I am a new PV householder - advice please. Unbalanced strings and wrong inverter

[juniperz]

Well the installation was completed yesterday.
I have the Power One PVI 3.6-OUTD-16A mounted on fire retardant board, with isolators labelled properly, and the 16x Suntech STP 245S 20Wd wired as 6+10. There is a wiring schematic (showing 6+10) in the cupboard next to the generation meter in the utility room, and a Wattson Solar meter (provided) quietly glowing. When I was home yesterday (wet and miserable), I didn't see it go above 600W, but my wife allegedly saw over 3000W today.

I guess I should be happy, but there is a bit of a sour taste because it took such a lot of effort...

Thank you all for your help - I don't know quite how I would have got to this conclusion without you. What did we do before t'Internet?

I took a few pictures yesterday, while the scaffolding was still up.

House​

Garage​

Comments welcome...
When I am home again on Thursday, I will take some internal shots too.
I will also see what the peak output has been from the inverter display, and what the startup voltage for the string of 6 has been set to. Power-One String Tool says it should be 185V, if I have interpreted that correctly.
Following recommendations here, we are going to go with Good Energy as the FIT provider.

 

[wstevew]

Are the cables not tied up off of the roof?

 

[cbw]

That is SOOO much better!

 

[sedgy34]

So you got there in the end!!! Also the configuration of strings and the inverter choice of modules are all good, looks like they have earthed the arrays as your earthing arrangment is pme.
Just thinking back to what they proposed to install makes me smile considering the effort all on here spent giving you the good advice you needed.
Happy result! Now watch them cheques come through your door lol we just need a bit of sunshine we can't help with that lol

 

[juniperz]

Are the cables not tied up off of the roof?

I am not sure how to respond to this. Presumably you think the answer is no, and that this is a bad thing?

 

[juniperz]

I am very familiar with both Growatt and Samil.
Growatt3600MTL has DUAL Trackers. It is much more better than Samil's 4400TL because some main reasons
1) Growatt has dual trackers, fit perfectly to two-direction-roofs. Samil 4400 only 1 tracker
2) Growatt3600MTL's cap current is 16A, G83, which means fast installation without application from DNO in advance
While Samil 4400TL looks like G59 certified, it needs 8 weeks for application of installation
3) 3600w is much more suitable for your request. 4400 doesn't match your panel design
I do think the Dual-Tracker 3600MTL is worthy to use.

I think you might have skipped a few posts ;-) (It did turn into a rather long thread!)
They quoted Growatt, erroneously fitted Samil but I cried "Foul" and finally got the Power One PVI 3.6-OUTD-16A, which also has dual MPPTs. The consensus seems to be that I got the best* inverter in the end.

* and before someone points it out, Solar Edge would have been the best but I tried hard for that, but wasn't prepared to pay an extra 10% of contract price and risk further delay.

 

[juniperz]

So you got there in the end!!! Also the configuration of strings and the inverter choice of modules are all good, looks like they have earthed the arrays as your earthing arrangment is pme.
Just thinking back to what they proposed to install makes me smile considering the effort all on here spent giving you the good advice you needed.
Happy result! Now watch them cheques come through your door lol we just need a bit of sunshine we can't help with that lol

I am afraid to say that me wanting solar seems to have triggered the most sun-less summer imaginable!!

 

[provr6]

I am not sure how to respond to this. Presumably you think the answer is no, and that this is a bad thing?

Can't tell from the pics, but its a good idea to have the cables under the panels cable tied so they don't blow in the wind, scrape along the roof and over time wear away. You can sometimes hear them in high winds, which can be annoying. It's worth doing as it only takes 5 mins.

All looks good to me, I see that 2 of the 6 panels are on the main roof with the other 4 on the garage. It dosen't look that much higher and looks to be about the same pitch so should be fine.

Get your fit application in now and check they have received it and its correct. You've still got plenty of time to make any corrections if need be. Well done.

