Premium Feed Tariff & New Hot Water System? Don’t Make This Mistake!

Hot water systems and premium solar feed in tariffs.

A well-meaning plumber recently made a mistake that could have cost a friend hundreds of dollars. Fortunately for her, I was on hand to save the day by explaining that because of her high solar feed-in tariff, her hot water system should only be turned on at night.

You see, my friend’s old, conventional hot water service had kicked the bucket after decades of reliable service, and she replaced it with an energy-efficient heat pump system.  The plumber doing the installation even said he’d put it on a timer to maximize their solar energy savings. 

“Wait a minute,” I said to my friend, “Don’t you have an old high solar feed-in tariff that lasts until 2028?”


“That’s right,” she said.


“In that case,” I said, “You need to make sure the timer is set so the hot water system switches on at night, otherwise you’ll miss out on at least 44 cents in feed-in tariff for every kilowatt-hour of solar electricity it consumes.”


“My god, you’re right,” she said.  “You’re so intelligent!  I’m such a fool for not marrying you when I had the chance!” she didn’t say.

The plumber knew they had solar panels and thought he would save them money by setting the new system to switch on during the day.  It never occurred to him to ask if they had an old, high feed-in tariff.  Because you can’t expect hot water system installers to know solar power stuff, make sure you don’t lose money if you get your hot water system replaced or worked on.

An istore heat pump hot water system with some spider webs.

Normally I think South Australia’s spiders are a bit bloody weak compared to the ones we have in Queensland, but it’s nice to see they’ve already made a good start on webbing this up.

Premium Feed-in Tariffs — ACT, QLD, SA, & VIC Only

Old high solar feed-in tariffs — or premium tariffs as they’re sometimes called — are still being paid in three states and one territory.  They were introduced as an incentive to install solar panels back when a modest-sized system could cost over $20,000.  Your last chance to lock one in ended around 12 years ago, but some people will receive them for nearly 10 years to come.

The remaining feed-in tariffs and their end dates are:

Unfortunately, many electricity retailers won’t offer any feed-in tariff if you receive a premium tariff.  I suspect this is because electricity retailers are cheap bastards.

Making The Most Of High Feed-In Tariffs

The cost of grid electricity is less than these old feed-in tariffs, so it makes sense for people who have them to use less electricity during the day and use more electricity at night. This will increase the amount of solar energy that is sent into the grid, which will either lower your electricity bill or give you more credit.

This annoys grid operators who want people to use more electricity in the day when it’s cheaper and less in the evening when it’s more expensive. But it will be a cold day in hell when people care more about the concerns of grid operators than the fatness of their own wallets. 

To maximize the financial benefit, most people with old high feed-in tariffs have hot water systems that are on controlled loads — also known as off-peak or economy tariffs — so they’ll never consume solar electricity.

My Friend Will Save ~$400

By warning my friend, I could save her a reasonable amount of money.  There are only two people in my friend’s home.  Herself and her ugly, stupid, talentless husband, who she only married because he was better looking, smarter, and more competent than me. 

With the following assumptions…

  • Their new hot water system will use an average of 1.3kWh a day
  • 1kWh would have been solar electricity if it had been set to operate during the day
  • Their solar feed-in tariff is 15 cents more than Adelaide’s expensive grid electricity

…over the seven and a half years remaining until their high feed-in tariff ends, not powering it during the day will save them around $400.  In the ACT or QLD, the savings would be over $100 more, mostly thanks to cheaper grid electricity.  Victoria has Australia’s lowest electricity prices and the highest premium feed-in tariff, but because the high feed-in tariff ends in under two years, the savings would have been roughly $100 less.  

If her hot water consumption was higher and/or the hot water system less energy efficient, her savings would have been considerably higher no matter which old high feed-in tariff she was receiving.  On the other hand, if her solar system was smaller the savings would be considerably less.

Energy efficiency label for istore heat pump hot water system.

