I missed out on the Solar Panel rush 5-10 years ago when the government was giving out massive grants and the energy buyback rates were awesome.
Given the recent price hikes in energy bills thanks to our useless government that privatised it all, is there any incentive to dump $5,000 on some panels? what is the ROI?
Is It Worth Getting Solar in 2025?
frostman on 11/02/2025 - 10:57
Comments
Must add that feed in tarrifs are a thing of the past so OP should not factor in any returns from those..
These have become minimal and have become 2 -way.
ie There are certain times when you get a feed in tarrif and at other times you pay to feed back into the grid.The idea is that they are now pushing for solar panels complete with battery which escalates the installtion cost significantly (like by about $10K-$15K)
Hence as you pointed out is all about the savings in your bills from not needing to draw power from the grid.
Adding a battery extends this time by about 2-3 hours only which isn't much at all, given the very high cost of batteries.Typicaly a solar panel seller should be able to answer OP's question
Adding a battery extends this time by about 2-3 hours only"
This is just factually incorrect unless you're using in the vicinity of 100kWh/day!
To put it in perspective, on a recent high usage day (hot weekend AC and TV's on all day, Washing machine, Dishwasher and Oven usage), my house used 25kWh total.
My panels generated a total of 35kWh for the day, roughly 12kWh of which was directly consumed by the house. Leaving a balance of 13kWh across the hours 8pm to 7:30am
In short, a typical 10kWh home battery would have gone close to covering the entire usage of the house (for "free") during the 11.5 non-solar hours.Sure it's a different story on a heavily overcast day, but genuinely bleak days can be counted on 1 hand across an entire year. and a battery will still cover you for a major portion of the day.
This is just factually incorrect unless you're using in the vicinity of 100kWh/day
To be fair, a household's energy usage is often concentrated into a few specific times in the morning and evening. These times are when some of the most energy-intensive operations take place - kettles are boiled, coffee machines and toasters are most frequently used, ovens and microwaves are in high demand, hot water systems kick in after showers - not to mention TVs, PCs and other recreational equipment.
Everyone's usage patterns will vary with their specific mix of appliances, daily schedules etc and the capacity of their household batteries. But it is possible that the original claim could be true for some people, particularly if the household battery is only 6-7kWh.
Looking at my own typical energy consumption, a 10kWh battery would carry me all the way through to the next morning on the average day, but each home will be a little different.
@klaw81: I think I was fair…
For the regular household items that you've listed, they might pull 4kW average for 15 minutes or so before levelling out to 2.4kW for the remainder of the hour (mostly due to the oven cycling on and off).
The oven is going to get turned off after 2 hours cause the spuds are well and truly crispy by then meaning you've still got ~6kWh of charge remaining to get you through the night.Gaming PC's are the one thing that might push up the average, but you'd still need multiple high powered machines to hit a continuous 4kW/hour.
Few houses have even one high powered gaming rig, let alone multiple. Thus fall out of the "to be fair" category to me.Electric hot water is going to be on a J tariff anyway and is therefore irrelevant to the discussion.
Depending on your situation, if you are in Adelaide, living at home during the day time and not planning to move out for the next 5+ years. Then yes without any calculation.
My one's RoI was approx 4 years (although did get them in the covid lul for $2250 for 6.6kw)
I think it's still worth it if you have a family or do working from home during the day.
My ROI was about 2.5 years less FIT. I calculated my savings based on what my electricity bill was to what it then became with Solar and it was 2.5 years. FIT is bugger all, so don't factor that into any of your calculations. Based it on your savings.
All depends on what your power usage is. $5k for a solar system would be a smallish one, so might not be worth it. You would ideally want to go for a solar + battery solution. Again, depends on your power usage.
Also a tip, you will need to change your habits. Don't run the dishwasher, washing machine or dryer at night, do as much as you can during the day when solar is generating to maximise the benefit.
You would ideally want to go for a solar + battery solution
For most people, a battery does not make financial sense…
100%, for me it isn't worth it. I would flatten the battery very quickly overnight or in poor sunlight.
It does when it's in a car.
EVs are so ridiculously cheap to run and there are some rediculously good deals second hand or new with MG/BYD.
EVs are so ridiculously cheap to run
approx. $7.50 to travel 100km.
So, not that much different to an economical petrol car.
