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Costs of solar over time

In 2012, I had a reputable installer fit solar panels to my house.

If has reduced my electricity bills somewhat –currently the savings are a bit over $200 per year (admittedly in a small household which doesn’t use a lot of electricity).

Last year the inverter failed and it cost around $1,100 to replace. I could easily have spent a lot more on the inverter itself if I’d taken up the tradie offer of ‘This particular model comes with a 10 year guarantee but it’ll cost you $4,000’ – ‘uh, no, thanks.’

When I identified the problem initially, the first solar electrician I called asked, ‘so let me guess – you’ve had the system about seven years?’ It seems like inverters have a shelf life and that cost needs to be factored into the longer term calculations for the system.

In other words, installing a solar system might not save you as much as the initial projections indicate.


Considering what you saved with the lower cost original purchase. Solar Quotes typically allows for a 10 year life for the better brands. They also rate each brand.

They build that into their payback calculator. I look at what we would have spent cumulatively on electricity over time. Hopefully over 7 years the power not purchased and credits have made it worthwhile.


You must have a very large system (e.g 10kW) with a three phase inverter?

Based on $1100 to replace suspect it would be around 1.5-2kW system. If this is the case, there are well known 10 year manufacturer warranty ones around this price or a few $100 more fitted. It appears your installer may be blowing hot air for some reason.


My system is 2kW. I think I’ve about broken even, allowing for the opportunity costs of the original capital and the replacement cost of the inverter – and there’s a feel good factor about pumping less brown coal into the sky.

The manufacturer of the original inverter went bust, so any guarantee would have been meaningless. As for the installer blowing hot air, I know of one person in my neighbourhood who paid a multiple for a gas hot water heater with a 10 year warranty. It appears to be exactly the same brand and type as the one I have, but mine only has the standard warranty, so I suspect the inflated price is a ploy for unscrupulous tradesmen or suppliers to dupe consumers. Apart from that, I’m not so sure of my chances in going back to a supplier after 9 or 10 years and getting them to actually honour the warranty.


There are many products where the model with 1, 5, 10, or 20 year warranties are the same product, but those with longer warranties have comparatively premium prices to cover the longer warranty periods. It is not unscrupulous, in a way it is similar to buying insurance - if you don’t need it why buy it - until you needed it.

My instinct is the manufacturers ‘win’ as they have more profit from the premium model number and many consumers equate premium with higher prices and want more than a basic, so even though they may be the same product (or may not be!) it weights sales volume to the mid or higher tier prices and the failure rates of all may be the same (or not if the products are actually different).


We had a 3 Kw solar system installed in August 2011. This in WA where the installation was just in time to get a 40c/kWh Net Feed-in tariff for 10 years, as well as Renewable Energy Buyback of 7c/kWh. By April 2020 the installation cost of $10,970 was just matched by the accumulated Net Feed-in tariff. Before the Net Feed-in tariff expires in May, we will be looking at possibly installing batteries. We have had absolutely no issues with the entire system thus far.


Good timing to catch that FiT deal.
Do you know how much of your own generation, ie “free” as in not paying the electricity company for usage, you used?

That needs to be taken into consideration when looking at the value of a system, but unfortunately many do not factor that in when considering the value of their PV system.


Would be nice to have the information, but would need software and hardware to store and analyse the data. Wasn’t easily available back in 2011 to my knowledge

It was certainly availble, but very few were using it. I’ve always advised people to use system monitoring, to keep an eye on performance and pick up problems early.
You can probably work out some sort of estimate based on your exports and expected output based on your location and PV array orientation, taking into account any shading.

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You can use a spreadsheet to analyse basic data which is reported on your power bill and by your inverter. It won’t give time based usage like that recorded by a smart meter, but can provide information to make decisions.

We used a spreadsheet for many years to track export, import, PV use for each tariff (peak, off peak and shoulder where applicable).

If one isn’t exporting much power (that being the amount exported is less than battery storage capacity and subsequent import usage), batteries are less likely to have much benefit as there will be limited excess generation for the battery storage. One needs to have significant export for battery systems.

