Channel 9 recently aired a segment with some very wild claims about battery payback.
“Hey everybody! Is your cornflake bill getting you down? Tired of spending a fortune on flaked corn? Want to slash your monthly cornflake bill down to zero? Well now you can, with the new Ron-Man Cornflake Storage Device. This compact unit is capable of fitting inside a single car garage and holds a 10 year supply of cornflakes. We guarantee you will never have to pay for another cornflake again for 10 whole years. That’s right! Free cornflakes for a decade! All you need to do is pay $12,000 up front for the unit and a $1 a day cornflake management fee. Who would have guessed free cornflakes could cost so little?”
“What’s more, it has a design life of 20 years1! While there is no way in hell we will actually guarantee it for that long, you can be confident it will last for 20 years because we told you it would!”
Unfortunately, I have some bad news, folks. The Ron-Man Cornflake Storage Device does not exist in reality. But who knows, maybe if I can line up the right investors, like, really stupid ones, I can make cornflake magic happen.
The really astute observers among you may have realized the cornflakes the Ron-Man device provides aren’t really free. Instead of buying them from the supermarket as needed, you pay a huge upfront price and, for some reason, a cornflake management fee. Because of the limited amount of cornflakes it dispenses each day, not even the weirdest cornflake guzzling family is going to save money using it, so to describe the cornflakes it provides as being free is clearly nuts.
Unfortunately, when it comes to electricity provided by home battery storage, Channel Nine News appears to be clearly nuts. In a recent piece on the Sonnen battery they very much give the impression installing batteries now can save households money right now, rather than lose it, which is what they will currently do for any household that is remotely normal.
If you want to see why battery storage does not yet make economic sense, I wrote all about it, using the example of the Powerwall 2, here.
The Story Begins
Channel 9 begins their tale with the story of Fred, who we are told,
“Was fed up with an electricity bill that was topping $1,700 a quarter.”
That’s a lot of electricity. If he lives where I think he lives that’s more than 3 times as much as the average family of 3 there uses.
They tell us that Fred,
“…first put in solar panels. That dropped his electricity bill to a little over $1,000.”
We are shown Fred’s roof, which has a total of 9 solar panels on it. I assume he has more where we can’t see them, because that’s very likely to total under 3 kilowatts, which isn’t going to come anywhere close to saving $700 a quarter or around $230 a month.
How Much Solar Does Fred Have?
Rooftop solar is a great investment and up around the Blue Mountains where Fred appears to live, it can have a simple payback period of under 6 years. But if Fred’s solar is saving him around $7.65 a day he must have a huge system. If he was paying 25 cents per kilowatt-hour for grid electricity and receiving a 6 cent feed in tariff, then with 50% self consumption his solar system would have to be averaging around 50 kilowatt-hours of electricity a day. In his location that would be roughly a 13 kilowatt system, which is quite large. If he is using 300 watt panels he’d need 43 of them, which is 34 more than we see.
Most people with large solar systems self consume less than one-third of the electricity they produce, so if his self consumption was typical, then his system would need to be even larger.
While it’s hard to make out, this screenshot of his screen suggests his solar output may be peaking close to or around 10 kilowatts, which suggests his system is 10 or perhaps more kilowatts.
A hard to read screenshot of a screen showing the Sonnenatterie interface.
I want to make it very clear I am just speculating on what sort of system Fred might have and I am not suggesting he doesn’t know what he is talking about. After all, he does have a lathe in his garage and no man with a lathe is an idiot. Or as the complete traditional Dutch saying goes, “No man with a lathe in his garage and two hands is an idiot.” As my father always used to say, “Mijn zoon is een idioot die alles wat ik hem zeg, zal geloven.”
Sonnen’s Battery Prices Have Really Come Down
In order to further lower his electricity bills, Fred bought himself a 10 kilowatt-hour Sonnenbatterie. He said it cost him $12,000 to $13,000. That’s a lot cheaper than what Sonnen used to sell them for. The last figure I was given by them was around $30,500 for 16 kilowatt-hours. That’s around $1,900 per kilowatt-hour uninstalled, while it sounds like Fred got his installed for around $1,250 a kilowatt-hour. Just so long as this applies to people who aren’t Fred, it’s quite an improvement.
