I'm thinking of jumping on the solar band wagon but not sure if we should.
We live in a single storey house in Melbourne.
No air conditioner, only 1 small TV, all LED lights hence below average electricity use. Our electricity bills are around $70/month.
Gas cooktop, gas hot water heater. Gas heater but hasn't been used for a few years. Gas bill around $70/month.
Is there any point getting solar panels given our low energy usage?
5-10 years probably
let say you pay nothing and disregard feed in
you get a cheap system $4000 and you spend lets say $35 a month and the other $35 is for daily supply
$4000 / 35 / 12 = 9 years max to break even provided it doesn't break by then like the systems 10 years ago
I don't think you should get it
Would have to agree, your usage is so low that I don't think it would be worth the cost. if you could get a system around $2K and provide the same drop in bills then maybe….
if you could get a system around $2K
I don't even know a place where you can get them for $2K?
I got one for $3.5k two years ago and even now, for the same system it is $4.5k.
@geekcohen: @geekcohen, yes haven't looked since I got mine 2018~2019, I've guessing the gov cash back is no longer there? My payback was just over 2 years so have been very happy (but jump the purchase to $4K + already doubling that payback time
My installer said there are plans to lower the tariff even further. So the ROI would go higher
@kaleidoscope: ya lots of factors involved
I've signed contract with the wholesaler a bit over 10 years ago and I'm set to get 52c feed in per kw for the next 5 years
power usage is around 26c atm
@Repposh: Not really nice for most, the energy retailers don't absorb the inflated feed in tariffs that the government legislated, it just feeds into the cost of electricity for everyone else. I don't blame those who capitalised on doing this, but it's basically a regressive tax that unfairly burdons the poor.
@Repposh: Hey Repposh, is your house/roof small or big? What is your age?
Lastly, are you thinking of getting a BEV in the future?….If yes, then you'll benefit A LOT with Solar Panels, and also benefit decently with Home Battery.
If no, then I would say you still can benefit from Solar Panels, but your usage is so low that it won't be as beneficial to you as other people. So it depends.
I think buying Solar Panels at this moment is relatively affordable for most people, in the future parts prices could go up, government grant can be cancelled, and labour for installation will go up. So it could be a case of spend 5 grand to save 10 grand, and get the benefits (however small) earlier or for longer. Solar Hotwater systems are pretty cheap and useful, but I would argue against it for the fact of limited roof-space which Solar Energy is more useful for.
Lifestyle, Age, and Home properties have big impact on this question. The ideal person is someone who is requires the energy, is young, and has plenty of roof-space. The least ideal person is someone old, who lives frugally, and has a small roof.
@Kangal: I actually don't know how big my roof is. I expect it's big enough to install a normal size system on the west side. The north side is relatively tiny.
Would love to get an electric vehicle in the future but I only drive around 60km per week so can't justify buying one at today's prices.
Have an electric bike though which gets a lot of use.
@Repposh: Honestly, sounds like a situation I would hold off on buying for now. You could stick that $5k into a fund, and it'll increase in value by the time you decide to get an EV.
Back in it's heyday, some people offset the cost of a Home Battery and Full Solar Panels, by using the energy for crypto mining. Not really feasible anymore, but just trying to put the idea forward that excess energy could be used for some other means of generating income.
@Kangal: Yup. A high yield investment vehicle perhaps? Or maybe Lego. I've heard that increases in value too.
@Repposh: Or a Lego of a High Yield Investment Vehicle 🤣
On a more serious note, it's your money, do with it what makes you happy (as long as it is legal and moral).
When asked Google about generating income from Solar Panels it gave the advice of; sell back to grid, use an EV car, do crypto mining, grow pot, make a micro brewery, and use for farming (that's some garden).
@Jono05: Not at the rate tarrifs are dropping.
Used to be 20c when I got, year later its 6.67c. To match that electricity would need to go up at a rate of 3x 😅
@kaleidoscope: Initial high FIT was to encourage uptake of solar. That’s not needed any more. Same as government rebates, they’re decreasing every year as well. Probably won’t be any rebates in a few years.
If you can get a good power company like Powershop (13c/kWh feed-in) then it's worth it. For self consumption it's useless as you consume half the electricity of the average 1 person household. You need to find a company with good feed in rates.
Totally agree
Change all your gas stuff over to electricity then it all becomes worthwhile. Get a heat pump hot water system too.
