Tesla Battery and Solar Panels

Mahalo on 26/05/2021 - 23:33

Hi.. renovations are going well.. thanks for previous feedback home network 🙏🏽. I am now looking for a solar system, I have been quoted for these systems as follow but I am also looking for a battery. Our average daily usage is 43.58kWh.

Quoted system:
Trina 28 370w panels
with Fronius inverter $6600-$6991
or with Solis Inverter $4491-$4591

Longi 28 370w panels
with Fronius inverter $6491
or with Solis inverter $4499

My question is do I need a battery? Installers told me the system above should cover most of our needs and battery would be lot more costly at this stage. I am also looking for feedback regarding the above panels and inverter quality.. Initially i wanted to get the Fronius Inverter but the installers are telling me the Solis is the way to go.. Note these are two different installers both say the same thing.

Thanks in advance for your feedback, I am in NSW by the way.

Electrical & Electronics Solar Panel Tesla Inc

Comments

  • auindie on 26/05/2021 - 23:40
    +1

    Based in Melbourne I went with Fronius and Longi combination last year and must say that I am super happy with the decision .Though it cost me an extra but the system has provided enough credits over an year to justify the investment .Based on my research the installation and service counts more than the product.Suggest to invest good time in deciding the installer and check their reviews and credibility .
    On the other hand Fronius inverters are bit noisy due to the inbuilt fan so decide a place where you don't get bothered by the noise during day time .For me the installer insisted to put it on a garage brick wall and must say that it was a wise decision to protect the system from rain and sun.
    Happy to answer if any more queries

    • Mahalo on 26/05/2021 - 23:48

      Thank you I totally agree, both installers appear to be good at what they do and have thousands of positive reviews. I will check them out before i commit and see if they are real reviews though.

  • mskeggs on 27/05/2021 - 06:11
    +10

    Your power usage is about double the average house. I would definitely try and spend some money on cutting that back first. Replacing lights with LEDs and insulation would be where I start.
    Spend $150 on a power meter that can graph your usage. Efergy is a reputable brand.
    This will tell you if your usage is when the sun is up or not.
    If you can move a lot of your usage to daylight hours, by running hot water heaters or pool pumps on a timer, for example, you might cover 75% of your power use without batteries.
    If you can’t do that, and you use a lot of power after dark then a battery makes a bit more sense. They are costly, but should pay for themselves within the warranty period - so any life that remains is a bonus.
    And you might have other reasons to spend money now in a lump to avoid ongoing bills. Many retirees take this path.

    Of the solar options, I would choose Trina and Fronius, both known brands with track records and local dealers.

    • Mahalo on 27/05/2021 - 08:21

      Thanks mate. Yes our consumption is pretty high and need to check what’s going on.
      I have a feeling that is the pool pump. Will also check the standby and turn off what we dont use. Lots of appliances are smart appliances and light as well so maybe these are consuming more energy too.

      Initially I wanted Fronius with Trina too.

      • kipps on 27/05/2021 - 08:54
        +3

        43kwh/day is likely significantly contributed to by air cons, heaters, pool, & electric hot water. Get the biggest solar system you can afford on the roof irrespective of how much you can reduce consumption. Get an inverter with a good consumption meter. The battery is unlikely to be financially viable or pay for itself during its useful life so I wouldn’t focus on it.

        • KRM123 on 27/05/2021 - 13:42

          Kinda true. Don't go too big or your FIT drops off significantly.

          AGL and Origin offer 16c and 14c FIT with limits.

          Origin allows 13.3kw panels with a 10kw inverter, but if you go over 10kw on the inverter you drop to a lower FIT around 7c/kw. 33% over the inverter size will maximise your STCs, making system cheaper.

          AGL only allow 10kw maximum panel size (they don't rate based on inverter), but a lot of people have still managed to sign up to their 16c/kw having 13.3kw on 10kw inverter by saying their system size is 10kw, however if or when they find out your system is 13.3kw on 10kw they will bump you down to their 7c/kw tariff (has happened to a few).

