Home Solar ROI

[JCOJ]

We installed solar panels on our roof last November and got an 11.88kw system with a 10kw inverter all for just over $10k after rebates.

We're with Origin for our power and they pay a 18c feed in tarrif and allow up to a 10kw system (which we got away with as our inverter is 10kw).

It is the best thing we did and regret not doing it earlier.

[Pete79]

Just finished crunching our numbers and the 10kw 3 phase system (producing approx 40kwh/day) we’re looking at should be around a 3 year ROI based on our current average consumption of 23kwh/day and a feed in tariff of 17c.

We get a little bit of shading from a big gum tree on the council road side, so we’re looking at an optimized system with each panel having it’s own dc/dc converter.
These panels and 3 phase inverter is a little more expensive then some of the cheaper simple systems out there, but we’re banking on the much better efficiencies of this system improving our ROI considerably.

[GeoffA]

Just finished crunching our numbers and the 10kw 3 phase system (producing approx 40kwh/day) we’re looking at should be around a 3 year ROI based on our current average consumption of 23kwh/day and a feed in tariff of 17c.

We've averaged 82kwh/day from our 28kW system, but we are in Victoria, so your 40kWh/day seems reasonable.

If only we could get a 17c FIT....

We get a little bit of shading from a big gum tree on the council road side, so we’re looking at an optimized system with each panel having it’s own dc/dc converter.....

Is that an Enphase system, or a TIGO optimiser on each panel?

When we were looking at it, the Enphase system locked you into their battery system.

A mate went with TIGO's on his 6.6kW sytem, and is very happy.

 

[lloydus67]

Best I can get in Brisbane is 16c for first 5kw then drops to 10c with red energy


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[PWE]

....unless you have 3 phase, then it's 30kW (for us, some are 15kW max) and away we go....

Who needs batteries??...

 

How easy is it to change a house connection from single to three phase?

[PWE]

We put a large system in about 18 months ago and have not had an electricity bill since. We have a pool and are all electric except for the cooktop. We also connected the off peak water heater to the solar to come on mid afternoon. Our panels face almost due west.
We have 10KW of LG solar panels on the roof, each with its own mini inverter, and a 14KWH Tesla battery. The whole thing came to about $29K. As I write this we have 6.6KW coming off the roof with almost all of it going back into the grid because the battery is full.

I did a discounted rate of return spreadsheet based on the following assumptions.
1. We would generate all of our own power for the 25 year life of the panels.
2. The battery would hold out for that period. I reckoned that a replacement battery in 10 or 15 years time would be much cheaper than now.
3. That power would escalate in cost by 2% a year from here on.

This gave an equivalent rate of return of just over 11 per cent per annum. That's better that we can get in super.  Incidentally, the ten year government bond rate is currently just 0.83 per cent per annum.

Keith

I have a similar system.
Have not seen a power bill since I have installed it and receive a nice cheque in October for the previous years feed-in surplus.
So every September I start at zero and get paid the credit in October.

[GeoffA]

How easy is it to change a house connection from single to three phase?

Talk to your local sparky and supplier.
As far as I'm aware, it's just a matter of money....

 

[Pete79]

We've averaged 82kwh/day from our 28kW system, but we are in Victoria, so your 40kWh/day seems reasonable.

If only we could get a 17c FIT....

Is that an Enphase system, or a TIGO optimiser on each panel?

When we were looking at it, the Enphase system locked you into their battery system.

A mate went with TIGO's on his 6.6kW sytem, and is very happy.

 

It’s actually a Solar Edge system.
Instead of the microinverters on each panel they use a dc/dc optimizer on the panel and a simplified inverter on the wall.

The length and position of strings doesn’t matter and the specific panels we’re looking at have smaller zones and perform better with partial shade.
You can track each individual panel performance similar to the Enphase system and the app looks pretty cool.


This is not the company we’re using for our system, but this is a pretty clear explanation of the panels we’re using.
https://www.infiniteenergy.com.au/new-release-canadian-330w-hiku-canadian-solar-split-cell-panels/

https://youtu.be/xmovy6xqUO8

[Pete79]

How easy is it to change a house connection from single to three phase?

We did 3 phase when we built the house, there was a couple of threads on here a few years ago with people looking at upgrading their house/shed to 3 phase, from memory it was a bit of a hassle.

FYI; Here in QLD we are only allowed to export 5kw per phase from solar.

[GeoffA]

It’s actually a Solar Edge system.
Instead of the microinverters on each panel they use a dc/dc optimizer on the panel and a simplified inverter on the wall.

The length and position of strings doesn’t matter and the specific panels we’re looking at have smaller zones and perform better with partial shade.
You can track each individual panel performance similar to the Enphase system and the app looks pretty cool.
....

We looked at Enphase and Solar edge, but most of our roof is pretty clear of shade. In winter we lose a bit early and late in the day, but not enough to worry about.
We have 20 TIGO optimisers on the panels that are impacted by flues, vent pipes etc, but it would have been prohibitive as well as unnecessary to fit them to all 90 panels.

 

[Craig Tomkinson]

3 Phase goes past our house 50m away I will look at price to hook up, then I want to build a bigger shed as I want to start building alloy trailers and few bit and peaces, so fit solar to the roof of the shed not my house,  are all your set ups battery ready for later on if you go off grid in the future, thanks for the great info everyone, Craig

[Pete79]

Best I can get in Brisbane is 16c for first 5kw then drops to 10c with red energy


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AGL are doing 17c for systems up to 10kw, but it’s a variable rate.
And pricing is due to be reviewed at the end of this month, so we’re not signing any contacts right at this moment.

