Our 2.2kW PV

[T S Magnum]

Hello one and all. I have been lurking for a couple of weeks and have learnt a great deal so a big thanks already. I thought it's about time I show myself (and show off my new kit!).

We bought our first house in April, then did a bit of FIT research and figured if we intend to be here a while we might as well start the 25 years sooner rather than later.

I'll admit to doing a pathetic amount of installation research beforehand, but we seem to have done well (fingers crossed) in finding a very capable installer. We're chuffed with the end result but are reserving judgement on the performance as the weather has been atrocious since the mid Nov installation  .

Anyway, here she is:


10x Sharp ND 220 panels (6 at 175 deg, 4 at 265 deg on a typical '30s semi) and an Sunny Boy 2000 inverter.

[biff]

hi ts,
     your panels look lovely,
      you need to insert a couple of struts underneath the purlion beneath the 4 panels to the left.
   the purlion runs from the party wall to the hip on the gable,there are already struts there at present (or they should be) but its possible that their bearing have been moved, you can use a car jack and reinsert the bearing,then spike in situ.do not try and push the roof up too much, just take the strain on the struts,
                          biff

[smegal]

I like your install.

[T S Magnum]

Ha! Forgot to say... real name is Ed! 

Thanks for advice Biff. That purlion has no struts but is pretty chunky and does have the king pin at its mid span. should I be worried? 

[JohnS]

I am surprised to see SE and SW panels on the same inverter. It will bring down the overall output as the set will only perform as well as the least performing group.  Bit like shading.

I would have thought that twin Sunnyboy 1200s would have been a better bet.  Alternatively a dual string inverter but I am not sure if there are any smaller tham 4kW.

What did the installers say and predict?  Mostly they use the inverter manufacturers predictions, or at least that is what mine did a year ago, and I have yet to see an inverter manufacturer whose software copes with the dual aspect.

John

[biff]

no reason to panic ed,
                just have a look and see if there is a  gap between the ceiling and the top of the wall on the corner of the room immediatly close to the camera,
    there is no danger of anything falling but over time things can twist and kick,
   notice the gaps in the pan tiles next to the ridge tiles bottom of pic, this is new,it dont have litchen growing in the joint yet, the ridge on the hip is kicking up while the panels are pressing down the other end, ??,
        just add another strut or as the brickies used to say, an" old man"(similar but in brickwork)  but 4" x 2"  is better.
                                                biff

[T S Magnum]

Thanks Biff I will see what can be done.

JohnS:

Hummm... Hadn't really heard of this concept before. Installer didn't mention it. Will it have literally that effect? I don't like the sound of that. I know of that effect when 'hard' shading was on a portion of the string - I have already observed it with the snow.

Installer predicts 1802 KWh PA. This is based on SAP 2005 and includes the orientation (so they say).

[biff]

dont worry ed,
             the panels look good,johns has a valid point but you have the gear and there is nothing that cannot be put right.
                            biff

[T S Magnum]

When you say put right Biff, how would we go about this? If we'd be better off with 2 inverters I should moan at the installer sooner rather than later I guess...

[biff]

hi ed,
    i would be the least qualified to tell you anything about eletronics,i can see at a glance that the panels cannot get the same amount of sunshine except at noon,so johns point is a good one,i would have to agree with him,
           however we have some really helpfull guys on here and i am sure they are watching closely,they will have no bother explaining things to you if you give them time.i know they are mulling things over before they speak,
                                      biff

[Iain]

Hi Ed
Nice to see another system installed
From what I have picked up from the performance on my system and info on the forum I would have expected your system to have either 2 smaller inverters(1 on each roof string) or an inverter with 2 separate trackers. I think shading will affect the output a lot on your system. My system gets shading on 3 panels from the chimney for a very short time each day and the loss of output is marked. I would think your system would be affected quite a lot. The picture of my output shows:- first slope- ambient light, second slope-with shading, 3rd slope- no shading

Try pvgis with yours as 2 separate systems and see what is predicted and compare with others and what you are actually getting. I dont know if there is software to predict shading effect on a system like yours.
I would think you are probably loosing a fair bit. Others will probably comment as well,
Keep the scaffolding up for a while!!!
Iain

[T S Magnum]

Thanks Iain. PGIS total for 6 and 4 panels in their correct orientation is 1637 kWh, so it sounds like the installer's prediction does not include shading  . Scaffolding is long gone but cables for each string run into the loft...

Today was a timely demonstration of system performance actually. Beautiful sun all day here in the North East. First really clear day since the installation in mid November.

Between 0915 and 0945 I know for a fact that the 6 panels were in bright sun while the other 4 were shaded (I was up a ladder fixing the gutter!). The Sunny Boy trace says around 0.1 kW for this period. I know it's December but that sounds pretty low for 1.32 kW worth of panels in decent sun! The trace below looks very 'peaky' around noon as Biff suggested it would. For the whole day we got 1.5 kW, does that sound low for such a sunny day?

[Other-Power]

Two stings on different facing roof spaces should be on seperate inverters or different MPP trackers.

The SB 2000HF which I assume you have? only has one MPP tracking although it takes two strings.

Your output will be affected by this arrangment and would say that the installer is not fully up to speed with what is effectivly man made shading.

I would have them sort it out, seeing as the wires are already in the loft it should be a days work for an electrician tops, a sunny boy 1200 for the 6 panels and you will have to have a different inverter for the 4 panels, not sure what to suggest as the Sharps are a lower voltage panel.  Second option is to get them to stick up another couple of panels and put in another sunnyboy 1200 for not to much more and for you not to mention their name to the local paper.

Sorry to put a downer on your system but its not right.  I design systems daily and this is somthing I have seen in other quotes from other companies in the past.

Jonathan

[T S Magnum]

^^^

Thanks very much for comments. The installer has agreed to replace the inverter with a SB 1200 and a Dorfmuller 800/50 for the 4 panel string (2 pairs in parallel).

[Other-Power]

^^^

Thanks very much for comments. The installer has agreed to replace the inverter with a SB 1200 and a Dorfmuller 800/50 for the 4 panel string (2 pairs in parallel).

Good news,

You should see yield go up even this time of year.

Regards

Jonathan