Cost to Replace Solar System?

EightImmortals on 24/04/2026 - 13:39
Last edited 24/04/2026 - 14:24 by 1 other user

Just moved into a new home which has a rather aging 4.2kw system already installed.

The highest output I've seen is around 2800 (and that was after I cleaned the panels) Just curious what might be the cost to replace the panels? I assume the inverter will need to be replaced as well. It's an old Solarmax one which was OK for its day from what I've read but they no longer make them.

There's no room for extra panels, can the current ones just be replaced, maybe with higher output units using the same working and mounting?

TIA

Home & Garden Solar Energy System

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  • singlemalt72 on 24/04/2026 - 14:00

    If you are replacing the solar system it would be best to start at the sun and work your way out, gets rid of the heavy lifting early.
    :P

    • 64
    • kanmen on 24/04/2026 - 15:53

      It's giving Project Hail Mary vibes

      • 5
    • GordonD on 24/04/2026 - 18:21

      it would be best to start at the sun and work your way out,

      It would be best to start with the sun because once you got rid of it you wouldn't have to work your way out. With nothing holding the planets in orbit they'd just head out into interstellar space themselves. And if you tried to tow the sun away to somewhere to dump it, the planets would follow by themselves.

      • 1
      • bigticket on 25/04/2026 - 13:41

        And if you tried to tow the sun away to somewhere to dump it, the planets would follow by themselves.

        Thats exactly what I'd do. Tow the sun and dump it the middle of nowhere, halfway during of the night so I don't get caught and order a new solar system from Aliexpress and tick the checkbox option that reconfigures each gulf state with coastlines along the Indian ocean and clear wide seas into the mediterranean sea.

        • 1
    • dd22qq on 26/04/2026 - 17:34

      Fun fact: The core of the Earth is hotter than the surface of the sun

      • 0
  • mskeggs on 24/04/2026 - 13:42

    Unfortunately, it's almost impossible to get a quote for solar in Australia. There are no sites begging you to enter the details so they can sell them to 3 suppliers, and no local solar installers to ring.
    Shame, but good luck.

    • 61
    • Baysew on 24/04/2026 - 14:26

      Perhaps our overactive App makers should focus on that.

      • 8
      • BOGOF on 24/04/2026 - 14:38

        Something should appear within the next 10 minutes.

        • 2
    • Dr Phil on 25/04/2026 - 13:53

      Well getting 3 quotes is the usual way to find out….Not asking here.
      Such quotes are site specific.

      • 0
    • drprox on 26/04/2026 - 14:09

      Lol. Funny as F 🤣

      • 0
    • EightImmortals on 24/04/2026 - 13:49

      Hey, enough of that, I was looking for OB real life experience before I start bugging people. Besides, how much spam-bombing will I suffer if I give over my email and phone number?

      • -7
      • mskeggs on 24/04/2026 - 14:07

        It will be the cost of a new system plus a little extra to remove the old one.
        Likely a few hundred dollars for the removal.

        • 6
  • GordonD on 24/04/2026 - 18:02

    Cost to Replace Solar System?

    Astronomical.

    • 44
  • tenpercent on 24/04/2026 - 14:01

    Cost to Replace Solar System?

    I don't know if you could replace the Solar System. But I expect it would be very expensive. The most expensive human endevour, ever. Let's hope for all our sakes it's not necessary for a few more years.

    • 17
    • HairyChickens on 24/04/2026 - 14:49

      I reckon about tree fiddy

      • 5
      • Nigemtb on 25/04/2026 - 09:33

        You ain't no girl scout, you the loch Ness monster

        • 1
    • freefall101 on 25/04/2026 - 17:35

      There's over 100 billion free stars in the milky way alone and likely trillions of planets, so far we've only found one that's occupied.

      I say just take one of the existing ones, who's going to stop you?

      • 1
    • Grunntt on 25/04/2026 - 12:18

      Maybe take the alternative option

      Unfortunately it's still a little expensive.

      • 0
    • nobro25 on 25/04/2026 - 22:59

      It's not hard…Ask Rick and Morty they can replace an entire universe as a car battery, replacing a solar system will be easy 😀

      • 0
    • try2bhelpful on 24/04/2026 - 14:09

      I think Voyager could give you a quote. It has a handle on the scope.

      • -1
  • Ryanek on 24/04/2026 - 14:22

    You're essentially paying for a new system plus removal. Just get the best price.