@jv: "An economic petrol car". I had a hybrid before my EV, and we used 6l/100km, that was $10-12 at current prices. If you have an EV plan you should be able to get electricity to take you 100km for $4.50. It's not close.
and we used 6l/100km, that was $10-12
That's $9 at current prices near me…
My 5l/100km car costs $7.50 to do 100km.
approx. $7.50 to travel 100km
Where did that figure come from? It sounds extremely high.
My own 12-month average for Model 3 RWD is about $1.35 per 100km.
That's 99% charged at home using EV charging plan at 8c/kWh, and a tiny bit of public charging at 51c/kWh. If I didn't have the EV charging rates at home and just paid the standard tariff rate, my average would be approx. $4.90 per 100km.
My 12 month average from the previous vehicle (Mondeo TDCi hatch) was just over $10 per 100km.
The latest model brand new Camry Hybrid would likely be around $8 per 100km, and the current RAV4 would be similar.
Regardless of which way you slice it, EVs are far cheaper to run than the most economical petrol cars.
Model 3 RWD is about $1.35 per 100km.
Where did that figure come from? It sounds extremely low.
Where did that figure come from? It sounds extremely low.
The basic calculation is simple enough. My EV charging plan costs 8c/kWh, and the car's battery has a capacity of 62kWh. A full charge gives me 420km on average.
So 62 x $0.08 = $4.96 for a full charge, and $4.96 / 4.2 = $1.18 per 100km. Add in a small amount of (more expensive) public charging brings me up to $1.35. My records aren't perfect because we never actually drive the car from 100% to 0%, but they're good enough to make a fair comparison.
Calculated another way, the car automatically tracks short and long term energy efficiency trends. My 12 month average energy efficiency is 13.3kWh per 100km, so 8c/kWh, you get $1.064 per 100km…..add in some allowance for more expensive public charging and voila - $1.35 is within a reasonable margin of error.
Obviously the cost of charging an EV is affected by a massive number of factors - but even so, that ChatGPT figure could only apply to enthusiastically driving an EV Hummer around California.
Amusingly, I just asked ChatGPT the same question and got a response of $5.40 / 100km, assuming a large SUV with an efficiency of 18 kWh/100km, and a $0.30 tariff - those are much more reasonable numbers (the Kia EV9 has a similar average efficiency)
Sadly, Tesla doesn't currently support V2H capability so I can't use the car as a home battery.
Where did that figure come from? It sounds extremely low.
I'm with OVO and I ONLY charge during the 8.4c window (12pm - 6am) or the free period (11am - 2pm), so my numbers would be even lower than klaw81's $1.35/100km. I've never paid for public charging.
Don't run the dishwasher, washing machine or dryer at night,
A bit hard when you're at work during the day.
All those appliances can be set to run on a delayed start.
Having said that, the biggest savings come if there's someone at home using the AC during the day by far.
All those appliances can be set to run on a delayed start.
Don't want to leave washing / drying in the machine after the cycle. Makes it too hard to iron.
Also, prefer someone is home when they are on.Makes it too hard to iron
You have time to Iron? I thought all your time was spent on OzBargain.
that's basically our use-case, i work from home and the minute there's enough sun on the panels i crank the bejesus out of the AC.
As per Zoob, you can set timers. I do it all the time for my dishwasher.
If you only work one day a week the it is not hard, but for the rest of us we are screwed by the feed out Tarif that will become standard in 12 to 18 months, unless you have a 1GWH battery….
I need to look into this, my installation is in progress, but no way I'm paying for generating too much power.
I'll get a battery whether it's economical or not if it comes to that…. I do want a battery anyway, but was planning on adding that when they're cheaper.@SlickMick: Check out the following:
1) feed in prices over the last 5 years
2) wholesale electricity prices during the day when they go negative on days when the sun shines
3) https://www.solaranalytics.com.au/community-news/export-char…
Personal circumstances will vary any recommendation.
If you work from home, or have people at home during solar generating hours, then it's a definite yes.
Agree. It will a fair while for me to get ROI, about six years, as I don’t have a north facing roof line and thus can only power half a day. It is estimated my bill (without panel payments) would still be about $280 with a 6.8kwh system. It also depends on whether I put them on the eastern roofline or the west’s. Slightly better west as that is a little bit north of west. But that is front of house and Mrs entropy not keen.
I would never get an ROI in a battery.Neighbour was able to get a panel return in three years.
What state/city are you in?
