• Dakota Brouillard

Understanding the Technology Behind Tesla's PowerWall

Updated: Jan 20

If you’ve been considering adding a Tesla Powerwall to your home, it’s important to understand what kind of amp-hours it’s capable of. When it comes to batteries, amp hours give you some insight into the capabilities of them at a glance.

So what kind amp hours are we talking about when it comes to Tesla’s Powerwall? The Tesla Powerwall is rated in kWh or kilowatt-amp hours; 13.5 kWh to be exact. With this kind of available amperage, you’ll be able to power nearly all your home electronics and then some.

While it’s essential to understand amp-hours' definition, it’s even more important to understand what it actually means and how it applies to Tesla’s Powerwall. Let’s take a more in-depth look at amp-hour ratings and how they can be better understood as a defining factor for battery production.

So, What Are Amp Hours?

Amp Hours are simply the measurement used to gauge a battery’s effectiveness; Better put, it’s a way to rate a battery’s ability to produce electricity, based on the capable amperage per exact hour.

Standard household batteries will typically be rated in mAh or milliamp hours due to their low overall power output.

Kilowatts-amp hours used to determine total usable capacity should not be confused with the batteries' power rating or total usable capacity, measure in kilowatts. Think about a battery as a 2-liter bottle of soda. The 2 liters of fluid the vessel holds can be compared to the power measurement of the battery, while the speed at which it pours from the bottle is more comparable to a battery’s total amp-hours.

That being said, a battery’s total power decides what size electronics you can power in terms of total consumption, while amp hours are how long those electronics can be powered. Due to the sheer size of the Tesla Powerwall in both total power and amp hours, you’ll be able to power several electrical utilities for a longer period of time.

Tesla Powerwall: Total Power and Amp Hours

When it comes to total power and output, a single Tesla Powerwall has the ability to retain 5 kW of total power and 13.5 kWh of actual usable capacity. Consider your standard car battery, what it powers, and the size to put that into a visual representation. The ratings for a standard car battery, on average, have a usable capacity of about 70 amp-hours, significantly less than the Tesla Powerwall in question.

After a quick conversion, the Tesla Powerwall, assuming a 12-volt circuit, has a total of 1,125 ah. So, if you can easily understand the kind of load your car battery is under, the Tesla Powerwall is capable of over 16 times more draw under the same circumstances.

It’s important to mention that the size of Tesla’s battery wall is considerably larger than your average car battery, so it’s expected to have a significantly larger bank of usable power.

To better understand how this works, consider your standard LED light using about 1.2 watts of total power, which on a 12v circuit means 0.1 amps are being used per hour of the battery wall’s available 1,125ah.

Is the Tesla Powerwall Capable of Powering My Needs?

Every person and situation is different since we all use electricity differently. If you understand your general electrical consumption (you can reference your current electrical bill), you can get a better idea of whether or not a single battery wall will fit your electrical needs.

As our world becomes more connected and more powered by electricity, Tesla has future-proofed their Powerwall. Tesla Powerwalls can be run in series, meaning they even fit larger commercial applications.

You can essentially create a multi-unit Tesla Powerwall system that’s perfect for your home, matching your total energy usage regardless of how large. Tesla achieves this power output and functionality by abandoning traditional lead and acid-based batteries used in your standard 12v based vehicle situations and opts for a Lithium-Ion solution, giving owners access to more power, faster.

Lead Acid Batteries vs. Lithium-Ion Batteries

To further understand the capabilities of Tesla’s Powerwall, understanding the functionality of the batteries used can be a helpful reference. As previously discussed, Tesla utilizes lithium-ion batteries instead of traditional lead and acid-based ones, allowing for more, constant power. Let’s take a look at the two kinds of batteries to understand better how Tesla achieves such a high amp-hour output on their Powerwalls.

