Enphase Batteries vs. Tesla Powerwall

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Estimated reading time: 8 minutes

If you're tired of dealing with power outages or if you feel like expensive peak grid electricity prices are eating away at your wallet, you could benefit from solar energy storage.

Even if you're someone who is new to solar technology, you've likely heard of Tesla. Their electric vehicles and other cutting-edge products frequently find their way to headlines and day-to-day conversations.

Tesla's energy storage device, the Powerwall, has been so popular that Tesla has had to implement waitlists and adjust their supply to meet the public's high demand. 

Tesla Powerwall 2

Outside of its popularity, however, is the Powerwall really all that? While it has several impressive features, it is important to compare its capabilities with those of other available energy storage options.

In this article, we will compare the Tesla Powerwall and Enphase Encharge batteries so that you can make informed decisions if you are interested in energy storage

We will start by going over the basics of both the Encharge battery and the Powerwall, and then we’ll evaluate the products based on pricing, efficiency, depth of discharge, battery type, warranties, and monitoring. 

Enphase vs. Tesla

Important Energy Storage Terms

Energy/storage capacity: the amount of electricity a battery can store 

Power: the amount of energy that can be pulled from the battery (high power ratings can supply more energy but burn through the storage capacity faster)

  • Batteries with a higher power rating are capable of powering heavy-duty appliances or many appliances at once, while high-capacity batteries can store more total energy and run your appliances for longer periods of time without needing to recharge.
  • To help you visualize power and capacity, let’s compare a battery to a water pipe. The energy capacity is like the amount of water that will push through the pipe, and battery power is like the size of the pipe itself. While a larger pipe allows more water to flow through, it also depletes the water source more quickly, so various levels of battery power and capacity can work well depending on your appliances and energy needs. 

Cycle: when a battery has been drained and recharged

Round-Trip Efficiency (RTE): how much energy your battery can provide your household compared to how much you can store 

Depth of Discharge (DoD): the percentage of a battery's energy that has been discharged relative to the overall capacity of the battery

Solar Energy Storage

Enphase Encharge Overview

Enphase is known for its reliable solar equipment. For the past 10 years, the company has been the market leader in microinverter technology. When it comes to energy storage, Enphase offers two Encharge batteries:

Battery Type

Storage capacity per battery

Continuous power rating

Encharge 3

3.36 kWh 

1.28 kW

Encharge 10

10.8 kWh

3.84 kW


It is important to note that the Enphase Encharge is only compatible with the M and IQ series Enphase microinverters. This means that you won’t be able to install an Encharge battery if you have a pre-existing inverter system unless it is Enphase. 

They are also modular, so multiple units can be used together to increase your home's storage. Enphase allows you to add a maximum of 40 units per installation.

The Encharge 10 is 43.13 in x 26.14 in x 112.56 in, and the Encharge 3 is 14.45 in x 26.14 in x 112.56 in.

Tesla Powerwall Overview

In April 2021, Tesla CEO Elon Musk announced that the Powerwall is now bundled with other Tesla solar products, meaning that Tesla solar panels and the Powerwall cannot be purchased independently. The Powerwall comes in one size, with 13.5 kWh storage capacity and a 5 kW continuous power rating.

Powerwalls are stackable, and you can have 10 stacked in total. A Powerwall's dimensions are 45.3 in × 29.6 in × 5.75 in. 

Tesla Powerwall

Pricing 

The Powerwall costs $7,000 on its own, and its supporting hardware costs come to about $1,000. For a full-system installation, EnergySage estimates that the Tesla Powerwall will cost between $9,600 and $15,600, including the equipment and installation costs.  

Since Powerwall purchases are now bundled with solar panels, if you already have panels and are only looking for energy storage, you would have to get a whole new system if you want a Powerwall. 

At Project Solar, we offer both the Encharge 3 and 10. We do not recommend batteries for every solar build, especially if you have an advantageous net metering program in your area. However, with Enphase’s recent price drop, batteries have become much more realistic for solar customers.

If you install battery storage along with your Project Solar system, you'll need an Enphase Smart Switch which allows your system to temporarily disconnect from the grid when you need to pull from your battery storage during a power outage. 

Since maintenance workers need to work on the electrical lines during a power outage, your panels will shut off when they sense the power has gone down for safety reasons, but the Smart Switch and battery storage allow you to maintain power in your home.

At Project Solar, our customers can either choose do-it-yourself installation or full-service. The following prices could possibly increase depending on your jurisdiction or based on permitting costs.

Important Note: To calculate your total price, remember that you will need to add the Smart Switch price to the battery price. For example, if you purchase an Encharge 10 and it is your first Enphase battery, it would cost $12,500 fully installed because you need the Smart Switch as well.