As an example, I’m in Brissy with a 15kW solar +10kW inverter on east-west config and my ROI initially started at approx 8 years with a battery but that’s now down to about 4 years as rates prices increase and our usage habits change overtime to accommodate for the solar. East-West actually means slightly earlier day and later day generation with not as long of peak power in the middle of the day so it actually works out well for breakfast/dinner appliance use for us. Granted the QLD government battery scheme helped to increase our battery capacity for about an extra grand, the energy independence is also a good feeling.
While yes, a bill without panels comparison is a good place to start, you’ll quickly learn to shift some habits to during solar hours to maximise your system. And if the $ isn’t too much of a limiting factor, go for as big of system as you can as panels are cheap as hell these days - especially if your estimated production will be lower due to your east-west situation.
Yes, absolutely. Panels have gotten cheaper from 18 months ago when I installed it and it has been a benefit even ignoring tariffs.
IMO get the solar rebates while you can, they won’t last forever. They make even a small setup bring great returns. Don’t buy a battery yet though, they’re still far too overpriced compared to wholesale battery prices these days (about $US100/mwh) and v2g may solve needing a battery at home in the next few years.
I just wish I went bigger. I did 5kw and the payback is faster than I calculated thanks to buying an EV to soak up the excess.
have you considered a second system?
With an EV itd arguably be worth going whole hog and upgrading (or utilising 3 phase) and install a large solar set up and upgrade your charging infrastructure.
Faster Charge times, better exports and more sun juice to the car
Is It Worth Getting Solar in 2025?
Nah… Sun is running out…
As long as your idea is to reduce your electricity cost (and not to profit), then yeah.
reduce your electricity cost
It can cost a lot of money to install solar, so for some people, it is not reducing costs.
Invest the cost of solar in the right
sharescrypto and you come out ahead imo
I missed out on the Solar Panel rush 5-10 years ago when the government was giving out massive grants and the energy buyback rates were awesome.
You haven't missed out on anything. 10 years ago the systems were crazy expensive and fairly low in capacity, but you made savings around the clock. Now the systems are very cheap, but you only make savings by offsetting your daytime use.
I just schedule my washing machine/dishwasher/AC/etc during the day and save lots.
What's your current bill and how much power do you consume during daylight hours (in particular between 10 and 3)
That will define the payback period.just use OVO 11am-2pm free electricity plan, no need to have solar
Saves you what……. maybe $2 so maybe $60 a month? Plus you probably pay higher daily supply and usage fees? Solar for me saves me about $4-$5 a day depending on the day, maybe a bit more. So about $120 maybe more a month?
usually they have lowest supply and usage charges in most places, you can use all loads during that time, washing machine, dishwasher, heat pump etc, ROI of solar is so low with respect to that, because you can only use what you generate during the day time
i got shit generation in winter, perhaps avg 6kwh a day, ovo saves big time as I managed to charge my full bat and preheat the entire home in winter. winter monthly bill is around $50+supply, October to April - $20 inc supply.
OVO's rates outside these times are far higher than competitors so you end up paying more (depending on area)
OVO rate is 35c per kwh
Ampol Energy 27c per kwh
8c per kwh difference. My last bill for 92 days came at 1,080kwh of usage. That usage x 8 cents per kwh = $86.40 extra for the privilege of those "3 free hours" per day.
Haven't touched on the daily supply charge however my current provider is also 15c per day cheaper.
Yeah it is all about the location and usage. I am currently with Globird due to a promo, but I was with OVO for a year before that. Last bill per month with OVO was $123 for 486kWh (including 119kWh in the free time) at 117.59000¢/day and 29.59000¢/kWh. I think we forgot to set heat pump exclusively for the free time for that month. We don't have gas either, got 3 RCAC + heatpump for water heating.
OVO three hours is a bargain.
I squeeze about 2/3rds of my usage into that window.
Averaging 18c kwh from the grid over 12 months with the ovo plan.
I cold squish it down even more if I moved the hot water to run of it instead the 8c window and bothered to change some of the other stuff during daylight savings hours.
When I crunched the numbers for my parents, the results were surprising.
Given their energy use, switching to the midday saver tariff (8c/kWh from 9am - 3pm, and offpeak 9pm to 9am) was far more beneficial than installing solar panels.
Their small, well-insulated house consumes little power, making the investment in solar financially unappealing. The payback period alone would have exceeded 10 years—just to break even.If you can shift most of your electricity use to between 10 a.m. and 3 p.m. while minimizing consumption from 3 p.m. to 9 p.m., the payback period for solar can stretch significantly.