Solar panels are a great return on investment for almost everyone: https://www.solarquotes.com.au/solar101.html#solar-savings-p…
It's probably still worth getting a small system. (Or get slightly bigger than you need so when your hot water system and car break down you can replace them with electric.)
That is misleading. For example, the article leads with a hypothetical 10c feed-in tariff, yet in Melbourne the rate is almost half that and it drops nearly every year. In fact, some areas are actually oversupplied with solar and the companies are rejecting feed in applications. There's even talk of charging YOU to export solar to the grid during peak periods, which is something you normally can't turn off other than by manually shutting down your entire system. (The calculator assumes a 1c annual decline in tariff but with a floor of 6c, even though the current rate in Vic is already below that.)
Assuming that any hypothetical feed-in rate will last over a hypothetical pay back period is a joke. The only real benefit of installing a solar system is to cover your own usage, and unless you work from home you won't even be getting much benefit from that for at least 5 days a week.
The calculator also doesn't take into account servicing and repair costs of what is a fairly complex system. Solar Victoria recommends that you get your panels serviced every two years, for which the going rate is an easy $250. Furthermore, if anything actually goes wrong, prepare to pay for an electrician to come out, and if your panels are damaged in a hail storm prepare to pay the excess on your home and contents insurance as well. Any one of those events can eat months of solar savings.
When we installed our solar system we were sold on a 4.5 year pay back period. In reality, it would actually be closer to eight even through we have two adults working from home 4 days a week and the aircon running high all summer, and ignoring the fact that our inverter has recently been down for two weeks straight (eventually replaced under warranty), and on and off for months before that with unspecified problems that were hard to make a warranty claim on because of the intermittency.
There is virtually no chance that OP, with electricity bills of around $70 a month, will come close to paying back their system in less than 7-8 years, and even if we take the article's hypothetical median 6 year Melbourne payback period at face value, is still longer than they might end up living in the house.
Currently there is no good evidence that having a solar system increases the value of an existing house either, so you're not getting anything back at the other end.
The main benefit of installing a solar system is that you can crank the aircon up to 11 on 40 degree days relatively guilt free while working from home.
Alternatively, a solar hot water system will be a lot cheaper, and might offer some benefit if you don't take long showers and don't mind running off a tank. Solar hot water systems have a much quicker return on investment and are decades old established technology.
Not sure what your math is like but anyone in Victoria who got their system installed before FIT dropped to 6c (2021) pretty much got their money back within less than 4 years. Unless the really low usage users like OP. If you work from home and and couldn't get close to that then you probably paid to much for your system.
solar vic doesn't know what they are talking about. There is is no need to spend whatever to service your system, all you need to do is do a occasional check on your daily production graph to make sure everything running or your system is not pumping 0w at mid day on a clear sunny day.
Solar hot water upgrade is cheaper but Australia overpaid it for a dud product. Stories of the leaky panel due overpressure is very common. Many rely on gas as a backup which kind of defeating the purpose.
They said
That is misleading. For example, the article leads with a hypothetical 10c feed-in tariff…
You responded
anyone in Victoria who got their system installed before FIT dropped to 6c (2021) pretty much got their money back
Its like any bargain that was 40% cheaper yesterday. Doesnt help OP today
Although totally agree with solar hot water comment
@RockyRaccoon: I'm not talking about OP, I'm referring to AngoraFish giving misleading info about his scenario which is not true, unless he's paying too much for his system and just doesn't want to admit it.
There's still a lot to be saved from solar with the current rebate, but just not for someone who only consume 3kwh a day like OP, and that's extremely low for comfort given the abundance of electricity in this country. To get to 3kwh a day on a 2+ person household you have to count bean literally.
@lgacb08: We literally only have one appliance which runs 24/7 - a fridge which is around 250L. We have a washing machine which is used around 1-2 times per week. Microwave, kettle, fans, electric blankets, TV, computer, iPad and other devices when required. No dryer, no dishwasher, no air conditioner, no swimming pool. Hot water and stove are gas so that probably explains low usage. We turn off lights when not in use, but other than that don't really go out of our way to save electricity.
The purpose of solar hot water is to reduce your energy costs, not necessarily to eliminate them entirely. Kinda like solar panels more generally.
We know of one case where the solar hot water system burst and flooded an investment property. Since the system was installed in the roof, there was major damage. Cost of dehumidifiers, plumbing, loss of income (tenants claimed 100% reduction plus costs to rent a hotel), new hot water system, electrician, carpenter came to almost $20K
I have Solar hot water and my tank is not on the roof. I would never have it on the roof for this reason.