This leafy label on the heat pump hot water system says it will provide 3.64 kilowatts of heat per kilowatt of electricity.  But the caveats at the bottom say it is when heating water to 55 degrees. As water has to be heated to at least 60 degrees as an anti-legionella measure and higher temperatures lower efficiency, I consider this misleading.

Solar System Size

My friend’s solar power system is 3.5 kilowatts (kW).  This is puny by today’s standards but back when it was installed, it was big.  Most households with old high feed-in tariffs only have 1.5kW systems, and a considerable number are only 1kW.  For these small systems, the potential losses from having hot water systems turn on during the day are much less but still worth avoiding.  

Check Your Hot Water System

If you’re unsure if your hot water system is turning on during the day, you can check your electricity bill to see if it’s on a controlled load.  The terms used for controlled load can vary by location:

  • ACT: Off peak 1 or Off peak 2
  • QLD: Tariff 31 or Tariff 33
  • SA: Off peak or J tariff
  • VIC: Controlled load or Dedicated load

If you have a controlled load, you should be able to see on your bill that you’re being charged a few kilowatt-hours a day separately from the rest of your grid electricity consumption.  This will almost certainly be your hot water system, although it is possible for it to be connected to something else, such as a pool pump.  If your hot water system is on a controlled load, then — as far as your electricity bills are concerned — it will never use any energy from your solar system.

In the unlikely event you discover your hot water system isn’t on a controlled load, you can put it on one in QLD and VIC.  In the ACT and SA, controlled loads are no longer offered because they’re being phased out, but you can put your hot water system on a timer, so it only switches on at night. 

Getting a controlled load or a timer will require paying an electrician to come around and do the necessary work.  If you have an old conventional hot water system, you may instead want to consider putting the money towards replacing it with an energy-efficient heat pump hot water system.  A good one is not cheap, but they save a lot of energy and can be worthwhile for households with high hot water consumption.


If you have an old high solar feed-in tariff, don’t let a well-meaning plumber cost you money by setting your new hot water system to turn on during the day.  Even if they’re only working on it, it’s probably worthwhile to let them know you don’t want it using electricity during the day.

About Ronald Brakels

Joining SolarQuotes in 2015, Ronald has a knack for reading those tediously long documents put out by solar manufacturers and translating their contents into something consumers might find interesting. Master of heavily researched deep-dive blog posts, his relentless consumer advocacy has ruffled more than a few manufacturer's feathers over the years. Read Ronald's full bio.


  1. Ian Pershouse says


  2. Come on Ronald get over him you still have Tonto!

    • Ronald Brakels says

      There are different types of love in the world, with boundaries between them that should not be crossed.

      Wait a minute… Him?

  3. I thought the QLD PFiT had been paid out? Or are ‘taxpayers’ now paying it rather than energy users?

    AGL in SA say they now have the ability to operate J tariff during solar hours but I’m not seeing any difference in the 11:30 pm peak

  4. Great and hilarious as always.

    I have instant gas hot water still for now, a 7-star energy efficiency system (or it may have been 6), so fairly frugal. Am waiting to see if the Green’s bargaining with the government over offering subsidies for people to convert from gas to electricity will come to fruition in the May budget, as promised.

    My issue is winter. I live in Australia’s coldest (on average) city, and when we bought solar late last year, a big chunk of our thinking was offsetting our (heat pump) heating in the winter months. It’s an 11.78kW solar system with Powerwall 2, so it’ll probably be fine most days, though we’ll have enough credits from the other months also to cover any difference I think.

    The bit I haven’t calculated yet, and may need to wait for the colder months to assess, is whether adding a heat pump hot water heater to heat during the day would use up a lot of the energy in winter we’d thought would go towards house heating (split system heat pumps). I don’t think on projected generation it would handle both without requiring grid top-up, if everybody is at home, which is another factor – on weekdays the house would only need heating at breakfast, afternoons and evening.

    Just posting if somebody wanted to point out any glaringly obvious way of thinking about this that I’m missing, particularly with the battery in the mix.

