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I know with electrical current and dissimilar metals, aluminium can experience electrolysis so sacrificial zinc anodes are used to manage the problem.
Am wondering if anyone has noticed their solar panel aluminium brackets or frame turning powdery or dissolving. I realise a climb on the roof doesn't happen regularly. :)
 
ANY metal can be subject to electrolytic corrosion either due to voltage produced by contact with other metals (it becomes a battery) or due to DC voltage from an external source.

On a household scale, there's a sacrificial anode in the hot water tank (with the common brands like Rheem or Dux) which transfers the site of corrosion from the tank to the anode itself, thus prolonging the life of the tank. You should replace the anode every 5 years (if necessary - at least inspect it that often to check its condition) otherwise once the anode wears out, the tank will start to rust and you'll end up with a leaking water heater.

On a larger scale, gas pipelines, oil platforms etc use the same approach.

In terms of stray DC currents causing corrosion, it's a major issue with trams (and anything else which uses DC from an overhead wire with ground return). On a larger scale, concern about potential corrosion of just about everything in Bass Strait (including gas pipes etc) is the reason a return conductor was added to the Basslink power cable, at an additional cost of around $350 million. The default (cheaper) option was to use the water itself as the return current path - but that came with corrosion risks.

For household solar PV, basically all the parts are aluminium so there should be no issues with dissimilar metals provided that you use rubber insulators under the L brackets to avoid direct contact with the roof. Due to the wiring arrangement, stray DC current is highly unlikely with a non-earthed system but is possible with an earthed array using a transformerless inverter (never heard of it actually being a problem though).

Anecdotally, the biggest risk for roof corrosion in a normal house is a poorly installed wood heater flue. The main mistakes are either the flue is too short (corrosion effects from emissions, particularly in places that are affected by fog / mist), or there is inappropriate contact of dissimilar metals associated with the Dektite which seals between the roof and the flue.

The old oil heater flues caused a similar problem back when heating oil contained 0.4% sulphur. But with the sulphur almost completely removed these days, there should be no issues with ongoing use of these heaters (not that they are overly common these days anyway). The effects from burning #2 fuel oil (used to be 0.5% sulphur, now reduced to 0.001%) can be seen on many commercial building roofs where such systems are / were installed.

If you want to see real corrosion though then a sulphuric acid plant is the place to find it. Not so bad these days with everything tightly controlled, but the old ones had rust like nothing you'll ever see anywhere else.
 
Thank you smurf. Thoroughly appreciated your post then. The insulation between roof and mounting brackets is the best way.
 
Hi.
I was just wondering how some of the solar panel installations are going?
Are people happy with what they have done.?
3kW & 5kW systems. returns!
Seems a big variation in prices know, but a fair bit of activity in my area to get them installed before July 1st.
joea
 
joea said:
Hi.
I was just wondering how some of the solar panel installations are going?
Are people happy with what they have done.?
3kW & 5kW systems. returns!
Seems a big variation in prices know, but a fair bit of activity in my area to get them installed before July 1st.
joea
Click to expand...
It depends where you live, how big a house and family you have, and how diligently you try and cut down your own consumption.
In WA, the FIT is less than e.g. in SA.
For two retirees in a retirement Unit, 2KW breaks about even. And that translates, roughly, into us effectively having pre-purchased our power needs for the next 5 years with free power for the next 5 years - that's when the FIT subsidy will run out.
 
pixel said:
It depends where you live, how big a house and family you have, and how diligently you try and cut down your own consumption.
In WA, the FIT is less than e.g. in SA.
For two retirees in a retirement Unit, 2KW breaks about even. And that translates, roughly, into us effectively having pre-purchased our power needs for the next 5 years with free power for the next 5 years - that's when the FIT subsidy will run out.
Click to expand...

Thanks Pixel.
Was wondering people with 5kW. system.
EG. where I live a 4.4kW is giving one family $360 credit/ quarter.
Another system just installed (5kW) is producing 23kW hrs. a day. for last 7 days.
joea
 
joea said:
Thanks Pixel.
Was wondering people with 5kW. system.
EG. where I live a 4.4kW is giving one family $360 credit/ quarter.
Another system just installed (5kW) is producing 23kW hrs. a day. for last 7 days.
joea
Click to expand...
Since 29/08/2011, our 2KW system has averaged 10.5 KWh per day.
The maximum was above 13; minimum about 5 (I take readings only every few days.)
 
pixel said:
Since 29/08/2011, our 2KW system has averaged 10.5 KWh per day.
The maximum was above 13; minimum about 5 (I take readings only every few days.)
Click to expand...
fwiw, I just added today's reading to a spreadsheet I've kept since last August.

SolarPower.gif
 
I have two systems, details as follows:

System 1 has 8 x 170W panels facing 20 degrees west of true north. Roof pitch is 22 degrees. Inverter is a 1100W Sunny Boy.

System 2 has 8 x 190W panels facing 70 degrees east of true north. Roof pitch is 30 degrees. Inverter is another 1100W Sunny Boy.

Highest daily output from system 1 has been 8.97 kWh and from system 2 it was 8.73 kWh. I don't check every day, but I check on perfectly clear days etc and those are the highest outputs I've seen.

The lowest output that I've seen was 0.17 kWh for the day. This was for system 1 in its' original 6 x 170W configuration prior to expansion. This was a heavily overcast day in winter.

12 months output for System 1 was measured as 1635 kWh. System 2 has been running less than 12 months so I have no firm data for that - it should be fairly similar to system 1 however.
 