Product

DIY Installation

Full-Service Installation

Encharge 10 

$7,002

$8,200

Encharge 3 

$2,334

$3,500

Smart Switch

$1,350

$4,300

Round-Trip Efficiency

“Efficiency” is a word that is often thrown around but rarely understood—especially when it comes to solar.

For the Powerwall and Encharge batteries, we will be looking at round-trip efficiency (RTE). As we discussed earlier, RTE is how much energy your battery can provide your household compared to how much you can store. This means that the less a battery loses electricity when charging and discharging, the higher its RTE will be. 

The Tesla Powerwall guarantees that 90% of every 10 kWh of electricity stored in the battery, you'll be able to use 9 kWh. Enphase's battery has a higher RTE of 96%, but when the electricity goes through the microinverters, the efficiency is 89%.

Solar Energy Storage

Depth of Discharge

Both the Enphase Encharge and the Tesla Powerwall have 100% DoD, meaning that both devices allow you to use all of its energy before it needs to be charged again. Although this attribute does not distinguish one device above the other, 100% DoD is encouraging evidence of both devices’ quality. 

Customer Support

While Tesla is infamous for its complicated customer service process, Enphase has proven that they have top-tier customer support. Enphase has been known to even detect system issues and proactively send replacement parts to the customer. When making a warranty claim or reaching out for assistance with an Encharge battery, you can depend on Enphase's active support.

Enphase Customer Support

Charging

In an off-grid event, the Tesla Powerwall has some charging limitations. The Powerwall has an AC-coupled battery, and it doesn't have the ability to carefully regulate solar power when the grid is down.

For example, if there is a power outage when your Powerwall’s capacity is full, your panels are still generating solar energy, and your home is not consuming what is being produced, the battery and entire solar system will turn off for 5 minutes, drain, and then turn back on. This will clearly waste solar power, and as the battery recharges, it can turn off again for 5 minutes if it completely charges again.

Not only is this inconvenient and wasteful, this weakness would also take a toll on the life of your battery. An event like this would require multiple cycles by draining and charging the battery again and again. 

The Enphase Encharge batteries, on the other hand, are still able to regulate solar output to fit the needs of a home when the grid has shut down. The battery will not become overwhelmed and need to shut down like the Powerwall during an outage.

Time-of-use battery usage is much more active than just back-up usage, but it is a common motivator for solar owners to purchase energy storage. Time-of-use battery usage can help the owner avoid their utility's expensive peak energy prices. With its current capabilities, the Powerwall would only be able to do 2,800 cycles with time-of-use battery usage. 

Solar Energy Back-up During a Power Outage

Types of Batteries

Tesla batteries are lithium nickel manganese cobalt oxide (NMC) batteries. This is one of the most common lithium-ion battery technologies, and Enphase uses lithium-iron-phosphate (LFP) batteries. Enphase's batteries are the first and only batteries to be tested under UL's test method for thermal runaway fire propagation, earning UL9540A certification, which speaks for the quality and safety of the Encharge batteries. 

NMC batteries, like Tesla's, are known for getting the most storage out of the least space, but Enphase's LFP battery is recognized as the more durable choice because it can last through more cycles, and it's a safer battery (EnergySage).

Warranty

The Powerwall has a 10-year warranty, and the Enphase Encharge has a 10-year or 4,000-cycle warranty. Both Powerwall and Enphase warranties guarantee that the energy storage units will maintain at least 70% of their capacity to store and discharge energy during the 10-year warranty.

However, the fact that the Powerwall has a flat 10-year warranty without a cycle warranty is concerning. Although the Tesla's cycle warranty is now "unlimited," the Powerwall equipment hasn't been adjusted to go through more cycles than it has before. 

Like mentioned earlier, the Powerwall would only be able to do 2,800 cycles with time-of-use battery usage, so Enphase's 4,000 cycle guarantee is much more encouraging. 

For more of the specifics of each warranty, check out the Enphase Encharge Battery Limited Warranty and the Tesla Powerwall Limited Warranty.

Monitoring

Both the Powerwall and the Encharge can be monitored through the Tesla App and the MyEnlighten App. Monitoring your system and storage through these apps will allow you to analyze your consumption, understand how you utilize your power, optimize your usage, and lower your grid consumption. 

Enphase Enlighten app

In Closing

Whether you are interested in time-of-use or back-up storage, Enphase offers the best-performing, most reliable solar battery on the market right now.  

Tesla has some exciting renewable energy solutions, but when you compare the Powerwall to Enphase Encharge batteries, it is evident that the Encharge 10 and 3 are quality energy storage devices that may better suit your energy storage needs than the Powerwall.