Lightning Solar & Electrical

Tesla Powerwall 2 Review: Is It Just An Overpriced Battery?

tesla powerwall

Tesla powerwall 2 is the most popular solar battery that we sell in Australia. Usually it’s between the powerwall and the LG chem, and most people seem to decide on the powerwall. 

Since 2016, powerwalls have blown up quite a bit in Australia. It’s not stopping there either, they are becoming increasingly popular among homeowners. As solar batteries become more affordable, (and they will) there is a bright future ahead for the industry. 

Having installed hundreds of powerwalls in my time, I have quite a lot of experience with Tesla’s product. So I wanted to share my review on the powerwall 2 from an honest personal experience. 

Most of you will want to know if it’s actually any good. I will even go back to the basics and answer, is a Tesla powerwall even worth it

Everyday I get asked, which is the best solar battery in Australia? 
Should I consider getting a solar battery for my home?
Are solar batteries a waste of money?
Should I choose the battery rebate over the solar panel rebate?

Well let’s go into detail and find out if a Tesla powerwall 2 is worth all the hype, or if it’s just an overpriced home battery. 

Table Of Contents

About The Company

Who is Tesla?

Tesla was founded in 2003 by a group of engineers wanting to change the automobile industry for the better. Successfully, they were able to manufacture electric cars that rivaled their competitors in terms of performance and sustainability.

The company then adopted a goal of creating a sustainable energy ecosystem. This resulted in them branching into the home energy storage industry back in 2015, with the first powerwall. With the success from their first home battery, the Tesla powerwall 2 was born.

Do they have offices in Australia?

Yes, Tesla has offices in Australia. This is super important for they can address any issues quickly and effectively. This applies to replacements for warranties, help desk issues or even sales questions. 

Tesla has been in the Australian market from around 2016. They have had multiple changes in their products pricing with regular fluctuations.

What Is Telsa’s Powerwall 2?

Tesla’s powerwall 2 is a solar battery that stores any power that is generated from your solar panels.

It doesn’t need to be added to your solar panels or inverters but instead can be connected up to your main switchboard. This makes it much easier for installation, and means you don’t require forking out for a new hybrid inverter. 

Any energy that is stored in your powerwall, can be used again when you next need it. This could be at night, during the day or even on cloudy days. This stored solar power will allow you to stop pulling energy from the grid and save money. 

It does not generate energy, but instead stores the power from your solar panels. A Tesla powerwall can store up to 13.5kWh of energy which is more than enough to power a home over night, until the sun charges it again. 

With its advanced software the powerwall can show you exactly how much energy is being generated, where it’s going (home, storage or grid) and if there are any issues with your battery or system. 

How Does A Tesla Powerwall 2 Work?

In simple terms, when your solar panels convert sunlight into direct current (DC) electricity it runs through your cables and into your solar inverter. Here it’s converted into alternating current (AC) to get used as power in your home.

Some of this AC current will get fed into your powerwall to be stored. When it reaches your powerwall, it’s converted back into DC current and stored in the lithium-ion battery. An upgrade in the powerwall 2 is that it is also an AC converter.

When it is needed to be used again, your powerwall will convert DC energy back into AC and send it to your home for use. The inverter has a 90% round trip efficiency meaning that 10% of energy gets lost by the time it gets sent back to your home.

diagram that shows how the tesla powerwall 2 works

How Good Is A Tesla Powerwall 2?

I’d happily say that Tesla’s powerwall 2 is one of the best solar batteries on the market today. When you compare it to the powerwall 1, you can really begin to see how far the technology has come. 

AC/DC Built-In Inverter

Having an AC inverter included makes the battery more available for all homeowners without the extra cost of installing a hybrid solar inverter. Not only this but its increased storage capacity of 13.5kWh mean that your home can be powered for longer. However, this doesn’t mean you can just connect the powerwall up to some solar panels, you will need an inverter to get this to work.

Powerwalls Stack-Up

Did you also know that you can stack up powerwalls for extra capacity. Unlike most other batteries, you can link powerwalls together to combine a large storage space for your energy. Although costly, it’s a great way of overcoming a limited capacity if you have a large building or use a lot of power. 

Liquid Cooling System

Additionally, a powerwall 2 comes with a liquid cooling system which sets itself apart from every battery on the market right now. This means it can perform in extreme conditions whether its -20 or +50 degreesC. 

Lithium-Ion Battery

By using Lithium cells in their batteries, Tesla is offering some of the best batteries that are available in the world. The 2170 lithium battery in the powerwall 2 is similar to those that are in the Tesla cars.  