Fred Expects His Battery To More Than Halve His Electricity Bill
Fred says he expects his electricity bill to be around $200 to $300 a quarter with the battery. According to the figures Channel Nine presents that’s a reduction of around $750 per quarter for a total decrease of $3,000 a year. But Fred is more optimistic and says he expects to save $3,000 to $4,000 a year.
That is a huge reduction and I can’t see how he worked that out. If we go for the middle of his estimate and assume he cuts his bills by $3,500 a year that comes to $9.58 a day. That’s close to $1 for every kilowatt-hour of battery storage he has.
It is impossible to save that much. If he has a standard tariff and pays 30 cents a kilowatt-hour, a low feed-in tariff of 6 cents a kilowatt-hour, and he uses his full 10 kilowatt-hours of storage every day then, even if we ignore losses, the most he can save is $2.40 a day. Not over $9.
Time-Of-Use Tariffs Help, But Not By Enough
In Sydney there are time-of-use tariffs with very high peak rates that are now around 55 cents a kilowatt-hour, but in the area where my spies tell me Fred lives, looking at the first time-use-tariffs for AGL and Origin that come up, I see that, including discounts, AGL has a peak rate of 34.6 cents with a feed-in tariff of 11.1 cents while Origin has a peak rate of 32 cents with a feed-in tariff if 15 cents.
This means that if Fred is on the AGL time-of-use plan then, ignoring losses, he will at best reduce his electricity bill by $2.35 a day, which is less than standard tariff example I gave.2
There is also a morning peak and on a time-of-use tariff the Sonnebatterie is quite capable of charging with off-peak electricity overnight and using it during that morning peak. But as the morning peak is only two hours long it is impossible for Fred’s battery to fully discharge its 10 kilowatt-hours of storage in that time. But because the shoulder rate is very close to the peak rate and only 1.1 cents less, I’ll just pretend it is all discharged during the peak period. This will reduce electricity bills by an additional $1.63 bringing the maximum possible saving up to $3.98 a day or around $1,450 a year, which is less than half the expected savings Fred says he is expecting.
The real situation is actually much worse than that. No one cycles their batteries twice a day. Or at least nothing human does. I have never seen anyone come close to doing it. In fact, I think I’ll offer a prize of $10 or a random item from my house, to the first person to show me evidence of a home that has averaged 2 or more cycles a day. (Note, depending on postage costs, the random item may be a horse.) Most people cycle their batteries around 0.8 times per day or less. A combination of Sonnen battery management and unusual electricity consumption patterns by Fred may get it considerably above 1, but it’s not going to get to 2. That’s ridiculous. But, if you can show me it’s not ridiculous, then you can be a winner.
Fred And Australian Consumer Law
Fred, if you are reading this, I’m sorry to have to break it to you that your battery is not going to save you as much as you hope. But just in case it proves useful to you, I will tell you about Australian Consumer Guarantees that protect you when you buy home energy storage, regardless of what a product’s written warranty says or what salespeople tell you. Your consumer guarantees include:
- Products must be fit for the purpose the business told you it would be fit for and for any purpose that you made known to the business before purchasing.
- Products must meet any extra promises made about performance, condition and quality, such as life time guarantees and money back offers.
This means if your battery does not live up to promises that were made to you, either in writing or verbally, you are entitled to a remedy, which could be a repair, replacement or refund. For example, if you were told you would cycle it an average of twice a day and you do not then you are entitled to a remedy. If a salesperson told you it has a design life of 20 years, then they have given you are verbal warranty that it will last for 20 years that applies in addition to its written warranty of 10 years.
If you told the salesperson the product had to reduce your electricity bills by $3,000 or more a year and it doesn’t, then you are also entitled to a remedy.
News Programs Should Occasionally Get Their Facts Right
In the past, I’ve covered why batteries aren’t yet a better option than a term deposit or paying off the house. That hasn’t changed. Home battery storage is not yet cheap enough to make economic sense, not for households anywhere close to being normal. While the Sonnenbatterie has apparently come down a long way in cost, it’s not enough to change this and the recent electricity prices rises haven’t done the job either. Thanks to increases in feed-in tariffs the economics of batteries have gotten worse and I’ll soon write an article on that.
