help needed guys please regarding inverter choice

[Shirehorse99]

hi guys

i am looking for some advice on my system. My installer and I are at a stalemate at the moment regarding the inverter he has installed.

i had my system installed on Nov 22 and due to the constraints on kit at that time, my system does not resemble anything like what i ordered.

my first order was 4Kw system with sunny boy inverter - after site visit it was agreed that i could only have 3.43Kw schuco panels and a sb3000 sunny boy inverter (due to roof size) - what i got on the day was 14 X Suntech 245W panels and a Fronius IG30 inverter. (3.44kw)

while i have no problems with the panels , i believe that the inverter is no good for my requirements. i am arguing that i need 2 MPPT trackers for my system - he says the fronius has bypass diodes ( whatever that means?) and will do the job although it is at its top end of its capabilities.

i have 6 panels on my roof and 8 panels on my flat roof.

what do you guys think i need - the flat roof does have some shading issues at this time of the year -

cheers

Mark

 

[Noddy67]

I presume the flat roof angle / aspect is the same as roof (ie exactly the same angle and direction). If not it should be two inverters or a dual-tracking inverter.

If it's the same angle/aspect on the face of it, you've got an 85% inverter/panel ratio... and a good industry standard is to be no worse than 80%.

But for me the first part is key - if there's a lot of shading that might also required two strings, but not if "at some time of the year" is fairly occasional.

 

[Shirehorse99]

no they are different angles

the main roof is 30 deg and the flat roof due to window issues is only at 12 deg on a bespoke stand - the direction is the same (210 deg)

 

[solarsparkie]

You need to be nice and start talking , its always hard retrospectivly as there is probably a book in it , were you sold one system and delivered another and found out afterwards your case is strong and losses can be calculated . If you were offered an alternative system and were provided a new sap calculation and accepted your case is weak. The truth is probably somewhere inbetween as is often the case

 

[SolarCity]

At the very least, the panels should be wired in two strings of 7.

"he says the fronius has bypass diodes"

Bypass diodes have nothing to do with it. Are you sure that's what he said?

 

[Shirehorse99]

solarsparkie- no sap calcs given - only knew what i was having when he turned up- and due to Dec 12 issues and him being fully booked there was no going back

biggs -yep, i thought he was talking s**t as well

 

[Shirehorse99]

what do you guys think i should be asking for inverter wise

 

[solarsparkie]

the diodes are in the panels , this will be a big book client just needs his sap calcs end of story and reflect on what he agreed on day of installation

At the very least, the panels should be wired in two strings of 7.

"he says the fronius has bypass diodes"

Bypass diodes have nothing to do with it. Are you sure that's what he said?

 

[solarsparkie]

you can have whatever inverter your heart desires , no sap calcs no contract

 

[SpitfireW'sale]

Sounds like incorrect advice to me.

The strings should be on the same angle and orientation as stated above by noddy. If there is a small difference this may be OK, but by your reply, there will be shading on one array when the other has direct sun. Also you would ideally have 2 balanced strings for the inverter, i.e. 2 strings of 7, not 1 string of 8 and 1 of 6.

You should have either two smaller inverters, or 1 dual tracking inverter. Bypass diodes will not help in this example. FYI the SB3000 is not a dual tracker, so would not have been appropriate either. Power One would be a good choice.

I am not sure how you will resolve this, as the initial suggestion of the SB3000 would have yielded the same result, unless you had been quoted on the SMA 4000TL for the Schuco panels, which is a dual tracker.

Hope you get things sorted out!

 

[Shirehorse99]

i have spoken to him about power one already but they said they only install sunny boy and fronius

 

[hionthehill]

if you he could in stall an EFFEKTA es3300 that woud do it nicley

 

[jupestar]

having the exact same problem with my fathers install. the original inverter they installed was some cheap thing (forget the make). anyway lasted less than a year. they replaced it with the fronius but only one string on a 3.99kwp install. the old inverter had two strings (although i suspect one tracker) so now he has 14 panels connected about 30 meters through his loft near his inverter connected to the other set of panels ( which was originally the second string) all the way back to the roof and then back into the loft again... basically two become one... hes got a bloody huge dormer between the two sets of panels and the panels are right up against it...

having a nightmare with the company to get it changed.....

 

[SolarCity]

It would probably help if you post a picture of install

 

[Noddy67]

the slightly better take - hopefully - is that the installer hasn't stiffed you with some tatty, second rate inverter that he won't be able to shift.


SMA SB's are fine... and should be fine for him to install on another system easily enough, freeing up the money to get you a powerone Aurora or similar.

I would also suggest that he couldn't have given you an appropriate SAP calc in the first place if he's put it all on one string, let alone changing/updating it.

Out of interest, what part of the country are you in... that information might get you a private message with more help too.

 

[Shirehorse99]

I'm still going to ask for a power one - if a cash adjustment is needed i will do it .
The job was a rush job - done in a day - so they could get as many in as possible. They just wanted to commission the job and come back to finish it off after the 12/12. They completed the flat roof last week ( panels have been weighted down on floor for 5wks)

Its a big company - part of carillon group - I don't really want to pay anymore than the 11250 I've paid now. I think after paying that amount of money I should have the system I specified

 

[FB.]

Sounds like incorrect advice to me.

The strings should be on the same angle and orientation as stated above by noddy. If there is a small difference this may be OK, but by your reply, there will be shading on one array when the other has direct sun. Also you would ideally have 2 balanced strings for the inverter, i.e. 2 strings of 7, not 1 string of 8 and 1 of 6.

You should have either two smaller inverters, or 1 dual tracking inverter. Bypass diodes will not help in this example. FYI the SB3000 is not a dual tracker, so would not have been appropriate either. Power One would be a good choice.

I am not sure how you will resolve this, as the initial suggestion of the SB3000 would have yielded the same result, unless you had been quoted on the SMA 4000TL for the Schuco panels, which is a dual tracker.

Hope you get things sorted out!

Have I misunderstood you or got confused?

Just the highlighted bits; I though that a Power One Inverter was capable of handling two unequal inputs in a more-or-less normal way, as long as all panels in each of the two strings were in the same lighing conditions (therefore bypass diodes not involved). ?
e.g. I thought that a Power One's dual inputs had no problems with (say) a string of four which get sun in the morning and a second string of six which get sun in the afternoon.

Sorry if I've misunderstood or misinterpreted your words.

 

[Shirehorse99]

Fb - is this post for me to answer ? - I haven't got a clue mate

 

[FB.]

Fb - is this post for me to answer ? - I haven't got a clue mate

Shirehorse -
No; the question was aimed at Spitfire - to clarify whether there is an issue with unequal strings going into a Power One inverter.

I thought that Power One inverters could handle two unequal strings - and that may be why Spitfire has recommended the Power One.

 

[Noddy67]

spitfire was just saying that it does need two strings... and then secondly that the PowerOne woudl be ideal because it has two strings which can be unequal.

I know Spitfire W and I know they know their onions / inverters.