          I'm about to install a 13.3kw/10kw system. Wouldn't bother with a battery right now. The payback is at least 15 years+ on a battery expected to last 10 years

  • hentabara on 27/05/2021 - 07:08

    You need to check daily usage, whether you use it mostly at night or during the day.
    Night: to buy battery.
    Day: doesnt need battery

    Having said that, i only use 12kwh per day. You need to check what you are using, as it seems excessive.

    • Mahalo on 27/05/2021 - 08:24

      Thanks I really think is the pool pump. But yes it is excessive.

    • knasty on 27/05/2021 - 10:06

      2nd alternative - if your night-time usage is high go onto time of use billing. Off peak power is cheap - I'm paying 12.2c on AGL. Daytime (peak) use will be offset by the solar.

      I changed my 1.5hp pool pump for a 2 speed efficient pump; it runs at <400 watts on low speed which still puts out >80% of the pressure the old pump did.

      • Mahalo on 27/05/2021 - 10:28

        we are also with AGL our off-peak is 12 cents and peak 42 cents.. see the summary below. We have more offpeak usage. I am not sure what "Shoulder" is that seems to be the highest

        Usage and supply charges Units Price Amount
        Peak 645.921kWh $0.4249
        Off peak 815.524kWh $0.121
        Shoulder 1780.887kWh $0.1833
        Controlled Load 2 679.518kWh $0.1165
        Standard Feed-in Tariff 0kWh $0.095
        Supply charge 90 days $0.7403

        my pool pump is a waterflow 1HP

        • knasty on 27/05/2021 - 12:55

          I'm in Endeavour Energy zone so here's mine:

          ENDEAVOUR ENERGY:
          Peak Energy: From 1 pm - 8 pm on business days.
          Shoulder Energy: From 7 am - 1 pm and from 8 pm - 10 pm on business days
          7am - 10pm on weekends and public holidays.
          Time of Use Off-Peak Energy: From 10 pm - 7 am on every day

          Given you are looking at a large system and feed in credits aren't great if you choose not to go with a battery I'd suggest a split array which faces the sun when you are using the most electricity. For me that meant 2/3 facing north and 1/3 facing west. The west facing ones don't produce as much in total but they do get it in the late afternoon which is when everyone is getting home, putting the oven on for dinner etc. If you get a battery a fully north facing system would likely make more sense.

        • KRM123 on 27/05/2021 - 13:43

          Look to get an energy-smart pool pump. Usually variable speed technology. Will cut down usage heaps. You can also buy an adaptor for old pumps that converts it to variable speed (just a powerpoint adaptor that goes between wall socket and the pump plug)

          If your handy and have a shed nearby your pool, you could also get a DC power pool pump, and get a bunch of dirt cheap 2nd hand solar panels off gumtree to run only your pool pump from DC. The pool pump will run all day. I'd still also recommend a dedicated solar system for the house as well.

          • Mahalo on 27/05/2021 - 17:24

            @KRM123: Thanks. Our pool pump runs from out chlorinator. I am going to monitor these.

            • KRM123 on 27/05/2021 - 19:27

              @Mahalo: Usually, the chlorinator has a plug with a timer, so it kinda just passes the AC power through to allow the pump to be running when the chlorinator is running.

              You should be able to just set the chlorinator to switch on in a window when you definitely know the pump is running off DC (I.e middle of day when its most likely to have enough power from solar to run the pump). You don't want to run the chlorinator without the pump.

              If that all sounds too technical why not try something like this? If you have an old single-speed pool pump you basically plug this into the chlorinator and then pool pump into this and it reduces your pool power requirements in a similar way to a variable speed pool pump. will save you heaps $$$ and usually pay for themselves in 1 year or so.

              http://www.uberpoolperth.com.au/equipments/pump-energy-saver…

              • Mahalo on 27/05/2021 - 19:28

                @KRM123: Thanks mate. Will look into this too 🙏

              • Mahalo on 27/05/2021 - 19:37

                @KRM123: So this slows down the pump? In the video they seem to run the pump for longer in low speed.