I know there are plenty of battery boosters out there creating hype about batteries, but hype does not beat pulling out an envelope and doing a rough calculation on the back to determine whether or not batteries can pay for themselves.
Unfortunately instead of getting their pencil and envelope out, Channel 9 went to Ivor Frischknecht of the Australian Renewable Energy Agency, who said:
“They’re available today, they’re affordable today, they’re gonna get cheaper over time.”
I hate to get all Meatloaf on you, Ivor, but two out of three ain’t bad:
Yes, batteries are available, they are going to get cheaper, but they are definitely not affordable today. Unless you are using some strange new definition of the word “affordable” which includes, “will lose a normal household money”.
I know it’s easy to get caught up in other people’s enthusiasm and forget about checking the figures. That’s how two of my marriages began. But it is important to remember to stop every now and then and pull out an envelope and scribble on the back of it. And I ask… No, I beseech Channel 9, please find someone who can give facts and not fluff.
That someone is unlikely to be a company that only sells home battery systems.
Footnotes
- Cornflake refill $8,000. ↩
- The savings are probably less than this. As most homes with solar are better off with a standard tariff, any reductions in electricity bills should be compared to what they would be on a standard tariff without batteries than to a time-of-use tariff without batteries. But I am going to let this fact slide for now. ↩
About Ronald Brakels
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Thanks for the great write-up please keep up the great work informing people.
one small note
“Mijn zoon is een idioot die alles wat ik hem zeg, zel geloven.” im sure that should be “Mijn zoon is een idioot die alles wat ik hem zeg, zal geloven.”
That said, if you are anything like me, you don’t REALY listen to your parents anyway 🙂
Joost
Yes… That does sound right. I have corrected my father’s saying in the article. Thank you for that, Joost! “Bedankt, stinkend” as my father used to say.
Given that the media could never be accused of letting the truth interfere with a good story, why would any sentient being take seriously anything reported on channel (insert your choice) ?
Yeap!! The grid is my battery….Not a very efficient one, but I generate much much more than I consume (winter excluded!!). The grid doesn’t go flat. Battery storage is still not cheap enough unless you attempt to creat something yourself like people do in the US and other countries. But I am sure they are breaching all sorts of regulations.
I’d be happy to run my lights, fridge and computer hardware off battery charged by my solar system.
Apropos “affordable today”, the merchants probably mean affordable as in a cost which does not result in bankruptcy. Quizzed closely, they’ll doubtless have to admit that they were not suggesting that it would in any way be _profitable_. I’m game enough to guess that they’re not even thinking about the opportunity cost of not putting the purchase price in a term deposit. Why would a battery vendor do that when a simple statement of electricity bill reduction serves as evidence of a saving? Offsetting the purchase cost, particularly with interest, is something which comes after the “saving”, optionally I’m sure. Otherwise even “savings” bunnies would wait like the rest of us. Mind you, nothing stops the technophiles and global warming saints, bless their beneficent pioneering hearts.
I’ll give it another 18 months for the prices to droop, then probably go the Aussie path. That Redflow ZnBr thing can be 100% discharged (must be once a week or so, for good health), and last I read, they guaranteed 68% energy efficiency after 10 years. Maybe lithium will hold up as well, but I can’t afford to buy both. As I’ll be off-grid then, the $6 per night petrol cost saving would pay it off well inside the ten years, I figure.
Yes your absolutely right Ronald.
I’ve had two written quotes for the 6kw Sonnen battery including installation. The first in November last year was for in excess of $17000 = $2830 per KW. I balked at this cost.
Again in March this year I obtained a written quote from a different installer for the same 6kw unit and the price was $13400. This still meant $2230 per kW.
I was recently given a verbal quote for around $11500 installed.
I am now waiting for my Tesla Powerwall 2 battery to be installed shortly at a cost of around $800 per kW and that includes the backup gateway option that will provide power to the house during a blackout.
Sonnen is a very nice piece of gear but it cannot cover its cost on the basis of home battery storage, but Sonnen are now being very innovative in there Flat cost offer which may be the start of something big. But as you alluded to but may be are to polite to say the tv add was pure BS.
