Green Building Forum - Solar pv edge

Solar pv edge

jamesingram — Sun, 29 Oct 2017 08:30:37 +0000

Thats interesting steamy, it say up 30% rather than 30% under sizing being optimal though, I might update my sma inverter sizing software and see what it says ( not done it in a while)
I know on my 4kW SMA inverter (4.32kW array) I've got has a setting, that i set, that is suppose to deal with this issue of low input outside best efficiency zone via some algorithm and increase early/late exposure generation. But this has to be set up via installer software so I'd imagine it's not often done

Solar pv edge

SteamyTea — Sun, 29 Oct 2017 08:50:24 +0000

You still have your SMA installer code don't you, so you can play about. Sometimes I wish I was still designing these systems but other times not.

I do seem to remember reading somewhere that the system size is now determined by the module size, not the inverter size. Not sure if that was for FiTs only though or for the DNO.

Solar pv edge

jamesingram — Sun, 29 Oct 2017 08:59:57 +0000

If I can remember it!
Re system considered size Its for FITS as people were doing what I did with regard to oversizing array but matching the inverter to the 4kW FITs limit for the banding. They clarified the definitions to stop it.
Which is a shame because it result in lots of poorly design systems being fitted in terms of maximising inverter efficiency.
I've always undersized the inverter 10-20% but was surprised by the suggestion of 5kW on a 3.6kW inverter (I do think easy of installation with regard to paperwork for the installer may be a factor here)
the 16A DNO limit has always been a separate issue.

Been doing some rooting around and found this
https://en.sma-sunny.com/en/7-reasons-why-you-should-oversize-your-pv-array-2/
Another recent article suggested a range of 1.15-1.3
And also this from a UK university study from 2008 that suggests 10-40%

Solar pv edge

jamesingram — Sun, 29 Oct 2017 09:07:42 +0000

"Conclusion The effects of time resolutions and inverter dynamic characteristics on optimum inverter sizing have been investigated in this paper and validated by simulation. Up to 3% inverter efficiency change as a funtion of voltage which needs to be considered in inverter sizing. The environmental data with time resolution higher than 10 minutes is recommended since low frequency data cannot guarantee accurate optimal sizing of inverter. The recommended guidelines for optimum inverter sizing is over-sizing the PV array 10% to 40% with respect to the inverter nominal power. This is different from the 130% rating given by the current guidelines specific to this inverter type. However, suboptimal orientation will require increased size of PDC,STC/Pinv,rated, which in extreme cases can be as much as 170% (north facing system). Fortunately, the losses due to suboptimal sizing are not too significant in the case investigated, as it is shown the efficiency for the given inverter are between 88.5% and 92.5% on an annual basis for all orientation"

Solar pv edge

jamesingram — Sun, 29 Oct 2017 09:17:46 +0000

As to fiddling with my own inverter it a sma 4kW rather than one limited to 3.68 I can adjust the max output so could set the cut off below 4kW to whatever I want via the installer software, be interesting to set it to say 3kW or less over the winter and see what difference it made , trouble is there are so many variables it would be hard to isolate a clear improvement if the was one.
Also as it would be a software rather than hardware output reduction in wonder if it would have the same effect on the efficiency curve?

Solar pv edge

SteamyTea — Sun, 29 Oct 2017 11:52:07 +0000

Is it an old 4000TL, leave it alone, they are reliable on standard UK settings.

Solar pv edge

jamesingram — Sun, 29 Oct 2017 16:02:01 +0000

yes its a 4000TL set at 4kW with 'optitrac global peak' set ,still not sure what it does but reading up on it at the time it seemed the best setting to have it on.
theres at lot on these inverters that isn't well advertised by the manufacturers such as the TLs having a inbuilt multifunction relay you can set to specific outputs.
looking at the efficiency curve on the spec its pretty much flat until <0.2 rated power which seems pretty good.

Solar pv edge

SteveZ — Tue, 02 Jun 2026 12:13:23 +0100

Solar Edge latest

Another optimiser bites the dust!

This is the third failure since 2012 in a 16 panel array. The other two were replaced by Sungift after Solar Edge provided the replacement and a contribution to the costs of installing the optimiser. Solar Edge has apparently withdrawn their contribution to the work involved in fitting the new one.

The latest failure, only spotted by looking at the display on the inverter as the website not longer shows individual panel outputs, gave me quite a surprise. The quoted cost of replacing the item, labour, scaffolding etc came to £1000 plus VAT.

I have asked that Sungift send me the new optimiser and I will try to get it fitted at a more reasonable price. Has anyone else had this sort of quote?

It was always one of the drawbacks of any roof mounted system that work on the roof would cost, but the 25 year warranty on the optimisers was a reassuring fact.

Any ideas about fitting an optimiser, although climbing on the roof these days is not something I'll be taking on.

Solar pv edge

philedge — Tue, 02 Jun 2026 13:34:20 +0100

Hire an alloy scaffold tower and change it yourself or with the help of a roofer/rock climber/tree surgeon.

If the optimisers are panel integrated there's a couple of links to install in the JB on the back of the panel. All straight forward to do.....if you've done it before! Solaredge supply the links so make sure you get them with the optimiser

Solar pv edge

philedge — Tue, 02 Jun 2026 13:43:01 +0100

Forgot to say all our optimisers are reporting individually on the My solaredge app and on Solaredge Go

Solar pv edge

SteveZ — Wed, 03 Jun 2026 15:52:15 +0100

Thanks for the info about the mySolaredge app. Tried to use it but only works for Android 7 or later. It will have to wait for a later phone when the present one dies

Fitting and pairing the replacement optimiser looks straightforward, so I think the quote is intended to dissuade me from using the company. Now, where is my ladder? Only joking, before the H & S E heavies weigh in.