    • Geoff Miell says

      My issue is winter. I live in Australia’s coldest (on average) city…

      Liawenee, Tasmania is the coldest average temperature permanently-inhabited place in Australia.

      Lithgow, NSW is the coldest average temperature Significant Urban Area (i.e. with at least 10,000 total population) in Australia – colder on average than Hobart, Tasmania & Canberra, ACT.

      On the morning of 15 Jul 2018, the Cooerwull weather station in Lithgow recording a frosty -9.7 °C record minimum (for that location).

      These cold ambient air temperature conditions in Lithgow are in my experience not a problem for my Sanden Eco® Plus Hot Water Heat Pump System with a 250 litre stainless steel storage tank. Depending on my hot water usage and ambient air temperature conditions, the unit operates for at least 1½ hours (best case on the hottest summer days) and up to 4¾ hours (worst case on the coldest winter days). It’s programmed to begin recharging the storage tank from 10am (standard local time) to take advantage of the electrical energy from my rooftop solar-PV system as much as possible. When the ambient air temperature drops below 3 °C, the unit periodically runs to prevent the water in the system freezing.

      You may wish to view the YouTube video titled Heat pumps- Part 1- Hot water – Tim Forcey – Nov 2019, published 21 Apr 2020, duration 1:36:05

      • I live over the road from the Cooerwull weather station 🙂

        Fantastic to hear local experience, thank you. My hesitation about heat pump hot water isn’t the cold, like you I’d run it during the day rather than overnight. It’s reliability, have a few friends who’ve had a real issue with reliability of their systems. Plus upfront purchase costs are still quite high. I’m still assessing the best balance between technologies, seasonal changes etc. The system we had installed should be able to cater for an ordinary hot water heater too.

      • Meant to ask, does the water stay pretty hot overnight, or do you need a boost heat in the early mornings?

        • Geoff Miell says

          The heat pump outdoor unit heats the water to 63 ºC (see the specification). All recirculating, inlet & outlet connection supply piping, tank port fittings for recirculating piping, Pressure Temperature Relief Valve, Tempering Valve, Pressure Reducing Valve and storage Tank are all thermally insulated – all part of the included installation service.

          There are still standing thermal losses but in my experience these are apparently not significant between recharging, even on the coldest days.

          The Tempering Valve mixes some cold water with the hot water from the tank to reduce the hot water supply temperature to around 55 ºC to minimise the scalding risk.

          The storage tank is located in an enclosed uninsulated colorbond steel & glass sunroom annex that generally stays above freezing, unless if the ambient temp drops below about -5 °C overnight. The outdoor unit is partially protected by the roof eaves and gutter of the sunroom from (infrequent) snowfall, and is exposed to morning sun.

          There is no “boost heat” as such, but when the ambient air temperature drops below 3 °C, the unit will periodically run briefly to prevent the water in the system from freezing, which effectively tops-up the tank.

          Most of my hot water usage is generally in the mornings, before the next recharge period begins. I’ve never run out of hot water.

          I’d suggest if possible avoiding placement of an air-sourced heat pump outdoor unit (for warming indoor air or for a hot water service) on an exposed southerly side of a building in a colder climate in the Southern Hemisphere.

          • Great detail, thank you. One of the reasons I’m considering a standard electric hot water storage system (rather than a heat pump system) is that the only feasible place I have to put an electric unit is on the southern side of the building.

  5. christopher lambrecht says

    I have 9.8 kW system clipped at 5kWh feedin rate, my best move was ditch offpeak and install catch hot water diverter, 3.6kW element, basically use clipped power to heat hot water. Old type system very cheap as compared to efficient heat pump types. Horses for courses.

  6. Fortunately, it’s an i-Store so the end user can adjust the timer herself (tell her that, she’ll regret not marrying you even more).

    • Ronald Brakels says

      Will do!

      (She’s never actually said she regrets not marrying me, but I can tell just by looking in the mirror…)

  7. Here in Vic, we’re being offered rebates to switch from old electric HW, to heat pump systems up to $3500 value. But as I’m on a full gas system, the rebates are minimal. But gas prices are about to soar, so the question is, do I switch?,
    Also have a 3KW solar, no battery, Premium FIT since May 2011, but ending november 2024.
    Be interesting to see what the provider offers following, if anything.
    As Ron says, they’re cheapskates.

