Virtual Tracker panel arrangement

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Re: Virtual Tracker panel arrangement

Postby Gordon-Loomberah » Wed Apr 16, 2014 4:06 pm

On the proviso that adding more panels does not affect your FiT (I dont know what the current rules are in Qld), you may be able to add some more panels facing east and others facing west, all tilted up at quite steep angles (perhaps 60deg or more, depends somewhat on the exsting panels rating and tilt) to make the most of the early and late sun.
Are your existing panels hooked up as 4 strings of 2 panels? It may be worthwhile to re-align some of them too. It depends a bit on how you want them to look on your roof.
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Re: Virtual Tracker panel arrangement

Postby pangi » Wed Apr 16, 2014 5:56 pm

Thank you I'll make a call to see if my FIT is affected. Is there any other componentry required (and is that the reason you asked for the wiring method)?
Curious... It would seem that the demand for solar has plummeted, or is about to, with current politics. I would have thought that maximising existing systems would be a lucrative little enterprise to fill the void. How come installers aren't jumping at the virtual tracker idea? I've tried to explain the method to a few people according to Gordon's description... Maybe I'm not using the right language?
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Re: Virtual Tracker panel arrangement

Postby karlajensen » Wed Apr 16, 2014 9:20 pm

your 8 panels on the PVE 1200 are wired as 4 pairs of 2 panels
There are string fuses one for each the pos and neg.

YES you can add as many panels as you like will not affect your FIT

need to add in pairs with additional string fusing and note that the DC isolator in your application will become
critical bottleneck.

each panel you have good for ~5.5A or near enough 4 strings = 22A
typically DC isolators only good for upto 32 A

hence what needs to be done is forget the original -leave that alone

install another 6-8 200W panels with their own DC board and string fusing and separate DC isolator
then parallel with the other strings output here.

Note that you need 72cell panels NOT 60cell panels ie 200W jobs common these days.

Could argue that as its ELV you could DIY legally as sub 120VDC VOC. (not to say it wouldnt give you a decent boot if you were careless.)

Apolloenergy has all that gear in stock in QLD.
Shopping list
8x DQ200MFA
4x double ganged HRC fuse holders
8 x 10A HRC fuses (may not be in stock)
10 pole enclosure IP65
ZFV32+W66 DC isolator with enlosure.
4x SL2R3.41 rails
16 x SLTB005 (TILE roof) or 16x SLLF002 Lfeet (check installation manual if close to roof edges)
14 x SLMC024 midclamps (assuming 1 row)
4x SLECF35 emdclamps
1x SLELBT02 bonding terminal
8x15M MC4 leads assuming panels to inverter <15m!

careful with cable from your combiner boxes to inverter = 44A current possible here.
hence should be at least 10mm2 and be DC rated tinned. (double up 6.0mm would be my method)

As existing cable to the anderson plug in the inverter is likely crimped will need new lugs if cable too small (ebay is your friend)
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: Virtual Tracker panel arrangement

Postby Bthree » Wed Apr 16, 2014 10:58 pm

karlajensen wrote:your 8 panels on the PVE 1200
careful with cable from your combiner boxes to inverter = 44A current possible here.


Karl, what happens to a PVE-1200 when you try and feed potentially 44amps into it

does it current limit or go bang ? serious question, I would like to do something like this.
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Re: Virtual Tracker panel arrangement

Postby Whitespeed » Thu Apr 17, 2014 7:47 am

Hi there Bthree,

I can answer that for you. When you overload a PVE1200 the excess amps will not make it go bang, however it will run very hot and potentially shorten it's lifespan.

I have a friend who while experimenting, fed his 1200 around 60a for half a day (not intentional) so I know they current limit quite a bit. When he checked on the inverter it was VERY hot and smelly but lives to play another day. You can tell if they are stressing, the top red coloured LED will start to flash slowly :)

Experimentation shows this inverter to be at its most efficient (at its 1200wh Max output with minimal clipping and cool running temps) with around 1500w input.