Arguing to a single anecdote is neither here nor there.
A solar hot water tank installed on the roof, if it did leak, should leak onto the roof and drain out through the gutters. Keeping water out of the house is kinda what roofs are designed to do. If there was a problem with the piping then that's a problem with the plumber, not the hot water system itself.
@AngoraFish: It's not anecdotal, just a fact, a house behind me has solar hot water leaking water and I saw water dripping out of the gutter and algae overgrown up there for over a year and tenant just didn't seem to care. Tank or not these panel type solar systems are just bad. What's worse about these system is inability to diver excess energy in summer and reliant on secondary energy source in winter so you always end up with the cost of back up energy source. Roof solar hot water is just plain money throwaway in some cold place like Victoria/Tassie.
@lgacb08: So that’s just one example. It’s like saying my Toyota Corolla broke down therefore every Corolla must be a bad car. You need data to track a larger number of failures vs total installed to get a true picture if the product is faulty or not
@lgacb08: They have a safety valve like every tanked heater. They can and often do develop leaks no matter what type of heater they are.
So that’s just one example. It’s like saying my Toyota Corolla broke down therefore every Corolla must be a bad car. You need data to track a larger number of failures vs total installed to get a true picture if the product is faulty or not
The only real benefit of installing a solar system is to cover your own usage
True.
unless you work from home you won't even be getting much benefit from that for at least 5 days a week.
Or a pool. Or a large family with large use of washer/dryer/dishwasher/aircon.
Definitely not true, I'm capped at a 5kW export with an 8.5kW inverter and I save about $600/year on self consumption. However, I sell $1400/year in exporting back to the grid. This means that self consumption only makes up for 30% of my cost savings, 70% is from selling back to the grid. My rates would be even better if I wasn't capped for living in the poor western suburbs of Sydney.
Yeah I wonder from an environmental standpoint and cost is it really worth it? I am not sure how much energy is used to manufacture the solar cells and the damaged caused to mine the materials for the raw materials. Also when the cells reach end of life, the waste disposal of the cells etc. Can they really be recycled? I am concern its all feel good stuff but the actually net results to help the environment is marginal overall. As the coal stations still need to operate no matter what.
Best to make the whole grid better for the environment.
In terms of saving money on your electricity bill it should but I have heard from people who have solar cells it isn't as cost effective or the big savings as it once was, as the electricity companies don't pay as much for electricity back into grid.
Anyway someone may have better answers than me as I am a bit of a fence sitter on this topic :)
I am not sure how much energy is used to manufacture the solar cells and the damaged caused to mine the materials for the raw materials
Over their life, solar panels are much better than fossil fuels. They pay back their carbon footprint in a year or two and last for 20-25 years.
Go and have a look at some information from other than Fox News to see how much they ‘cost’. Look for reputable sources like CSIRO.
In terms of saving money on your electricity bill it should but I have heard from people who have solar cells it isn't as cost effective or the big savings as it once was, as the electricity companies don't pay as much for electricity back into grid.
This is true the financial incentive isn’t there anymore. Years ago they gave you 60c/kWh but only on a 1.5kw system. Now it does take longer to get a return, but it’s well within the warranty period of the gear. Think 3-5 years, not 1-2 like it was. But it does depend on how you use your power. The best method now is to use the power you generate, not plan on making money from sending it into the grid.
cool will do. I think it will also depend where the solar cells are manufactured too. ie in terms of the carbon footprint to manufacture the actual cells and impact of the mining.
And before you ask, panels can be recycled. The market is improving and will continue to improve with more panels being removed from service due to failing performance. Right now you need to pay a bit per panel, but that fee will reduce as quantities increase.
@Euphemistic: But right now recycling the panels is still in its infancy, and is very expensive ($20 per panel, plus any freight or removal charges) for the average Australian (they can't afford to, hence end up in a landfill, even if that's banned in Victoria) and not readily available to do so.
And the energy used to break them down? The glass is removed and heated to 500 degrees Celsius to melt all remaining plastic components.
Also, not 100% recycled. The silicon particles are etched away, due to the metal impurities being only 85% reusable.
So is it green? Yep, not there yet, at all, so stop pushing that agenda and push for this area to be better, take accountability for it.
@RocketSwitch: Right now there shouldn’t be many panels needing recycling either.
Most people concerned about panels in landfill are thinking end of life for the panels (20-25y life minimum). This will be well into the future and by then, it’s likely that recycle businesses will have enough stock for it to be economical.
