[RE-wrenches] Comparing storage options: Tesla, sonnen, LG Chem, Pika

Tue Mar 5 00:09:00 EST 2019

Hi William,

Please see my responses below.  Note for what it’s worth, that I wasn’t the one who originally crafted the descriptions of these four storage products.  I found it elsewhere, modified it a bit for accuracy and decided to share it with the Wrenches.  I don’t claim that this list is at all comprehensive, choosing instead to look at four of the major players at present.

Also, attached is the spec sheet on Powerwall.

marco

Marco:

Thanks for the primer.  A few questions:

I heard that the LG factory had shut down due to high failure rates of the product.  Any word on that?

--I can’t comment on that as I’ve heard nothing to that effect.  Anyone out there who’s been installing the RESU10H heard anything?

You say the Powerwall has “one of the best ratios of cost to capacity.”  I ran a few numbers:

For the Tesla Powerwall:

        For the MK 8L16 battery:

--What’s the number of rated cycles at 100 percent DOD for the MK 8L16?  Comparing batteries without taking DOD limitations and cycles into account doesn’t make a whole lot of sense to me.

It looks like the Powerwall has a much higher cost per watt hour than a garden variety flooded lead acid battery.  Could this be true?  

--Note that the current AC Powerwall 2 (the first version of Powerwall was DC only) has an integrated 5 kW inverter.

Does the $7,000 include electronics for this higher cost?

Is the Powerwall suitable for standalone systems?

--Powerwall is not officially sanctioned for 100 percent off-grid, stand-alone applications.

What kind of inverter will work with the Powerwall?

--Since Powerwall is AC, i.e., AC coupled, it should work with most other UL1741 inverters out there.  At my house, for example, I have Power One micro inverters on my solar array. The diagrams on p. 2 of the spec sheet are helpful to understanding the system design options.  Interestingly, if the grid goes down during a sunny day and my loads are all being met by solar AND my Powerwall is full and there’s nowhere for any additional solar production to go, Powerwall shifts the AC frequency of my home’s nano grid to 66 Hz which causes the PV inverters to shutdown because the power quality that they see is out of spec.  This causes the Powerwall to discharge, thereby dropping its state of charge.  Once the SOC reaches, say 95 percent, Powerwall shifts the frequency back to 60 Hz and my inverters come back on again.  And this frequency up and down action can take place through the course of the daylight hours depending on loads and solar potential.  Again, remember that this frequency shifting only takes place during grid outages.

Will Powerwall integrate with a generator?  

--Not at present.

Does it have dual AC inputs?  

--No at present.

Does it have built in transfer switching?

--Powerwall or Powerwalls must be accompanied by the Tesla Energy Gateway which acts as a smart transfer switch/disconnect in the event of a utility power outage.

How much energy does the cooling system consume?  Is this taken into account in the rating?

--Don’t know the answer to that question.  As far as the usable energy capacity as well as peak and constant output of the integrated inverter, I believe any power used for cooling is factored in.

Can independent contractors access Powerwall batteries or do you have to have some kind of affiliation with Tesla?

--Only Tesla Certified Installers have access to the Tesla Energy line of products.

Thanks in advance for the information.

William Miller

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Marco Mangelsdorf
Sent: Monday, March 4, 2019 1:01 PM
To: 'RE-wrenches'
Subject: [RE-wrenches] Comparing storage options: Tesla, sonnen, LG Chem, Pika

A useful, quick comparison of the currently available major players in residential energy storage for grid-tie.

Tesla Powerwall

tesla powerwall battery

Capacity: 13.5 kilowatt-hours <https://news.energysage.com/what-is-a-kilowatt-hour-the-difference-between-kwh-and-kw/>  usable; whole house back-up capable with 200A utility service or less 
Warranty: 10 years, 70% capacity

The Tesla Powerwall is an energy storage industry leader for a few reasons. First and foremost, the Powerwall is the battery that brought energy storage into the mainstream for many homeowners. Tesla, already well known for its innovative electric cars, announced the first-generation Powerwall in 2015, and overhauled the “Powerwall 2.0” in 2016. The Powerwall is a lithium ion battery with a similar chemistry to the batteries used in Tesla vehicles. It is designed for integration with a solar panel system, but can also be used solely for home backup power.

The second-generation Tesla Powerwall also offers one of the best ratios of cost to capacity of any product available in the United States. One Powerwall can store 13.5 kWh – enough to power essential appliances for a full 24 hours – and comes with an integrated inverter. The battery cells within the Powerwall are manufactured by Panasonic within the Gigafactory in Nevada. 

The Powerwall comes with a 10-year warranty that assumes your battery is used for daily charging and draining. As part of their warranty, Tesla offers a minimum guaranteed capacity. They ensure that the Powerwall will sustain at least 70 percent of its capacity over the course of its warranty period.

 sonnen eco (now wholly owned by Royal Dutch Shell)

cid:image003.png at 01D4CD10.013F3F40

Capacity: starts at 4 kWhs; not whole house back-up capable
Warranty: 10 years, 70% capacity

The sonnen eco is a 4 kWh+ home battery manufactured by sonnenBatterie, an energy storage company based in Germany. The eco has been available in the U.S. since 2017 through the company’s installer network.

The eco is a lithium ferrous phosphate battery that is designed for integration with a solar panel system. It also comes with an integrated inverter. One of the main ways that sonnen distinguishes the eco from other solar batteries on the market is through its self-learning software, which can help homes with solar panel systems connected to the grid increase their solar self-consumption and manage time-of-use electricity rates.

Like Tesla, sonnen also offers a minimum guaranteed capacity. They ensure that the eco will maintain at least 70 percent of its storage capacity for its first 10 years.

LG Chem RESU10H

cid:image007.png at 01D4CD10.013F3F40

Capacity: 8.8 kWh usable; not whole back-up capable
Warranty: 10 years, 60% capacity

Another major player in the worldwide energy storage market is leading electronics manufacturer LG, based in South Korea. Their RESU battery is one of the more popular options for solar-plus-storage systems in Australia and Europe.

The RESU is a lithium ion battery.  The only battery option currently sold in the U.S. is RESU10H, which has a usable capacity of 8.8 kWh. It comes with a 10-year warranty that offers a minimum guaranteed capacity of 60 percent. 

Pika Energy Harbor Smart Battery

cid:image009.png at 01D4CD10.013F3F40

Capacity: 8.6, 11.4, 14.3, 17.1 kWh usable; whole house back-up capable up to 200A using a Generac automatic transfer switch
Warranty: 10 years

The Harbor Smart Battery comes from Pika Energy, an inverter manufacturer that has recently entered the energy storage space. Unlike some other home batteries, the Harbor Smart Battery is specifically intended to be installed alongside a solar panel system and can be used for both on-site consumption of stored solar energy and grid services like demand response.

The Harbor Smart Battery uses a Panasonic-manufactured lithium ion battery cells and comes paired with a Pika Energy Island inverter, which can be used for both on-grid and off-grid home energy storage.  The Harbor is backed by a 10 year Panasonic warranty.

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