Second net FIT system – maybe hybrid down the track.....

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Second net FIT system – maybe hybrid down the track.....

Postby Firegirl » Thu Apr 24, 2014 11:56 am

Hi Folks!
We live on South Coast NSW and have had a 1.52 kW grid connect system (8 x Suntech STP-190-18Ub panels, feeding an SMA SB1700 inverter) since 2010. It has performed much as expected given its less-than-perfect orientation and elevation. (Details in “Introduce yourself” forum). We are on the 60c gross FIT, and with our modest consumption have been in the black ever since.

Would like to add an inexpensive additional net metered system. l have checked with the distributor(Endeavour) and retailer (Origin) and apparently this is allowed, and we would receive a “generous” 6c per kWh for any surplus exported, without compromising our existing gross FIT. When the 60c gross FIT ends in 2016 it should then be very simple to change over the existing system to net feed also. I can imagine somewhat of a scramble for installation of interval or smart meters then, as those on the gross FIT suddenly realise they are receiving only one tenth of the tariff they used to get.

Suitable roof space is limited to a small roughly triangular section on the garage with NW orientation, 45 deg elevation, that gets full sun 11.am to 3.00pm in winter. Existing system and meter box are also on garage. Red arrow shows where new array would go. Could fit 6 1580 X 808 size panels in landscape mode with a “pyramid” of 1,2 & 3 panels. Portrait orientation won’t fit. Larger 250W panels won’t fit either without hanging over at the corners.

garage 11.25am June.jpg
garage 11.25am June.jpg (72.1 KiB) Viewed 5819 times
Taken from roof of house...

We already have a new unused SMA SB1200 inverter that we could use (older technology & less efficient maybe, but rugged, and no cost). Start voltage 120V, MPPT 100-320V, DC max 400V. For panels, something like Daqo DQ200MFa (72 mono cells) on a single string of 6 in series for 1.2 kW. OCV 45.4V, optimum power V 36.7, short circuit current 5.65A. Coldest here was -2 deg C at ground level, so max voltage expected should be around 6 X (45.4 + (27 x 0.0031 x 45.4) = 295V, and the min voltage in summer, assuming cell temps of 85 deg C might be about 6 X (36.7 – (60 x .0031 x 36.7) = 179V, both values well within the inverter’s MPPT range, (and not surprisingly very close to the values for the 8 X 54 poly cells on the existing system).

So what are the thoughts of the folk out there who know? Specifically:

1. Can we purchase and legally install the panels on the roof ourselves? I can see this is a fiddly job to do correctly and have it look OK. There are some really dicky looking installs in our area! We would leave the supply and installation of the cabling, conduit, AC and DC breakers, rooftop DC isolator etc. to an electrician to do.
2. Re the electrician, I understand they would not need to be CEC accredited unless we sought to claim RECs (or whatever they are called these days)...????Have I got this right?

And for more general comments/criticisms/suggestions:
Sometime after the gross FIT ends I would consider going hybrid. I can’t see us going totally off grid given our winter shading issues and capricious climate. We would have to drop the dedicated off peak tariff for hot water (unless the powers-that-be allow it to be used for battery charging also) and go onto TOU metering, so batteries would only charge from the grid when necessary at the cheapest rate. A small LiFePO battery pack (24 or 48 V?), approx 6kWh should cover the late afternoon/evening use to no more than 70% DOD. An inverter/charger of say 3 kW continuous would cover us 99% of the time. Presumably the grid can supplement the inverter output as necessary if the device is smart enough? Inverter and batteries both located in garage. Maybe later add some more panels with individual microinverters, or several short strings of amorphous panels on one GTI, on the house (about 20 m away and suffers lots of moving shade for 6 months of the year). Everything AC coupled.

The graph below shows average daily consumption/generation, the data being weekly readings from switchboard meters. Hot water is off-peak plus fire boosted flat plate solar that suffers winter shade. Flat bits are interpolations due to missed readings because we were away (or I got lazy/busy/forgetful). Consumption peaks are visitors staying (there is a separate small electric HWS for the guest room over the garage. :cry: ). The deep troughs in generation are weeks of overcast weather, except Sept 2010 that was a 5 day blackout. The generally decreasing trend in consumption is due to progressive adoption of fluorescent then LED lighting, a more modern TV, and finally a modern fridge... :)

Weekly power.JPG


I doubt with our modest consumption that any of this would be cost-effective in the shorter term but it would give us protection from blackouts if we were prudent with our usage (we have a portable 2 KVA Honda generator to add to the mix if grid is down for long time in winter), and it would be interesting, and green......Apologies for the long post, and thanks in advance for your thoughts.
Leslie Anne
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Re: Second net FIT system – maybe hybrid down the track.....