How did you crunch the numbers? Do you have a spreadsheet for it?
Yeah, I built a custom spreadsheet for this about two years ago, but I can't find it now.
Their average daily usage is around 25 kWh, and optimistically, about two-thirds of that could be offset by solar—so roughly 15 kWh per day. At a rate of 30c/kWh in Perth, the maximum potential savings would be $4.50 per day.
However, factoring in cloudy days and two months of travel each year, a more realistic average saving is around $3.50 per day. If their actual electricity cost is only 8c/kWh—or even averaging peak rates to 12c/kWh—the real savings drop to about $1.80 per day.
That translates to roughly $650 per year in savings compared to the midday saver tariff. With a $6,500 system, the simple payback period is about 10 years.
how can we switch to this ?
the midday saver tariff (8c/kWh from 9am - 3pm, and offpeak 9pm to 9am)
A different angle —> if you have a smart meter then churn every 1-2 months for the sign-up bill credits & cashbacks. Significantly reduces your annual cost.
How do you churn every 1 to 2 months? Are there any limitations to this like having to hold the account for 3 months to get the sign up credit?
https://www.ozbargain.com.au/tag/electricity
Just take a new sign-up offer and switch providers as often as the last bonus has been utilised. No tricks to it. Plenty of offers available. Only need to have electricity for 30 days in most cases. Go through the offers and read the comments, it's all there.
It depends!
You might want to download your usage data from your energy provider (network) portal and you can see by the hour what your usage is. Assuming your solar can eliminate you daytime usage work out how much that is.
Get a hybrid inverter. Growatt (cheap, some call nasty, I've been lucky with 4 of them) has a cheap hybrid inverter that is battery ready and then all you need to wait is batteries to get cheaper. They'll be people who will tell you to go all electric but replacing working gas hot water for a heat pump and then forking out another $2k isn't necessarily the best option. Also cheap hybrid inverters from Huawei / Sungrow etc.
Home batteries are going LFP if you would believe which means a lot cheaper per kwh. I find it is better to actually not be an early adopter (betamax vs VHS) best to be around mass adoption when prices are driven very low (which is around about now). When V2G/H starts to come out for EVs home battery prices are going to get smashed as they no longer have an monopoly.
Getting a high enough feed-in-tariff to substantially offset energy usage is almost impossible these days.
The only way to make solar panels pay for themselves is if you use enough energy during the day (during periods of solar production) to substantially reduce your energy costs.
The good news is that $5k gets a pretty decent solar installation these days. Back in the days of yore when feed-in tariffs were high, $5k wouldn't buy you diddly squat.
Everyone's routine and usage will differ, so it's pretty hard to give good general advice. Your best bet would be to have a closer look at when you use most of your electricity, and how much of that usage could feasibly be shifted to a time when solar could supply that energy rather than taking from the grid.
You could consider alternative energy plans that can offer cheaper rates at a particular time of day - if you are capable of time-shifting energy usage into those times, you may find that you can reduce your costs substantially without needing to spend any money at all.
If you do decide to install solar, make sure your system can accept a battery in the future. They're not viable for the average household right now, but prices are falling fast enough that they may well make sense in the near future.
You basically need to assume that at some point your FIT will hit zero, that's the way the market is headed. Where I live in NSW they've gone from ~9c to ~5c in about 18 months, and the wholesale FIT is frequently negative (ie, you pay to export.)
So it's really about whether you can utilise the energy yourself by heating your pool, charging your EV, or putting it in a battery, etc.
Isn't negative FIT a major risk to the ROI of new systems that do not include batteries? Or can new systems be set up so as not to export excess energy so that negative FIT is not an issue?
I don’t know of any retailers that will actually pass the negative tariff on to the consumer yet. But yeah you can generally limit your export from your inverter.
It's more worth if you properly calculate your usage on a daily basis for all your needs. Long gone are the days when you could cover your needs and export excess for a reasonable price enough to cover initial input expenses. Even subsidized, it's probably not worth it for purely the exporting point of view.
This will be viable again when batteries reduce in price to store excess energy for you to go relatively off grid. Or until everyone says EVs are so bad that you can buy them second hand for cheap and you just salvage the battery for home storage. EV battery can easily be repurposed for home energy storage. Especially if they already have V2G.