 

[jason121]

tiles have not have cut or is it me seeing things

They need to go out and buy a bending spring ruff conduit work

 

[MickF]

It LOOKS quite smart, however, my Snagging List would include:
Cable Entry Weatherproof (Photo 12)
Cable Entry protected from chaffing (Photo 12)
Cables secured / tied to rails / not dangling on roof (photo 9)
Make sure gaps under tiles aren't too great / grind backs of tiles if nescessary to make them sit flush so that water won't ingress under them. (photo 5, house, not acceptable)

Use a hole cutter to put conduit through eaves (photo 5)
Conduit labelled (DC Cables) ...
Conduit secured - The could have brought it out further along the eaves or taken it along the wall and secured conduit to rail on Garage Roof (photo 3 / 4)
Clamps should be on the 1/4 points of the panels +- 1/8th (photo 9) - Also applies to house to some degree.


What does the inverter, cu, isolator and meter installation look like?

 

[MickF]

aha I see the problem on the position of the clamps - they have vertical rails, but not in a cross rail configuration, they've just got vertical rails, so no chance to position them properly

 

[sedgy34]

your a mean bunch lol:smilewinkgrin:

 

[juniperz]

aha I see the problem on the position of the clamps - they have vertical rails, but not in a cross rail configuration, they've just got vertical rails, so no chance to position them properly

Thanks Mick. Not sure I understand that bit though.
Does it relate to grinding the backs of the tiles? Or to "Clamps should be on the 1/4 points of the panels +- 1/8th"?

I work away, but I will post pictures of the inverter, cu, isolator and meter installation when I am back home Thursday night.

 

[MickF]

It related to the position of the clamps on the panels (usually 1/4 point +- 1/8th so 1/8th - 3/8th = 1 1/4 cells through 3 3/4 cells)

Best practice for landscape is to mount rails horizontally as normal and then put another set of rails across them (cross rail) that way you are not restricted by where the rafters are and so you can get the supporting (vertical) rails in the right position. If you can get the vertical rails to line up with where they should be without doing it that way - you're very lucky - especially with 4 panels in a line. Of course to do it that way costs more with twice as much rail, plus the cross rail brackets.

I wouldn't have commented on it with just the main roof, they are probably just about ok without measuring. The garage roof is well out of normal range - the panels should have mounting instructions which specify the acceptable clamp positions. There are only a couple of panels that allow you to clamp on the short sides, so they got a bit of it right - the prinicpal, just screwed up on the practice part.

What is scary is just how many installations have been probably been done like this, at least juniperz has had the guts to ask the questions and challenge his installers - perhaps they should come and read this thread, but then again they probably think they don't need to.

 

[juniperz]

your a mean bunch lol:smilewinkgrin:

I can't quite decide whether I want to know about the bad things. I don't think these things are show-stoppers, unlike fitting the wrong inverter and arguably not mounting on fire retardant board.
After all the grief I have given the installer, I am not sure how receptive they will be to this feedback, especially as the scaffolding may be coming down today - I haven't been at home since Monday.

 

[Somecamel]

Not to rock the boat here at all but on the smaller string (6 Panels) did they reduce the startup voltage to 185v?

 

[MickF]

Better to keep the boat rocking now, that will save them the expense of putting up the scaffolding again in a couple of weeks.

When the wires chaff through in a couple of years / the roof leaks in the next big downpour, and they have gone out of business. Who is going to pay for it then?

These faults are actually just as, if not more important than the string / inverter combination.

They will not be able to sign off the commissioning certificate or issue a buidling regs certificate with the way it is.

 

[juniperz]

Not to rock the boat here at all but on the smaller string (6 Panels) did they reduce the startup voltage to 185v?

I may be a complete amateur, but I did say above, that I would check that when I get home. It's almost as if I know what I am talking about! Thanks to you contributors.
Will have a think about the building related concerns when I have a chance - busy day.

 

[MickF]

Well done juniperz, I think it's incredible that you are able to keep your cool with all that's been going on

 

[sedgy34]

Thanks Mick. Not sure I understand that bit though.
Does it relate to grinding the backs of the tiles? Or to "Clamps should be on the 1/4 points of the panels +- 1/8th"?

I work away, but I will post pictures of the inverter, cu, isolator and meter installation when I am back home Thursday night.

You could have posted the best installation in the world and still have op pickin faults with it!

