Tesla battery + solar now "significantly cheaper" than grid power

Tesla battery + solar now “significantly cheaper” than grid power

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Just 14 months ago, the writing was on the wall for grid-only electricity supply. Turns out the gap between grid only and PV+battery+grid is growing much more quickly than we imagined.

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In November 2016, our analysis shows that a Tesla Powerwall and a 5kW rooftop solar system could deliver electricity around the same price as grid power. Our latest estimate shows solar and storage is now significantly cheaper.

In late 2016 Tesla launched the Powerwall 2, halving the price of storage relative to Powerwall 1.

In a note in November 2016 we analysed the economics of one of these batteries plus 5kW of rooftop solar plus grid for back-up and exports, relative to grid-only supply for a household with north facing roof in Adelaide that consumes 4800 kWh per year.

The comparison worked out the annual bill with and without PV and battery.

We assumed a 10 year battery life, 20 year PV life with no residual for either and assuming the household financed it with a household mortgage.

For grid offers we took the average of all 76 market offers from the 14 retailers making offers in the market, assuming in the first case that all discounts in those offers were achieved and in the second case assuming only that the unconditional discounts were achieved.

The results of the analysis are shown in Chart 1 below, which shows that for these assumptions, households are typically better off installing 5 kW solar and a battery rather than relying on grid only supply.

Chart 1: Tesla Powerwall 2 plus 5 kV PV plus grid versus grid-only in Adelaide in November 2016

Since that time many other battery suppliers have come to the market (Global-Roam’s Battery Finder website now counts 203 different residential battery systems for sale in Australia).

The Climate Council estimates that there were 20,000 home battery installations in 2017, more than triple the 6,750 new installations in 2016.

And a couple of weeks ago the South Australian Government announced a policy to install 50,000 Tesla Powerwall 2’s plus 5 kW PV in a deal that would involve the government owning the assets but the households involved paying 27 cents per kWh for the electricity.

This notes looks again at the economics using the latest information on prices.

For a start, on the same basis (average of all market offers) the average price (for a 4800 kWh per year customer) in the 72 markets offers from the 16 retailers in the market today is 42.4 cents per kWh (assuming all discounts achieved ) or 46.4 cents (assuming only conditional discounts achieved).

This is 12.5% higher than the average prices calculated in the same way in November 2016.

Tesla now estimates a higher installed price of their Powerwall 2 ($11,075 versus $10,300) taking the mid-point of the installed price they quote on their website now compared to November 2016.

The price of 5kW PV has however fallen considerably from $7,318 to $5,500 (taking the average price quoted on solarchoice.com.au then and now).

And PV feed-in rates have more than doubled from around 6.8 cents per kWh in November 2016 to typically around 16 cents per kWh now).

Bringing this information together and using the same analysis that we used in November 2016 we get the results in Chart 2 below.

Chart 2: Tesla Powerwall 2 plus 5 kV PV plus grid versus grid-only in Adelaide in February 2018

The combination of 5 kW PV plus Tesla Powerwall 2 plus grid is now significantly cheaper than the average price achieved from grid-only supply even if all the discounts in the grid offers are assumed to be met.

The difference between Chart 1 and Chart 2, over just 14 months, is remarkable. The writing was on the wall for grid-only supply 14 months ago and while we expected the gap between grid only and PV+battery+grid would grow larger, this is happening more quickly than we imagined.

South Australia’s consumers bought 20% less electricity from the grid in 2017 than they did in 2010. I imagine that by 2025 the amount will be at least 20% less again.

Bruce Mountain is director of CME

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  1. trackdaze 3 years ago

    Utilities will want a compelling case for keeping us connected.

    • Mike Dill 3 years ago

      I have a hard time figuring out how that is going to happen. When battery prices drop an other 50% it will be cheaper to go off-grid.

      • Ian 3 years ago

        To avoid needing a generator clogging up the garage, still likely better to stay on the grid

        • Jonathan Prendergast 3 years ago

          And to be able to export your excess energy in summer once you have designed a larger system for winter generation

        • neroden 3 years ago

          You don’t need a generator. Bluntly, most of us in the Northeastern US are used to going a day or two without power every year… and if you accept that level of reliability (99.5%), then you will be fine just with a giant solar system and batteries.