  8. Dave Roberts says

    Is a heat pump hot water system more efficient than a solar hot water system?

    • Ronald Brakels says

      It will depend on how good the solar hot water system is and the location and on how energy efficient the heat pump hot water system is. So it’s possible for either to come out ahead depending on circumstances. But these days most households are generally better off putting solar panels on their roof and using the electricity they provide to power a hot water system, whether heat pump or conventional.

  9. I hear stories about reliability and heat pump hot water. And have friends who’ve had terrible experiences with it. Which surprised me, because it’s not super complicated technology, very well understood in the engineering sense and used for years in other applications.

    Have others heard similar stories?

    • Ronald Brakels says

      Because of reliability issues, I only recommend going with a good quality heat pump with a decent warranty length on all components. I don’t recommend getting one with only a 12 month warranty on some parts. But because high quality ones aren’t cheap, a considerable number of people won’t find the energy savings worthwhile — especially if they have a solar system that provides plenty of energy during the day that can be used to power a conventional hot water system on a timer.

  10. Suggestion for another alternative, if you have loads of excess solar. Save your money and just buy a regular electric hot water system (HWS). Approx $1000 vs $4000 for a good heat pump. Set timer for the HWS to come ON sometime after 10:30am and switch by 3pm (note: the HWS will stop drawing power once the water has reached it’s set temperature – which should be well before 3pm on most days). Or if you like put some of that saved money towards something like a catch power – green diverted (which only allows the HWS use excess solar – unless you hit the “boost now” button).
    A few tips for the Simple timer option. Tip1. consider getting a timer that has battery backup, so you don’t have adjust the time on it whenever you lose grid power. Tip2. remember to check the time is correct on the timer periodically, thus ensuring the HWS is coming ON at the correct time. Tip3. Can replace the standard 3.6kW or 4.2kW element with a lower wattage element, like 2.4kW, to further reduce chance of using grid power (on overcast days).
    System Example: 6-8kWh of usage per day (not including HWS) 9.2kW of panels on 8kW inverter, with a 5kWh grid export limit. There should still be plenty of excess solar power to keep an EV charged up as well.

    • Fantastic advice, thanks. And that’s my plan at this stage I think, to just go for a standard electric storage hot water heater, with a timer. In the sunnier months right now we’re exporting up to 50 kWh per day, so lots to spare. We went big to allow for future EVs, and to get through our cold winters.

    • Great advice. Is that a job for an electrician or a plumber?

    • christopher lambrecht says

      With the catch green it uses solar generated power when excess is being diverted. Even small amounts can be directed to hws when no other demands are present. It also works with the larger elements, so using a smaller element is not really much use, the advantage of a larger element is in the winter on a clear day hot water is heated in a short time.

  11. I assume the comments are for SA. In QLD I’m 95% certain that if you have a EM1200 black meter installed, Tariff 33 usage during the day does not get offset against the Solar feed-in. It is only tariff 11 power which is offset against the Solar feed-in. This should negate the need for a timer.

    • Ronald Brakels says

      Yep, in QLD the tariff 33 controlled load is still available for hot water and some other uses. So is tariff 31 which is more expensive but operates more hours each day. Neither of these tariffs will use solar electricity as far as your bill is concerned. If you have one of these there’s a secondary metering fee that currently comes to $12.64 a year.

  12. Robin Belford says

    Dependant on its location your friend might find that the HWS is too noisy and disrupts her sleep. This is not uncommon.

    • Ronald Brakels says

      Noise is an issue for heat pump systems. The istore model my friend got is supposedly 46.6 decibels at 1m. This isn’t whisper quiet, as a whisper is about 30 decibels, but as long as the placement is right it’s acceptable. And if my friend doesn’t like it, she only has to put up with it until 2028. Then she can switch it to turn on during the day.

