Backing It Up: Which Energy-Storage Solution Should You Choose?

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    You’ve decided on a solar array for your house, but you’re also worried about backup power. Researching storage batteries can be exhausting, so we decided to highlight two of the best-performing storage solutions on the market: the Enphase IQ Battery 10T and Tesla’s Powerwall 2. Both high-capacity storage batteries can power your home if you lose access to the grid. Let’s get into the details.

    Basics

    Enphase IQ Battery 10T

    The Enphase IQ Battery 10T is a fully integrated AC battery system made-up of three battery storage units. Fully charged, it will give you 10.08 kWh of power, which can power your house for about eight hours under normal conditions. That same 10 kWh can run your home for up to twenty-four hours if you stick to the essentials–phones, computers, WiFi, refrigerator, and a few lights.

    Tesla Powerwall 2

    Tesla’s Powerwall 2 has more storage capacity with 13.5 kWh, which translates to around ten hours of normal use, or twenty-eight hours of charge if you stick to the abovementioned basics.

    Integrating either battery with solar will recharge the battery when the sun is shining, allowing for much longer run times. Here in the Pacific Northwest, with two battery units paired together, an average home with solar could run from June to September continuously! It’s the dark winter months where run times are shorter.

    The Enphase IQ Battery system can only be paired with Enphase IQ micro inverters. Whereas, the Tesla Powerwall 2 is solar agnostic and can pair with any existing solar system.

    Both solutions are easy to control using proprietary apps:

    tesla powerwall app
    enphase battery app

    The Enphase app gives you aggregate monitoring of your battery and solar system along with granular monitoring of each individual solar panel. The Tesla Powerwall app on the other hand, only provides aggregate numbers for solar production, battery capacity, power taken from the grid, and onsite consumption.

    Specifications

    Round Trip Efficiency (RTE)

    RTE is the amount of power that the battery can store and then return for use at a later time. The more efficient a system is, the more energy you will have on hand if a power outage occurs. 

    The Enphase IQ battery system advertises an AC efficiency of 89% while the Tesla’s Powerwall lists a 90% minimum rating, essentially parity.

    Battery Types and Life

    The Enphase IQ 10T is a lithium-iron-phosphate battery. The battery is naturally cooling, so it doesn’t need a fan. The Tesla Powerwall 2 has a rechargeable lithium-ion nickel-manganese-cobalt battery pack and uses an internal, hermetically sealed heating and cooling system. 

    Tesla and Enphase provide a warranty stating that their batteries will retain at least 70 percent battery power in ten years. The difference is in the details. Enphase batteries can deliver a surge of peak power for ten seconds, and they should be able to do this at least 7,300 times during their lifetime. The Powerwall advertises unlimited operating cycles in its lifetime.

    Operating Conditions

    The Enphase IQ Battery can operate between 5-131 degrees Fahrenheit without condensation, and it is rated for altitudes up to 8,200 feet above sea level.

    The Powerwall is water- and dust-resistant, and it even works in 100% condensing humidity, and it can withstand temperatures between -4 degrees and 122 degrees Fahrenheit. It is rated for altitudes up to 9,800 feet.

    Warranty

    Enphase offers a ten-year warranty with an option to extend the warranty by five years, but with the caveat that the warranty will end once the battery reaches 7,300 full discharge cycles. The Tesla Powerwall 2 also has a ten-year warranty, but the RTE efficiency may decrease over its lifetime.

    Benefits to Multiple Batteries

    There are two characteristics that should be taken into consideration when sizing a battery system. One is the capacity of the battery: how long it can run (measured in kWh). The other is the power output of the battery: how many or how large of loads it can run at once (measured in kW). If you only install one battery, you’re limited in capacity, but more importantly limited in power output. One Enphase IQ Battery or Tesla Powerwall can only run loads such as lights, outlets, and maybe a refrigerator. Larger loads such as AC units, clothing dryers, pumps, and ovens will need to be isolated from the battery entirely.

    Pairing multiple batteries together doubles or triples your battery capacity while also also increasing your power output. For example, if you install two Tesla Powerwalls, your capacity doubles to 27 kWh (roughly twenty hours of run time) and your power output doubles. This means you can run bigger loads such as AC units and pumps. In fact, if you have three or more batteries installed, you can run multiple large loads at once. 

    One additional note, the Tesla Powerwall 2 can stack up to ten battery units on a single 200 amp service for a total capacity of 135 kWh. The Enphase IQ Battery system is currently limited to three batteries with a max capacity of 30 kWh.

    Price

    You can expect to pay about $19,000 for an Enphase IQ Battery 10T, which includes installation, permitting, and design. A single Powerwall battery costs approximately $21,000 with installation, permitting, and design. These prices are before government incentives. You can request a free estimate for either battery on our website and see what the net cost would be after incentives

    Adding additional batteries comes at an economy of sale. A single battery installation includes fixed costs such as permits, design, project management, and the installation of the automatic transfer switch, which is the bulk of the labor. A single battery will also require that you isolate larger loads. That said, each additional battery comes at a discount. Primarily because the fixed costs have already been covered and we no longer have to isolate larger loads. T

    he base price for one Tesla Powerwall 2 is roughly $21,000, however, adding a second battery comes at quite a discount with an installed cost of $30,000 (before incentives). A third Powerwall 2 would be roughly $41,000. Adding a second battery eliminates the need to isolate out larger loads.  This allows for a whole home backup, reducing the labor cost when you move from just one battery to two.

    Price Breakdown

    The below costs may vary depending on the application and layout of your home.

    enphase battery vs tesla powerwall price breakdown 2023

    Final Thoughts

    The Enphase IQ Battery and the Tesla Powerwall 2 are two of the best solar batteries on the market. Either battery will help you maximize your solar-power system and give you peace of mind during a power outage. A lot depends on your specific application and your energy storage needs

    If you’re still undecided, request a free battery quote, and we will help you choose which battery is best for you.

    Enphase IQ Battery vs. Tesla Powerwall 2 Quick Reference Guide

    This table compares a few key specs between the Enphase IQ Battery and the Tesla Powerwall.

    Enphase IQ Battery vs Tesla Powerwall 2 Quick Reference Chart

    Final Note

    Both the Enphase IQ Battery and the Tesla Powerwall 2 are AC coupled systems.  If you’re interested in a DC coupled system, or want to understand the difference, check out our article comparing the Tesla Powerwall 2 with the Powerwall +.

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