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    • EightImmortals on 24/04/2026 - 15:36

      Thanks. :)

      • 0
      • GordonD on 24/04/2026 - 18:06

        Yes, that's the situation. It is quite technically feasible to just replace the panels with fresh ones. But no solar installer would want the job. They'd want to pull all the existing panels off the roof, chuck them and the inverter away, and sell you and install a completely new system that they'd be able to guarantee has no components that were likely to fail soon.

        • 3
  • welcomeUniverseWorld on 24/04/2026 - 16:52

    I have never clicked on a title as fast as I clicked on yours. Mate, your title is 100% awesome!

    • 5
    • Simon Beech on 24/04/2026 - 16:59

      username checks out

      • 2
    • EightImmortals on 25/04/2026 - 08:27

      I'm impressed a couple of you caught the double entendre. :)

      Looking to be a expensive for either ATM.

      • 0
  • SBOB on 24/04/2026 - 15:50

    Price of a new system plus a few hundred $ to remove the old.
    None of the existing will be reused except maybe mounting rails (and even then they depends on panel size,mounting requirements and increased system size)

    • 3
  • AustriaBargain on 24/04/2026 - 15:58

    You'd have to replace everything in the Solar System, so literally all the wealth in the world.

    • 3
  • knasty on 25/04/2026 - 10:30

    Given you already have a solar system you will get the battery rebate so I'd be looking at getting a decent mid-sized battery system with a 10kW inverter so you can charge it for free over lunchtime and leave the solar as-is.

    • 3
    • AdrianW on 25/04/2026 - 15:17

      "Charge it for free" - depends which state, no free power in WA.

      Those panels definitely needs replacing. The OP didn't mention how many he had, but new panels will produce significantly more power than 2800W.

      Getting a battery and new inverter at the same time and the panels will hardly cost much more anyway - the STCs almost offset the entire price of panels.

      The OP may also be able to get more panels on other roof directions.

      • -1
      • b2tf on 26/04/2026 - 09:48

        VIC was not part of the free power and now the state govt announced they are implementing it later this year.

        You could also charge the battery using cheap offpeak rates. Do the numbers, getting battery first may work out better than replacing solar.

        • 1
  • BuddhaBoy on 26/04/2026 - 13:01

    I glanced through this and thought this is a sci-fi question. An expensive one.

    • 2
  • morebunnings on 27/04/2026 - 14:25

    Might be cheaper to keep your solar and get a battery. Got a 42kw battery installed for $7600 a few months ago, without upgrading my ancient 2kw solar system.

    Im on the Globird power plan that gives 3 hours free power per day, and pays $1 if you dont use power between 6-9pm.

    So far this billing period (21 days in), power bill is $8.15 with 717kwh used and 123kwh exported to the grid.

    • 2
    • browser on 28/04/2026 - 00:26

      Do you use the free hours to charge the battery? How much can you top up the battery during that 3 hours? Assuming it's programmed automatically?

      Between 6pm and 9pm, can you program the battery not to output for say 30 minutes? So you would draw from the grid and not get charged.

      • 0
      • morebunnings on 28/04/2026 - 05:54

        Yeah, battery charges at 10.5kw/hour for 3 hours, and it gets a bit more from the solar. Then is on self discharge for the rest of the day. Sometimes it might use a little bit of power from the grid in the morning if it gets too low, or there wasn't any sun.

        I use ~33kw/day (~20kw for my electric car), so don't really set it to export mode.

        • 1
        • browser on 28/04/2026 - 08:32

          That's a good deal.

          • 0
  • Stewardo on 24/04/2026 - 14:54

    10k ballpark +gst and fuel surcharge

    • 1
  • Elppa8 on 25/04/2026 - 00:31

    Had a quote recently for similar although with a 18KWh battery.
    Apparently to upgrade the panels which will have a higher output, the whole system needs to be replaced due to the old system won’t be compliant with current regulations.

    The system would go from 4 to 6.8Kw with battery installed in May was $13000.

    • 1
  • 2esc on 25/04/2026 - 09:02

    What direction are they facing?

    Our old exactly are they?

    The amount new panels produce may not be a huge improvement that you are hoping for.

    10%? 30% output improvement will that be worth the financial outlay?

    You could be disappointed with the results.

    What is your hot water system? Depending on what that is you could make big gains there.

    • 1
    • GordonD on 25/04/2026 - 09:50

      What direction are they facing?

      Did a bit of thinking on this subject that might be interesting to people installing panels now.

      When solar panels were expensive and the FiT was good the optimum panel orientation was north to maximise kWh/day output and $ return.

