# Forum Home Renovation Solar Electrical Systems  Am I being short changed?

## Wombat2

Had the 3Kw system installed today :Redface:  15 panels - max output 200watts each so total output 3000 watts. 
Hidden away out of sight on the side of the Inverter Model is an SMA2500 - Nominal output 2300 watts.(max 2500Kw) The instruction manual is for an SMA2500/3000 - the specks for the 3000 says nominal output 2750 (max 3000Kw) - a little closer to the mark. 
Checked the contract - it states a 3Kw system consisting of 15x200Watt panels and an SMA inverter - Am I being reasonable to expect a SMA3000 model inverter?

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## jago

I dont know anything about Solar...I would expect the system to be able to run at its stated capacity, otherwise why pay of for the extra panels. 
You have a system with the potential to deliver 3kw the inventer is 2.3kw thats 3.5 panels not being used! They might have you if it doesn't state the actual model. 
So you paid for a 3kw system and its not unresonable to expect it "do what its says on the box"

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## SilentButDeadly

It is certainly possible that your new system will shed load during peak performance conditions given the fact that the inverter is similarly sized to the panels.....the question I would ask is how often might this happen bearing in mind we are talking peak as opposed to nominal operating conditions. 
Just remember that the SMA capacity is based on 3000 watts AC......and your panels output in DC....so what you many need to consider is what voltage and current your panels can supply to the inverter. 
All that said.....for your system.....I'd have stepped up to an inverter with a capacity closer to 3500W. 
For example, Rainbow Power Company (based close to your area) supply a 3100W Latronics inverter with their 2.96kW system.......and they've been doing this sort of stuff for decades.

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## president_ltd

> Had the 3Kw system installed today 15 panels - max output 200watts each so total output 3000 watts. 
> Hidden away out of sight on the side of the Inverter Model is an SMA2500 - Nominal output 2300 watts.(max 2500Kw) The instruction manual is for an SMA2500/3000 - the specks for the 3000 says nominal output 2750 (max 3000Kw) - a little closer to the mark. 
> Checked the contract - it states a 3Kw system consisting of 15x200Watt panels and an SMA inverter - Am I being reasonable to expect a SMA3000 model inverter?

  yes. 
short answer is they have under-spec'd the Inverter. 
lets say that you could in fact achieve maximum output on your panels.  200W/panel x 15 panels = 3000W.  there will be losses in the DC cabling (call it 0.3% loss), there will be losses in the inverter going from DC to AC, call it 94% efficient since you're not on a transformerless inverter. 
add up the losses and your 3000W peak is now 2811W.
since that is above what the inverter is capable of, your output WILL be clipped because of it. 
suggest you take it up with them and also strongly recommend you ask for a SBx000TL Inverter.  it'll cost more than a non- transformerless unit, but its higher efficiency and that efficiency will pay for itself every day.
(lets say its 97% efficient versus 94%.  lets also guestimate that your system will generate 15kWh/day, that efficiency difference in the inverter right there is ~450Wh/day, or 164kWh/annum.  it all adds up. 
longer answer is that any inverter choice is a multi-faceted thing.  you need to be aware of quite a few variables, including what voltage range the inverter operates in, the voltage range of the MPPT etc.
you can download the free Sunny Design software from www.sma.de and put in your panel make/model and cable distances etc and it'll tell you if its within spec. 
or reply with the make/model of your solar panels and i'll fire it up here for you and post the results.

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## Wombat2

The panels are Suntech STP200-18/Ud 
I spoke to someone at SMA and they said panels of the size would need the SMA3000 or 3300 - The SMA2500 would just shed the surplus and be power wasted. They considered that in our position we would have no problem reaching peak output ( North facing - elevated no shadow north end of Sunshine Coast) 
Waiting for the installers to get back to me