[GeoffA]

FYI; Here in QLD we are only allowed to export 5kw per phase from solar.

Most residential properties struggle to fit enough panels to export more than 5kW, no matter the number of phases.

 

[Craig Tomkinson]

the panels are 300 watts now or bigger are they

[bmwfreak]

and a feed in tariff of 17c.

Bloody Nora, we have the choice of one retailer, or no retailer. Started off 3 years ago with feed in of 10.8c and now down to 7.6c.

Craig - we have 15 x 340 panels on the shed roof. They were described by the salesman, at the time, as ‘Industrial size’ which we needed due to lack of roof space for the more common ‘domestic size’ For the 5kw we wanted.

[Craig Tomkinson]

Thanks

[achjimmy]

It’s actually a Solar Edge system.
Instead of the microinverters on each panel they use a dc/dc optimizer on the panel and a simplified inverter on the wall.

The length and position of strings doesn’t matter and the specific panels we’re looking at have smaller zones and perform better with partial shade.
You can track each individual panel performance similar to the Enphase system and the app looks pretty cool.


This is not the company we’re using for our system, but this is a pretty clear explanation of the panels we’re using.
https://www.infiniteenergy.com.au/new-release-canadian-330w-hiku-canadian-solar-split-cell-panels/

https://youtu.be/xmovy6xqUO8

We have a SolarEdge system and have been very happy for the 5mths so far. Using 330watt blade panels. I got onto origin with 21c feed in just before they dropped it to 18c so it’s 21c till feb next year.

[lloydus67]

Most residential properties struggle to fit enough panels to export more than 5kW, no matter the number of phases.

 

Hi Geoffa
I have a 4.5 kw micro inverter system,  2 panels per inverter



This is my bill for 29 days in may. Well and truely winter, short days
179 kw generated, so average 6.2 kw per day


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[GeoffA]

Hi Geoffa
I have a 4.5 kw micro inverter system,  2 panels per inverter

This is my bill for 29 days in may. Well and truely winter, short days
179 kWh generated, so average 6.2 kWh per day


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Hi Lloyd,

I was talking kW. Your bill has quoted kWh. They are different....

By the way, your FIT and service charges look pretty good. Better than mine, anyway...

 

[bmwfreak]

Prior to our solar installation we had the old spinning disk style meter. This called for a meter reader to physically turn up every quarter to take readings. Quarterly charge for the reading was $10.28. Solar added and new digital meters installed, which are read remotely and the meter reading charge is replaced with a meter ‘Service charge’ at $5.09 per month, giving the retailer a $5.00 per quarter profit, over the old meter, not including the savings on manpower ?

[Pete79]

Well the ROI on our new solar system just keeps getting better....

I was reading through all of the contract documents today and noticed that the inverter actually has a 12 year warranty (and 25 years on the rest of the hardware).
This gives me a couple more years before I need to factor in that replacement cost. 

And I did a bit more shopping around for electricity plans today as well. Looks like I've found a winner.
Currently paying $1.26 per day supply charge, new plan is 99c.
Currently paying 27c/kwh, new plan is 26c.
Feed in tariff is 18c/kwh.
All locked in for 12 months.

I've made a few assumptions and down played the actual solar production due to some potential shading issues.
They say a 10kw system should produce 42kwh/d, I'm doing my numbers with an average of 38kwh/d.
We currently consume an average of 23kwh/d, I've made some guesses on running the new pool pump and estimated an average of 28kwh/d?
Also took a stab in the dark for our day time/night time usage. We're home all day and I only run my office AC on the extreme days, all of the cloths and dishes washing is done during the day and the whole house runs on LED lights.

But anyway, I've just made some assumptions and chucked some numbers into a very basic spreadsheet to get a rough idea of how this investment will look for us.
Basically no matter which way I cut it, we're looking at a 3 year payback.
Even going really silly with my usage numbers I still couldn't stretch it out to get to the 4 years.

Pretty happy with this choice. 

[Fizzie]

Basically no matter which way I cut it, we're looking at a 3 year payback.
Even going really silly with my usage numbers I still couldn't stretch it out to get to the 4 years.

Pretty happy with this choice. 

 

Go to it, Pete

[austastar]

Hi,
    My numbers are pretty rough, (2015)
$1000/ year usage.
$7000 install cost.
$0 running cost from installation date.
Gain a few hundred dollars credit every year which will erode when the feed in tariff drops from parity (28c) to 7c.

Only regret?
They changed the meter to digital. I loved watching the old spinning disk running backwards. Very therapeutic.

Cheers

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[briann532]

There have been a few threads on this.

Someone on here was involved with Solar from memory... They were saying if your not home during the day when the most power is available - wasnt worth it - unless you have batteries.. they charge up during day, you use morning/night from batteries

GUILTY as charged.

Yes, I do this for a living (sometimes as well as being a wirejerker and people pisser offerer!!!!)

If I can't design a system for a client that has a 3 year ROI (return on investment) then something is wrong.
Had a few clients not happy as shading, roof space etc led to much longer return periods.
It then simply isn't worth it.
Half the time they end up with a sales company promising the world and they get had. Hey I tried I sleep well.

Seriously though if you can't get a 3 year payback period get a better designer on board. The technology is there and the equipment is affordable.

Batteries. Well the weather has been pretty good lately hasn't it?

[Bird]

wait till everyone signs up .. and then -> Australians with rooftop solar panels could soon be charged for exporting power into the grid, under proposed changes


https://www.abc.net.au/news/2021-03-25/australians-with-rooftop-solar-charged-export-electricity-grid/100026336