Wanna go off-grid? Now you can officially do it with Tesla Powerwalls.
For the ordinary on-grid customer, batteries are optional. They’re nice to have if you can afford them. Although they’re unlikely to pay for themselves, there are plenty of people who want them for backup, lower power bills, and the joy of using much less grid electricity.
But if you’re off-grid (as I am), batteries aren’t optional – they are how you get through the night and have the lights come on in the morning.
So I was interested to catch up with Tesla’s decision to make a company-backed entry into the off-grid energy storage market. I also spoke to installer I Want Energy, which has experience with the Powerwall in off-grid applications (and, as I was to learn, an enthusiastic convert to the technology).
As a key Tesla dealer in the Tasmanian market, I Want Energy CEO Rob Manson told SolarQuotes he and some staff had the chance to tour the Nevada Gigafactory and the Palo Alto vehicle factory in November 2019, and that’s when he first learned Tesla was looking at a move into the off-grid energy storage market.
Manson said Hawaii was the first region to receive Tesla-backed off-grid installations, and there are now 200 of them. Australia, Manson said, was the second country to be part of the off-grid strategy, and he’s spent about 12 months talking to customers.
“I have several battery products, but in my view Tesla is going to become the dominant off-grid battery.”
That’s because Tesla does the best job of meeting the requirements of off-grid customers according to Manson.
“First, you have to analyse the customer’s loads – we get them to fill in a sheet which details how many hours they’re going to have the lights on, how many hours a week for their vacuum cleaner, their washer, their clothes dryer.”
For off-grid installations, the load analysis has to be more in-depth than if the household is grid-connected.
Manson said in the past the installer would work out the required capacity and order a lead-acid battery bank twice the size, because the lead-acid batteries they used could only withstand 50% discharge before they suffer damage.
That’s one reason Manson was pleased to have Tesla entering the off-grid market: Li-ion batteries such as the Powerwall can be discharged 90%. That makes the battery’s footprint much smaller than a lead-acid battery bank.
The other attraction is Tesla’s active interest in the performance of the battery over its lifetime. To give the battery the best chance of serving its ten-year warranty, Tesla collects the Powerwall’s telemetry.
“They want to view it remotely so they can troubleshoot it if they need to”, Manson pointed out.
And like the Tesla car, the Powerwall’s software doesn’t stand still.
“I’ve been driving a Tesla car for about six years, and I get excited when I get an update pushed into it over wireless. The same thing holds for the Powerwall battery and its gateway, you know the system is only going to improve over time.
“As they gather data, they can tweak the system to make it more efficient.”
Some years ago, I needed to replace a battery bank and investigated the Powerwalls available. It would have been nice to take a technology newer than lead acid, but at that time I would have needed at least two Powerwalls to replace the 24 two-volt 1,100 Ah batteries I was replacing.
Things have moved a long way in about four years: Manson said a single Powerwall would easily serve up the 13 kWh of battery storage I need, and the battery will become more efficient over time.
Because the Powerwall has its own charge controller, Manson said, the installer can choose any quality grid-connect inverter to serve the household (I Want Energy uses Fronius, and Tesla identifies SMA and SolarEdge as also suitable).
And like any off-grid system worth its salt, the Powerwall’s gateway can auto-start a backup generator if needed. Be warned, however: at the moment, Tesla only nominates two compatible backup generators: the high-end Himoinsa HYW Single Phase Series, and Kubota GL Series.
The Temperature Challenge
The only catch in the Australian context is the temperature parameters – the Powerwall has to be kept between 10°C and 30°C.
Manson said an installer he spoke to while touring the factories said the lower temperature is the hardest to meet at high altitude in Hawaii. In Australia, I’d guess the upper temperature will pose the greater challenge.
“Tesla suggests that the battery itself should be within the heat envelope of the home”, he stated.
Having the batteries in a separate shed, which most people using large lead-acid banks do, is not ideal.
However, most houses will have a suitable location where the internal temperature remains below 30°C, and I Want Energy has been working with homeowners and architects to ensure new builds have a suitable battery install location.
Another point to note is that Tesla’s off-grid brochure suggests that their off-grid systems require a minimum of 2 Powerwalls. That’s about $23,300 worth of batteries.
From Tesla’s Off-Grid Application Notes
About Richard Chirgwin
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The bloke you’ve been interviewing has not let his obvious lack of knowledge of off grid design get in the way of speaking with self appointed great authority.
