Buyers Guide to Tesla Powerwall Vs. Enphase Battery


Buyers Guide to Tesla Powerwall Vs. Enphase Battery

Over the past decade, solar power has come into its own as a viable and trendy alternative or supplement to household energy needs. However, to take full advantage of solar energy and energy conservation, an energy storage device (aka a battery) is essential.

While solar energy is not a new idea by any means, it has come into its own with the emergence of Tesla. The addition of Tesla’s Powerwall has pushed Tesla to the forefront of the solar energy and home battery market. The release of the Enphase Encharge system hopes to challenge that. Read on to find out more about the competing Tesla Powerwall and Enphase Encharge batteries.

Buying a Home Battery

Whether or not you have a solar system in your home or not, having a home battery is a good idea for several reasons.

  • Enables you to offset peak energy hours.
  • Provides energy during power outages.
  • Allows you to store solar energy.

For many, the main reason to buy a home battery is to take advantage of net energy savings. In short, your home battery is connected to the grid and charges during the “off-hours” or non-peak hours when energy prices are lower. This stored energy is used to offset energy usage during peak energy hours when energy costs are higher.

Another important consideration for purchasing a home battery is the capability to continue to use energy and power home appliances during power outages. With these top-of-the-line offerings, you should not notice any disruption in the grid, enabling you to proceed with your day as usual.

Finally, a home battery allows you to take full advantage of a solar array. Solar panels produce energy so long as the sun shines. Paired with home batteries, excess solar energy is stored and used at night. Furthermore, without a home battery, solar panels will not work during a power outage (for the most part).

While all home batteries on the market should accomplish similar operations for your home, narrowing down your choice between the Powerwall and the Encharge takes more nuance.

Comparing the Powerwall 2 and the Encharge

A glaring difference between the Tesla Powerwall and the Enphase Encharge is the relatively recent debut of the Encharge. While the Powerwall is by no means ancient (and thereby tried and true), it does have the advantage of being on its second generation. This seniority allows the Powerwall a certain pedigree and a large user base compared to the new Encharge.’

However, there are other factors on which the two batteries can compete.

  • Cost
  • Warranty
  • Size (capacity and power)
  • Efficiency

Without a proven track record for either offering, you will have to look at the various aspects of each product and let them speak for themselves.

Cost

The cost should not be the main determining factor when selecting a home battery. After all, a more expensive battery may save you money in the long run. However, the cost is still an important consideration, and all things being equal, a deciding factor.

These costs include installation and supporting hardware as Tesla does not allow DIY installation.

Tesla Powerwall 2 Cost

Since its start, Tesla has had a significant impact on the solar and energy industry. With innovation and unique marketing, Tesla has pushed solar to become more reliable, efficient, and cost-effective. These factors have made it possible for users to purchase top-of-the-line products at a reasonable price.

Pro Tip: Ordering a Tesla Powerwall? Save $100 instantly by using a Tesla referral link from another Tesla owner.

As of today, the Tesla Powerwall costs around $15,000. For home batteries, this price is as low as it gets for this level of quality and reliability. However, it should be noted that the Powerwall is sold in one size with a capacity of 13.3 kWh. This factor reduces scalability (more on that later) and may increase the final cost.

Enphase Encharge Cost

With its newest offering, the Enphase has released what hopes to be a direct competitor to the Tesla Powerwall. Similar to the Powerwall 2 in many aspects, the Encharge differs in that it offers the large home battery Encharge 10 and a smaller Encharge 3.

The Encharge 10 (which is, in fact, three Encharge 3s) costs between $18,000 to $20,000 with a capacity of 10.1 kWh. The smaller Encharge 3 (capacity of 3.36 kWh) comes in at between $6,000 and $8,000.

Conclusion: Cost Comparisons

While on the face, it may seem like an obvious choice (Powerwall’s 13.3 kWh capacity at $15,000 versus Encharge 10’s 10.1 kWh at around $19,000). However, depending on your energy needs, the cost of the Encharge may be cheaper due to scalability. See the table below.

 Tesla Powerwall 2Enphase Encharge 10Enphase Encharge 3
Capacity (kWh)13.310.13.36
Cost ($)~$15,000~$19,000~$7,000

Since the Tesla Powerwall comes in one size, you will have to buy another full Powerwall even if your first Powerwall is just slightly underpowered. If one Powerwall comes even the smallest bit short of fulfilling your energy needs, a second Powerwall is going to add considerable cost to your solar system.

With the Encharge, a smaller Encharge 3 added to the Encharge 10 would fill the additional energy need and save you money.

Warranty

Under normal circumstances, a home battery will charge and discharge once per day (one cycle). Like any battery (think of your car or mobile phone), these cycles deteriorate the battery over time and diminish its capacity to store energy. The warranty guarantees the battery to meet a certain threshold over a given period.

While the warranty may seem like a small thing to consider, it becomes imperative if your battery suddenly malfunctions or fails to meet the energy production rates you expected. To fully understand what is covered, let us look at the fine print.