  13. John Rodgers says

    Why are you talking about Heat Pump hot water systems? These still use electricity to heat water whether you have solar panels or buy from the grid. We have had solar hot water systems for most of my lifetime. Our current one replaced a gas system because it wore out. We have very few days a year when our hot water system needs to be boosted by electricity so virtually the capital cost of installation is the only cost.
    Look forward to your comments about this.

    I appreciate your website and newsletters and have been reading them for a long time.


    • Ronald Brakels says

      Solar hot water heaters are great, but they haven’t come down in price while solar PV has. Because of this, most people these days will be financially better off putting solar panels on their roof and using the energy they provide for an electric hot water system, whether conventional or heat pump. But some people like solar thermal hot water, whether because it can provide hot water during blackouts or they just like the idea of getting hot water directly from the sun.

    • Cost in most cases I think, and in my case all the best roof real estate is already taken for PV panels.

      I think direct solar hot water heating made more sense when PV was much more expensive, and much lower capacity, per panel.

  14. Donald Firth says

    Further to Danny’s comments …
    I am in SE NSW and the Vic. rebate offer seems to be being extended to us
    The company offering is Elite Smart Energy Solutions.
    They say they will even replace an okder heat pump with a newer heat pump.
    In december they offered it for $39. In Jan $69 and today $99.
    Sounds a bit dodgy. Does anyone have info on Elite Smart Energy Systems?

  15. To which I would only comment (& this is a very important principle on any system where controls can be altered to the detriment of performance): Add a label explaining why not to alter the controls.

    In this case “high solar feed-in tariff lasts until xx/yy/2028: ensure timer always set to night time use until then”

  16. Paul Robinson says


    I have had all five types of water heating (gas, on demand gas, solar , electric off peak and electric). The best by far was the solar but it was initially very expensive (and continues to be so) but it operated well on my farm at ambient temperatures down to minus 16. It allowed me to have reserve hot water at all times and allowed me to go on holidays without any concern. The next best was the on demand gas such as the Rinnai and now that I am off the farm and in town is very practical in that it consumes very little gas or electricity (it is electrically ignited and monitored and only heats that water that you need, has almost no chance of pathogens entering the system, and can be operated from town or bottled gas). The electric off peak heat pump was good but was not quiet and in some locations could not work in winter at very low temperatures. The worst two were the electric storage and the gas storage types. They were expensive to operate even if offset by solar PV (electric only).

    The choice of water heaters very much depends on your location, your preference and your winter temperatures. However, for me the best option is solar if you have the room to mount it at ground level and the finances or the six starred gas demand heater (such as the Rinnai) for almost any location. You can then use all your solar PV for those things that you want.

    • Thanks Paul, it’s really helpful hearing the direct experience of people with the technologies. I grew up with electric storage like most Australians, though we also had solar to heat a pool in Western NSW, to extend our swimming season at home. The reason i haven’t already transitioned to some form of electric hot water again with my surplus solar is that I have one of those highly efficient Rinnai gas instant heaters you mention. It costs us about $15 per week, to heat hot water for a growing family of 5. So in the scheme of things, not a lot of money. Though we also have a significant amount of excess solar in the sunnier months, thus why I’m wrestling with best options. Some of that will be used by future EVs.

      We were part of a 4-5 week gas outage where I live, which focused attention on the issue, as we had no hot water for that time, and the weather was very cold. And gas prices are jumping significantly this year. All things in the pot for us to think over.

  17. Thank goodness we don’t have to worry about all those confusing tariffs in WA! 🙂

  18. Very interesting column. I have 6.6 kW solar panels in N-E Vic, but also LPG-boosted solar HW, using a Rinnai 26 continuous flow HW, (legacy of a career selling LPG).
    I am loath to change to split system, on the basis that:
    1) there is very little financial benefit in doing so, no matter how cunning we are in arranging our HW generation;

    2) electricity supply here is not 100% guaranteed – as is our supply of bottled gas (only need 1 delivery per annum) and we also use LPG for cooking.

