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

[babba]

Oh how hindsight is a wonderful thing.

Is that what its called now ?

 

[Earthstore]

I do think Babba has a point, there have been so many threads recently where customers have come here for help because for whatever reason they have chosen an installer that is not competent, I have also noticed that the professionals are becoming less helpful, and I have to say I am included in this.
Maybe customers could choose more wisely, I know it can be difficult as it is quite technical, but I feel the public are buying on price only.
Remember, penny wise and pound foolish.

 

[SolarCity]

There does seem to be a lot of threads like this but I don't think it is fair to say to a customer "you are buying on price alone and you got what you deserved." We all know that paying more doesn't guarantee competence - we can all name firms which are useless yet charge ludicrous prices. As far as a customer is concerned, they see MCS and REAL badges and that should be enough.

My personal opinion is that training isn't good enough and the MCS isn't strict enough with regards to competence.

This is not the customer's fault.

 

[juniperz]

Even better get an installer who knows what they are doing. I dont understand how people can take such risks to save a few quid ????

I will try not to be offended :cool3: This wasn't about saving a few quid. I thought I had a competent installer, and signed a contract. I then chose to look at the installation half way through, and found a problem. They have offered to rectify their mistake (installing wrong inverter) and use fire retardant material for the board, so I can't void the contract (or whatever the expression is). The good people here on the forum have been extremely helpful while I try to get this sorted out. Without the internet I would have been stuffed.

 

[sedgy34]

When is your installation date

 

[juniperz]

When is your installation date

Well it was last Friday, but I stopped them half way through when I discovered the problem. I am waiting for them to come back with a proposal inorporating Solar Edge + optimisers today, then when I have made a decision (the alternative being to revert to the quoted Growatt inverter wired 8+8 or 6+10) I will ask for next Friday since I will be home then. Friday 13th. Gulp.

 

[sedgy34]

What modules have they given you, sorry I havnt been following what the issues were.

 

[juniperz]

What modules have they given you, sorry I havnt been following what the issues were.

It's in the first post:
"I was quoted for a Growatt-3600MTL with 16 Suntech STP 245S panels. We have a large roof, but it is hipped, so the installer proposed 12 panels on the house roof and 4 on a garage roof with same orientation and similar roof elevation. I did a bit of research on the inverter, even had a reply from Growatt saying that the panels should be connected 8 + 8.

So, today they came to install. The electrician has done all the internal wiring but they need to come back Monday to finish the panels and complete the electrical side.
2 Problems:
1) I just looked at the inverter in the attic and found it is not Growatt, but Samil SR4K4TLA1 (also badged Solar River and also known as Samil 4400w)......"

Might get back here at lunchtime

 

[sedgy34]

sounds like growatt prefer balanced strings for there inverters were possible, ive just seen some pics on here and i would make them re doo the work as they dont know how to install neatly!!! also we fit suntech 250s so why cant they 12 modules would get you 3kw but the 4 on there string not sure if that will work, also the board the inverter fixed too is not fire retardent is it, these clowns dont know how dangerous DC actually is.

you should speak to the manufacturer of the inverter to see if 1 string of 4= 980w will work


also dont pay them until everything is working and most of all LABELLED

 

[wstevew]

Is there a regulation thar says an inverter must be mounted on a fire retardent board.

I read a document from SMA that claimed that in theory the constant heat from an inverter will over time dry out wood and could cause a fire. But they concluded the heat from their inverters still would not be enough but were still concerned about wood dust which can ignite at lower temperature.

 

[Gavin A]

I believe it's a manufacturers instructions thing

 

[wstevew]

Thanks

 

[jerriais]

It is good practice to install on a fire proof board, especially when installing in a loft. We use it for every job except if we're on a non-combustible surface. Only trouble is it's not so strong so will usually need to be backed up with ply on the reverse side.

 

[juniperz]

I finally got a revised price from the installer - it was going to cost an extra 10% of the total cost to go for Solar Edge + 16 optimiers, so I have decided to stick with them removing the incorrect inverter and installing the one they quoted for - I don't think I would have got the return on that 10%. They are also going to mount on fire retardant board and do proper labelling.
I have given them this question (paraphrasing some of the advice from here - I hope I phrased it correctly):

"We will have 4 panels on the 35% garage roof and 12 panels on the 30% house roof. I know that we should not have these wired as 4+12 into the 2 MPPTs as the 4 would not generate enough voltage. We have talked about wiring the panels as 8 + 8, but with the roof pitch difference, I believe that it would be better to wire as 6 +10 as this would reduce the losses because 10 panels would not be affected by the pitch difference."​

 

[sedgy34]

If I were you I would check with inverter manufacturer technical helpline just for peice of mind as you seem to be doing the installers job for them