  • David2017 on 27/05/2021 - 08:11

    I agree with Hentar. Unless you're running two pools or there's 12 people living in your house then your usage is high.

    A Powerwall is about $14K installed. Most solar installers aren't pushing them because they don't have the training to install them. You need a battery if the answer to any of these questions is yes.
    If you have a blackout do you still want to have power? The PW owners in Queensland on Tuesday didn't notice the Callide explosion.
    Do you want to store the excess energy that might get exported to the grid so you can use it at night?

    If you're using most of your 43kw/h during the day your solar may not make enough power to charge the battery to use at night. If you're using most of your power at night a 14kw battery won't last long given the amount of electricity you're using.

    • Mahalo on 27/05/2021 - 08:28

      Good point if the pool pump is the issue I am using most of the electricity during the day.
      Another power consumer could be the dryer. Since we are building we use the clothes dryer a lot too.
      We are a family of five with three kids under 10 so it is excessive consumption.

  • norrisrules on 27/05/2021 - 08:11
    +2

    Having a battery is pretty awesome. Ours has already saved us from ~10 power interruptions in 2 years, 2 of which were several hours long. It's awesome being the only house in a neighbourhood with lights on :)

    Given that solar feed in credits are only going to get worse, I wouldn't base any decision on how many credits you can get selling solar. Either shift your usage or get a battery. Some people are also moving their hot water from controlled load (night time) to during the day to utilise their solar

    • Catullus on 27/05/2021 - 11:13

      Yes. That's the idea, have HWS on normal day circuit to use the solar, but also incorporate a timer so it can't heat at night irrespective whether you have battery or not.

      • kipps on 27/05/2021 - 11:20
        +2

        Don’t use a timer - use a relay in your inverter. My Fronius turns on HWS when net production hits enough power to power HWS. That way you’re not heating water when it’s cloudy.

  • Mahalo on 27/05/2021 - 08:33

    Right.. good advice there need to reassess our usage

  • pgp82 on 27/05/2021 - 08:54

    We recently installed a 10.36kw system with Jinko 370w (28 panels) and a Fronius 8kw inverter for $6500 installed. Installer was great and made sure everything was connected properly and did a very neat job. If you are in Sydney I can put you in touch with the installer. I would stick with Fronius over Solis. Very happy with the performance of the system so far. But yeah your usage seems quite high :).

    • Mahalo on 27/05/2021 - 10:12

      Seems that from the advice getting here Fronius is the way to go which is what we originally wanted.. The difference is a couple of thousand dollars

      • netjock on 27/05/2021 - 11:34

        Fronius is the Tesla of inverters. There is a following.

        I've had 3 growatt inverters in 3 installations 4kw, 2x 5Kw and it does the job. 10 year warranty like the Fronius.

  • apple2016 on 27/05/2021 - 09:53

    Tesla powerwall or any battery is good if you want to store and re-use the power as feedin tarrif is quite low these days.
    Also if think your next car would be an ev, maybe investing in a battey might be a good option as you would most likely recharge the car at night.

    • Mahalo on 27/05/2021 - 10:13

      Thanks i think a Tesla car is probably not in the very near future but definitely one day

  • c64 on 27/05/2021 - 11:43

    Our average daily usage is 43.58kWh

    running a factory?

    • Mahalo on 27/05/2021 - 12:06

      haha if i was growing something between the walls i wouldn't be complaining about the cost but no. just something here is sucking up energy and i am going to have to find out what it is.

  • netjock on 27/05/2021 - 11:43

    How big is your system? 28x 370w is 10.4kw. You should have 1.33x total panel Kw to your inverter. Is your inverter 8kw and 3 phase?

    The extra cost of Fronius seems a bit steep.