          But it’s nice to be able to export your excess summertime power and let someone else (industry? a steel mill?) use it.

          • Mike Dill 3 years ago

            With an adequate solar array and two days of storage I would have been at 94% for 2017, and 95% for 2015. That leaves 20 days per year when I need something else.
            I was hoping to use my EV as a ‘mobile’ battery that could charge elsewhere to fill the remaining gap, which looks to be possible with ‘Vehicle to Home’ (or V2G). The other option was running a generator on those days.
            As long as the network connection costs less than (or nearly the same as) what I get for export, then not having to use a generator and staying on the grid will make sense.

          • neroden 3 years ago

            You’re quite correct: as long as the network connection is cheap enough it makes sense to stay on the grid. The battery alternative is perfectly *viable*, but it is currently more expensive.

            So the real question is: how cheap will the network connection be in future years?

          • juxx0r 3 years ago

            Something is not right there. If you have 2 days storage and adequate solar array, then you have three days storage after accounting for the solar from the preceding two days under batteries. In order for you to need 20 days where you need something else, this then means you have insufficient solar for 30-60 days in contiguous 3 day or more blocks. This therefore means you live in a horrible spot for solar or your array is not adequate. As Neroden says, 99.5% availability is doable quite easily.

          • Mike Dill 3 years ago

            you are right, the percentages I had were from one day of storage. I had about 20 days when it was cloudy (or worse) for more than 2 days in a row, or continued to be cloudy for a longer period.

    • DJR96 3 years ago

      The compelling case is that a connection is needed to export power to. The need for the distribution network (needs to be regarded as a re-distribution network) is as strong as ever and an essential piece of utility infrastructure.
      So the fixed costs to customers need to come down, even if that is countered by increasing energy prices.

      • Rod 3 years ago

        Unfortunately their business model thus far has been increasing the fixed costs. They really need to rethink as once customers cut the cord they are unlikely to be enticed back on.

    • Peter F 3 years ago

      They can offer an even higher feed in at peak time apparently Reposit offers up to $1.00 under certain circumstances. An incentive to have west facing panels which will lower and shift peaks even further would be good

      • Greg Hudson 3 years ago

        From what I have read, those Reposit ‘circumstances’ are pretty few and far between. How on earth anyone with a Reposit is ever going to pay off the $2k (approx) cost is beyond me. Try and find any data on their web site. (Good luck).

  2. Mike Dill 3 years ago

    Now I just need my PW2 to be delivered this year…

  3. Jonathan Prendergast 3 years ago

    I think your analysis would see an ever better result for 10-15kW of solar only rather than solar & battery, with current feed-in-tariffs

    • Finn Peacock 3 years ago


    • bruce mountain 3 years ago

      Indeed, there are of course many combinations of solar and battery capacity. Since export prices substantially exceed production costs it would be profitable, but I don’t think it would radically alter battery utilisation or the abritrage value of the battery. Runs the sums and let me know if you think this is wrong.

      • Mike Dill 3 years ago

        Where I am, they are talking about changing the time-of-use tariffs, as solar is already driving down the wholesale prices during the day to about 6 cents per kWh. Daytime prices (both ways) will be about 6 cents, and then the prices will go up as the sun goes down.

        • Jonathan Prendergast 3 years ago

          Yes, FiTs are only a 12 month proposition at best. And could change or disappear quickly. The Vic ESC FiT draft proposal is encouraging that high FiTs will be around for a while. Bruce’s analysis is based on energy market fundamentals, so will be more resilient to change.

      • Jonathan Prendergast 3 years ago

        Your analysis appears correct. Unfortunately I don’t have time at the moment to do a full analysis for SA to know for sure. Your analysis also makes an important point, and households batteries are important in SA.

        In most parts of the grid, we need more energy and generation more than we need storage. Even in SA, with gas generation running during sunlight hours, more solar capacity ASAP would be beneficial for the energy system and prices. So it is also important that households should probably max out their solar prior to getting a battery.

