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

[JulianC]

That's two votes for Solar Edge. Can someone explain why this is the best solution? I could suggest it to the installer. Let me guess - is it really expensive??

Basically, the single or dual MPP tracker function is taken out of the inverter and individual MPP trackers (power optimisers) are fitted to each panel (usually mounted to the rail behind it). Therefore, the output of a particular panel is optimised, independently of what is going on with those around it. Such a system can accommodate different roof orientations and pitches and even different types of panel in the same string. The last job we did was the first time we fitted one but it was the only real option (3 panels SW facing on a main roof at 50 degrees and 7 panels W facing on a garage at 45 degrees, with added shading complications). Does cost more than a similarly sized Fronius or SMA inverter, but not massively so tbh. Dunno how much the cheap Chinese inverters cost....

 

[juniperz]

If this is the right inverter, it doesn't look much different in cost compared with the Growatt 3600 that they originally quoted.
Solar Edge Inverter 3680W 16A AC Clamped - SE-3680 at Swithenbanks Alternative Energy | Grid Tie Inverters | Solar Photovoltaic
Presumably it is the MPPTs for each panel that bump up the cost.

 

[JulianC]

One of these per panel: Solar Edge 250W Power Optimiser with MC4 Connectors at Swithenbanks Alternative Energy | Grid Tie Inverters | Solar Photovoltaic

 

[juniperz]

I couldn't resist downloading the Solar Edge Site Designer software

The software doesn't seem to include the UK-specific 3680W 16A AC Clamped - SE-3680 so I uesd the 4000

 

[juniperz]

With a conventional inverter, the wiring seems to be in series for each string, with the panels daisy-chained.
With a Solar Edge Inverter 3680W 16A AC Clamped - SE-3680 and 16 lots of Solar Edge 250W Power Optimiser + Panels, are they wired in parallel, so that 16 pairs of wires need to find their way from roof to inverter?

 

[JulianC]

Each panel is wired to an optimizer, then the optimizers are connected in series strings as per usual

 

[jason121]

Each panel is wired to an optimizer, then the optimizers are connected in series strings as per usual

reading these comments on the solar edge, i am thinking of using them on job with 2 roofs slightly different angles.
I know segen stock thems anywhere else ?
Also is there any other wiring to them besides the DC side ?
and can you excess information from any location thru the web.

 

[JulianC]

Got mine from Segen. No additional or unusual wiring required. However, the main inverter is transformerless so array frame bonding may be required depending on which version of the DTI guide you're working to! Didn't connect up the communications side of things on our job 'cos the customer didn't have an internet connection but as I understand it, you can access the monitoring through the interweb from anywhere (someone with more experience please correct me if I'm wrong)

 

[daytona600]

the best car made in china , would not compare to the worst car made in europe
get them to fit a real inverter suitable for the application ideally a poweredge due to string layout or dual MPPT sma/powerone

 

[juniperz]

I did manage to stand them down over the weekend, so nobody turned up yesterday. Apparently "senior management" are investigating. I had suggested something like a Solar Edge Inverter 3680W 16A AC Clamped - SE-3680 and 16 lots of Solar Edge 250W Power Optimiser + the 16 Suntech 245w panels that are in my garage. Though why I, the punter, has to suggest this {insert deity} only knows.

 

[daytona600]

you signed a contract with them they should supply exactly as ordered or equivalent or better in lieu
example girlfriend ordered a new kitchen , after fitting she noticed work tops where different you know what women are like with kitchens
she phoned to complain next day the MD of the company turned up with one of those huge amercian freezers
free as way of letting her down

 

[Worcester]

and Daytona600 is as good as his word too, he's not just saying it, he practices it as well.

 

[juniperz]

Busy week... The installer has come back saying they will install the quoted GroWatt inverter, use fire retardant board etc.
I am going to struggle to get out of a signed contract where they have offered to comply with the contract.
Whats the worst that could happen with
Growatt 3600MTL (2 MPPTs)
12 x 245w panels on a 30% roof
4 x 245w panels on a 35% roof
Could be wired 8+8 according to Growatt tech support, though that was before I knew about roof angle, and they haven't answered my recent question.

In another thread, FB said

As Gavin says: in summer it won't matter.
But with low sun in winter (or early/late in the day at other times of year), the difference in angle will make a big difference to panel output, so the bypass diodes will be working overtime.

By my reckoning, a 5-degree difference (35 v 30 degrees) in angle affects as follows:

Mid-day, June sun: 0.5%

Mid-day, March/Sept sun: 5%
(comparable to morning/afternoon summer sun)

Mid-day, December sun: 20%
(comparable to early-morning/late afternoon spring/autumn sun)

Will that amount to much over the year?
Is bypass diodes working overtime a big problem?
Thanks...

 

[sedgy34]

Busy week... The installer has come back saying they will install the quoted GroWatt inverter, use fire retardant board etc.
I am going to struggle to get out of a signed contract where they have offered to comply with the contract.
Whats the worst that could happen with
Growatt 3600MTL (2 MPPTs)
12 x 245w panels on a 30% roof
4 x 245w panels on a 35% roof
Could be wired 8+8 according to Growatt tech support, though that was before I knew about roof angle, and they haven't answered my recent question.

In another thread, FB said


Will that amount to much over the year?
Is bypass diodes working overtime a big problem?
Thanks...

When did you sign the contract as you have 7 days cooling off period

 

[juniperz]

When did you sign the contract as you have 7 days cooling off period

It's nearer a month ago.