Postby davidg » Thu Apr 24, 2014 9:52 pm

Firegirl wrote:2. Re the electrician, I understand they would not need to be CEC accredited unless we sought to claim RECs (or whatever they are called these days)...????Have I got this right?

NSW is like VIC I believe, then no the installer must be CEC accredited or the sparkie doing it must "supervised" by an accredited installer to get it connected to the grid, this is normally required by the distributor (poles and wires), choosing to claim REC's = STC's as they are called is your choice.
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Re: Second net FIT system – maybe hybrid down the track.....

Postby Tracker » Fri Apr 25, 2014 10:18 am

..
IMHO..
you could first apply to the local power distributor for a second NET feed in system..
The cost of a new system is not that significant these days.. eg.. I bought an INSPIRE inverter for fourty bucks and can find an installler who will source, supply, and install an acceptable set of panels.. you don't need an inverter as you have one.

At the risk of being criticized, I would install panels overhanging the ridge, as a rectangular block of maximum size.. I would not claim STC's, so that I could break the rules a little. I assume that you are saying that three panels will fit l to r..
If you can fit a frame, legally, on the ground, then you can do it at height.. ;)
You could fit brackets to the actual wall, to support the top rail .. nine panels or more should be doable
Where there is a will, there IS a way.. if you ran from the wall, down to the gutter, how many panel rows might fit..

Your goal is to provide background power to reduce day time consumption..

PS... full score for being right up on the best thinking...
..
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Re: Second net FIT system – maybe hybrid down the track.....

Postby Firegirl » Fri Apr 25, 2014 1:19 pm

Tracker wrote:..
IMHO..you could first apply to the local power distributor for a second NET feed in system..

Yes, this is exactly what we intend to do initially with the new system on the garage roof. A small system to offset daytime use might even pay for itself in 10 years or so...although one never knows as they move the goal posts so often :x

Tracker wrote:..At the risk of being criticized, I would install panels overhanging the ridge, as a rectangular block of maximum size.. I would not claim STC's, so that I could break the rules a little. I assume that you are saying that three panels will fit l to r..
If you can fit a frame, legally, on the ground, then you can do it at height.. ;)
You could fit brackets to the actual wall, to support the top rail .. nine panels or more should be doable

That is a brilliant idea which I had not even considered...neater than overhanging corners on a triangular array and would allow 50% more panels. Unfortunately HWMBO :shock: is insistent that nothing overhangs. Oh well, ours is a team effort after all. :D :D

I am wondering, in applying for a new net system, can we apply for the system we might hope to have in 5 years time, say 3.5 kW (5 kW total with the existing 1.5kW gross FIT system), and only install 1.2kW initially? I would prefer to do that if possible because as indicated above I don't trust the powers-that-be not to change the rules....
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Re: Second net FIT system – maybe hybrid down the track.....

Postby Tracker » Fri Apr 25, 2014 2:57 pm

Firegirl wrote:.....neater than overhanging corners on a triangular array and would allow 50% more panels. Unfortunately HWMBO is insistent that nothing overhangs.....team effort...


and so is paying the bills.. - What is the problem with OverHang..

Unfortunately, if you want to consider MORE, and especially if you want to work towards HYBRID and possible OFF-GRID, then you will have to think outside the square.. or even better - thinking of the square option Especially given the very leafy nature of the area..

I am wondering, in applying for a new net system, can we apply for the system we might hope to have in 5 years time, say 3.5 kW (5 kW total with the existing 1.5kW gross FIT system)...



....only install 1.2kW initially? I would prefer to do that if possible because as indicated above I don't trust the powers-that-be not to change the rules....


You could do that.. You have the inverter now, suitable for a likely total PV of about 1500W...

and, if that is the garage, what is the house like, or is that the house also..
..
.
Retired Engineer and keen PV experimenter - Always ready to learn and share.
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Re: Second net FIT system – maybe hybrid down the track.....