A while ago, Sonnen’s James Sturch posted here.
Perhaps he can enlighten us concerning the size of the solar, claimed savings,
battery costs, and the state of charge that doesn’t appear to exceed 25%.
Hi a.thomas,
There are now loads of quality news articles and blogs and end user reviews online detailing the facts, performance and capabilities of the sonnen systems so I don’t really want to get into a debate on this blog site.
To briefly answer your questions though, generally a PV system will export around 75% of generated energy without storage, this is a common percentage not quoted by Sonnen but taken from various other impartial industry authorities on the matter. On this basis then the export volume will give you a good indication on the storage capacity required. Remember though when looking at systems a lot of products quote total capacity and not usable / warranted capacity. Also, a lot of systems only allow a maximum of 1 cycle p/day with their warranty, some even less.
The point regarding 1 cycle /p/day is an interesting one, firstly Sonnen will warrant 2.7 cycles p/day, yes, it’s hard to achieve this volume but we do have systems that exceed 2 cycles p/day. Remember though that the systems have a design life of 20yrs so this 10,000 / 10 yr warranty helps to illustrate the overall product quality and design longevity.
The way in which we do multiple daily cycles is currently via tariff optimization, for instance we have a system in SA that is set to charge at 10pm from off-peak cheap power, the 3-ph 10kW system is then charged by 1am. The customer then has loads that kick in at around 6am when the family get up, the system can be pretty much discharged by 9am as the output rate is 3.3kW p/hr so by the time the family go to work and school the system will then charge back up again via the 8kW of PV. There are loads which come on during the day such as the pool pump that often exceed the PV production so the battery will discharge, this makes up the difference. This system has been often performing at 2.1 and 2.2 cycles p/day, I would share graphs but you can’t upload images to this blog…. I presented this case study along with some other at the 2017 Australian Energy Storage Conference so our ability to perform higher than the 1 cycle p/day is well known in the industry.
With the sonnenFlat product we will also sell energy back to the grid for grid services which also help to increase the cycle count, the end users benefit from this service as on their own they would find it hard to sell to the spot market.
The state of charge in the graph on the screenshot in the blog is the purple line, it fluctuates between zero and 100 percent, there are a few days when it only gets down to twenty five percent, when we show zero percent though that is the usable capacity, our batteries are not actually completely depleted of energy.!
With regards to system cost, that is something that our retail partners can comment on as installation costs will vary depending on the unique requirements and parameters of each location, just like with PV.
All the best, James
Hi James,
Thanks for the comment. Feel free to email any images to [email protected] and I’ll add them to your comment.
Please can you advise how Fred will save “$3,000 – $4,000 per year” with this battery?
Best Regards,
Finn
Thanks for your reply, James. I see that Finn has replied. Would you be so kind as to submit the data and answer his questions?
In this case, interested parties must scrutinise the video, which is ambiguous.
Moreover, State of Charge can be relative to existing capacity, and not the original capacity.
I can accept that Sonnen’s battery may be capable of many cycles, but that doesn’t tell of actual capacity or financial return. It seems to me that the household load must be higher than is typical, if the multiple cycles are to
be usefully employed. I understand that Sonnen Flat can create additional loads, but what is the return or total system cost?
The article obviously questions the income claimed in the video, and I would appreciate your clarification of those claims.
Thanks, again
Poor report BUT checkout Andrew White article in the Australian 06/07/17.
Its a virtual power plant of connected domestic batteries, being rolled out in Germany 6,000 units going with 10,000 orders.
Coming to Aus
Nice article as always Ron. However my interpretation of the video and yours differ. Yes they showed a roof with 9 panels but that was followed immediately by a roof with a large number of panels. It’s quick and the shot doesn’t even go to the end of the roof so can’t count them. Then the screenshot you say is peaking around 10kW. I think it shows the daily output clipping at 25 kW. The vertical axis is marked up to 25k and it says Power(W) to the left. So if he really does have 25kW of PV that would generate about 32,000 kWh a year. I didn’t think a domestic customer is allowed to feed in more than about 5 kW per phase. At 50% self use and 50% fed in, the average value would be say (11 + 33)/2 = 22 cents/kW giving $7000.and even Fred and Channel 9 are not claiming that. So Fred, since you have been an electronic engineer all your life, would you like to post some details on this site? Cheers and thanks
Peter (an electronic engineer)
The yellow line is the solar output – peaks at 5-10 kW. The blue/black line is battery state of charge – obviously a different scale – which confirms that the battery is only cycling <1 cycle per day.