In reality, if you are setting this up as a virtual tracker you should never see 44a at the input. If you are you have got the panels too close to the same orientation and will be wasting their output to clipping. Remember clipping wastes your panels output and potentially shortens the inverters lifespan for no gain.

I would be aligning your array to see an input of no more than the 1500w and to sustain this 1500w for as long in the day as possible.
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Re: Virtual Tracker panel arrangement

Postby Tracker » Thu Apr 17, 2014 8:35 am

Whitespeed wrote:.....Experimentation shows this inverter to be at its most efficient (at its 1200wh Max output with minimal clipping and cool running temps) with around 1500w input.


Out of curiosity... the PVE1200 has normal Mode and Battery mode..

What happens if you select battery mode, but connect to a normal array at say 75v..
It will obviously nbe turned on at all times .. ie. Over 54v

What efficiency difference would you get..?

I was thinking of using one in battery mode and when the battery reaches float, activate a cobtactor to switch out the battery and connect direct to the PV...

I do suspect that in battery mode, it just works.. without MPPT optimization,, whereas in normal mode, it will be using MPPT optimization, and woukd thus be more efficient... :D
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Re: Virtual Tracker panel arrangement

Postby Whitespeed » Thu Apr 17, 2014 10:15 am

The idea behind the dual mode on these inverters is to get the most out of the available input.

So yes you have answered your own question. The battery mode is designed for an input with very little variation. The MPPT mode is to get the most out of varying amp and volt inputs.

If you choose Battery mode for PV input you would be effectively putting "blinkers" on the inverter :)

I guess if you where after the most efficient way of using one AND you had off grid as well. Then My guess would be to run in battery mode, grid feeding off the battery, leaving your MPPT cc to charge and handle the panel variances.

No need for passive tracking then, the battery will absorb and smooth over the peaks and troughs of the days oversized solar arrays input.

Of course, if you where setting up a small off grid just to provide this buffer, then charging inefficiencies would loose you any gains you have made.
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Re: Virtual Tracker panel arrangement

Postby Tracker » Thu Apr 17, 2014 9:42 pm

Whitespeed wrote:......Of course, if you where setting up a small off grid just to provide this buffer, then charging inefficiencies would loose you any gains you have made.

ATM... I am charging and allowing the battery mode to kick in and export whatever it can...
Thanks for confirming my suspicions...

I have (shall we say) a number of them, and so the most efficient response will be to just use two or three and be done with it...
..
.
Retired Engineer and keen PV experimenter - Always ready to learn and share.
2 x CMS2000 (fan cooled) GCI and SE 170W panels
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Re: Virtual Tracker panel arrangement

Postby thechad » Mon Jul 07, 2014 12:33 pm

Loving this post.

I have been thinking about how I could get more out of my (North facing) 2KW (Daqo 8 x 250w) system for a while now...I had been thinking I need to add another inverter...but this looks like a better option - esp. as I just want to cover base load for longer and not add extra feedin.

The current system is on a two story house and it has a nice curve (see below from a full san day back in Jan(?) but I have a good West facing roof space that would extend the curve out to the right (until it is obscured be the roof of the house next door just perhaps half an hour before sundown)

Given it is a 2KW inverter (Aurora), I want to make sure I do not overload it...but perhaps that will not be much of an issue?

I will print this thread ut and have a read through at lunch time.

It would be great to hear any suggestions on how might I go about understanding the optimal number and alignment of panels and the potential generation?

While I am an acomplished do-it-yourselfer, I'd prob. get the new pannels installed...so any suggestions on who might offer this service in Melb. West (and knows about this specific application) would be appreciated.


Cheers.
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Re: Virtual Tracker panel arrangement

Postby Gordon-Loomberah » Mon Jul 07, 2014 12:41 pm

Have you tried contacting Energy Matters about adding more panels? They can certainly do arrays facing in different directions.
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