      But now there's too much solar power being generated in the middle of the day, to the degree that power in the middle of the day is going to be free soon. So now you want to generate power in the morning before the free period, and in the afternoon after it. During the morning and afternoon power usage peaks. So the optimum solar panel orientation isn't N any more, it is NW and/or NE.

      Tried it with a couple of solar panels on a portable frame I could point towards the sun in the afternoon and morning, and I was quite surprised how much power was still being generated right until 7:30pm when the sun set behind the house next door. Sure, it not as many kWh/day as if it was north facing, but it was generating more dollars of saving because it was being generated when power from the grid would have been the most expensive.

      Of course if you have a battery it doesn't matter. You can generate the power in the middle of the day, and use it at peak hours.

      So unless the OP is getting a battery, the best choice might be to leave the old N-facing system in place, not spend money removing it, but to find some other E- and W-facing roof locations that might not have seemed optimal in the past, but which would add generating capacity in the mornings and evenings. To have a system that generates power in the morning peak hours and the evening peak hours when power from the grid costs money, not spend money generating more power in the middle of the day when power from the grid is free.

      • 5
      • Jackson on 28/04/2026 - 13:14

        Of course if you have a battery, it doesn't matter

        This is the reality now, however it's worth just filling your roof

        • 0
  • fozzie on 26/04/2026 - 13:35

    2.8kw in autumn isn't bad actually, for an old 4.2k system. My system has 7kw panels and inverter 5kw and I only get up to 4kw now, however in summer I get the full 5kw.

    • 1
  • bargaino on 24/04/2026 - 19:48

    Try calling Coles New World

    • 0
  • cloudy on 24/04/2026 - 21:47

    Is it north facing? and how old is it?

    • 0
    • EightImmortals on 25/04/2026 - 08:28

      NW I think, no idea about the age maybe 10-15 years.

      • 0
      • sween64 on 25/04/2026 - 22:19

        I thought it was closer yo 4.6 billion years

        • 2
      • cloudy on 26/04/2026 - 15:40

        The reason why I ask is because it sees your system is operating pretty normally.

        A few things to consider given it’s a 4.2 system.
        You will probably only get the full 4.2k per hour when the sun is peak, like 12pm on a sunny day in summer. Given it’s no longer summer you won’t get the max. I think given it’s April you’d get 85% of the nameplate. So 3.6kw.

        I also check my folks system output, which is now 16 years old. It still produces up to 80% of its old capacity.
        So mix in those two results and you get 3.6x.8 =2.88 kw max output
        Which is very close to your number.

        • 2
  • backpaqer on 25/04/2026 - 09:11

    I'd try argue that the removal should be free as the mounting rails and cable conduit that can be reused could cancel out and end up not adding time to the overall install. If the existing system is still functional, I would suggest that you hang on to that so they don't have to pay to transport and dispose of those and find a farmer who could benefit from those for an off-grid system.

    • 0
    • AdrianW on 25/04/2026 - 21:09

      Newer panels will almost definitely be a different size, they've been getting bigger.

      That said, when I had my system replaced 6 months ago they removed the old system (panels, rails and inverter) at no additional cost - although I did get the same installer we had the first time.

      The original install had 20 panels - two rows of 10, but the new install in the same place is now 3 shorter rows but is still 20 panels. The rows start higher and go a bit lower. We had additional panels installed on other orientations as well this time.

      • 0
  • JCSyd2000 on 25/04/2026 - 14:12

    Solarquotes? They’ve been around since 2009. Currently partnered with Choice consumer group.

    • 0
    • WhyAmICommenting on 26/04/2026 - 15:17

      And owned by Origin last couple years, btw

      • 0
  • Anavar on 25/04/2026 - 22:49

    Unfortunately its not something that can be replaced at any cost.

    • 0
    • WhyAmICommenting on 26/04/2026 - 15:17

      This is essentially correct. But to provide some actual info - panels get better every year and old inverters wouldn’t cope well with new panels.

      Essentially, you replace the whole system and sell the old one to someone on gumtree who will use it somehow off grid etc

      • 0
  • Ooops on 26/04/2026 - 12:35

    Depending on where you are, it might not be worth changing. That's because, for example, in Victoria, for old systems the fit is $0.6/kWh vs newer system which is $0.01 and dropping.

    • 0
  • SoapyWooder on 26/04/2026 - 18:07

    It costs everything and more

    • 0
  • cswine on 26/04/2026 - 19:12

    gonna be a lotta money

    • 0
  • Parasite on 26/04/2026 - 22:14

    How much energy do you use during the day? Not much point installing a new system if you don't utilise what the current one produces.