“Well, Holmes, I think there are more panels, on a different roof”
“Observe the gap in the clouds to the left, Watson. I believe it is the same roof”
“Good to see the future of the grid is determined by such observations, Holmes”
“Perhaps, but isn’t that text on the axis, a percentage sign, and not kW?”
“I am not sure. It is a regular cycle, though, Holmes”
“Ask Mrs Hudson to make inquiries of Sonnen, so we may resolve this singular matter”
Appro of a completely matter, do you realise that Tonto will turn 24 on 1st august. Apart from
The usual festivities (?carrot cake) are you planning on updating the bio on this website?
Cheers joe
I see the confusion. The 22 in Tonto’s name is not his age, it is his iteration. He is the 22nd horse I have owned called Tonto and is currently nine years old.
Every time I get a new horse I tell him, “Listen up horse! Your name is Tonto n and unless you want to end up like Tontos 1 through n-1, you’d better watch it!”
It works n-n percent of the time.
Hi Ronald, Yes at first I was also confused about the age,,, but had already clarified it for me,,,
By the way, I congratulate you on your mathematical skills. As a mathematician, I understand series and sequences.
Jokes aside,,, this is a very informative website, and I always look forward to the contributors blogs.
Cheers,
john nielsen
My gel cell battery system cycles twice a day in summer and once in winter even on cloudy days. my batteries are now 9 years old and still going strong. I have heard tell that most installer will only do a Zcell system with 2 batteries because I tried to buy one. Geez you’d think that they would be happy to sell you just one to ad to a operating system, BUT NO you have to use their controller and inverter and it must be installed by their designated installers.
Think I might just buy some more gel cell batteries OF THE SHELF.
I meant on-grid and I presume you’re off-grid, but since I didn’t specify that I guess I am honor bound to send you a prize. I’m not mailing you my horse, but if you want a random object from my house, email me an address to send it to. No need to provide evidence. I believe you.
Everybody else, the prize is still open for the first person who can provide me with evidence of on-grid home battery storage that is cycled an average of 2 or more times a day. Over at least months. But I’ll further specify it is for a system that was bought and not cobbled together and I’ll also ask people to leave out lead-acid battery systems. This is because I’ve never heard anyone claim the way to battery wealth is to cycle on-grid lead-acids multiple times a day, but when it comes to lithium iron phosphate batteries I think sometimes there is a bit of exaggeration going on.
My mindset is attuned to off-grid, admittedly, but I see the battery merely filling power holes produced by clouds, during the day. (If not, then the PV array is underdimensioned, and the system isn’t fit for purpose.) I.e. any “cycling is only e.g. 10% discharge – good for a long battery life.
It’s only at night or in deeply cloudy weather that a deep battery discharge occurs, then. OK, with only 1/3 of rated output from the array in winter, due to lower sun angle, shorter day, and more clouds, there will be more deep discharges, which the Z-cell would stand up to better than anything else, I figure.
Yes, it needs 100W @ 36v to boot after the weekly 100% discharge cycle, but I figured that a lead-acid back-up, or a dedicated DC-DC converter fed from the PV array would suffice there. The only good reason for 2 of them is to avoid having to start a generator in a week of lousy weather. A little generator is miles cheaper! (I think Tonto’s stablehand has mentioned that once or twice.)
We need to collect a few potential but doubtful customers, and present a potential bulk order, subject to ironing out some of the BS that’s in the way.
Yes, the small start-up doesn’t dare sell into a set-up with untested inverters and chargers, but their website does indicate that they’re keen to broaden the range, and have a testing lab for the purpose. Any solar power system has to be installed by a CEC certified installer for STCs, as I understand it, and any wiring above ELV needs a licenced electrician, so I won’t quibble about their installer having to be trained on the product as well. I will though, be giving them a hard time in order to get a DC-coupled system if that’s possible. (You mustn’t charge a Z-cell with more than 30A, so my MPPT wouldn’t do in any case, without current limiting.)