      • Steve Garside 3 years ago

        “Tesla now estimates a higher installed price of their Powerwall 2
        ($11,075 versus $10,300) taking the mid-point of the installed price
        they quote on their website now compared to November 2016.”
        The warranty says 37.8MWh ‘operational limit’, which works out to be
        29c/kWh storage cost, if the battery were fully cycled for each day for 10 years. The storage process is 88% efficient, wasting 1.8kWh/cycle, where the total of 15.7kWh could be sold as FiT.

        It is very unlikley the battery can be fully charged and discharged every day for 10 years. Even without detailed calculation, it’s obvious the battery undermines the better return from solar alone.

        • bruce mountain 3 years ago

          No I don’t think you can say that. Firstly why assume the storage capacity of the battery is its warranted capacity? Do you assume the life of your motor car is the duration of the warranty provided by the dealer? Secondly, the economics of battery is the ability to arbitrage. You can not assume the economics of battery without having regard not just to the solar production cost but also to the grid-price of electricity which the battery displaces

          • Steve Garside 3 years ago

            I assume the warranty period or ten years would be enough.
            Even if the battery were fully cycled each day, and used for arbitrage, return is better without the battery. $11000 is $3/day to be recovered every day for 10 years.

          • Brian Tehan 3 years ago

            I’ve recently done very similar modelling, of my own, to that in the article and I agree with you. I calculated the return on solar and solar plus batteries. Solar break even was around 5 or 6 years for an efficient home but adding a battery blew it out to more than 10 years. Solar pv is now an economic no brainer but batteries are for other reasons – you might decide that the power independence is worth it or you might be frugal enough to sell some of your excess via Reposit and get a better return.
            And who gets this 16c FIT of which the article speaks.

  4. Gordon Bossley 3 years ago

    Remembering I’m an amateur in this space, everything I’ve read and seen suggests there will some time soon be a glut of supply. The price of electricity will go to levels no-one seems to be anticipating. The economy will change accordingly.

    In the meantime there are consumers whose demand way outstrips their physical capacity (space) to install PV.

    Before the glut, there’ll be a point where the retailers will be desperate to buy your spare juice!

    Strength will come from collective bargaining?

    • Mike Dill 3 years ago

      Look up a guy named Tony Seba. He has a concept called ‘god parity’ where the price of energy from solar and batteries is less than the network cost of power delivery. At that point, it does not matter how the generators make the electricity, as it is cheaper to have solar and storage. He expects it might take 7 to 10 years.
      Eventually every residence and commercial operation will have solar. Solar panels will take up a lot of what is now marginal land, and communities will buy solar development for the high density housing tracks.
      As solar PV gets to be more than 40% of demand, there will be times that the ‘value’ of that energy will be nearly zero. At noon in some places you already see days when the pricing goes negative. We just need to find creative ways to use that ‘nearly free’ resource.

      • neroden 3 years ago

        Network cost of power delivery where I live (northeastern US) is state-regulated, and they charge about 5 cents US / kwh.

        When solar + batteries hits that price (and it’ll be a while — has to drop by more than 50% so it’ll probably take at least six years — and the “residential premium” over utility-scale has to go away too, so it’ll take longer), then yes, that’s the end for the grid.

        Long before then, it will make sense to put in *some* solar and batteries to “peak shave”.

  5. Brian Tehan 3 years ago

    Maybe SA? I think the FIT is quite low? The best return, by far, in Victoria and NSW, is buying a big solar PV system, the bigger, the better – there are practical and regulatory limits of course. It’s way ahead of PV plus battery.

  6. Ian Myles 3 years ago

    A challenge with the analysis is no consumer is average. Like a farm, you have floods or droughts. Location is critical given material difference in grid pricing. Using my own data from Ausgrid, it was amazing how many days i would not be able to fully dispatch a battery, i did not consider how many days i would not be able to charge the battery. Secondly there is no argument solar is economic. The question is does adding a battery improve the economic outcome from the solar base. With a feed in tariffs of 11c i do not believe it will be that attractive for the average user with an arbitrage of ~$0.42/KWh in the most generous area (Ausgrid). At zero things might be more interesting, but even then I believe it is questionable. An IRR of at least 4-5% is required to cover the borrowing costs to fund it for many households.