The quoted temperature limits are intriguing – the Power 2 manual (https://www.tesla.com/sites/default/files/pdfs/powerwall/powerwall_2_ac_owners_manual.pdf ) states the ambient temperatures should be in these ranges:
Operating Temperature -20°C to 50°C
Optimum Temperature 0°C to 30°C
I guess this has something to do with the need for high reliability when off-grid and maybe that the Powerwall internal temperature control system cold be compromised if it goes flat and there is no grid power available.
After following SolarQuotes for the last several years, I must say how nice it is AT LAST to see some recognition of the off-grid solar market. I understand that grid-connected solar systems are the lion’s share of the market, but we off-gridders continue to be almost entirely ignored.
This is not even remotely fair, as we are entirely dependent on workable, reliable systems, in contrast to suburban users who adopt solar primarily as a lifestyle choice, and who suffer no inconvenience and only the slightest financial penalty when their solar systems switch seamlessly over to grid power.
I once toyed with the idea of using Tesla Powerwalls, but how many off-gridders are able to provide a stable environment within the range of 10 to 30C?? I will soon be able to, when my earth-sheltered house is completed, but my existing system resides and will remain in a steel shed, where the year-round temperature extremes exceed outdoor conditions.
No, Tesla is never going to be on my shopping list.
It’s good see your living circumstances aren’t a lifestyle choice.
A bit glib, for someone who knows nothing about me. But that aside, the fact remains that grid power was not an option for me.
Installing a little reverse cycle heat pump and insulating the battery containment can be done for less than you might think. Secondhand aircon units are given away, and the piping run is so short that an absolute vacuum is not strictly necessary.
@ Richard Williams
Extra solar panels and an automated temperature controlled battery room, like a wine cellar only a different temperature range, would solve the problem for those who really want to move from lead acid.
Redflow Z cell might suit for you. It has a wider range of temps.
https://redflow.com/products/redflow-zcell/ , and for temp range see:
https://redflow.com/wp-content/uploads/2017/11/Redflow-ZBM2-FAQ-1710-Public-Web.pdf
Or Redflow ZBM2
https://redflow.com/products/redflow-zbm2/
I was interested in Z Cells for a while, but Redflow does not support single cell installations in off grid sites, due to the need for regular maintenance shutdowns. That makes them impractically expensive.
1. Why is there only two generators approved? If the generators produce 240V @ 50hz there should be no restrictions on the make of the generator, as the Powerwall is AC coupled. Or is the issue the auto start controller which must be triggered by the Powerwall
2. I have a Sunny Boy which was advertised as being able to divert power to other uses once the battery reached a certain recharge level, however this advertised function does not work as stated. I was hoping to use this function to heat storage hot water for hydronic heating once the battery was recharged. So my question is what power diversion functions are available within the Powerwall, when the battery is fully charged? Does the Powerwall have load shedding capabilities, (the ability to cut off appliances if the battery reaches a set depth of discharge)
3. “Manson said a single Powerwall would easily serve up the 13.2kWh of battery storage I have, and the battery will become more efficient over time.” You have 52.8kW of battery storage, so usable is 26.4kW. ???
4. The temperature parameters are restrictive but not insurmountable. What impact will they have on the warranty is the parameters are exceeded? Will temperatures outside these parameters de-rate the power output of the battery?
5. The Tesla off-grid website page says 1 Powerwall is required and not 2 as per your article. So which is correct 1 or 2?
6. The Tesla off-grid website page says temperatures above 0 degrees for optimal performance but your article states between 10-30 degrees. Again, which id the correct operating temperature?
https://www.tesla.com/en_AU/off-grid
Thank you for the article
“Why is there only two generators approved?”
I suspect that has a lot to do with the USA being an extremely litigious society.
They appear to sue everybody at the drop of a hat. And sometimes they wont wait for the “hat to drop” they sue because they don’t like the hat. 😉
Duncan, There is a 3rd supplier, recently approved. Jubilee Energy in Brisbane. We supply Kubota engined Generators (Yes i am employed by them) Our gensets have gone through 500 hours of testing with the power-walls. They have been tested vor voltage stability, Frequency stability, Droop on load demand. Our Deep Sea Electronics controller will communicate with the Tesla protocols. So yes in theory any Generator will work, BUT, will Tesla warrant the powerwall should the generator cause a power-surge? I doubt it.