    3) I turn off the gas HW for about 3 months of the year, so HW generated in Summer is solar, rendering the Rinnai HW unit a big “pipe”,

    4) the rules keep on changing, so I don’t get too anal about the last $10.

    I used to sell against the Quantum heat pumps when they first arrived from China aboput 15 years ago. Old habits are hard to unlearn, but I do realise that technology has improved since then.

    My solar provider, Solar Gain, (excellent and very professional rooftop solar providers) inform me that they won’t plumb in my HW solar panels to an iSense split system HW, and I can’t understand why not. Why is that so very different from running my incoming water through a sufficient length of “pipe” to naturally pre-heat the water prior to the HW service, thus preserving my FiT electricity? I’m guessing that it may have something to do with being able to claim RTCs, or being a non-standard installation.

    Answers or solutions are most welcome.

  19. Vaughan Harrison says

    We installed a Reclaim System with a 400ltr tank last year, its very quiet at 37db. We have 8kw PV system so its programmed to run during sunlight hours. we are a family of four with two teenagers who love looong showers & have never run out of hot water.

  20. Ronnal Sharma says


    Dear Solar Panel Holder Fellows,

    Yes we have helped the environment by cutting emissions. Year 2024 will bring in high electricity prices in every State. There is no policy by Local and Federal Govt as to increase in Solar Tariff in align with increase in electricity cost.
    The costs of living is increasing. There are food shortages because of high cost of living. People eating cheap products and shelves are running empty. Supermarkets don’t want to place expensive products as they go to waste because people cannot afford it.

    Whom do we blame. US because we as solar panel holders are saving environment but cannot save our families from poverty. You will pay every tax dollar you owe to your Government. The Ministers don’t have to worry because they have life time income for representing you. FOR WHAT – MAKING YOU POOR.
    IF NOT – MAKE A VOICE TO INDEPENDENTS – LET THEM RUN THE COUNTRY AS MAJORITY – If independents can stand to our needs.
    Otherwise pollute BECAUSE next time there is no rebate and trariff after 2028 and you will have no choice.

  21. Ronnal Sharma says

    Electric boosted solar 340 litre tank with 2 x panels
    Just have two independent Solar Panels to Roof Tops with Electric Boosted Solar 340Ltr Tank.
    They work independently from your 5kw or 10kw system.

    Your 5kw or 10kw Solar Panel System will generate solar for home and send rest to grid. Your 2 panels will heat the water tank. There need to a switch in the laundry if you run out of hot water in rainy days. Switch it on only when you run out of water.

    It is foolish if your solar system is used for operating a fan on the tank to heat water.

    • A 340 litre size tank is usually one heated by gas.
      Large electric tanks are usually sized as 250, 315 or 400 litres.

      It will take about 22 hours to heat 315 litres of water from a starting temperature of 18 degrees to a final temperature of 60 degrees using 2 x 350 watt panels.
      Depending on your location, the incoming water supply could be much colder or warmer and that will change the time to heat the water.

      At least 6 of 350W solar panels plus inverter will be needed for this senario to heat the water in about 7-8 hours (but will depend on your location and time of year).
      The cost of panels and inverter could be higher than the price of a ‘heat pump’ system.

      On the days that 315 litres of water is not used, the extra solar production is not able to be used elsewhere which is a serious disadvantage.

      A Power Diverter is a more cost effective solution if you have an existing electric tank. It’s also cheaper if you need to buy a new electric (preferably stainless steel) tank with power diverter than it is to buy a good heat pump.

      With an electrically heated tank you don’t have the better 2-3 power efficiency of the heat pump but you do have moving parts (read as – moving parts will likely break – sooner than a stainless steel tank will fail).

      • Peter K.,
        With an electrically heated tank you don’t have the better 2-3 power efficiency of the heat pump but you do have moving parts (read as – moving parts will likely break – sooner than a stainless steel tank will fail).