Tesla Powerwall 2 Warranty

Tesla guarantees the Powerwall 2 to maintain a 70 percent capacity over 10 years under normal usage conditions. For Tesla, these normal conditions constitute one charge and discharge cycle per day. These conditions are usually associated with solar storage and energy backup.

For those who choose to use their Powerwall to take advantage of off-peak energy and solar, multiple cycles a day will cause the battery to deteriorate at a faster rate. In this case, the warranty’s fine print does not guarantee the battery for 10 years but 3,200 cycles instead.

Enphase Encharge Warranty

The Encharge is guaranteed with a 70 percent capacity over 10 years or 4,000 cycle warranty regardless of usage. This simple warranty allows you to use the home battery in several ways without worrying about exceeding the warranty.

Conclusion: Warranty

Both home batteries have a guaranteed warranty of 70 percent capacity over 10 years. However, the difference lies in how they are used.

 Tesla PowerwallEnphase Encharge
Standard Use (Discharge once/day)10 Years 70% Capacity10 Years or 4000 cycles 70% Capacity
Non-Standard Use (Discharge >1/day)3200 cyclesn/a

If you plan to save money by taking advantage of multiple systems (solar and off-peak energy), considering the number of cycles you are likely to go through in 10 years is advisable.

Size (Capacity and Power)

The size of a battery ultimately dictates how much energy you can store and use at any given time. Its power and usable capacity define the size of a battery.

  • Power, measured in kilowatts (kW), is the amount of available energy at a given time.
  • Total power is the maximum power that can be released (usually for a few seconds).
  • Continuous power is the amount of power that can be safely released over a long period.

The battery’s total capacity, which is measured in kilowatt-hours (kWh), indicates the maximum storage capacity of the battery. However, in general, we are interested in the usable capacity, which indicates the maximum energy available in a fully charged battery.

One can think of power and capacity in terms of water running through a pipe. The pipe size correlates to power (larger pipe equals more power), while the amount of water available correlates to the usable capacity. The larger the pipe (higher power), the more water (usable capacity) will flow through it.

In this scenario, a larger pipe can deliver more force (power) but decreases the water supply (usable capacity) rapidly compared to a smaller pipe. Therefore, houses with large appliances that use a lot of power need high power and high capacity.

Tesla Powerwall 2 Size (Capacity and Power)

The Tesla Powerwall clocks in with an impressive usable capacity of 1.3 kWh with 5.0 kW of power.

The Powerwall can put out a peak power of 7.0 kW but only for 10 seconds at a time.

Enphase Encharge Size (Capacity and Power)

The Enphase Encharge 10 falls slightly short of the Powerwall in power and capacity, with a usable capacity of 10.8 kWh and 3.84 kW of power. The smaller Encharge 3 follows up with a usable capacity of 3.36 kWh and 1.28 kW of power.

Both batteries are capable of 10 seconds of peak power of 5.7 and 1.92 kW, respectively.

Conclusion: Size

While it is clear that the Powerwall boasts a larger size than the Enphase Encharge, it is essential to consider your needs when selecting the correct battery for you.

 Tesla Powerwall 2Enphase Encharge 10Enphase Encharge 3
Total Capacity (kWh)14.010.53.36
Usable Capacity (kWh)13.310.083.36
Peak Power (kW)7.05.71.92
Continuous Power (kW)5.03.841.28

If you have a large number of high energy requirements, you may need the increased power of the Powerwall. With its larger usable capacity, the Powerwall will last longer at low power and perform well at high continuous power.

Efficiency

The efficiency of a battery is reflected by three factors:

  • Its depth of discharge
  • Its round trip efficiency
  • Battery degradation over time

The Depth of Discharge (DoD) is a measurement that compares the total amount of energy that a battery discharges relative to its total capacity. When looking at the DoD of a battery, a high DoD translates into a highly efficient and high-quality battery.

The roundtrip efficiency is a measurement that indicates the amount of charge is lost during charging and discharging. Ultimately, this measurement indicates how efficiently a battery can store and release usable energy(or how little is lost). Therefore a higher round trip efficiency suggests a more efficient battery.

Finally, the degradation of a battery is precisely that; the amount the battery degrades over time. Since all batteries are expected to lose a portion of their functionality throughout their life, manufacturers define acceptable degradation over a set period. A battery that meets this criterion is considered to be efficient.

Tesla Powerwall 2 Efficiency

With a DoD of 100 percent, the Tesla Powerwall certainly meets the criteria for efficiency. Combined with a round trip efficiency of 90 percent (10 percent energy lost), the Powerwall is one of the most efficient batteries on the market.

Finally, an expected degradation of 3 percent reflects the high quality of the product.

Enphase Encharge Efficiency

The Encharge (both sizes) also boasts a DoD of 100 percent; however, the round trip efficiency comes in 89 percent. As with the Powerwall, a degradation of 3 percent indicates a high-quality product.

Conclusion: Efficiency

Since the Powerwall and the Encharge display the same metrics, you might think they are equally efficient besides a mere 1 percent difference in round trip efficiency. However, that 1 percent difference translates into an extra 0.1 kWh more output per 10 kWh, which results in a substantial difference over the battery’s lifetime.