Overall, a Tesla powerwall 2 is a really good solar battery in the day and age. However, I do think that solar batteries still have some improvements to make. One big one is the price, for homeowners it’s hard to justify spending so much on a solar battery. However, if the budget is there then a powerwall is possibly the best option on the market. 

How Long Does Tesla’s Powerwall 2 Last?

The lifetime of a powerwall

Tesla is providing a 10 year product warranty for the powerwall. It states that the product will be free from defects for 10 years following its installation date.

They are also guaranteeing 10 years of “unlimited cycles” of charge, with an energy retion of 70% in 10 years. However, this only applies to self consumption and backup only but they will be the most used consumption settings.

Any other applications or combination of applications (for example a virtual power plant or charging it using energy from the grid) then your warranty is dropped to around 3,200 cycles. This is around 8 years worth if your powerwall completed a charge cycle every day. 

However, this is how long a powerwall will last under its warranty. There is no evidence to suggest it couldn’t last another 10 years after this. Granted, the energy consumption may drop significantly, but the battery will still charge. Therefore, it’s an open answer… The powerwall could last 15-20 years.

Charge cycle of a powerwall

Well, if you are keeping your energy to a minimum by using a few lights, the refrigerator or watching some TV then your battery should last around 12-15 hours. This is quite good when compared to some other batteries. 

However, if you started to use a lot of energy such as air conditioning or a dishwasher then you will drain your powerwall much quicker. By doing this your battery may only last 4-5 hours instead. After that you will need to pull energy from the grid. 

I suppose if you were using next to no energy then you could make your powerwall last even longer, but by the time the sun comes up to charge it again it won’t have made any difference.

How Many Solar Panels Does It Take To Charge A Powerwall?

This is really important to work out before you invest in a tesla powerwall 2. So let me run through how to work this out to see if your system or future system is worth combining with a powerwall. 

Also, just to note that if you have a small solar panel system, it’s really not worth installing a powerwall because of the cost as well as the fact it may struggle to fully charge it

So Tesla has stated that the powerwall has a round efficiency trip of 90%, this means that when energy enters and leaves the battery some is lost. So to fully charge the powerwall 2 you will have to actually generate more than the capacity to cover any energy that is lost. 

The capacity of the powerwall is 13.5kWh, so instead you may have to generate 15.2kWh to cover any energy lost and provide a full charge. 

Taking this into consideration, if your solar system is not generating more than 15kWh in the winter months then you shouldn’t bother investing in a Tesla powerwall 2. You can check this by looking at your energy bills to see how much power is being sent to the grid by your system. 

However, if you are producing more than 15.2kWh and it’s being sent to the grid, then why not look to start to store that power and become independent? You can save even more money, and pay off your system and powerwall within a reasonable time frame. 

Can You Go Off Grid With A Powerwall?

Yes, technically you can go off grid with the Tesla powerwall. Honestly, you might struggle with just 1 powerwall, but if you were to link several together then it would be easy. Again you are going to need a big solar system for this, to ensure you can full charge your powerwalls. 

Personally though, I do not recommend spending all the money it costs to go “off grid”. You can significantly reduce your energy bills and ‘virtually’ go off grid with a decent size solar system and the powerwall (without having to remove your grid connection)

Not only this but going off grid is actually bad for the environment. It essentially means that any of your excess energy generated through solar panels is wasted.

This clean, renewable energy usually would get shared within your community when you sell it back to the grid. However, without a grid connection it gets wasted… From an environmental view this doesn’t make any sense.

Pros & Cons Of Tesla’s Powerwall 2

Pros of powerwall 2

Lets You Store Your Energy

No energy gets wasted from your solar system. Instead it get stored for later consumption. This can further save bills and provide energy independence. 

3 Energy Consumption Modes

The powerwall offers 3 different energy consumption modes

  1. Self Powered
  2. Back-Up Mode
  3. Advanced Time-Based Control

Biggest Capacity Solar Battery

Tesla’s powerwall can store more energy (kWh) than any other solar battery on the market today.

Long Lasting 10 Year Warranty

Your powerwall is guaranteed to last 10 years under a warranty, after this we suspect it to continue lasting to around 15-20 years (although dropped performance).

NMC Technology (Nickel Manganese Cobalt)

Powerwall uses stable and reliable lithium chemistry to offer a long lasting, high performing product. 

Reduce Your Energy Bills Further

Solar batteries can help reduce your energy bills even further. By storing the power and using it when you need, less power is taken from the grid. 