    • David leitch 3 years ago

      Even assuming your demand profile this assumes that the only argument is IRR. Where household consumption is concerned IRR is only part of the discussion. Some consumers will just prefer more grid independence or the appearance of it. Double glazing does not pay for itself but nevertheless enhances the quality of life for householders enough to offset cost for some consumers. Some people like higher quality kitchen appliances.

      I agree I’m shifting the debate. In my case the economics are slightly more favourable except that most of the PV panels I’ve been quoted are at a higher price. Haven’t looked at if for months though.

      The other point is that household battery prices just didn’t move down in 2017. Industrial battery prices did but that’s another story

      Another point is that given grid delivered average electricity household consumption is down around 5.4 MWh in South Australia (AGL FY17 data) with an implied daily average consumption of say 14.7 Kwh you could argue that a Tesla Powerwall 2 is overkill. Its hard to know what the real underlying consumption is as you’d have to know how many AGL serviced households there are and the impact on consumption.

    • neroden 3 years ago

      Different people have different IRR hurdles. If you’re sitting on a whole lot of cash earning 0% in the savings account at the bank, then this looks great.

  7. Kratoklastes 3 years ago

    Now do it for a state where the government hasn’t screwed the pooch by force-feeding overpriced ‘renewables’ and fragilising the entire national grid just so that some virtue-signalling cult members can bask in their own self-righteousness.

    • Mike Westerman 3 years ago

      Take another lump of coal with your cuppa and lie down a while..

    • bruce mountain 3 years ago

      In what sense has the SA Government force-fed over-priced renewables? The state’s premium FiT is ancient history and the large scale stuff built in SA is pursuant to the federal RET, not state policy.

    • Terry Constanti 3 years ago

      In one sense you are right, the politicians decide things that make engineers cry themselves to sleep.

  8. Chris B 3 years ago

    Off grid in suburbia can be done. We’ve done a 10 kw effective system with 18 kw of battery (gel) reserve at 30% DoD. Total cost under was under $15k and no grid connection costs. Our break even over 10 years is under 8kw a day usage.

    • solarguy 3 years ago

      Chris, is your PV 10kw, what brand of batteries and what type? What brand inverter? Did the price include installation?

      • Chris B 3 years ago

        The PV is 15kw, but not optimal angles, so effective around 10. Batteries are direct import from China, can’t recall brand, but up there, (200ah C10, 10 year life on 30% DoD) Inverters are mid range. Self and Electrician installed.

    • bruce mountain 3 years ago

      That is a remarkably low cost. can you share the specs?

      • Chris B 3 years ago

        Hi Bruce,

        Rough overview:

        60 SH panels (Ex insurance – 3 -4 yrs old $60 each) Shipped from Qld

        24 Fengyan 200ah C10, gel Batteries. ($260 each) imported
        3 x 4kw inverters from MUST-Solar. imported
        5 mppt controllers from Wipanda. imported
        Circuit breakers, leads, switches locally sourced.

        Set up: 48 volt, 1200 ah. 4 banks of 6 interconnected with 10amp battery balancers. Trimetric monitor.

        • bruce mountain 3 years ago

          Excellent, really smart. Would be fascinated to see how it has performed.

          • Chris B 3 years ago

            The system has been running now since last August, but we have only recently achieved our interim occupancy, so have not run full load over a long period.

            However, we have done some long weekends in it, with oven, cooking and spa all being used, and it has stood up well within expectations. (Our hot water is 315L Electric heater timed to come on during peak sun.)

            The biggest gap between reality and theory has been cloudy days. I followed the solar power forecasting tool on Solar Quotes for some time when planning, and based on our cloudy day output, they are too generous in regards to what PV will produce on cloudy days. Of course there are lots of variables in measuring such things, and fortunately we have designed in reserve.