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## Wombat2

Thank you for your email.   I really appreciate the feedback and will offer you a detailed response and refer this matter on to my Team Leader to see what she can work out for you. 
To shed some light on things, and to be perfectly frank with you,  I just checked the signed contract and can confirm that it was one of very few system generated contracts that omitted some inverter detail at the time when there happened to be a system glitch (whilst weve been going through expanding/system improvement processes).  See attached. For a short period, our system generated contracts did not automatically include or pick up the details on the inverter make/model.  I apologise for this oversight  that I didnt pick up on the fact that the inverter detail was missing on contract, but thats what should normally appear.   
Our 3kw system bundles have always included either the SMA2500 or as an alternative, the PVI3600 (and theyre out of stock until Sept at earliest). They were the only two options ever available with our 3kw system from the menu of systems to pick from (engineered for best output). Any deviation from the existing packages available on the menu  ie. SMA3000 as you suggest, would have meant me going to management and asking about it. Im assuming we chatted about that and theres a good chance I checked up on that for you. I had to tell a few clients that we were having difficulty getting those SMA3000s in and suppliers were unable to give us any definitive date on their arrival  so if I did ever get back to you on that subject, that would have been the message and Im sorry if this was not relayed to you.  
At this point, I shall refer this matter to our Team Leader ********** for advice on what we can do for you in this scenario. She will be in touch with you soon.   
Does Short and curlys come to mind? :2thumbsup:

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## president_ltd

> The panels are Suntech STP200-18/Ud 
> I spoke to someone at SMA and they said panels of the size would need the SMA3000 or 3300 - The SMA2500 would just shed the surplus and be power wasted. They considered that in our position we would have no problem reaching peak output ( North facing - elevated no shadow north end of Sunshine Coast) 
> Waiting for the installers to get back to me

  yep.  here is what Sunny Design says.  note all the warnings!  
NOTE: if you ask Sunny Design to put a SB3300 or 3800 in there instead, ALSO NOTE that it has warnings.  in fact it says that it can effectively only make use of 13 of your purchased 15 panels!!!!! 
see the attached screenshot with SB3300 and SB3800 is no better!
same with SB3000TL. 
you effectively need a multi-string setup with SB4000TL minimum to use those 15 panels with SMA inverters!! 
whoever you bought this from seemingly did NOT design it. 
feel free to download the (free) Sunny Design yourself and have a play.
i think this might be something you want to do when you call them back.....  :Smilie:  
Aurora inverter may be a better option for you here but you'd need someone with knowledge of its MPPT / inputs / voltage ranges etc to spec out the design and string layout. 
To be honest, selling a transformer-based inverter with its lower  efficiency in this day and age is not ideal.  the TL ones are simply way  better.

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## Smurf

> yep. here is what Sunny Design says. note all the warnings!  
> NOTE: if you ask Sunny Design to put a SB3300 or 3800 in there instead, ALSO NOTE that it has warnings. in fact it says that it can effectively only make use of 13 of your purchased 15 panels!!!!! 
> see the attached screenshot with SB3300 and SB3800 is no better!
> same with SB3000TL. 
> you effectively need a multi-string setup with SB4000TL minimum to use those 15 panels with SMA inverters!! 
> whoever you bought this from seemingly did NOT design it. 
> feel free to download the (free) Sunny Design yourself and have a play.
> i think this might be something you want to do when you call them back.....  
> Aurora inverter may be a better option for you here but you'd need someone with knowledge of its MPPT / inputs / voltage ranges etc to spec out the design and string layout. 
> To be honest, selling a transformer-based inverter with its lower efficiency in this day and age is not ideal. the TL ones are simply way better.

  I've done the same calcs.  *Main thing I'd be worried about is the maximum voltage being supplied to the inverter. If this is a single string set up, then there's a problem that could end up wrecking the inverter.* 
As for actual energy yield loss, it would be pretty minor since the vast majority of the time the output from the panels won't be at peak. In that context it's an economic decision - is the extra output worth the cost of a larger inverter? That is, of course, assuming no issue with input voltage... 
Using my own much smaller solar PV system as an example, presently have 1.02kW panels connected to a 1.0kW continuous output inverter - no problems at all once you consider losses, that output won't normally be at peak etc. Using the Sunny Design software, I could add another panel (taking the total to 1.19kW) and still have virtually no losses. Add another one (total 1.36 kW) and then there are some losses, but still minor. Anything beyond that point and the losses mount up pretty quickly.