 Tesla Powerwall 2Enphase Encharge 10Enphase Encharge 3
Depth of Discharge (%)100100100
Degradation (%)3.03.03.0
Round Trip Efficiency (%)90.089.089.0

When looking at efficiency, it is clear that over the long term, the Tesla Powerwall beats out the Enphase Encharge.

Additional Considerations

If the critical metrics discussed above are not enough, or if you want to be fully informed before making a decision, consider the following battery aspects:

  • Chemistry
  • Thermal Cooling
  • Inverter

These are not always on a consumer’s priority list when comparing home batteries, but they can be important in decision making.

Chemistry

Based on a Lithium Nickle Manganese Cobalt Oxide (NCM) battery, the Tesla Powerwall has a higher than average density and an average power rating. Additionally, the use of cobalt increases the safety of these batteries. The relatively cheap cost of production for NCM makes them a suitable choice.

Unlike the Powerwall, the Encharge batteries are a Lithium Iron Phosphate (LFP) variation. This variation tends to have a high power rating but comparatively low energy density when compared to other lithium-ion variations. The use of iron increases the safety of the unit as they do not overheat and require no additional cooling.

  • Both the Powerwall and the Encharge are considered safe and have extensive safety ratings.
  • The Encharge LFP variation is the safer option as it inherently produces less heat.

Beyond this consideration, the NCM batteries are able to store more energy while the LPF provides more power, so both have their advantages.

Thermal Cooling

Hand in hand with battery chemistry, thermal cooling is essential for the dissipation of heat during battery usage. This cooling is critical during peak and high power usage. While extreme heat dramatically affects the function of batteries and may cause them to fail dramatically, extreme cold can also prevent them from functioning correctly.

With an NCM battery, the Powerwall produces a significant amount of heat. This excess heat is offset by a liquid cooling system unique to the Powerwall. This system allows the Powerwall to operate at high capacity and function in a wide range of temperatures. This ability to offload heat quickly extends the lifespan of the battery.

  • Like other batteries, the Powerwall has an optimal operating temperature range from 32℉ to 86℉ (0℃ to 30℃). However, the liquid cooling system allows the Powerwall to operate in temperatures from -4℉ to 122℉ (-20℃ to 50℃).
  • At low temperatures, the Powerwall can preheat cells in what is called preconditioning, enabling them to function.
  • Like the Powerwall, the Encharge operates best from 32℉ to 86℉ (0℃ to 30℃) but is still able to operate with ambient temperatures reaching from 5℉ to 131℉ (-15℃ to 55℃).

Using the LFP variation of the Lithium-ion battery, the Encharge eliminates the need for a cooling system. In other words, it is adequately cooled through passive cooling, allowing it to be fully enclosed without fans or other moving parts.

Both the liquid cooling system of the Powerwall and the passive cooling of the Encharge provide advantages and disadvantages.

The primary disadvantage of requiring a cooling system is adding a point of failure in the battery. If the cooling system were to fail for any reason, the battery would cease to function until repaired (barring thermal runaway). 

However, the advantage of this system lies in its ability to function at extremely low temperatures. Lithium-ion batteries cannot charge adequately at temperatures below 5℃. The thermal regulation system allows the Powerwall to overcome this obstacle and operate at freezing temperatures.

Inverter

Both the Powerwall and the Encharge home batteries are AC batteries. This requires the use of a battery inverter to convert between AC and DC. The primary reason for this inverter is for use with solar arrays. However, as both units come with inbuilt inverters, they can be used without solar and used for backup.

  • The Powerwall, like many home batteries, functions with a single large inverter. This inverter may be sourced from several companies.
  • Departing from the standard single inverter design, the Encharge is designed with a unique array of 12 micro-inverters that work together.

The unique design of the Encharge unit has a significant advantage and one slight disadvantage compared to the single inverter of the Powerwall.

Using an array of twelve micro-inverters, Enphase ensures that if one goes out, you still have access to the energy stored in the battery while losing merely a fraction of the power (less one inverter allows for 92% of the total power). On the other hand, a failure of the Powerwall inverter results in battery function.

The disadvantage of the micro-inverter design is the difficulty in locating the inverter that has ceased to function. Fortunately, all of the inverters are provided by Enphase, allowing a single company to deal with the issue.

Is It Worth Getting a Tesla Powerwall?

With the competition on the market growing, it is fair to wonder if it is worth it to buy the Tesla Powerwall since it is no longer the only choice. However, this decision is still up to you and your needs.

Based solely on the factors considered above, the Tesla Powerwall is still worth it to purchase. Even with the competition, the Powerwall stands out as a mighty home battery. Its efficiency and power cannot be beaten. However, the Encharge gives the Powerwall a run for its money in other areas, such as options and warranty.

If you want to stick with a tried and true name you trust, it is worth it to buy the Tesla Powerwall. If you want to branch out to a newer product that has fantastic specifications, that does not seem like a bad idea either. Between either of these two home batteries, you cannot go wrong. It all comes down to your size, power, and cost needs.

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Greg

Hi, I'm Greg. My daily driver is a Tesla Model 3 Performance. I've learned a ton about Teslas from hands-on experience and this is the site where I share everything I've learned.

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