Bright Future

The future of batteries is bright. They have come really far in such a short period of time, even solar has for that matter. I wouldn’t be surprised if technology were able to help batteries advance even quicker. 

Cons of powerwall 2

Not Very Eco-Friendly

If you are storing all of your power, none will get sent to the grid. From an eco point of view this is seen as less friendly. 


The cost of solar batteries is still high, not all homeowners can afford them. Although in say this the price is becoming more and more affordable as the years go on. 

May Not Pay Itself Off (Limited ROI)

Due to the high cost in price, it could take you a while to pay off the cost of your Tesla powerwall 2. Therefore, it wouldn’t make a large return on investment. 

The Tesla Powerwall 2 Review

Price 9/10

When compared with other batteries like LG chem or Sonnen, the price of a powerwall is the cheapest. So within the solar battery industry, Tesla powerwall is actually the best priced battery per kW. So, when you look at it like this, the powerwall is quite good for price. 

Overall, solar batteries are expensive though. The technology is still quite undeveloped and new meaning it comes with a hefty price tag. In saying this, the future is extremely bright. We’ve seen the jump from the powerwall to the powerwall 2, and the price decrease with it. 

There are also many subsidies available by the government to help homeowners with solar batteries. Still, they are also not as effective as the solar panel rebates. Probably due to the high cost of solar batteries. 

I honestly think in the future these solar batteries will become more and more affordable. For the time being Tesla will get an 9/10 until it becomes affordable for all.

Warranty 9/10

Again when you compare this to other popular solar batteries Tesla is coming out in the middle. Their warranty is better than LG chem but beaten by Sonnen. They all offer 10 year warranties however Sonnen is able to provide the highest throughput (total lifetime energy).

This is pretty good by Tesla, hence why I gave them such a high score. Having this warranty to back up can go a long way. This is also a jump from previous batteries years before.

Also, Tesla has the bankability to back up its warranties. Due to the also being a world leader in automobiles it means that if something were to happen in the solar industry to make them bankrupt, they still have the automobile business for security. 

By looking at solar batteries in general, a 10 year warranty is good enough. Given that the battery is most likely still going to work after this period as well.

Performance 9/10

In terms of performance, right now you cannot get much better than a powerwall. That may be because of its advanced technology, or simply because there isn’t enough high-end competition. Either way in this moment in time, Tesla’s powerwall is one of the best performing solar batteries you can buy. 

Due to its use of advanced technologies that have been tested within the Automobile industry, it sets itself apart from the rest. Even with its liquid cooling features giving it an edge in all conditions paves the way to the top position as a battery leader. 

When you compare this to other batteries you can see that the powerwall comes out on top. Offering a continuous 5kW power supply and a peak of 7kW, this makes this battery incredibly worth the money. You might be thinking that 7kW peak is too high, but if you are using a lot of energy you would expect a battery to perform like this.

Chemistry 9/10

Tesla are using lithium-ion batteries; specifically lithium-ion nickel manganese cobalt oxide which are well known to be high performing, long lasting batteries. This is the same chemistry make up that LG Chem uses, but it is also rumoured to be the most risky. 

This is because they have relatively high density of power and it could run a risk of a thermal runaway (when the battery has an uncontrolled thermal reaction). However, the presence of cobalt makes the battery safe and available for use. 

However, if you compare this to Sonnen’s battery using the chemistry of lithium iron phosphate the powerwall doesn’t seem as good. LFP has a longer lifespan and doesn’t require the same level of cooling that NMC batteries require. 


Well, in my honest opinion… Tesla’s powerwall 2 is one of the best batteries available on the market today. I can highly recommend this battery to homeowners that are looking for a solution to slash bills and get away from the grid. 

For anyone who needs more storage the availability of linking powerwalls together comes in handy. Not only that but the price of the powerwall will eventually come down. Now in SA and VIC there are battery rebates to help first time buyers as well. 

I would say if you have the budget, get a powerwall but don’t remove your grid connection! That’s too expensive and probably not worth the time or money. 

Let’s not forget how cool the powerwall looks as well. It’s sleek and can be installed on a wall mount or on the floor. Either way if you are looking for a solar battery the powerwall is a great investment to make. 

Over the next few years I think we will start to see the rise of solar batteries and them becoming more affordable. 

Let me know your thoughts in the comments, if you have a powerwall how would you rate it?

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Written By:

Luke Cove
Managing Director
Lightning Solar & Eletrical
local brisbane cec installer

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