Love the info supplied. What did the web sites say that you found when you entered your details of current power usage, place you are in and size of the solar system?
It's the Ozb way.
Depends on your specific use case, most importantly, how much of your usage you can move to the daytime.
It's a no-brainer if you have an EV that you can charge during the day, as an example. There are also plenty of people who are at work or otherwise never home during the day for which solar will practically save them nothing (given that feed-in tariffs are almost zero these days).
Also depends on how open you may be to getting a battery, how much electricity you use overall, which direction your house faces, where you are located, amongst many other factors.
Depends on what your usage habits are, it's actually worth it.
I've got that $33 government sponsored heat pump hot water tank that runs only during daylight hours, plus some low income government energy grant, and a pretty much non existant 3.5c/kwh… and somehow I've legit paid ~$47 in electricty for the past 12 months with Dodo. I'm in NSW so your milage may vary.
Average daily usage over the past four quarters is 7.02kwh/day.
Suggest reading the following which provides info in answer to your question (I don't have any connexion with it):
https://www.solarchoice.net.au/solar-panels/is-solar-worth-i….
Short answer yes.
Every person's situation is different - so you will need to do your own calculations. I'm waiting for vehicle to grid (V2G) to become commonplace as I think this will be a game changer. Essentially you run your home using the EV battery during peak periods & recharge the EV after midnight ( when prices are cheaper), or during the day from solar panels. Good luck with your deliberation
If your house doesn't have good insulation, then keeping the house cool during the day(when the sun is out) will help with the electricity bills if you need A/C at night. Anyway all houses consume some power during the day so installing solar will help but a lot less during winter. If you are calculating ROI, then it's just a matter of time.
I'm a data nerd so have kept stupid amounts of information on my power/solar journey since 2018 when I had the panel installed. My ROI was only about 2 years thanks to a confluence of a great deal and new rebates at the time and an out of pocket cost of only about $2.5k. 6.6kW of panels on a 5kW inverter (like everyone else :P)
We are heavy power users with a higher than average base draw which helps.
My bills are lower in Summer (thanks to more sun) and higher in Winter (even with ducted gas heating) thanks to less sun (and it's amazing how much power my old gas heater draws to run its fans).Since ~Jan 2022 to ~Jan 2025 I have generated ~22MW, consuming 12.5 and exporting 9.5.
Using proper TOU rates for peak and off peak to calculate real savings and using a FIT of only 3.3c kWh that has equated to a saving of $3,500 over that period or a shade under $1,100 / year.My spreadsheet is setup in a way that I can drop in different rates and it will recalculate to compare across different supplies or rate offerings. Out of interest, if I reduce the FIT to zero the impact is ~$100 / year less in savings. Long gone are the good old days of high FIT's where you could make decent money from export. It's pretty much worthless today.
I'm currently exporting only about 3MW / year, IF I could put 100% of that into a battery I could save an extra ~$1,000 year. The reality is that you can't since in summer I could be exporting 20kW+ in a day where in Winter that might be ZERO on many days thanks to lower overall production. When I model things properly the reality is about 65% of that number.
Let's round that up to $700 / year extra from having a battery.
Let's say you put in a 10kWh capacity battery.
I personally would want ROI to be closer to 5 years on the battery which means it has to cost only about $3,500 for that 10kWh battery.I haven't heard of any scenario where solar isn't worth it.
I initially felt that I'd missed the boat on incentives so wouldn't bother, but just recently decided to proceed. When I realised that the incentive has always been there but reduces each year I felt a bit dumb. There was probably an optimum time when costs had reduced but incentive was still decent, but now is better than later IMO.
I got solar in 2018 and switched to time of use electricity plan. Works well for us as the solar deals with most of the demand during peak hours, meaning 80% of what we draw from the grid is on the cheaper shoulder/low tariff rates. I got a fairly high range system so longer payback period of around 7 years; plenty of options around with sub 5 year payback.
Too much info provided. Cannot compute.
Actually, yeah go for it. Good ROI in your case
Definitely depends on your usage. My eyes water at some of the electricity bills that people talk about on reddit or ozbargain.
When I looked into it recently, I wasn't convinced it was worth it. Our electricity bills for an entire year were like $1500 for example (it was less than that but I don't remember the number) and the daily supply charge or whatever they call it was like $400-500 of that. So that left like $1000 of usage and of that like 70% was going to be after like 4-5pm.