          • Greg Hudson 3 years ago

            ”(Our hot water is 315L Electric heater timed to come on during peak sun.)”
            Which leads me to ask (again) why on earth doesn’t the SA Govt mandate ‘off peak water heating / controlled load)’ move from 11pm to 11am which would give all those solar panels something to do instead of going nowhere…

          • Calamity_Jean 3 years ago


        • solarguy 3 years ago

          Sounds like the batteries are actually AGM’s not true deep cycle gels. My BAE batteries are true deep cycle gel’s and are German made, have a very good name with a long history of lasting the distance, cost wholesale to me $12,500 inc.

          Cheap AGM’s aren’t likely to last anymore than 5yrs @ 30% DOD mine will last over 15yrs at same DOD.

          You may think you have a bargain with the gear you purchased, but I’m confident you will find things will go tits up soon. There is no substitute for quality. And good luck with any warranty claims!

  9. Norman Deards 3 years ago

    Who pays $0.46 Kwh? It cost me $0.22 Kwh and $0.11 kwh off peak. Let’s do the sums on those figures!

    • Mike Westerman 3 years ago

      Plus your fixed costs: $1.2/day adds 5c/kWh to many households. Some of the quoted 22/11 c/kWh figures don’t include the network charges – yours?

      • Norman Deards 3 years ago

        You are correct. $1.15 per day network charge adds $0.04 per Kwh. All including GST by the way, but still way short of the charges quoted in the article to calculate the payback. I’m all for solar power but some of the payback calculations used to justify installations are just wrong.

        • neroden 3 years ago

          The pricing from the grid in Australia is designed to be cryptic and confusing: different people are paying very different prices.

        • bruce mountain 3 years ago

          Post your bill please and lets then see. If you are paying 22 cents per kWh in peak and 11 cents per kWh in off-peak you are paying a price far below anyone else in South Australia. Again, post your bill and put your claim up for scrutiny.

          • Norman Deards 3 years ago

            Here are the latest Tango tariffs for my area. I’m not in SA. I’m in Victoria.
            I’m quite capable of calculating my costs thank you.

          • bruce mountain 3 years ago

            Several things: 1. My analysis was for Adelaide not for Victoria. 2. None of the Tango tariffs you sent identify prices of 22 cents peak and 11 cents off peak. You made the claim mate, make good on it.

          • Norman Deards 3 years ago

            Here is a screenshot of my latest bill where you will see the tarriff. My son just signed up for a flat rate of $0.18 kwh in Melbourne. SA prices really are expensive! https://uploads.disquscdn.com/images/a9d51112eea1f37cad375eb950bbeae29d3ce6efc07fd2a34d0479f53370de96.png

          • bruce mountain 3 years ago

            Thanks. But that is not a peak/off-peak tariff with 11 and 22 cents inclusive of GST as you said. It is a block rate tariff with 20.4 and 23 cents block rates inclusive of GST (and most of your consumption is at 23 cents).

            With respect to your son’s 18 cents, I have checked out the data. Today there are 10 (out of 320) flat market offers with a rate of 18 cents inclusive of GST or less. But don’t forget the fixed charge. These offers do not have the lowest fixed charges.

          • Norman Deards 3 years ago

            My cost is just over $0.19 Kwh for the summer months from the last bill, taking all charges and rates into account. But I also get government assistance being a pensioner which brings it down to just over $0.15 Kwh all including gst.

          • Norman Deards 3 years ago

            Hot water ,controlled load, is off peak at $0.11. either way the sums for solar are much different than with rates at $0.46 kwh. That’s the point I was making.

    • bruce mountain 3 years ago

      I have all the publicly available offers in SA in my database updated twice daily. Why don’t you post a copy of your latest bill and I will work out your average price.

      • solarguy 3 years ago

        Bruce, It would nice if could answer my question above.

        • bruce mountain 3 years ago

          Which question please?

    • Greg Hudson 3 years ago

      I know of at least one person paying *** 70c/kWh *** why? Because he has not been bothered to do some comparison shopping. I’ve just killed my Red Energy bill (29.8c) to Alinta @ 18.83c/kWh Anyone paying 46c should check out the Govt comparison web site(s) or iSelect or CompareTheMarket to at least find a better offer (IMO)
      Where do you live Norm ?