Good article thanks. I recently replaced my 16 yo Lead Acid home battery with another 30kwh Lead Acid as I felt there was no new battery technology that integrated car charging. I intend to buy a model Y and was hoping that Tesla would eventually have an off grid controller like a Zappi available to allow automated off grid car charging that worked with an off-grid home PowerWall. Does anyone have any idea if Tesla has this on the drawing board or will I have to get something like a Zappi. I rang Evolution and they said it is possible to configure a Zappi for off-grid use but ideally I’d like a more integrated solution like full Tesla.
“….the Powerwall can be discharged down to 90%.”
I’m assuming that is a typo ? 10% ?
Good catch. Thanks for pointing that out. The typo has been fixed.
An interesting article. This real story here is about Lithium batteries in Off Grid. Any battery or piece of electronics will provide longer life when subjected to a more stable temperature, even Lead Acid.Tesla are just one of many Lithium batteries already available and deployed in Australia, and like any product will have its limitations. I have lived Off Grid for 26 years and with Lithium for 3 years now and without a problem.
In my opinion here, there are 2 important considerations.
1, Electricity is an essential item, do it properly or don’t do it.
2, Whichever product you chose, make sure you can comply with the manufacturers requirements, otherwise you may have no warranty.
Yes, i work in the industry and live Off Grid, i have made many mistakes and learnt from these.
“That’s one reason Manson was pleased to have Tesla entering the off-grid market: Li-ion batteries such as the Powerwall can be discharged down to 90%. ”
Should this be 10% or some other figure ?
I’ll try again as my comment was awaiting moderation and appears to have been deleted ?
This is a problem in Off Grid design. We hear manufacturers saying take Lithium down to 10% SoC. If you do this in an Off Grid design and a Generator fails to start at 10%, then you have very little time until lights out. Smart design would only allow a Lithium battery to go to perhaps 25%-30% SoC.
The Tesla iPhone app (for grid-connected) allows the user to set a % “reserve for power outages” so you can select say 30% if that is appropriate for your circumstances. I assume the same option is available for an off-grid installation.
Obviously you have to consider the consequences of losing power when there is still a reserve in the PW2. I would think the number of incidences of fully draining the battery would be quite low and so it may be worth the risk of reducing battery life by taking it down to a low value and postponing total power loss.
There will always be some power remaining so that the battery’s internal protection measures keep going (unless it is manually powered off). That last point might also be the reason for the very conservative temperature range for off-grid installations, compared with on-grid.
Fixed now. Sorry for the delay. I was slow off the mark there. I am very sleepy because Scott Morrison kept me up all night.
I have a Tesla Powerwall installed for over 2 years. I have maintained a grid connection because when my system was installed the Tesla Gateway, which interfaces between the inverter, battery, grid and home, did not support an alternative energy source like a generator for times when there is not enough solar. Has this changed?
Not having seen much of the specs, but from what has been said of O/G Tesla inverter, it seems as if it is AC coupled only and AC coupled sux, as it won’t charge the battery if something goes wrong.
To many people seem to be drawn to Tesla anything, like a redneck to Trump.
People, there are very good DC coupled O/G systems out there that have lasted the test of time and can use any battery tech you like.
P.S Li Ion batteries are like other batteries in that you will get less cycle life the deeper you discharge them. So going to 90% DOD frequently ain’t a good idea.
Yes i believe that the Tesla is AC Coupled. Technically your absolutely correct that if the battery inverter shuts down then the AC Coupled PV system cannot operate, where DC Coupled would.
However for a battery inverter to shut down would mean that the battery went flat, Off Grid design must not allow a battery to go flat, the generator should have kicked in before the battery went flat. And if the generator failed to start for what ever reason then the battery will likely go flat unless the battery inverter has an emergency recovery mode which some now do.
The biggest problem i see with AC Coupling is the use of AC Frequency shifting, which i agree sux, no way would i have this in my home.
Where as some companies will use communications to control the PV inverter and no frequency moving. DC Coupled will have no frequency shifting.
@Shaun,
Can you provide backup for 90% discharge fact are bad for lithium batteries?
Lithium-ion batteries can be discharged to 90% quite easily without issue.
Tesla warrants that you can do a daily full cycle (that is drain the battery flat, although in reality, it leaves 5% reserve) for 10 years and the battery will have at least 70% capacity at the end of the 10 year period.