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## president_ltd

> IAs for actual energy yield loss, it would be pretty minor since the vast majority of the time the output from the panels won't be at peak. In that context it's an economic decision - is the extra output worth the cost of a larger inverter? That is, of course, assuming no issue with input voltage...

  agree with this. 
but never say never.
in this winter timeframe of frosty cold days here in melbourne, i've seen the sun come out from behind clouds and the 4.96KW of panels we have be generating 5.1KW of power.
it doesn't last for long, but it does happen.  :Smilie:

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## Wombat2

Here is a picture of our panels http://img.photobucket.com/albums/v698/Wombat2/092.jpg  
It's late afternoon and the neighbours tree is just starting to shade - other panels were putting out 120 watts. The join in the 'V' of the roof is running north/south.  From my reading of the literature I'd be better off with the PVI 3600 as it allows for 2 inputs - guess that would mean a second cable run.

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## president_ltd

> Here is a picture of our panels http://img.photobucket.com/albums/v698/Wombat2/092.jpg  
> It's late afternoon and the neighbours tree is just starting to shade - other panels were putting out 120 watts. The join in the 'V' of the roof is running north/south.  From my reading of the literature I'd be better off with the PVI 3600 as it allows for 2 inputs - guess that would mean a second cable run.

  DEFINITELY. 
with two distinct 'sets' of panels (and in partciular with one of them getting shaded in the way it is, you want 2 MPPTs.

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## Wombat2

An update: 
I sent the above photo to the consultant I am dealing with and said I was prepared to wait till they have some PVI3600s in stock for a change over and pointed out with the shading the 2 MPPTs would be an advantage - she agreed and passed on the info to her supervision - yet to hear back. 
In the mean time I am home all day for the first time since installation.  Full sun and clear blue skies and putting out 2243 watts - true to the literature that says nominal output 2300. The electrician that installed it was insistent that our meter would not run backwards and we would not be getting credit for the power feed until Energex changed the meter - been standing there watching the meter spin backwards and the dials counting backwards so don't know what he was on about - still our original meter. At 7:45am it was putting out 954 watts with the sun 2" over the north ridge - I think that is pretty good for that hour of the day. 
Edit: end of the day 13.8 KWh produced total after 40 hours of output = 49.5 KWh - that's 4 days so we are getting output of some sort for 10 hours each day.

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## Wombat2

After a search of their invertory they found an SMA3000 inverter from a cancelled contract  :Rolleyes:   I have been offered this to be installed at no additional cost !
This unit has a nominal output of 2750 watts and been superceeded and replaced by a transformerless unit that is way more efficient. The offered unit is still leaving 1.2 panels out of the loop so to speak by only utilizing 91.6% of the PV array's output. 
I have declined the offer.

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## Wombat2

This is their comeback:  _Thanks for your response._  _Ive just been advised that our 3kw bundle with the PVI3600 inverter has recently been discontinued in our system menu.  I guess hadnt noticed the recent discontinuation of this particular 3kw bundle in my dealings with other clients.  Given our supply issues with getting hold of these PVI3600 inverters,  management have decided to update our menu with only what we have or can be sure of receiving so that were not caught out again._   _We are happy to offer you the SMA3000 as a swap over, but as things have changed, cannot offer the PVI3600.  _   _Please keep in mind our engineers have tested all these components and matched our panels/inverters for maximum output and efficiency. Theyve taken into account all performance losses due to weather/dust/etc and what mix of panels/inverter work best._  _We maintain that the SMA2500 has been correctly matched for best output on the 3kw system but at the end of the day, its your choice.  With regard to your request for a larger inverter however, the only thing we are in a position to offer you is the last SMA3000 we have in stock. _   Hmmmmm.....what to do ?