Postby Firegirl » Fri Apr 25, 2014 6:26 pm

Tracker wrote:if that is the garage, what is the house like

The house is not much larger than the garage, about 20m away to the north-east. Pickies below are taken midwinter...you get the idea re shading. They show the north-east aspect of the house - the "back" which faces onto the public reserve. You can just make out the end of the solar HWS tank, just below and to the right of the chimney on the north-west facing end at the right. The shade is similar for a couple of months either side of the solstice. There is minimal shading over summer when the array(s) on the garage roof would do the job anyway.
houseNE 09-12.jpg
houseNE 09-12.jpg (44.93 KiB) Viewed 5757 times

houseNE 11-55.jpg
houseNE 11-55.jpg (49.38 KiB) Viewed 5757 times

Accepting that there is minimal feed-in-tariff..and likely to be less in future, given Gordon's recent post in another thread..any panels on the house would need to be able to contribute some winter kWH to be worthwhile installing at all. Unless of course the offending trees came down in a storm, got struck by lightning or the council changes its mind (I was successful only in having a few dead limbs removed in the interests of public safety..) Where panels on the house could contribute is on cloudy days (we get a lot of those..) The sky above the house is open, the trees are to the side, so with the more diffuse light on a cloudy day, shaded panels on the house might not be far behind the unshaded panels on the garage, and in such conditions, with a hybrid or off-grid set-up, every little bit helps.

If we did choose to put panels on the house I imagine it would be unsuitable for any series string of panels. That's why I was wondering about individual panels with microinverters (assuming they come down in price a bit). Or maybe several short strings of amorphous panels...have read that they do better in shade but have not seen any data to convince me.
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Re: Second net FIT system – maybe hybrid down the track.....

Postby davidg » Fri Apr 25, 2014 8:13 pm

Firegirl wrote:If we did choose to put panels on the house I imagine it would be unsuitable for any series string of panels. That's why I was wondering about individual panels with microinverters (assuming they come down in price a bit). Or maybe several short strings of amorphous panels...have read that they do better in shade but have not seen any data to convince me.

amorphous panels are big for the amount of output. If space is limited forget them however your roof as you show is a prime candidate for micro inverters no question. NSW has no issue with a system of I think from memory up to 5kws per phase as net system regardless of the Gross System.
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Re: Second net FIT system – maybe hybrid down the track.....

Postby Tracker » Fri Apr 25, 2014 8:47 pm

davidg wrote:. NSW has no issue with a system of I think from memory up to 5kws per phase as net system regardless of the Gross System.

I understand that it is a LIMIT of 5kW
But I am reliably told that strange exceptions do appear, giving cause to wonder about rules.
I understand that it makes no difference if it's gross or Nett ... suggesting that they just want to be confident what maximum export is possible..

As for the issue of house shade... I would be looking at trying to minimise that shade, as a starter...
Spending money on technology to help overcome the problems, seems the wrong way to start ...
..
.
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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Governments won't save the world :-) They will just TAX it :-(
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Re: Second net FIT system – maybe hybrid down the track.....

Postby brucedownunder » Sat Apr 26, 2014 7:11 am

Interesting post.

I'm sort of in the same boat ,re shading.

I've a 1050 system on my garage roof, and I have seen regularly 70 watts and less on the inverter lcd , during the time of shading .---I've NEVER EVER seen more than ,say 900 watts ,EVER. Even on a bright sunny unshaded situation ..

I've also got another 1050 watt system ready to add,but on a unshaded area. I'm not game to ask origin if I can add , .because my existing "bad " installation returns pathetic power,overall.

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Re: Second net FIT system – maybe hybrid down the track.....

Postby Tracker » Sat Apr 26, 2014 7:55 am

..
SHADE.. Poison for Power..

Some years back, I had the opportunity to experiment, having talked my neighbours into systems..
Identical systems, but with a twist.. one had a very ordinary TV antenna at it's north point..
A TV antenna whose shadow could be barely found on the panels..

[url]http://forums.energymatters.com.au/post25227.html?hilit=TV%20antenna%20shade#p25227[url]

But whose effect resulted in. 20% power loss..

You MUST look at the most iniquitous twig as a serious enemy ... :evil:

I'll give it a Bump.. :) ;)

So any shade is death to power.. dapple sunlight is extermination..

One possible low cost solution could be to selectively choose components to advantage.. having done your best to remove as much shade as is possible. Don't leave a twig standing... :o

Find a LOW VOLTAGE inverter such as a PVE1200, and then group panels in small strings, across the roof,
This is done knowing that shade on ONE PANEL will effectively kill the whole string.
Have many strings, and you reduce the death rate..
This will also be useful, when you change to Hybrid or OFF-GRID... just change to a charge controller and you will have appropriate voltages already...
My solar shed effectively has 24 strings, each with an isolation diode, just tobesure-tobesure.. :mrgreen:
..
.
Retired Engineer and keen PV experimenter - Always ready to learn and share.
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Governments won't save the world :-) They will just TAX it :-(
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