It is also worth noting that at this point in time a battery system won’t be an economic proposition. It isn’t known if and when they are likely to be. Battery systems are also not overly reliable at this stage either. Both are covered by other threads in this forum.


This Choice article is undated so it makes it difficult for readers to interpret where prices may currently be, eg, is the article a few years old so battery prices may now be more affordable, or is it recent so it may still be a few years wait.

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At least January 2020 if not later in the year, based on the link to the tests which are dated.


Another option for sizing up the costs and relative benefits of a battery.

The calculator does not put a value on the environmental benefits, or increased energy independence. That’s a different decision?

Solar Quotes also has a comparison table with most of the available battery options. The same can be used in conjunction with the guides on the Choice website.


We have had our system installed since May 2011. We estimated it would take 7 years to recoup the costs. It took eight years. Our inverter, SunnyBoy, has the facility to download generation (Sunny Explorer). I download at the end of each month and so have data from when it was installed. I also have the value of each 3 month generation in dollars and we are currently over $2500 in front of the original cost. Our summer generation really pays for our winter lack of generation. We also get the much higher payback for our input. We believe it has been a very worthwhile investment.


And these figures only cover $$$. There are other less obvious benefits too - not the least of which is the uptake of domestic PV systems which has dragged power suppliers/market (kicking & screaming) into the 21st century…


Continuing the discussion from Costs of solar over time:

We installed our first 10 panels Apr 2015. I have kept a spreadsheet record of costs and feedin tariff returns since then. The first panels cost $6,500, they were the top Chinese brand and we had micro inverters (very new tech at the time) installed because we spread the panels across two areas of the house. We were paying 22.74 c per Kwh for power and about $1 daily supply charge. Our costs pre panels around $2200 per year including daily supply charge. I estimate similiar to burdith it would take 7 years to pay off the system. The first 12 months our power costs were reduced 50%, plus feedin return was $40. Estimated pay off time by end of 2017 was 5 years. 2016 power cost rose to 27.74. 2017 Installed another 10 panels, March 2018 installed a battery. Cost of power by 2018 32.22, daily supply now $1.20 per day. Total cost of whole system $24,000.
Savings hard to estimate for these reasons: both retired now so more power used, installed a new all electric kitchen and reverse cycle air con in each room. We use off peak power to top up the battery on days of low solar reducing costs further. On very hot days we turn on more than one air con to keep the house cool and still keep the battery at 100%.
Currently pay approximately $500 per year after feedin plus daily charge $400. Estimate time to pay off total investment will be less than 10 years.


Interesting reading, our system is seven months old, and cost $5k to install (zero rebates), to date we have harvested $760 from the system, thus I expect our annual recovery to be about $1,100. Payback in 4.5 years.
I am not sure if I am calculating the savings in the same way as other people. I calculate it in two parts:

  • The energy we sold (sold Kwh * feed in tarrif)
  • The energy we generated and consumed ((total generation - energy sold) * what we pay for power)

So taking yesterday as an example, we generated 29.2 kwh, and we fed 15.5 kwh back to the grid.
we currently pay 25.894c/Kwh and get 10.2c /kwh as a Feed In Tarrif.
So our earning from the solar yesterday was (15.5*10.2)+((28.2-15.5)*25.894) = 513c ($5.13).

I know that this ignores the 10% pay on time discount from the energy supplier.

I believe this is the most accurate way to calculate how much your solar system is saving us.


Welcome to the community @Plendo.

I do the same.

At the end of each year many of us with Solar PV will still have paid something for our electricity. It’s always much less than we would have paid without solar PV.


On one occasion since 2017 I’ve paid a bill of just over $30 - only because I withdrew over 1000$ credit that had accumulated at just the wrong time (unusually cloudy for a short while between the withdrawal and end of billing cycle). It’s back into around 500$ credit now - I’m fairly happy with that … system paid for itself in around 2 years …


26.05 reasons for that to be so good? There’s likely others. Some in the community are just exceptional!

For the rest of us including,
Anyone newly into rooftop solar needs to factor in the latest, not so generous feed in tariffs. Maximising self consumption might provide the best return.