Smurf1976 said:
I have two systems, details as follows:

System 1 has 8 x 170W panels facing 20 degrees west of true north. Roof pitch is 22 degrees. Inverter is a 1100W Sunny Boy.

System 2 has 8 x 190W panels facing 70 degrees east of true north. Roof pitch is 30 degrees. Inverter is another 1100W Sunny Boy.

Highest daily output from system 1 has been 8.97 kWh and from system 2 it was 8.73 kWh. I don't check every day, but I check on perfectly clear days etc and those are the highest outputs I've seen.
Click to expand...
I started with 6 x 175W Suntech panels and a 2KW Orion inverter. Roof pitch is about 30 degrees, orientation North-East. In the first year at 1KW, the output was 1,666 KWh.
Soon after, we added another 6 panels to bring it up to design capacity (and lock in the full WA subsidy at 40c/KWh.)
 
My Dad just got $350 credit for the qtr. Not bad, and the gas bill was $150, so after paying both (including the ambo levy in QLD, $60 annually), he will still be left with $150 credit this qtr.
 
We are in the process of obtaining quotes for a solar power system.

After much research, we have decided on 10 x 190W Suntech panels and a 3kW Aurora inverter, which gives us the option of expansion down the track. The beauty of this inverter is that it has two separate inputs, so if we do get more panels in the future, they can be a different type and not clumped together with the others.

I wonder how many people realise that if they install a system with spare capacity, with a single input inverter they have to add panels that match exactly to the originals? Too bad if they are not made anymore!
 
Eager said:
I wonder how many people realise that if they install a system with spare capacity, with a single input inverter they have to add panels that match exactly to the originals? Too bad if they are not made anymore!
Click to expand...
You can get away with a bit but certainly you can't just mix and match panels here and there.

My "8 x 170W" string actually has two 190W panels in it but due to losses with unmatched panels the effective output from them is 170W each.
 
I can't add extra panels to my 1.52kW system even though my 1.5kW inverter hardly ever reaches its maximum rated AC output capacity (1.65kW) as more panels would result in the open circuit voltage from the panels exceeding the maximum rated open circuit voltage for the inverter.

That's what I've been advised from the manufacturer, Growatt.
 
I'm not familiar with that particular inverter but if the maximum input is 400V then that would be right.
 
Eager said:
I wonder how many people realise that if they install a system with spare capacity, with a single input inverter they have to add panels that match exactly to the originals? Too bad if they are not made anymore!
Click to expand...

Eager
That is a very good point and was not mentioned in the Quotes I was given and the Specifications do not cover it as well.
It is a interesting project to install solar panels as you find out a number of good points.
1 Many of the houses have not got the tariff set up correctly to benefit the owner.
One electrician only uses $26/quarter for hot water with a couple and two children. "tariff
benefits.
2 Many electric hot water systems are using excess power for no household benefit.
i.e. cold water mixer and heater settings.
3 A leaf on one panel will reduce output considerably. Dust is another problem.
4 It appears many boards have been tampered with, to have an additional wire added
to claim free power. Meter Links are now installed in conjunction with solar
installations to prevent this.(In our area with Ergon)

One farmer I know had his meter going in reverse, however they accepted the extremely low cost of the shed it was installed in. i.e. $25 per quarter. :)

There seems to a very wide variation in prices to set up a similar system. I do not know if this is from volume buying or "greedy contractor". In our area we have found variations of up to $4700 for a 5kW similar(same inverter) system. While efficiencies were claimed to be very similar. (Country town)

And finally go to the Golf Club to find out from the solar grid connect "experts".;)
joea
 
To NSW solar panel owners,

is anyone getting credits for net-metered (ie non-Solar Bonus Scheme) feed in tariff (FIT) kWh? If so, which supplier? Might save me a lot of searching.

I understand the recent IPART recommendation was for 7.7c on voluntary basis, but when I rang IE they said they don't currently offer anything on non-SBS net FIT. For mine, if electricity suppliers are receiving non-SBS householder exports for free - then by rights they should offer at least something to the source panel owners.

Thanks anyone who can help.
 
Morning all,

Great thread, and just read it from top to tail - some great information in here. The Good Lady and I have been looking at putting solar into this place, it's just the two of us and the house isn't huge. Our water is gas, and heating is mainly done by wood heater.
We've worked out that a 3 or 4kW system would do the job easily, and would fit on our roof. Our conundrum, is who to go with. There are literally thousands of installers (in Melbourne) and their prices seem to vary wildly.

Any recommendations? We had a guy from Marks Group quote us just under $6700 (and by all intents and purposes his system looks the goods, quality and guarantee wise), but a similar looking system (although not *quite* as good) by True Value is being advertised for under $3000... We asked the Marks Group guy how this compares, and predictably he said a lot of negative things about True Value.

We have done a bit of online research, but 99% of reviews seem to be by people who have had the systems installed but have not yet utilised it for a billing cycle of more. ie. They are reviewing the "installation experience" rather than how much money they are saving, or whether or not the system works. Of course, most negative reviews (from any old installation company) make comment on either the mess they leave (then clean up) or the amount of time the Electicity Company take to re programme the meter. IMO nothing to do with the installation company.

Bottom line - is an installer like Marks, or Leesons who have plenty of good feedbak worth paying close to seven grand for, when a "budget" type installer like True Value advertise well under $3000. We're in Melbourne FWIW.

(disclaimer: I'm a long suffering Bomber supporter who recently noticed TVal's sponsorship but don't hold that against me, be kind).

Thanks in advance for any advice people.
 

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