I have a Tesla PW2 and it regularly goes down to 5% DoD (or 95% discharge) every Winter. I’ve had the PW2 for more than 3 years. It has 98% battery capacity remaining, so 2% degradation in 3 years. (13.262kWh usable capacity now vs 13.5kWh when I first got it). So, I’m well under the threshold for battery degradation as per Tesla’s warranty claim. No problem whatsoever with reaching more than 90% discharge. My battery utilisation is about 48% year round (less in summer and more in winter). At that rate, I expect the battery should be at 85% usable capacity in 7 years time. I’ll come back then and report where it’s at if this website is still up.
However, lead acid batteries, it’s never recommended to go beyond 30% DoD as it will shorten the batteries remaining cycles a lot quicker. There are numerous manufacturer charts that demonstrate this. Not even up for debate.
AGM battery can be pushed out to 50% DoD, but that will too shorten the battery’s daily cycle limit.
The advantage of AC coupling is that you can mix any brand of AC inverter with the Tesla PW2 as this solves compatibility issues with the myriad of different branded AC solar inverters installed. Originally, the Tesla PW1 was DC coupled but this was severely restricted in terms of market penetration and hence why Tesla abandoned it and endorsed AC coupling, it opens up the market for more sales.
I can “virtually” go off grid by turning off the main switch. Solar and the Powerwall work very well together. (it’s happened a few times already for more than 24hrs at a time due to downed power lines).And I could do so for the Spring/Summer/Autumn seasons. Two disadvantages of doing this: I can’t export my excess solar production, so miss out on solar feed-in tariff of 21c/kWh and winter would need imports due to low solar production. Unless I get a gas heater/cooker/hot water. Then yes I could be “off grid” all year round. Saying connected to the grid, the excess solar feed in basically pays for my winter bill and I still have credit at the end of the year of about $700.
DC coupling is more tricky and rather limited in range of products that support each other for DC coupling – for what? just a few more percentage points in round trip efficiency?
The Tesla Powerwall is at the moment the far the best of breed when one considers all the tech specs, warranty and ease of application on a $ dollar value.
Yes, some people want exotic setups but they will be expensive.
Lead acid batteries are crap for energy storage. They’re messy, bulky, and just plain ugly. It’s 19th century tech. I deal with them everyday with UPS systems. I manage over 90 UPSes at work.
The problem with lead acid battery is they suffer from Peukert’s Law. Lithium batteries don’t suffer from Peukert’s Law. If you don’t know Peukert’s Law. It’s simply that the lead acid battery’s capacity changes at different sets of discharge rates.
For example, if you have a 100Ah LA battery and you discharge at 5A, it should last about 20 hours.
However, if you discharge at 10A, you should get 1/2 the time of 10 hours. But it won’t, it will be less than 10 hours and it gets worse the higher the discharge rate for any type of lead acid battery. This is the one of the disadvantages of lead acid batteries. To get maximum discharge energy capacity for each cycle, the discharge current should be as low as possible. Which is why you need a set of series/parallel battery banks to spread the current discharge to a lower value for all batteries to get maximum energy capacity for discharge.
A lithium battery will have the same capacity regardless of discharge rate. And this is where lithium has the advantage.
Your comment about people going to Tesla are like rednecks to Trump is a bit irrelevant. I don’t like rednecks or Trump but to compare people who buy Tesla products? Way off base and is a bit of a flippant comment to post.
Hey graham,
How do you find out what capacity you have left on the Tesla pw2.
Thanks— also can you please update the capacity it is on now if you don’t mind ✌️?
@ Brett…
No need or reason to be comparing people drawn to products are like adherents to politicians. Keep those comments to yourself.
What you’re saying is no different to saying people who are drawn to VW-Audi-BMW are like brainwashed Germans to Hitler.
Here is a very good article about the differences in charging/discharging of lithium battery and AGM (lead acid battery). Even though it was written over 5 years ago, it still stands. One cannot change the basic physics of how lead acid and lithium chemistry works when charging/discharging.
Written by Victron……. they should know how batteries work, so the article is reputable to refer to
It clearly shows how just how crap lead acid batteries are.
https://www.victronenergy.com/blog/2015/03/30/batteries-lithium-ion-vs-agm/#:~:text=It%20is%20generally%20accepted%20that,%2C%2080%25%20DOD%20is%20used.
Interesting discussion
Being German, I fully agree nevertheless that one should compare Trump with Hitler. Very similar indeed in what they try to achieve.
But other than that, yes, attacking people like this is anything but appropriate.
…and Godwin’s law is alive and well