Even if you were paid nothing to feed power into the grid it's still good for the environment to hav panels and do it. If there's too much daytime solar power than the government will just figure out a way to store it in the future.
No air conditioner, only 1 small TV, all LED lights hence below average electricity use. Our electricity bills are around $70/month
No AC is the big saver, lights don't consume much at all, even CFLs
Yeah heating and cooling is where all the costs are (including dryers, hot water and cooking).
No electronics, even gaming PCs or home theatre equipment, make that much of a dent in your bill.
That's still crazy, the supply charge usually comes to around $340/year which means that they only consume $42 of electricity in a month. This is approx. 5kWh in a day as opposed to the average 2 person household which uses about 19kWh/day. We've used $900 of electricity in 3 months during winter haha…
Do you have electric hot water, air con, cooking and heating?
It'd mean you can run an air conditioner basically for free during the day. I'd get the panels and buy an AC, life is too short to just suffer through the heat. Split system is also efficient for cooling, though panels won't help at night. Unless you get a battery too.
You can also run it during the day in winter to heat your house for free.
Not if it's solidly overcast, which would be quite a few days in Melbourne in winter, and definitely not when you're getting up in the morning or cooking dinner, because in Melbourne in winter it'll be dark then.
But sure, if you stay home and inside during the middle of the day Saturday and Sundays, and it's not overcast or raining, and you didn't already heat the house up before the morning sun came up because your arse was freezing off in the dark, then definitely.
I just set it to run during the afternoon before I get home. A decently insulated house retains a lot of heat.
Maybe his house has good insulation or he is a stoic who welcomes the heat as a challenge of his will power.
Haha that'd be nice! I keep the curtains closed on hot days so the sun doesn't get in, then crank up the fan.
Are you single? Tolerating the heat is admirable, but if your home were more comfortable on hot and cold days then potential mates may be more inclined to want to spend time with you there.
If you’ve got the money, and are staying out for 3-5 years I’d go ahead and install. Then, when gas prices start to hurt, you can look at electric cooking and water heating to replace it using your solar power.
IMO it’s a no brainer to plug into solar if you have the opportunity.
Electric cooking sucks, but I like having only 1 bill.
Decent induction stovetops are great! It's the old technology that sucks.
Induction stove-tops and electric ovens are complete and utter trash compared to their gas alternates.
@infinite: What's so good about gas ovens? My experience is that it's got less temperature control (especially at the low end) and they're a lot more temperamental. Both ways they take a while to heat up and get to temperature
@Zephyrus: Our old gas oven was almost instant heat, we wouldn't need to pre-heat it at all unless we were baking pastries
New electric oven takes 4-5 minutes to get up to heat, food is soggy if we try to cook it without pre-heating first, as you'd expect
@infinite: Have you used a proper induction pan? We replaced our gas burners with an entry-level Westinghouse induction stove and found that our old 'good-enough' pots and pans barely worked anymore, but after getting a proper induction pan it's been amazing
Our new electric oven isn't as good as the old gas oven though, used to be able to just pop something in and come back later, now we have to spend a few minutes pre-heating it for the same result
Induction stove-tops… are complete and utter trash compared to their gas alternates.
Absolutely false. After using good gas stoves for nearly a decade, I've recently moved to a high quality Bosch induction cooktop and it's marvellous. Nothing like the old electric tops that I think people equate them to. The only thing I miss is the ability to char veggies straight on the gas burner.
Uighurs:
https://www.timesofisrael.com/she-exposed-chinas-crimes-agai…
"Forced Uyghur labor is being used in China's solar panel supply chain, researchers say
[…..]
The Biden Administration called China's treatment of the Uyghurs "genocide" in its 2021 human rights report.
China's polysilicon factories are concentrated in the Xinjiang region and were responsible for more than 42% of the world's total production of raw solar materials last year, according to the research."
[…..]
https://www.businessinsider.com/forced-uyghur-labor-china-so…
and the Taiwanese, amongst other residents of the Asia Pacific region who are being menaced on an increasing scale by China, would disagree.
Of course, I have not yet made reference to the "Cobalt kids(a term that I just invented myself - but quite apt))"
https://www.wilsoncenter.org/blog-post/drc-mining-industry-c…
Thanks Mr Conspiracy.
Conspiracy?
REALLY?
If any of the above things are untrue, please point these out to me.
Here is one source supporting my assertion from one of the ALP's "true believers":
Human rights concerns in Xinjiang
Ministerial statement
(from Foreign Minister Penny Wong)
01 September 2022
"The Australian Government is deeply concerned about the findings of the Office of the High Commissioner for Human Rights’ report on Xinjiang.