Pros and Cons of Acid and Lead-Based Batteries

Lead acid-based batteries have been around for a long time and can still be found in most modern vehicles. They perform well in cold weather, and their considerably high power-to-weight ratio makes them perfect for the high surge currents required of starters found in most vehicles. While they remain relatively inexpensive, lead-acid batteries come with their own setbacks that prevent them from being the best option available.

By default, most lead-acid batteries have a low energy-to-weight and energy-to-volume ratio, meaning they’re considerably heavy for how much overall output they’re capable of. Due to their design, they require replacement fairly often, which is why they’re such an inexpensive option. While battery technology continues to improve, the lead-acid battery will always serve a purpose for its ability to discharge quickly.

Pros and Cons of Lithium-Ion Batteries

In general, Lithium-Ion batteries have a considerably longer shelf life in terms of how long they remain effective. They require much less maintenance than their acid lead counterparts and are significantly lighter as well. Due to their long life-span, it’s been long discussed that the battery market will eventually steer towards a Lithium-Ion dominated one.

Lithium-Ion batteries are not without fault, however. Take, for instance, their inability to take charge in temperatures under 32 degrees Fahrenheit. This severely limits applications in environments that see cold winters and can make it near impossible to utilize in constantly cold climates. While lithium-ion batteries' production cost continues to trend downward, they currently carry a much higher cost than other battery types.

How it Translates to Tesla’s Powerwall

Now that you understand the difference between these two types of batteries note that the Tesla Powerwall is equipped with a lithium-ion battery pack connected to an AC converter. The converter transforms the DC typically used in an automotive application into the AC typically found in homes.

Tesla markets their Powerwall with usable capacity at the forefront, or the 13.5 kWh previously mentioned. Since Tesla uses lithium-ion batteries, the Powerwall features what is known as a 100% depth of Discharge (DoD), meaning all of the 13.5 kWh can be accessed by the homeowner if needed.

Unlike similarly rated lead-acid batteries, the lithium-ion batteries found in Tesla’s Powerwall lend it to incredible power storage in a relatively small-sized package. Coupled with the batteries' long shelf life and Tesla’s “over-the-air” update system, you can rest assured your Powerwall will stand the test of time.

Applying Your Understanding of Amp Hours to Real-World Application

To summarize so far, amp hours are essentially the rating for how much power can be utilized by your electrical needs. Knowing how to describe the effectiveness of a battery is only a small part of the battle when applying it to understanding the worth of a battery overall.

Now that you have a solid understanding of what those amp hours actually are and how they apply to Tesla’s Powerwall, how do we go on to determine the quality of these batteries? The easiest way to determine this is to see how effective Tesla’s Powerwall is in everyday application. Let’s take a look!

Can Tesla’s Powerwall Power My Home?

Due to its rechargeable nature and massive storage bank capability for power, the Tesla Powerwall is more than capable of powering your home. Depending on your average power consumption, it can power your home in the event of a power outage or of replacing dependency on the grid.

Due to their low maintenance, plenty of people all across the country are choosing Tesla’s Powerwall for all of their electrical needs. Do yourself a favor and research your local area to understand better whether the Powerwall can be a solid option for you.

How Does the Tesla Powerwall Receive Its Power?

To charge the batteries, your Tesla Powerwall will require some sort of electricity “input.” While the most common options used to charge the Powerwall consist of solar panels or Tesla’s solar roof, it can also be connected to the grid to receive storage power. In most situations, people opt to go the solar route, but it’s important to understand it’s not your only option.

Keep in mind your power source is a determining factor of your system's overall efficiency and something you should keep in the back of your head as we continue.

If I Choose to Go Solar, How Many Panels Will I Need?

Many factors, including total sun exposure and your solar panels' effectiveness, have some determination on your solar output. However, some basic math can give you a general idea of how many solar panels you’ll need to fully charge your Tesla Powerwall in a day.

Assuming your panels are capable of drawing in 300 watts of power, you’ll need right around 18 total medium size solar panels to effectively keep your Powerwall charged.

Depending on your power usage, you may be better off going with a solar roof option. Check with local professionals first to see if these are options that would work for your situation.