      • Norman Deards 3 years ago

        Hurstbridge NE of Melbourne

  10. solarguy 3 years ago

    Bruce, in chart 2, is the $500 export additional and not inclusive?

    • bruce mountain 3 years ago

      I don’t understand the question. The exports are the exports, but for the sake of Excel’s charting approach, i needed to net off the exports so that the height of the battery+PV+grid chart could be compared to the others (which don’t have exports)

      • solarguy 3 years ago

        Bruce, you just answered the question, $500 export pa is additional to the benefits.

    • baseload renewables 3 years ago

      My take on it is that the annual battery charge (in blue) states “net of export”. The export of $500 in red is there for information, and I’m assuming this is for solar PV export and perhaps battery export (not sure which tariffs were used nor if battery export would be worthwhile at all, which is a whole other conversation on technical and economic assumptions). When this $500 is subtracted from the $1107.50 p.a. cost of the battery, the net battery cost p.a. was about $607.50 (shown in blue).

      I’m not sure if any NPV was factored in to buying the system, which would reduce the potential savings, e.g. a 4.22% ROI p.a. of money invested in $16,575 of financial instruments would return $700 p.a. but as I said this may or may not have been factored in. Also not sure if SA has any additional tariffs for PV systems and metering charges like here in Queensland, but based on the fixed charges appearing to be of equal size in the graph (in black), it would appear to me that there are no such charges.

      In any case, based on the analysis and assumptions, it appears then that the savings is about $700 p.a. or $900 p.a. for the BESS/PV system v conditional discounts or no conditional discounts, respectively.

  11. Mark Potochnik 3 years ago

    Looking at the charts. https://www.livingin-australia.com/sunshine-hours-australia/ you are sure blessed with sun hours. Much better than Germany or Northern US. Much less Canada or other countries… Just add a bit more storage and go off the grid. Only reason to hook to the grid is to get rid of excess in summer. #1 is to insulate to cut air conditioning and heating.. Need much more to add and EV and avoid that gasoline (petrol)….
    And no power outages…..

  12. Mark McClurg 3 years ago

    Two fundamental flaws in that analysis. A. Your $5.5k solar system will be with a cheaper Chinese inverter brand. That will never last 10 years. You will be lucky if it goes past 5 years. B. The Powerwall 2, is warranted for 10 years…. It may last 10 years although I doubt it,, but if it fails in year 8, it’s not a full replacement, but a percentage of replacement cost assuming it passed the warranty claim test which requires continuous internet connection for remote diagnostic testing. On the flip side, it’s worth it for new build constructions, where it’s more easily absorbed into overall build costs…

    • neroden 3 years ago

      FYI, the Powerwall is going to last the full 10 years. The trustworthy lifetime is believed to be 5000 cycles. If it cycles daily, 10 years is only 3650 cycles.

      • Mark McClurg 3 years ago

        Why then have a limited ‘balance of life’ warranty and not a full replacement warranty?

  13. neroden 3 years ago

    Note that the solar + battery is cheaper *even if you don’t export anything and just throw it away*.

    This is of course specific to South Australia with its sky-high grid prices (due to market manipulation), but it’s going to be true elsewhere soon, as batteries and solar keep getting cheaper. It’s probably already true on pretty much every island, where grid prices are high even when there isn’t market manipulation. (Lord Howe Island, are you listening?)

  14. Marcelo Pacheco 3 years ago

    The key reason for this initiative is it adds solar to the grid while increasing its resiliency and reducing consumer costs. Its a tripod initiative.
    Costs are just one of its legs.
    Its something that can be adopted to very large extents, as long as each system has 2 hours worth of autonomy, sudden changes in cloud coverage/rain can be easily dealt until fossil backups are only.
    Which is the difference between your Australia and my Brazil. We have a boatload of big hydro, so we can add pretty much all the solar/wind we can install, but we have zero subsidies other than net metering. Even with recent supply (drought) problems caused by atypical (aka potential climate change induced) years.
    Batteries will drop in price by a lot in the next decade, likely much more than solar will. But this requires lots of customers now to keep existing factories 100% busy and justify starting up new ones. Look forward to Tesla having a Giga Factory just for Australiasia, or even one just for you guys.