    Do you need a battery: it depends on your usage. If you use enough of it after the sun goes down on time of use on highest rate then maybe it is worth it. Also how can you shift your usage during the day during day light hours.

    • Mahalo on 27/05/2021 - 12:07

      we only have a 1 phase and yes getting a 8kw inverter.. we seem to use a little more during off peak

      • netjock on 27/05/2021 - 13:11

        Fronius is between $2k - $3k for 8Kw single phase.

        Solis is between $1k to $1.5k for 8Kw single phase.

        Both quick google search.

        I'd ask the installer to adjust their expectations or justify why it is much more for the Fronius.

  • SingletonOfT on 27/05/2021 - 11:57

    I highly recommend getting something like IoTaWatt to see what is using your power and during what times like on this graph

  • Drakesy on 27/05/2021 - 12:21

    That energy usage though.
    Would have to be running a big air conditioning system 24 hours a day/it's a huge house to hit those numbers.
    Or OP has like 8 fridges
    Or charges an electric car every day - would need to be doing ~220k's a day to justify it.

    Would definitely look at increasing efficiency in addition to the solar panels.
    Out of interest how big is your energy bill?

    • Mahalo on 27/05/2021 - 19:27

      Nothing like that.
      I have 1 tv
      An old fridge which going to test as it can be sucking up energy as well if faulty???
      I pay around 3.5-4K in electricity a year

      • Drakesy on 27/05/2021 - 21:54
        +1

        Jaysus
        Definitely look at the fridge

  • brad1-8tsi on 27/05/2021 - 18:19

    I did the sums on adding a battery to the system we put in in 2018 (now paid for). Batteries still have a 6-8 year payback for our usage. Not worth it for us.

    • DoctorCalculon on 27/05/2021 - 20:08

      If you owned an EV, it would make sense if you are charging overnight.

      • brad1-8tsi on 27/05/2021 - 20:34

        I don't know.

        I do <10k km a year these days (lots of Public Transport use) so an EV isn't a financial choice I'd make. Also, our house with the Solar PV hasn't got off-street parking, so charging from home would be challenging.

        The apartment hasn't got solar PV (yet). If we get a distributed system we will rethink the need.

  • Feeblely on 27/05/2021 - 18:47

    can someone help me know if it's work adding battery, if 50% usage comes at night? Daily usage is 20kWh.

  • DoctorCalculon on 27/05/2021 - 20:07
    +2

    I pay around 3.5-4K in electricity a year

    This is completely insane, OP.
    Roughly how big is the size of your household?

    Also, do you have a smart meter? If so, have you looked into Powerpal to measure your usage during the day?

    Average daily usage is 43.58kWh

    I almost fell off my chair when I read this figure. Could you possibly have a faulty meter? Or, are you mining bitcoins in your basement? ;-)

  • Kiro on 28/05/2021 - 07:52
    +1

    ive got 32 250w LGs with furonis 3 phase inverter couple to a tesla 2 battery and cant complain. bill went down from ~2k per quarter to between 100 and 200 per quarter.

    i too have a pool with 3 pumps and 3 fridges and 2 AC systems. i was thinking of adjusting times of when pumps run etc but really from what i see im getting away with my solar compensating during the day when my pumps run anaway.

    adjusting pumps in pools to run during hte night its the way to go but really it comes down to trial and error and see what combination works for you.

    with a large solar install i would get 2 teslas as my now can recharge a tesla 2 in 4 hours from flat.

    • DoctorCalculon on 28/05/2021 - 23:47

      ive got 32 250w LGs with furonis 3 phase inverter

      Did you convert your meter to 3-phase before or after installing solar panels?
      Also, why didn't you go with the enphase micro inverters?

      • Kiro on 29/05/2021 - 20:25

        Already 3 phase.

        At the time the micro inverters cost a small fortune.
        I think to quote micro inverters they roughly said double in price but regardless I have a great set up.

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