So I asked myself, do I spend thousands to reduce by electricity bills by maybe a few hundred bucks a year? Maybe if I had an electric car, electric hot water, split systems in every room (we have evap cooling which is cheap as chips to run, our summer electricity bills were barely higher than winter, unfortunately we have gas ducted heating) then maybe the numbers would shift.
Obviously it wouldn't be a total loss, but weighing up the small saving vs opportunity cost elsewhere, not sure. I think I will do it soon but would much prefer batteries to be more economical.
I am also concerned that ill invest thousands in something that has a pay back period of like 5-7 years and then move house, one of my friends just did this, solar hasn't paid off yet and they are moving house so will have to go through it all again.
Check out the calculators at Solarquotes for your situation.
Also check for reviews/info on offered components. Really, really avoid just going with a 'door to door' 7nless you really check it out.
Please, please do your basic demand management first or you're really just p@ssing money against the wall.
Likely worth it but 'depends'It's dependent on your energy usage profile.
If you use lots of power during the day, then solar is still a no brainer. But if you are out from dawn to dusk, and no one is home during the day so you have only base loads, then the question of what is the point comes into it.
We quoted a customer the other day who had $2,700 a quarter energy bills (Yes, a quarter, resi customer) so for him it is absolutely worth it. He's estimated payback on the system was a few years and he will be saving upwards of 5k per year.
It just depends on your circumstance.
Also, keep in mind that feed in tarrifs are likely to continue to drop. When i quote customers on solar power systems here in Newcastle, I don't even account for any benefit from the FIT as it's likely to go to zero [not to mention, the charge that our energy distributor is imposing on solar exports because there is a saturation of solar power. More on that here https://www.newysolarco.com.au/fees-for-solar-power/ ]
So yeah, think the advice is it it completely depends on your own scenario.
Also, when i read this
Out of pocket, the newer system was about $1200 cheaper like for like that the system 4 years older than it (as just a basic 6.6kw system) and came in at just under $3k installed
Under 3k installed screams of a cheaply completed install. You can compare components for days and settle with a standard high value panel, like the Jinko Tiger Neo, but at the end of the day where the people offering solar jobs for under 3k for a 6.6 kw system are saving is in the quality of the installation itself. Considering this is supposed to be a financial investment, you'd be wise to spend it on a good installation. In house installers are a must.
I recently installed solar on my house. I've gotten the first bill. I think I just realised something. It is impossible to exactly calculate savings with and without solar, because you don't have a figure for the "self usage" portion. Am I missing something? Or do you just estimate that through the solar app?
Some inverters have software and app that show the amount of self-consumption. Other people have dedicated monitoring on specific import, export and consumption cables in their switchboard.
ok so i estimated the self usage. It's simply production-purchased energy.
on first bill alone. Our payback is 4 years conservatively. I cannot be 100% because I don't know the spread between off peak and peak usage, to be conservative, I calculated all self usage to be off peak. Also in December we were away for over 2 weeks on holiday so our self usage would typically be a lot higher.
Interesting to see what the situation is in winter because the mrs pumps the heater over night, and we often get home past 5 when it's already dark.
Yes, savings will be highest in summer simply due to longer periods of solar production, and will be lowest during the shortest days of winter. You can make the most of excess production during the summer by cranking the AC for free.
Unfortunately there's nothing much you can do about the cost of running heating after dark, except to get the house as warm as possible while the solar is still running (use timers etc) and use the various insulation techniques to minimize energy use after sunset. Or install a battery, I guess….
look forward to running the calcs in winter!
idk about others but have installed panels 5 years ago and 1 year ago (on parents place) and the ones installed later were much cheaper (same brand, equivalent new model with higher W per panel)
Competition and increased supply and improving tech has massively cut the price to produce Solar Systems (inverters less so, but panel prices have declined sharply) that the reduction of gov grants, has been outstripped by price decreases overall.
Out of pocket, the newer system was about $1200 cheaper like for like that the system 4 years older than it (as just a basic 6.6kw system) and came in at just under $3k installed.
ROI on the otherhand is another story. FIT's are practically fkall so might as well have panel placement on E-W orientation to maximise household use vs export gen (I wish i could change mine now).
ROI from an ease of life though imo is much improved. Ill do the laundry and the dishwasher and run aircons all day knowing its effectively free and have much more relaxed summers over the last 5 years so personally already paid for itself