage may be on the way. You can use our Find Rebates tool to look for solar rebates in your area.