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Spirit Moves the Market: Tesla Powerwall 2 and Powervault 3 Warranty Updates

Erica Charles 13 Jul 2018

Four weeks ago, we compared the warranties of Tesla’s Powerwall 2, Powervault 3 and Pylontech.

This week, both Powerwall 2 and Powervault 3 have updated – and improved – their warranties.

Powervault has in fact changed the underlying chemistry of its battery and launched GridFlexTM, but more on that next week…

For Powerwall 2 customers, the update is retrospective which is good news for our Powerwall 2 customers.

Now to the fine print….

Powerwall 2 Warranty

Tesla has always guaranteed its system for 10 years. But until this week, there was a restriction on total throughput (to 37.8 MWh) if the battery was used for peak charge avoidance (‘time-based-controls’) as well as solar storage.

Tesla has now lifted that restriction, and so Tesla now guarantees the Powerwall 2 will be free from defects for 10 years, will have an initial capacity of 13.5kWh at installation, and at 10 years will retain 80% of its capacity. It doesn’t matter how many cycles the customer has used for solar storage and / or time-based control and / or back-up, this warranty stands. It's the "Unlimited Cycles" warranty.

The warranty is only limited if the battery is used for something else, in which case throughput is limited to 37,800 kWh. At the moment it’s not clear what that something else would be, although provision of grid services may be on the agenda.

Note that the lifting of the warranty restriction on systems used for ‘time-based-controls’ is retrospective, so that’s good news for many of our customers who are already using the system to avoid peak time grid costs.

As our Tesla rep is keen to point out, the warranty is beautifully simple, no lawyer required to understand it. And there’s a UK free phone number to claim (not China, Korea, Germany or a sales reps mobile like others).

Powervault 3

If you battled your way through our last warranty blog, you may remember a few issues with Powervault 3’s previous warranty:

  1. You had to contribute towards the cost of a replacement battery if warranted capacity fell below 70% of initial capacity during the first 10 years.
  2. After 10 years you couldn’t claim, even if the battery hadn’t provided the “MWh Under Warranty” as stated on the data sheet.
  3. The formula used to work out how much you had to contribute to the replacement cost was wrong and the warranty was pretty challenging to understand.

Powervault has certainly made the warranty clearer, so (3) has been addressed.

And a distinction has been made between the actually battery pack and the rest of the kit within the system (primarily the inverter / charger). The rest of the kit is warranted for 10 years without restriction, albeit you will have to pay shipping should anything need replacing.

But you still need to contribute to the cost of a replacement battery pack fails to provide 70% of initial capacity during the first 10 years.

This is where the warranty is in marked contrast to Tesla's.

With Powervault, it’s like buying a washing machine with a 10 year guarantee, claiming after six because the drum packs up, and being told by the engineer that because you’ve run the machine 2000 times already and the machine’s only supposed to last 3000 times, you need to pay for 2/3 of the cost of a new drum…. 

With Tesla, you can run the machine as many times as you want, and if it fails to perform within 10 years, they will fix it or send you a replacement, at no cost to you.

Back to Powervault. The requirement to contribute to the cost of a new battery pack is there despite the fact that the datasheet gives a large figure for “MWh Under Warranty”. 

In fact as it turns out this “MWh Under Warranty” is not guaranteed at all beyond 10 years. We think it very unlikely that customers will come anywhere close to utilising the warranted capacity within 10 years. Powervault disagrees because they think that with their new GridFlexTM product many more cycles will be used within 10 years. But what if the customer doesn’t want the GridFlexTM product?

As I say, more on that next week.

Overall though, both warranties have improved. So that's good news for the home battery storage market.

Topics: Solar PV battery storage, Tesla Solar Battery, Powervault 3

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