Does Tesla’s Powerwall Have Enough Power to Get My House Off the Grid?

Due to its massive storage capacity, the Tesla Powerwall is fully capable of supplying you with all of your electrical needs. Keep in mind; they are only effective as their input. To get your home off the grid, you’ll need a significant amount of total solar input to keep your Powerwall charged. Plenty of homeowners have gone this route, and if you search the web, you’re sure to find some examples.

In summary, yes, Tesla’s Powerwall more than likely has enough power to take your house off the grid, but it’s important to check with local professionals to see how it can be best applied to your home and situation.

Can I Use My Generator to Power My Tesla Powerwall?

Unfortunately, Tesla Powerwalls are typically installed to put the unit between the home and the power grid. While there are obviously some standalone situations, it should be considered, in general, that you’ll be unable to charge your Powerwall with your generator.

Essentially, to charge your Tesla Powerwall with a generator, your installation will not be standard and will more than likely cost significantly more. It’s best to consult with a professional in your area to get more details on the concept.

Better Understanding How the AC/DC Conversion Impacts Amp Hours

The Tesla Powerwall is equipped with an AC/DC converter that turns the DC generated power within the Powerwall into an AC form usable within your home. This conversion comes with some asterisks that are important to consider to best understand the capability of available amp-hours.

Tesla offers two versions of their Powerwall, one with an inverter included and one without. Each one is meant to fit a specific need for power and best suits particular use styles. Let’s take a look at those two different options and the applications for both.

Tesla Powerwall with Inverter Included

Since the inverter is converting the DC power to AC power, some power loss comes with this. When it comes to the total amount of average power loss during conversion, the consensus is about 10% total, which is a considerable amount.

Basically, in a standard inverter setup where the home is connected to the grid, the power used is converted twice. It’s converted once from the AC inflow to the battery storage center, DC, and again back to AC to be used by the household. According to Tesla, their system's total roundtrip efficiency is about 92%, which isn’t too bad considering the power is being converted twice.

With the AC version, you can export unused power back into the electrical grid, meaning you’ll get paid for your return depending on your state and the area you live in. What’s better than a power management system that has the ability to pay for itself?

Tesla Powerwall without Inverter Included

While there is technically still conversion going on here, there’s considerably less happening. In systems where the primary source of power for your Tesla Powerwall is coming from solar production, solar panels produce DC power, which is exactly what the Powerwall needs. It is then converted once upon delivery into the appliances and electronics being powered within the home.

This option is great for people who utilize solar during the day, and any overcharge goes into the Powerwall for night use. Basically, you power your electrical needs in the day with solar, and any overcharge goes into the battery bank. Then, when the sun goes down, you have access to your previously stored energy.

With less power loss, efficiency overall is increased, meaning you can get the most out of your Powerwall by pairing it with a solid solar setup. The whole setup should essentially pay for itself with just the savings you’ll get from spending money on electricity.

Due to its maintenance-free (for the most part) approach and over-the-air updates, you’ll be a power generating, independent machine in no time!

Now You Understand: Amp Hours and What They Mean for Tesla’s Powerwall

As technology continues to carve its path, it’s fair to state that homes everywhere will continue to reduce their dependency on our power grid at large. As more consumers look into increasing their home’s efficiency, understanding the battery market terminology can make you a more informed customer overall.

Amp-hours can be defined as more than just a power output rating for a battery. When you combine this rating with external forces, you get a better battery rating understanding. Many outside influences affect total amp hours; knowing what battery best fits the situation is a crucial piece.

From how you get your power to charge the batteries to understanding the impact power conversion has on overall efficiency, there’s more to it than just a measurement. You want a battery that performs under stress and external forces, not just one with good numbers on paper.

While Tesla’s Powerwall is a top player in the power storage game on the battery market, making sure you get the right option for your conditions and usage is just as important. Make sure you understand the outside forces that matter more than your total amp hours, and you’ll walk away from a better-educated consumer!