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Discuss Is this the right inverter? in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net

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volans

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Can someone give some advice - please? I have just solar panels fitted 7 to a south south east facing roof, & 2 to an east south east roof. Initially I was informed that I would need 2 inverters or a split inverter. I have ended up with a Suntellite SL-TL 2800. I know very little about inverters but have a feeling that this one is wrong for the installation, but having read up on mpp tracking & strings I have concluded that I need twin tracking and/or strings, I can't work out if the inverter has this or not!

Pete
 
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SolarCity

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Arms
I've had a look at the datasheet for that inverter and it is difficult to understand. Not sure if it has two MPPTs or not.

Either way, 2 panels would not be enough to operate one of the MPPTs (unless you have a panel with a huge voltage!). I would say there is a strong possiblity that you are on one string - not a good idea on a system with two different orientations. Can you post a picture of your inverter?
 
V

volans

  • Thread Starter Thread Starter
  • #3
My computer froze while replying, so if you get this twice, apologies.
Here are 3 photos, one front & 2 side. Thanks.DSC_0005.JPGDSC_0009.jpgDSC_0010.jpg
 
The amount of times I tell members of the public about dual MPPT's and low amount of solar panels on one MPPT is unreal.

the problem is many installer ill inform people on systems and they end up with the wrong inverter.

so those two panels on your roof you might as well put them in the bin!

you would of been better with solar edge system as I think two panels may be too small to start the smallest inverter on the market !!!
 

whinmoor

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Arms
The issue now is: the installer has designed, quoted and installed a system which the customer agreed to. Probably this is a rush-job to some degree to meet the FiT deadline. Assuming that the workmanship is sound, has the installer kept his side of the contract by installing what was specified? Is it the customer's fault (caveat emptor) for not researching the system/equipment in enough detail? Or, does the installer have a duty of care to design and quote for a suitable system? Does the customer have any comeback in such a situation where the system produces less electricity than SAP predicts?
 

SolarCity

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Arms
I think this points at a larger issue.

The amount of times we are having customers come on to this forum and ask advice about their systems only to find that their system has been installed poorly is incredible. I don't think that all these installers can just be cowboys. I think a lot of the blame must go to the training centres that ignore important info like this yet focus on polar bears and ice caps for example. It is entirely conceivable that these installers are trained, qualified and certified to install yet have utterly no idea what an MPPT is.

Personally I think that the PV route is far too easy for installers. They can spend a couple of days training, get an MCS document made for them and then rely on kits - presumably in the mind that they can then forget the design phase entirely.
 
V

volans

  • Thread Starter Thread Starter
  • #10
I received 7 quotes for this installation and the one I chose was not the cheapest by a long chalk. This one seemed toknow what he was talking about - can't fit them there because of shadows, need split/two inverters etc. (bull **** baffles brains? - not that I'm saying I've got any brains ). When it comes to the crunch one has to trust someone, and if they are an approved installer it is assumed that they are o.k. I have been in touch with the installer & was assured that it is a dual mppt & will work correctly, so it looks like I've got a battle ahead. Trouble is, reading the above, can any improvement be achieved?
 

Worcester

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Mentor
Arms
@SolarCity ... so what do you think of MCS's recent consultation excercies and likely proposals... Will it solve these bad designs?
MCS recently tightened up the requiremnts for heat pumps due to too many badly designed systems underperforming, and brought out their own guidelines. There should have been no need, as a well designed system would be no different under the new guidleines, however you could get away in the past wuith a badly designed system that would underperform.
We lost one contract earlier this year when we insisted compliance with the new spec 7 days before it came in, someone else bid using the old spec at 30% less than us and the client now has a system installed that will not perform as he expects but he'll only know after 5 years of excessive energy charges as the system underperforms.... Future systems will perform adequately because of these new design standards.
 

SolarCity

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Arms
@SolarCity ... so what do you think of MCS's recent consultation excercies and likely proposals... Will it solve these bad designs?
Unlike a lot of others, I am cautiously supportive of them.

One thing we definitely need is a certification body which is more interested in competency than whether or not our meetings have been recorded.
 

Gavin A

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Arms
I echo that. I'm sick of the level of incompetence we see on this forum, and the number of shocking installations I see where good design and installation principles have been ignored entirely.

I think the training providers and accredited course suppliers should share a huge amount of the blame for this - I was appalled at some of the rubbish my sparks were taught on the course I sent them on last year, some of which was actually dangerous, and I doubt they mentioned anything about stuff like dual MPPT etc.

In the consultation I actually asked that the assessors used to assess competence should meet the level 3 installer criteria for the relevant technology, which I think would be a vital component of raising standards. We had a former gas fitter with zilch solar experience assessing us last year who wanted us to have bonded the frame on a system which used an SB1200 isolating transformer inverter, just because it looked like it might be touchable from a velux (it actually wasn't anyway).
 
S

SpitfireW'sale

  • Thread Starter Thread Starter
  • #14
I received 7 quotes for this installation and the one I chose was not the cheapest by a long chalk. This one seemed toknow what he was talking about - can't fit them there because of shadows, need split/two inverters etc. (bull **** baffles brains? - not that I'm saying I've got any brains ). When it comes to the crunch one has to trust someone, and if they are an approved installer it is assumed that they are o.k. I have been in touch with the installer & was assured that it is a dual mppt & will work correctly, so it looks like I've got a battle ahead. Trouble is, reading the above, can any improvement be achieved?
I don't know of any dual MPP inverter that could power a 2 panel string into 1 of the trackers. We would normally suggest something like 1 X Mastervolt Soladin 600 and 1 X SMA 1200 for a system like this, but would check that on PVSol (or manufacturer design software) first, obviously.

The installer may have made a simple mistake. I'd go back to them with your new info and see what they say before passing judgement.
 

Worcester

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Mentor
Arms
Trouble is, reading the above, can any improvement be achieved?
You have two options:
Accept what you have contracted for
or
Challenge it.

To challenge it you need to ask the installer to show you how his chosen system will perform correctly with the 2 MPPT's that he said were nescsarry in the configuration that he has designed, adn give him the chnace to reply fully in laymans terms.

So there are 4 possible solutions
1) You've got what you've got.

as there are two areas of installation with different orinetations, in a first class design, they should either have been
2a) on Seperate MPPT's - (dual tracker)
HOWEVER: The chosen inverter needs to be able to cope with only 2 panels on that one string - I doubt this is the case. If it is fine, ask the installer to show you, else you have 2 other solutions, both of which require you challenge the installer further, wether you have legal contractual grounds to do so or whether caveat emptor applies, I cannot comment.
2b) Possibly two inverters, though whether there is one small enough for the 2 panels I cannot say, the Soladin 600 is about the smallest, though two enecsysy micro inverters (see below) would do the job. plus an inverter properly sized for the main roof.


If you decide to challenge the installer further, then the two best solutions are
3a) Micro-Inverters. Enecysy or Involar - you have one inverter per panel, so gauranteed no mismatch.
or
3b) SolarEdge Optimisers, these are attached to each panel, and effectively give each panel it's own MPPT, without actually being and inverter, so with the appropriate interface, they can be attached to any inverter (obviusly it would be best if it was a SolarEdge invertert, that way you don't need the interface.

That's really it unfortunately. You need to give your installer the chance to fully explain how it will work they way he has designed and installed it. If there are some compromises in the design these should be reflected in the output figures (kWh / annum) that you were quoted. If those compromises have been included there, then that's the end of it (legally)
 

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