The report is informed by extensive research, including the first-hand testimonies of Uyghur and other minority peoples in Xinjiang.
It concludes that serious human rights violations have been committed in Xinjiang.
It states that allegations of torture or ill-treatment are credible, as are allegations of individual incidents of sexual and gender-based violence and that some of the violations may constitute crimes against humanity.
Australia has consistently condemned human rights violations against the Uyghurs and other ethnic and Muslim minorities in Xinjiang and across China.
[…..]"
https://www.foreignminister.gov.au/minister/penny-wong/media…
Here is another source dealing with solar panels constructed in China:
"Labor’s green obsession is blinding them to the shameful truth about Chinese solar panel production
While the US has impounded more than 1,000 shipments of Chinese-made solar panels under the suspicion they were made with forced labour, the Albanese government has been all too silent,"
writes Nick Cater.
https://www.skynews.com.au/insights-and-analysis/labors-gree…
Two of my own comments are mixed in with the 136 (mostly for, some against) made about the article.
Thanks for pointing this out. Agree modern slavery should be abolished from the supply chain. It's sad that Australians played such a huge role in inventing solar panels but no manufacturing is done here
Yeah coz we have to pay people here… instead people would rather cheap stuff made in countries with cheap or slave labour.
@djsweet: Modern slavery exists in most countries too. Just people are unaware of it.
America has a big prison population for a reason.
I was a bit surprised to see Australia does it as well to a degree.
@djsweet: If we had to pay people to manufacture items here in Australia, they would cost 5 times as much.
If you read the wiki page on solar panel, it was the American who invented solar panels?
In 1881, the American inventor Charles Fritts created the first commercial solar panel, which was reported by Fritts as "continuous, constant and of considerable force not only by exposure to sunlight but also to dim, diffused daylight."
If you dont like Chinese goods (and i mean ALL Chinese goods if you dont want forced labour concerns) then there are australian made panels
It is not only forced labour concerns.
It is also the threatening nature of China's approach to neighbouring countries and the Asia Pacific region.
"Saving the planet", a fantasy anyway, does not rate against the REAL danger of Chinese militaristic aggression.
@Leadfoot6: The US has the biggest armed force in the world.
The US has the highest military spending in the world.
The US sail their aircraft carriers to every corner in the world, showing muscles, declaring wars to nations like Afghanistan, Iraq, and many more.
Yet, there is an Australian here on Ozbargain trying to falsely paint a picture where China is the aggressor on a post about the solar panels.
If you believe the crap of those 'forced labour' in China, which is totally not true, then you should read how the US treat their general public on the recent environmental disaster : https://www.google.com/search?q=ohio+east+palestine+disaster…
@Smilence03: Falsely????
You need to study some modern history and also helpfully, some current affairs.
The USA is the only reason that we were not invaded in World War 2 where my father who served in the RAN fought alongside our US Allies(and earlier in the war with the RN in Europe), and the only reason that the Soviet Union and China were not able to expand their empire during the Cold War.
You seem completely ignorant of the world before the Millenia.
Sad.
P.S. I can't help the mismanagement by the Transport Secretary Buttigieg of the train derailment.
Joe Biden tells the world how he used to drive trains for Amtrak.
He is as deluded as most of the Democratic Cabinet.
Anyway, I watch a good number of hours of US Fox News every night.
I am MUCH better informed of US and world affairs than you will ever be.
Majoring in Modern History in the 1970's in high school gave me a very good grounding in such matters.
I'm wondering how much formal study of modern history that you have done?
P.S. Just for your benefit, I will again post the link to the material released by the Australian Foreign Minister, Penny Wong.
https://www.foreignminister.gov.au/minister/penny-wong/media…
You might like to write to the Minister and tell her how Wong, er, I mean wrong, her Department is with the Uyghur situation.
Please report back with the response that you get from that Department.
It will make for interesting reading.
@SBOB: And your sources for world events/current affairs would be?
And just FYI, TikTok or Facebook are not really credible information sources.
Aircon is the biggest reason for people to get solar panels.
You are a clear case of somebody who definitely will not benefit from solar.
Wait until you buy an electric car, or switch away from gas. Not worth it now.
