Parallel and Series connection of Panels

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Parallel and Series connection of Panels

Postby Yogi99 » Sat Apr 30, 2011 7:00 pm

Hi to any solar experts.

I have just had a 2.3Kw Panel system installed.

It has 12 * 190W panels. The installer initially wired them all up in series. However the open circuit voltage was two high for the inverter.

So to fix it he split the system up the easy way to match his install, 8 Panels in one series group and 4 Panels in the other series group and then paralleled them. I did ask him if this was right and I got yer thats all good.

But to me that sounds wrong as in the voltage output from one bank is higher then the other so to my logic i will only get current from the bank of eight.

Can anyone confirm this is ok or if its wrong.
Last edited by Gordon-Loomberah on Sun Jun 19, 2011 7:42 pm, edited 1 time in total.
Reason: Edited subject for spelling
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Re: Parrellel and Series connection of Panels

Postby Gordon-Loomberah » Sat Apr 30, 2011 7:15 pm

Welcome to the forums Yogi99 :)

Your logic sounds correct to me at first glance, but more info required! Does the inverter have 2 independent MPPT inputs? If so, what is the MPPT operating voltage range? What is max Voc of the inverter? What is the Voc of the panels?

However, if both strings are going to 1 input, then you are definitely going to lose a lot of power.
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Re: Parrellel and Series connection of Panels

Postby Yogi99 » Sat Apr 30, 2011 7:27 pm

Hi Gordon,

Thanks for such a prompt response.

Both Strings are wired in Parallel on the roof IE going into the inverter on the same positive and negative cables.

The inverter is an ever solar TL2000AS.

The MPPT voltage range is 125 to 450V

The Max VOC of inverter is 500V.

The panels I am not sure as its on the underside.

Edit: Looked it up and it looks like the panels VOC are 44.8V
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Re: Parrellel and Series connection of Panels

Postby Gordon-Loomberah » Sat Apr 30, 2011 7:48 pm

OK, assuming the panels are fairly standard monocrystalline, the Voc would be about 45V, 12 of them gives Voc= 540V, so you have to wonder what the installer was thinking (maybe they weren't) when they attempted to connect them in 1 string, when the Vmax of the inverter is 500V.

Do you have any readings of the output yet? Your inverter only has 1 MPPT input, so I'm sure that string of 4 will be useless, you need to get the installer back to make it 6+6.
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Re: Parrellel and Series connection of Panels

Postby Yogi99 » Sat Apr 30, 2011 8:26 pm

Hi Gordon,

The inverter voltage from PV is currently at 150V but its only making 300w as its late in the day. I will look tomorrow when its at full sun. But Basically if the Voltage from the PV is greater then 4 * 44.8V =179.2V the bank of 4 is sitting there doing nothing.

Thanks for that. Second opinion is always good before getting on ones high horse.

My brothers system is a 1.9Kw and he has made 10 + units today with 10 * 190W panels and I have only made 8 units with 12 * 190W Panels - and the panels are facing nearly due north with no shade.

For anyone watching this was not an energy matters install. It was in WA and by Bright Generation, via Retra Vision but even then they sent out subcontractors to do the job. So who to blame ?
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Re: Parrellel and Series connection of Panels

Postby Inspector » Sat Apr 30, 2011 11:51 pm

I can't remember the % off the top of my head, but AS5033 Appendix outlines that during the testing of the installation, any strings in parallel can't be more than say 5% difference in voltage between the strings (basically implying the number of panels needs to be indentical for each parallel string).

This is a perfect example of the type of system/installer I would refer to Clean Energy Council for review of that installers accreditation.

Name and shame the installer :)
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Re: Parrellel and Series connection of Panels

Postby karlajensen » Sun May 01, 2011 4:43 pm

Yogi99

in my experience the contractors you speak of are some of the very best around. It's highly possible the sparkie was pulling your leg as these blokes do like doing that kind of thing (ie having a joke and a laugh).

Perhaps its like the old pilots joke
passenger says to pilot
"OK, so I've worked out what all of these instruments do but I cant figure out what this one is doing"
Pilot responds with
"look love, I'm havent got a clue what most of these things do but I've worked out that when I pull the stick back, the nose goes up and when I push forward, it does down so I think we'll be right!"

Reported to CASA by passenger as being incompetant where in fact the guy has 10'000hrs of experience under his belt and knows exactly whats going on!

Have you spoken to Retravision or BrightGeneration yet?

8 units is not entirely unreasonable my 2.6KW (14 185W panels) made 12+ the other day, but 10 the day before that, a high cloud that affects you doesnt necessarily affect someone a suburb away can knock a couple of kW out of the mix without too much trouble.
8E + 8W + 8Nth Garage CMS2000-1 with ~4500W in 3 strings of 8.
Fronius Galvo 3.0 inverter with ~6.6kW panels
12x ZNShine + 12x 180W Solarfuns both NW + ZNShine 12x190 facing SE.
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Re: Parrellel and Series connection of Panels

Postby karlajensen » Wed May 04, 2011 12:00 pm

Yogi99

The boys tell me that the sparkie was new with the company and had been using a different inverter that had a 600V max input hence when he realised that there was an issue (over 500V) made a blunder doing the re-config into two strings. :o

The boss didnt need to give him a bollocking,
the other sparkies aren't letting him forget it anytime soon :oops: and I think he's buying beer this week. :D

He was there in the dark last night getting it sorted.
Let us know how it goes today nice and Sunny here in Perth today. 8.8+ and its a ripper system as each of my 2.59 arrays are doing around 9.8 -10.2 kWhrs / day at the moment
8E + 8W + 8Nth Garage CMS2000-1 with ~4500W in 3 strings of 8.
Fronius Galvo 3.0 inverter with ~6.6kW panels
12x ZNShine + 12x 180W Solarfuns both NW + ZNShine 12x190 facing SE.
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Re: Parrellel and Series connection of Panels

Postby Yogi99 » Fri May 06, 2011 1:04 am

Hi Karl,
All good now. 10+ Units a day, system was outputting 1900W yesterday at Mid Day previously it was maxing out at about 1200W.
So thanks
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Re: Parrellel and Series connection of Panels

Postby hughie088 » Sun Jun 19, 2011 6:26 pm

Hi every one
I recently have done a solar power (feed back to grids), 12X190w panels and with 3200 invertor. firstly the installor wired them all in serial system and afetr few days they came back to change them in paralleled two groups of 6 seried panels. which to be understanded the out put waitts is same. but I had note that invertor has start later than before the rewiring, when all the panels are in seires the invertor started much early even just the sky had a very little lights, now the invertor would be turned on much later and running the checking and not generating any power untill to 8 o'clock. dose any one can explay that.
Thanks,
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