    I have an ancient small system that still works but I don't think I would bother replacing it now many retailers offer free energy during the 3-4 hour windows during the day

    • 0
    • ialam99 on 27/04/2026 - 06:40

      Yep im in a similar boat. My solar system is 8 years old and a little small in todays standards. I had an option to upgrade that recently when I installed a battery but with all retails about to offer 3 hours free, I couldn't justify upgrading my solar. If my solar systems break, I'll just charge it off the grid rather then replace it I reckon.

      • 0
  • JungliChilli on 27/04/2026 - 08:28

    OP, peak output was 2800W after cleaning the panels, keen to know what the peak output was before cleaning them!

    • 0
  • faricity on 27/04/2026 - 09:26

    Just get quotes on a new system (rails, panels, inverter). The installers with their own staff will and can quote for removal if you ask them. The ones that use contractors might shy away or give shady answers. You must replace everything to get government rebates called STCs. Also get a battery at this point in time while the rebates available.Battery will range approx extra $5k on top of solar so maybe $10-15k total

    Depending on the dimensions of your current panels and your roof, its approx $5000 plus or minus $1-2k depending on brands and installer reputation for 6.6kw.
    I also had 5kw of panels removed. I didnt get an exact $ figure but it was all bundled in with removal and installation. II also had like 1 month gap cause i wanted my roof restored and painted.

    • 0
    • EightImmortals on 27/04/2026 - 11:29

      Thanks, have only been here a couple of weeks, will see what the next couple of power bills come to and see if it's worth it. :)

      • 0
  • Cheap Gamer on 28/04/2026 - 07:59

    You wanna replace the sun and planets? That'll cost ya mate.

    • 0
  • YRT on 24/04/2026 - 17:10

    Our 6.6kw East West install produces around 4kw atm. Our other house has 5.3kw North West, which gives about the same 4kw output atm. So.. 2.8kw sounds about right for a 4.2kw system in winter / late autumn.

    The battery rebate requires 5kw minimum fyi

    • -1
    • GordonD on 24/04/2026 - 18:09

      he battery rebate requires 5kw minimum fyi

      No, not correct. The minimum size BATTERY that gets you a rebate is a 5 kWh one.

      • 4
      • Jackson on 28/04/2026 - 13:09

        So what is the minimum panel output? I tried to find this one and I found plenty of installers that wouldn't install anything less that 5 and sometimes 6.6kw. I know people who have shaded houses that would have been happy to put a single panel on the roof to get the battery rebate

        • 0
  • mrvaluepack on 25/04/2026 - 17:44

    Solar is not worth it anymore. The government is actually currently trying to discourage solar by offering free electricity during peak periods.

    • -2
    • p1 ama on 25/04/2026 - 21:41

      Not sure why you're negged - this is actually true, we have too much solar generation during the day already and wholesale prices are close to zero or negative during peak generation times. As such, the free 3-4 hours of electricity retailers are offering.

      Solar only makes sense with batteries as you can save your generated solar to use or deploy when electricity is more expensive in the evening.

      • 4
      • mrvaluepack on 25/04/2026 - 22:25

        Thanks, most people dont really understand whats happening with Australia's energy grid or how solar works. I actually interact and work with AEMO on a weekly basis.

        Negs must be from solar installers lurking on this site lol.

        • 3
        • p1 ama on 26/04/2026 - 00:37

          I actually interact and work with AEMO on a weekly basis.

          That's awesome - I previously worked for the AER many years ago!

          • 0
        • soan papdi on 21/05/2026 - 19:29

          A while back, I was told to put panels facing east and west instead of the conventional north side as there's enough coverage now. Does that make sense still?

          • 0
          • YRT on 21/05/2026 - 22:16

            @soan papdi: All north + battery, no need for E/W install

            • 0
    • JimB on 27/04/2026 - 10:24

      I don't have solar yet.

      But I thank all the solar home owners and the Government for offering free electricity so I can run the appliances/air cond during that time frame.

      I will eventually get solar when I get an EV.

      At this stage Solar is only worth it if you can consume it all or have a battery to store to use overnight.

      • 1
      • mrvaluepack on 27/04/2026 - 11:18

        You are welcome.

        Nah even with an EV its not worth it. The free electricity plans make any upfront solar installation costs redundant.

        • 1
        • JimB on 27/04/2026 - 11:21

          I'll work out my usage once I get an EV and see if it's worthwhile.

          Fortunately my tariffs are lower than other people in my state, 23c per kw.

          • 1
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