But just now I’m battling with the design decision of slab-on-piers or the Cupolex variant of waffle pods, while finishing off plans for the little abode to keep my PV off the ground. (And the rain off my head) I baulked at paying $6k for an architect, and have nearly finished the 8 drawings, pending some input from the engineer, and the truss people. But the price of all batteries will improve in the next 18 months. Who says procrastination doesn’t pay?
@Erik
Regarding Off-Grid solutions, you have touched on many important points, some of which relate to current global design standards and trends and some which are outdated and a hangover from the 1950 -1960’s ELV days and the Australian PMG Department telecoms industry more specifically; and those days have well and truly been consigned to history by experienced DC power systems engineers operating in this space.
Your reference to DC coupled design tells me that you are a person who is thinking in greater detail about the subject though, and on this point you are absolutely correct. The devil is in the hardware and controlling software logic design detail though.
Primarily, there is a chalk and cheese difference between DIY Off-Grid systems design and implementation, and commercial design and install contracts, and foremost is an engineering reality that designers/integrators/installers must implement in their core system logic above all other considerations at the outset if they expect their Off-Grid business to survive and thrive beyond the first installation. Surprisingly, this point is not often mentioned in Off-Grid forums; but design engineers need to acquire a forensic understanding of how and why this is “the key design imperative” to master to ensure overall system functionality, performance, endurance and cost effective maintainability, before contemplating a move into Off-Grid sector.
Priority 1 – Fully Featured Remote Monitoring and Control System Technology (RMCU):
The system manager for a Standalone Micro-Grid or Off-Grid System is the installer (he carries the financial risk and system fit for purpose legal obligations and responsibilities) not the system owner. A critically important point.
This critical distinction however does not apply for On-Grid or On-Grid Hybrid installations because the installer is the beneficiary of a free partner (Grid) who is effectively looking after the end user and the system installer. But this (free and substantial partnership) does not exist for Off-Grid installations. The installer therefore bears the full responsibility and obligation to design fail-safe systems that guarantee Standalone Micro-Grid & Off-Grid customers continuity of electricity supply 24/7; no excuses accepted.
An Off-Grid system must therefore be a ‘semi-intelligent’ one, controlled by a dedicated RMCU as the system brain able to control every functional aspect of the system. It will make decisions in real time; protect the system at all times; inform and direct as it determines, the system installer and end user via local connectivity; SMS and other media methods also, and control the overall system functionality at all times.
Best practice RMCU’s are intuitive and learn through observed performance. They modify system functionality (performance and control algorithms dynamically) based on feedback from precision sensors and transducers. Importantly the RMCU provides both the installer and user with predictive maintenance and breakdown forecasts based on MTBF statistics.
Ad hoc crisis system maintenance indicate inept system logic and engineering skills by the system designer/installer, who will in all likely-hood be heading out of business after the first install.
Don’t confuse an RMCU with a standard intrinsic inverter monitoring capability which is entirely separate.
A dedicated RMCU operates via sensor and transducer feedback and invokes appropriate decision making and controls. It operates independently of but controls all of the system PCE, inverters, standby generators, energy storage units, power sources, and load management equipment etc.
A well implemented RMCU controlled system emulates the traditional Grid by eliminating the need for any end user intervention in the normal functionality and operability of a Standalone Micro-Grid or Off-Grid system.
Importantly the RMCU should provide for ‘mission critical’ control connectivity with the system manager remotely 24/7 through inbuilt dual redundancy communications (SMS and Web).
Based on all that above, it adds clarity to why a fully featured and autonomous Remote Monitoring and Control system design strategy precedes all other system design considerations for Standalone Micro-Grid & Off-Grid Systems.
Lastly Erik, you should consider the clear advantages that a 600 V + DC coupled system offers, not the least being a permanent ‘essential services’ autonomy under any conditions. Higher LV system bus voltage means less current in key components, which equates directly to greater efficiencies all around that can, and should, definitely be exploited by your system design team.