 

[provr6]

Not to rock the boat here at all but on the smaller string (6 Panels) did they reduce the startup voltage to 185v?

What's is the calculation to determine the min'm start up? I think it's something to do with one of the voltage specs on the panel x the No. of panels.

Is it detrimental to lower the start up voltage to the inverters min'm start up voltage in all situations?

 

[juniperz]

Better to keep the boat rocking now, that will save them the expense of putting up the scaffolding again in a couple of weeks.

When the wires chaff through in a couple of years / the roof leaks in the next big downpour, and they have gone out of business. Who is going to pay for it then?

These faults are actually just as, if not more important than the string / inverter combination.

They will not be able to sign off the commissioning certificate or issue a buidling regs certificate with the way it is.

What does the last sentence mean? I believe that the installer has to notify Building Control within a month or so, but if they think they have done a satisfactory job, what is to stop them just completing the two certificates you mention? Will Building Control come and check?

 

[MickF]

I reckon it would be possible to visit any install any body chooses and find soemthing that could have been done better with it.

However if someone says 'what do you see wrong with this?' it would be wrong not to give them your opinion, up to them then what they do about it. At least most of those items are fairly easily fixable.

And all credit to juniperz to act on the advice he's been given.

 

[MickF]

What does the last sentence mean? They are making declarations that everything this is right, so they shouldn't

I believe that the installer has to notify Building Control within a month or so, but if they think they have done a satisfactory job, what is to stop them just completing the two certificates you mention?
Nothing at all

Will Building Control come and check? They won't unless someone asks them to

​

 

[provr6]

What does the last sentence mean? I believe that the installer has to notify Building Control within a month or so, but if they think they have done a satisfactory job, what is to stop them just completing the two certificates you mention? Will Building Control come and check?

I think the previous post is a bit misleading (not mickf's but the one above your quote). They will be able to sign it off and commission it even if it's wrong (in their eyes its not wrong).

In terms of notifying building control within a month or so, I think you are referring to the Part P certificate. They have to issue their certficates within 28 days of comissioning (date on the mcs certificate) to Building control who will then issue a Part P certificate either directly to you or to your installer (some installers will ask for this to come to them and only release when paid in full).

This won't affect your fit registration. Strictly speaking Building control shoud be notified before the work started (not for Part P but to check the installation was being done to building regs - Don't worry too much though). Building control won't be interested in coming out and will issue the part P without looking at your install (unless you ask them to).

 

[Somecamel]

What's is the calculation to determine the min'm start up? I think it's something to do with one of the voltage specs on the panel x the No. of panels.

Is it detrimental to lower the start up voltage to the inverters min'm start up voltage in all situations?

Better still use this Power-One String Tool

 

[juniperz]

Better still use this Power-One String Tool

That's what I said at the top of page 7. And did ;-)

 

[Somecamel]

That's what I said at the top of page 7. And did ;-)

My bad, I need to learn to read

 

[juniperz]

And all credit to juniperz to act on the advice he's been given.

I have just hit 50 posts in a Solar sub-forum - I think I need to get out more!

 

[juniperz]

I think the previous post is a bit misleading (not mickf's but the one above your quote). They will be able to sign it off and commission it even if it's wrong (in their eyes its not wrong).

In terms of notifying building control within a month or so, I think you are referring to the Part P certificate. They have to issue their certficates within 28 days of comissioning (date on the mcs certificate) to Building control who will then issue a Part P certificate either directly to you or to your installer (some installers will ask for this to come to them and only release when paid in full).

This won't affect your fit registration. Strictly speaking Building control shoud be notified before the work started (not for Part P but to check the installation was being done to building regs - Don't worry too much though). Building control won't be interested in coming out and will issue the part P without looking at your install (unless you ask them to).

I just had a chat with one of the inspectors from Building Control. He didn't seem too concerned about the risk of water ingress from the brackets lifting the tiles, or brackets or untied cables. Certainly didn't think a visit was necessary, though also suggested that if the installer is in a "compentent persons scheme" they could self certify for structure and weather proofing, and he had no jurisdiction. No idea whether my installer is in such a scheme, though they are quite a large firm, so maybe they are.

I think I am on the verge of giving up the fight and getting on with my life...