    • solarguy 3 years ago

      Good, but you can most likely do better with some extra PV.

      • Michael Van Zwam 3 years ago

        I bought my 4kw system back in 2010 for 13k. I am looking to upgrade my system now. Considering that when i run my Air conditioning the Powerwall 2 gets hardly any charge. I estimate that with a 5-6kw system this will not be an issue. Also the efficacy has increased. Back in 2010 5kw system would have been 26 pannels. But now i can get a 6kw system with only 22 panels. For Way less then 13k

    • Daniel Hatfield 3 years ago

      That’s mine from the same period. No battery. 3 person household. All electric..no gas. I’d love battery but until there is a major incentive to get one it would be an ethical decision rather than an economic one.
      I believe (at current energy prices…I’m not good at half century predictions) it would be a 50 year payback

  15. heinbloed 3 years ago

    Latest auction results from Germany

    PV achieved an average price of € 0.043/kWh (200MW auctioned)
    on-shore wind power achieved an average price of € 0.047/kWh (700MW auctioned)

    The Federal Grid Agency:


    machine translation:


  16. Daniel Hatfield 3 years ago

    This is certainly true for the 20kw+ per day users but not for the low energy users.
    As discussed by many guests on your podcast, bringing energy consumption down in the first place is key.

    We have 4.5kw solar and an average quarterly bill of $30. All electric house with no gas. I work from home so the house is used almost 24/7.
    NSW FIT 12.9c

  17. Brad 3 years ago

    The analysis would be even better if it was correct

    • bruce mountain 3 years ago

      ah, huh, and the errors are ….

      • Brad 3 years ago

        Its location dependant

        My tariff is 25.89c and feed in 10.6 excluding GST

        Don’t get me wrong I like solar just had another 5kw installed, however the battery storage doesn’t quite stack up yet

        • bruce mountain 3 years ago

          Ok thanks. Can you post your latest bill or at least state all the rates and discounts. Your FiT is way below what you can get now.

          • Brad 3 years ago

            I’m in regional Qld , our area is still regulated and Ergon is the only retailer

            This is the latest bill before 5kw system, existing one is 2kw, just moved here in November, 24kwh average daily use is high, I suspect it’s the antique carrier aircon

            Last place was 16kwh per day with aircon running just as much


          • GregS 3 years ago

            Thanks for sharing – that’s a heck of big bill.

            How big of a house? Any other big electric draws? Like swimming pool?

          • Brad 3 years ago

            Older small 4 bedroom , 2 fridges, old carrier aircon, dishwasher,electric cooktop and oven, that’s it

          • GregS 3 years ago

            Ouch! Sounds like not much insulation either

          • Brad 3 years ago

            Has roof insulation

            I’ll swap out old carrier for two 5kw invertor units

            And if I ever get my emphases log in I will have a better idea of what’s chewing it

      • palmz 3 years ago

        They also only did a blended payback! They should have shown the savings from a only PV system next to the one with battery’s @ the end of the 10 year period.

        has the battery payed for its self in its own right? and inverters are not likely to last 20 years crap ones might only have 5 years they should last 10 or so years (hopefully more)

        • bruce mountain 3 years ago

          Blended payback? The object of the study here is the combination of battery and PV. You can not extract a battery here “in its own right”. Its value is to arbitrage and access to PV is a key part of that arbitrage. If you want to share the economics of PV only, go for it. Write it up and post it. And I did allow for 1 inverter replacement.

        • solarguy 3 years ago

          I have replaced a few SMA inverters under 5 yrs old, but only a few. Not many are going to last 10yrs or over for lots of reasons. Only come across one that was 15yrs old and still working faultlessly.

          • Mike Westerman 3 years ago

            Ripple filter caps? Seems normal problem with switcjed power supplies n similar

          • solarguy 3 years ago

            Don’t have clue, I just replace em. One thing I can tell you though, is SMA warranty claims are a pain in the arse.

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