Lawrence Coomber
Long winded and troublesome to comprehend after a night on the psfsfsfsfsfsf but the gist is very good. Almost every single journalist is now espousing fake news, often to satisfy journalist’s own personal flatulence toward society, as we are indeed lemmings who believe whatever they print. Whatever happened to the term truth? One generation and all credibility is gone. Go for the instant trash story but wipe out generations of integrity, honesty and a sense of ‘place’ in local communities. Who is to blame – the so called professionals or the amateurs willing to share news and information?
Sonnen are looking at marketing their system differently as per their connected grid in Germany. You’ll be able to get a complete system from Sonnen at no upfront cost and they will charge you a fixed fee for electricity no matter how much you use – any export electricity is controlled by their software and they can sell it back to the grid on the wholesale market. So your panels won’t necessarilybe charging your battery in times of peak demand – instead that energy will be getting sold back to the grid. Essentialy they are building a large scale powerstation and storage across the domestic network.
The scheme you talk about, announced as ‘Sonnen Flat’ in Australia requires you to to buy the solar and Sonnen battery upfront (don’t expect much change from $20k) and THEN pay a fixed fee per month for your electricity. If we can get Sonnen to send us the actual contract terms, I’ll review it in a blog post.
RE. Sonnen Flat perhaps I misread their website however I thought i read that, for the price of installation $13/14 K of a sonnen 8 kw battery you would receive $30.00 per month from Sonnen.
You are able to use as much of your own solar as your home requires and access the battery up to (down to?) a certain point.
Sonnen will use (some of) the electricity stored in your battery to sell to the grid for grid “stability purposes”. It’s still a pretty poor return on investment even if i use half the battery capacity each night.
The other thing of note is that You must have a 5 kw solar system. that automatically precludes those of us in Ausnet services area in Vic because solar systems are limited to 4.5kw (in most cases).
We just got a letter through the mail marked Attn:Registered Homeowner from the Solar Service Group. This said that if our house was eligible, SSG will discount almost half of the total cost for solar batteries (including installation). A phone number and code to register interest was given. I rang, to find that they are offering Enphase batteries, in 1.2 and 2.4 kWh sizes (they said kW but said since everybody does, they do). “in turn participants will be asked to provide feedback on the overall impact on costs…” . The prices of these two sizes were $4053 and $6800 respectively! Asked what saving I could expect they said $400 a year (I suppose on the bigger one). However if you shift 2.4kWh a day from FiT of 11 c/kWh to peak rate self-use of 30c/kW that differential of 19 c/kW gives 45c/day – $166 a year. simple payback 41 years. Small one 49 years. Need one say more.
Sonnen Flat contracts count all consumption towards your cap – regardless of source – yes, Solar, Battery, grid – if current flows from your battery, your solar or the grid into your house that is all counted towards your annual agreed amount that is after their monthly fee – free (strange use of the word free given its a fixed fee for a price cap within a ceiling until its broached…
I was interested in getting some battery added to a new solar system I am getting quotes for. The main reason is to be able to limp through any blackouts we might have this summer – see headlines today.
One company providing a quote said that I could add an Enphase battery to achieve this – both (a) running off the battery at night or (b) using solar power if the blackout is during daylight hours. At an additional $2k this seemed like reasonably priced insurance.
However..
1. I have read elsewhere that Enphase batteries can’t operate “off-grid” which I assume means it won’t solve (b)
2. If that is the case, is there another way of achieving my aim without the $5k plus for a battery system that would solve (b).
As well, I read that the power provided by (a) would be unlikely to run anything of use in the house i.e. lights, fridge
Look forward to your insights
Hello Mark.
I am afraid the Enphase battery is unable to operate during a blackout and you are right that it can’t provide much power anyway. I wrote about it here:
https://www.solarquotes.com.au/blog/enphase-batteries-are-impressive-but-very-unlikely-to-save-you-money/
It sounds like the best solution for you is a generator. This is the most cost effective way of dealing with black outs.
If you get a generator then you have a choice between getting one properly installed, which is very convenient and makes it easy to survive blackouts, or you can just get a portable generator and run an extension cord inside if you need to use it. This is what my parents do. They have a very small generator which is enough to run their refrigerator, freezer, lamps, and TV and laptops if they want. This is much less convenient, but has the advantage of being cheaper and let’s take it camping or lend it to friends or relatives if they have a blackout.