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## jago

> This is their comeback:  _Thanks for your response._  _Ive just been advised that our 3kw bundle with the PVI3600 inverter has recently been discontinued in our system menu.  I guess hadnt noticed the recent discontinuation of this particular 3kw bundle in my dealings with other clients.  Given our supply issues with getting hold of these PVI3600 inverters,  management have decided to update our menu with only what we have or can be sure of receiving so that were not caught out again._

  
What tosh blaming lefthand/righthand and computer system.   

> This is their comeback: _We are happy to offer you the SMA3000 as a swap over, but as things have changed, cannot offer the PVI3600.  _   _Please keep in mind our  engineers have tested all these components and matched our  panels/inverters for maximum output and efficiency. Theyve taken into  account all performance losses due to weather/dust/etc and what mix of  panels/inverter work best._  _We maintain that the  SMA2500 has been correctly matched for best output on the 3kw system but  at the end of the day, its your choice.  With regard to your request  for a larger inverter however, the only thing we are in a position to  offer you is the last SMA3000 we have in stock. _

   :No:  
Sorry... you accept no liability for a mismatched system but are willing to offer me a (I take it) more expensive inverter at no cost,so why not the one I want then. 
I  would be going higher up the food chain in this company and contacting somebody for a legal read on the situation.

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## Wombat2

Letter to CEO got a response in less than 24hours - on site meeting with installation manager coming up at a mutually agreeable date and time. 
Had discussions with SMA again -found out: 
2500 is being 'run out'
3000 is discontinued
3000TL is being run out
3000HF is the current 2010 model and replacing all of the above 
Checked price thinking I'd pay the difference if need be - he looked it up and said 'nothing in it 3000HF virtually same as 2500'  :2thumbsup:

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## jago

Glad to hear you're getting somewhere...stick to your guns and a good will gesture would be for them to waive any cost difference baised on the fact they originally gave you an unmatched system, their mistake. 
Good PR for the company would be; they made a mistake and then rectified it, its called the power of 10 in Sales; a good experience will be told by the purchaser to 10 others  a bad experience will be told to anybody that listens and that multiplies. 
Keep us informed.

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## Wombat2

Just had the installation manager here- his argument is that they have installed the right inverter for the size of the panels - he says as there are losses of 0.8% and the maximum that I can expect is 2400 watts - My argument is I signed a contract for and expect an output of 3000watts - things got a little circuitous at this point. I asked what number and how were the RECS calculated - he didn't know and had to ring the company and was told on the capacity of the panels - I produced an email from the Dept of Renewable Energy and Resources that said _A system is eligible for RECs based on the peak rated output of the entire system, therefore if the peak capacity of the system is limited by the size of the inverter, then the system is only eligible for RECs up to the peak capacity of that inverter._ - His initial statement - "That's wrong" Then after a while he says no he sees what the Dept means and that his company has not done anything wrong as the inverter is not limiting the output of the system.  He also said if I had a 3000 watt inverter it would not produce any more power.  
I then argued that they ( and the whole industry) is misleading the population as if I buy a 3000 watt system and they install one only capable of 2500 AND THE INDUSTRY CONSIDERS THAT NORMAL then the Office of Fair Trading is going to be interested. He stated that if they install a 3000 watt inverter then I will still not be satisfied as it won't put out 3000 watts and still be calling in the Office of Fair Trading. I assured him I would be satisfied with a 3000 watt inverter coupled to 3000 watt panels. 
He has taken my grievance away to discuss with his superiors - WTF He's the Installation Manager can't he make decisions ?

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## jago

Sorry this is serious but I would laugh if that happened to me ...sounds like they sent in what they thought  was a ball breaker only for them to walk away holding his...well done. 
WTF he cannot add up either as 0.8 of 3000 watts is 24 watts what they have done is do .8 x 3000 which is 2400 which would be a 20% loss across the system, is that what they're saying? I would suggest that he's a not very good at maths.... 
When speaking to anybody from here on in I would be asking ; do they have the power to make a decision on this/these matter if not please pass me up the food chain.  
Contact some of the other Solar companies and ask questions about this inverter and your set up and potential losses ,maximum power generated etc. 
Contact  the OFT and get there read on the matter they will guide you. :2thumbsup:

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## Wombat2

Just been informed they will change the inverter for a SMA3000TL in 5-7 days provided I sign an agreement to pay the amount owed as soon as done  :2thumbsup:

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## president_ltd

per Sunny Design with 15 x Suntech STP200-18/Ud and SB3000TL: 
 - your MUST use 2 strings of inputs one with 7 panels the other with 8 panels
 - you CANNOT have 1 string of 15 panels as that is above the "open circuit voltage". 
providing its the 2 string setup you're all good.  :Smilie:

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## Wombat2

Hang on- the SMA3000TL only has 1 input (the 4000 and 5000 have 2) - also my design software no longer shows the 3000TL only the FH - can you send me a screen dump please? 
Found it - works OK for me - one thing I was shown that does have an effect on result is the panel temperature has to be adjusted to 0° as the default is   -10°. At -5°C it goes into overload - hope we never go that low on the Sunshine Coast

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## Wombat2



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## jago

> Just been informed they will change the inverter for a SMA3000TL in 5-7 days provided I sign an agreement to pay the amount owed as soon as done

  Well done ...well sort of! I wonder if they watched any of this? :2thumbsup:

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## president_ltd

> Hang on- the SMA3000TL only has 1 input (the 4000 and 5000 have 2) - also my design software no longer shows the 3000TL only the FH - can you send me a screen dump please? 
> Found it - works OK for me - one thing I was shown that does have an effect on result is the panel temperature has to be adjusted to 0° as the default is   -10°. At -5°C it goes into overload - hope we never go that low on the Sunshine Coast

  i'll check when i get home and post a screenshot, but in the version of Sunny Design i have, it showed 15 was a problem.
i left the temperature at default.  think it was 0 deg C?
maybe i told it i was in Melbourne and that was the difference.  :Smilie:   
regardless, while there is only a single MPPT on SB3000TL i'm referring to how its physically cabled into that input.  i.e. 8 panels in series and 7 panels in series then paralleling those 2 strings into a single input.
that avoided the issue in the first place.

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## president_ltd

yep get the same result as you if i adjust minimum temperature from -10 deg C to 0 deg C. 
if you're sure it cannot go below 0 then i guess you're fine.
if you get hail i wonder if that counts as below 0?

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## Wombat2

Nah - we have warm hail  :Tongue:

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## president_ltd

> Nah - we have warm hail

  my au$0.02 worth is i'd still request it to be 2 parallel'd DC runs with 7 panels in series on one and 8 on the other. 
historic records show 2.5 deg C minimum on 17 july 2007 for gold coast at Gold Coast climate, averages and extreme weather records
its forseeable that if you're in the hinterlands or higher up that you may have lower temperature conditions. 
then the issue is avoided altogether.

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## jago

> historic records show 2.5 deg C minimum on 17 july 2007 for gold coast at Gold Coast climate, averages and extreme weather records
> its forseeable that if you're in the hinterlands or higher up that you may have lower temperature conditions. 
> then the issue is avoided altogether.

  
You just changed Wombat2s address by a couple hundred K's south...thats a downgrade from Noosa to Surfers or from Maleny to Mudgeeraba.lol  :Biggrin:

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## Wombat2

Our property lies at the top of a valley running north-east to the sea - 500 m to the west is the top of the ridge. We have never had frost even when there has been frost on the ground to the west of the ridge - the rising warm sea air obviously keeps the frost away, besides by the time the sun was high enough to be generating voltages that would cause a concern the air temp would have risen a bit as well. - I'll run the risk

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## president_ltd

> You just changed Wombat2s address by a couple hundred K's south...thats a downgrade from Noosa to Surfers or from Maleny to Mudgeeraba.lol

  its all north from the perspective of us chilly victorians.  :Smilie:

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## Wombat2

The new SMA3000TL is installed and producing - trouble is it has been raining and overcast ever since. BUT even in this weather it had a moment where it put out 200 watts more that the other ever did on a bright sunny day.

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## jago

Glad to see you are a feeder and not a consumer anymore...weatherhere is c rap aswell. :2thumbsup:

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