Aircon would be nice :)
I was in a similar situation to you - low usage, gas cooking and hot water (but WA based). I installed a 6.6/5kW system then two split systems to keep the house at a comfortable temperature year round with no bill impact (there were already two split systems but I avoided using them before solar). Down the track I expect to replace the HWS and stove. If I'm still producing excess after that I'll consider adding an EV charger.
Also hot water heating for larger families.
As you are a low consumption household you are relying on a high FIT (feed in tarrif) to get a good rate of return on your solar system.
Unfortunately solar has been really really effective that it has dropped the price of wholesale rates during solar producing hours massively.
But this has also meant that solar is not worth as much to buy off you and sell to the market.
I have had my solar system for 4 years now and I'm a low consumption household like you, my system has paid for itself already.
However when I first installed the minimum FIT providers could pay was 10.5c per kWh, I was lucky enough that I got on the AGL solar savers plan with a 20c FIT for 4 years.
However now the minimum FIT providers can pay from July 1st is 4.8c kWh.
You can get higher FIT plans, eg I'm on 10.5c with Simple Energy, the usage and daily charge are higher but for us low usage households it's worth maximizing the FIT.
If you get the standard size system (6.6kW) and are north facing then in Melbourne you can expect to generate about 8000 kWh each year.
So 8000 at 4.8c FIT would generate $384 annually if you didn't self consume anything (not possible but just demonstrating the worst case)
IMO it's not really worth low usage households getting solar in Victoria atm
So worst case scenario is return of $384/year? If system costs $3690 that would take 9.6 years to pay back assuming it doesn't break down first
Yes that's correct and even then it wouldn't be because you should be able to self consume at least 5-10%. Lets say you self consume 10% and your current tarrif is 22c kWh? Guessing that's about ballpark. Then that's an extra $137.60 so $521 a year. It is actually hard to see the FIT going much lower than 4.8c, part of the Victorian FIT pricing includes the environmental benefit of the abated emissions using solar so it can only go so low.
As I said I'm low consumption to but not as low as you I think. We have got our self consumption up to 30% with aircon and simply using dishwasher and washer during solar producing periods. So as I said I'm on simple energy 10.5c FIT but the rates are higher for usage and daily charge. My intention is to change to a cheaper low FIT plan about June when solar isn't producing as much and low rates become more important, then I change back to a higher FIT plan about September/OCT.
I think you could get that payback down to 4-5 years with some smart usage and plan swapping.
I'm at work during the day so can't really increase self consumption. The only appliance we have is a fridge. Only 250L so doesn't use that much. No dishwasher, no dryer. We use less than 3KWh per day at the moment
@Repposh: Wow 3 is low usage. Ok lets say you went with Simply energy now at the 11c FIT. I'm just taking a guess and going to say with your usage rates the higher charges are prob going to add 25% to your monthly bill so from 70 to $87.5. But the FIT at 11c would equate to $880 (assuming no self consumption). So $880-($17.5x12)=$670 savings from solar.
I think the numbers are there that if you want to go down the path you should look into it further, but it's not a install and forget, you are going to need to hunt the high FIT every year and do the sums.
@donkcat: So I had a look at the energy compare website to get some rates.
For my area, there are three retailers with FIT between 10c and 11 c. Then there are 8 with FIT between 6c and 7c, and 13 with FIT below 6.
I plugged my figures into a spreadsheet, using the following assumptions
Based on my current usage (3kWh per day)
So it is definitely possible to make it work from a financial perspective, however it does require FIT above 10.
@Repposh: How are you calculating the payoff? Are you making any assumptions about self consumption of solar as well?
That's particularly important as you're better off using all the solar you produce if you can than exporting it, since usage charges are > FiT.
For example if all of your 3kWh was used during the day when the sun is shining (unlikely), then you're getting it for free instead of paying the usage charge for it, so solar is saving ~25c3kWh (whatever your usage charge is) per day. Then whatever's left over for production gets the FiT (subject to caps). So 10c~17kWh. So solar is paying back ~$2.40/day in this case.
So payback in this case would be about 6.5 years for a $4000 system. The more usage you can push to daylight hours, the faster it can be paid off.
If you use most of your energy at night and can't shift to sunlight hours, you're not going to get much benefit from solar without a battery. But environmentally, since you're in Vic and most of your energy still comes from brown coal at all parts of the day, more solar production always better.
@NigelTufnel: I'm assuming a conservative self consumption rate of 20%. Am at work most of the day so opportunities of shifting energy use are limited. That said, since our usage is relatively low (@ less than 3kWh per day) the difference between 20% and 100% is only $90 per year.
How long are you spending on staying there to get ROI