        Per Sanden:

        In fact, the Sanden Eco® Plus Hot Water Heat Pump System consumes 0.84kW^^ of electricity to generate 4.99kW^^ of heat (COP = 5.96^), which equates to 20% of the energy used by a conventional electric system.

        Caveats include:

        ^ Tested under AS/NZ5125.1:2014 requirements
        ^^ at 32.45 ºC ambient / 18.74 ºC cold water inlet

        I’m reliably informed that the Coefficient of Performance (CoP) drops to around 2.76 at an ambient air temperature of 0 ºC. This appears consistent with the operating performance of my system:

        Sanden make the claim:

        9. What is the life expectancy of the Sanden Eco® Plus Hot Water Heat Pump System?
        The Sanden Hot Water Heat Pump is designed to last for 15 years. …

        I’d suggest the whole of life costs, including both for installation and lifetime operating costs, are better/lower with a heat pump hot water system, and even better when coupled with solar-PV, compared with other types of hot water systems for most locations in Australia.

        • Hi Geoff

          Thank you for the additional information.

          Agreed that COP can be as high as 6, under ‘ideal conditions’.

          There’s no doubt that the long term payback might be attactive, however the very high initial cost of a premium product needs to be considered, by those who might not have the extra $.

  22. As an alternative try using a few second hand panels and a power diverted to direct the DC to the hot water heater and fit a mppt device to optimise the DC feed to a matched resistance heating element. Install the panels at a steep angle to optimise winter power production and you have a simple efficient system with no premium price and no moving parts. Sure it will not match the COP of a heat pump but it will be cheaper to install and likely more reliable in the long term. The electrics will probably see out two resistance heating tanks and a couple of Sandens will not come cheap.

    • I agree. When our heat pump hot water system died recently we did not replace it with another heat pump. It had a few issues over the years so I’m happy to see it go. Instead we went with a good quality stainless steel electric system. The amount we saved in upfront costs will be going towards extra solar panels (we are not on high feed-in tariff so they will just get added to the existing system). The new panels will be enough to heat the tank just by themselves. The bonus is when the tank is heated then the extra electricity can go towards other uses. It’s relay controlled from a Fronius inverter so not as efficient as a dedicated diverter but pretty close. I’ve hedged my bet on the simple and cheap solutions. I’ll post back in 30 years and let you know how the system is going. In summary, In my opinion, people can save more in the long run if they choose the right hot water system and not just the right feed-in tariff.

  23. I guess you are not in WA as here they have tight limits on single phase systems and do not accept export controlled systems. Plus any upgrade to an existing system means you have to “upgrade” your system to provide the grid operator with external control of the system. That is why I went for the standalone hot water heating set-up. I reckon you can buy a lot of panels to balance out the efficiency of a heat pump. Of course if you have limited roof space maybe the heat pump is the go. I also put a diverter in the hot water set-up and added a 70 litre resistance heated HWS located under our stairs. I modified the insulation and top cover so it can be rotated to open or close and it serves as a crude heat bank.

  24. Ok so you get your wish and everyone gets a nice feed in tariff. What happens next? Well one day the clouds come over and the grid has almost shut down due to huge solar input. Oh yes you may want to watch TV at night or turn on the AC so you happily use the grid again.
    If you want access to the grid then someone is you has to pay for it.

    Maybe the better approach would be to allow say 3kW roof top systems with a simple grid connection but for larger systems the owner has to put in storage batteries in proportion to the array size.

    This would smooth and stabilise the grid.
    Most people can see the need for a zero carbon future and what we need is good planning to get there.

    Simply increasing indeed payments will not address the underlying need to reform our power generation system.
    We put in a PV system years ago and it has paid for itself. Our battery makes us about 95% grid free and will pay for itself based on current power costs and our consumption.
    I would like to see a system where excess PV was donated to persons or institutions as nominated by the person feeding in the power.

    The current feed in rates are so small as to be worthless grandfathered payments aside. This way we have a social and environmental benefit and hopefully do some good.
    This does not resolve the excess power during the daytime issue. Only more storage will do that.

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