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Energetic_2

Welcome... I'm fairly new myself so may not be qualified to do welcomes...

Shading that would cover the whole panel would limit the system to the current carried through that panel so it's going to have an effect. Have you got a picture showing the roof throwing the shade in it as well, i can model it in 3D and give you a % of degradation if you like. Need to know the degrees from south and the panel and inverter also.

e

dannyboyroberts wrote: »

Ok a little background, it would be a 3kw, 30 degree pitch and the shading is only a problem for about 2-3 hours a day from November the 10th until Febuary the 10th, I have some pictures of what the shading would look like.

It's my neighbors roof, assuming that from december - febuary it is these pictures in reverse.

Because the panels are arranged in series, and one panel has been completely covered from December to January, in the morning, it would mean that the whole system would output nothing ? Or am I confusing things ?

What I'm wondering is how much money/kw do you think would be lost from this, and would it still be worth the time. Thanks a lot everyone

Oh and one last thing, the last picture says Febuary 2013, it should be January 2013










BTW, I'm newish to the forum, hi everyone :T

Energetic_2

Martyn1981 wrote: »

Thanks E. It was the string 'bit' that concerned me, as the tech sheet seemed to suggest only one input. I thought that odd, but the max voltage being so, very, very high (top of head I think the bigger SMA TL's are 550V?) made me ponder if it was a single MPPT and single string inverter.

I really shouldn't keep looking for stuff like this, can't help it.

Mart.

It only has a single tracker but it will have multiple inputs to that tracker. Purely to allow splitting for voltage flexibility. The two inputs are connected internally which is why the strings have to be equal. Sorry not to have clarified that, it's the important bit...

Cardew

Energetic wrote: »

The rule of thumb for inverter /panel sizing in the UK is 80%. The reason for this is that the inverter is operating under peak more that it operates at peak (due to UK climatic conditions) and hits a better efficiency in that range of the power curve. You would not size like this in North Africa for example...
.

The above discussion hasn't covered the point about the siting in UK.

You rightly mention North Africa, but there is a big difference between North Scotland and Cornwall. A 1.7kW inverter for a 2kWp display in Cornwall would presumably experience more clipping than the Scottish set up.

Energetic_2

Cardew wrote: »

The above discussion hasn't covered the point about the siting in UK.

You rightly mention North Africa, but there is a big difference between North Scotland and Cornwall. A 1.7kW inverter for a 2kWp display in Cornwall would presumably experience more clipping than the Scottish set up.

Indeed, I did say it was a rule of thumb.

Martyn1981

Hiya Energetic, looking for some thoughts, following a chat with the neighbour yesterday.

He borrowed my barrow to take in a ton of coal stuff (didn't see exactly what it was) and some logs I'd put aside. We started chatting about PV and ST.

He's on a limited budget, but was thinking about a ST system. Currently his heating is from two solid fuel burners, and his water is electric.

His roofs are opposite to mine, so clear WNW, but bay window roof on ESE. He was looking for ideas, and left when his brain started to hurt.

My opening suggestions:

ST only, perhaps 2 30 tube systems, one E one W.
PV only, 4kWp, 2E & 2W
PV only 5kWp 2E & 3W
PV and ST, tubes E&W, plus PV 1.5E & 2.5W

Measurements in PV terms, 8 standard panels on front (as I have) 12 standard panels on rear.

Also I got DNO approval for 5.9kW of inverters, I assume he would get permission to exceed 3.68kW too. But 5kWp with a chimney in the centre south (as mine) may mean that there would be limited capping anyway. (With PO's on the WNW roof I saw 4.2kW sustained in late July on my systems, so perhaps 4.5kW possible, from my 5.58kWp).

As water is heated via leccy, I'm thinking Immersun (or similar) for all PV options.

Doubt he can do PV & ST, but best to consider all options. Also his neighbour is a ST installer, and a great guy, so possibly a DIY ST install.

Roofs are 30deg, and generation (for me) is very, very summer weighted, presumably ST would be similar? So whether PV, ST or both, there is little hope of getting much hot water Nov, Dec & Jan.

Lastly, wife and two late teen daughters. Oh yeah, and also the house will have a gas connection, if that provides a better option, but currently he has no gas kit, or annual gas costs.

Thanks for thoughts, suggestions.

Mart.

tunnel

Energetic,

I have a system installed,2.04kWp,consisting of 8 x 255W panels(can't remember for the life of me what make they are). The inverter is an SMA 2000,problem i have is late afternoon the house next door progressively shades the panels from one end to the other. In winter its not so much a problem(sun doesn't go far enough round) but in summer i can be producing 1600-1700w an hour ,then when the shade hits it drops dramatically.

Would swapping the inverter to a solaredge and adding all the gubbings that goes with it to each panel make a difference. ie,would the power reduce accordingly as each panel shades, for arguements sake say...8x panels 1600w,7 panels 1400w,6 panels 1200w etc etc and at what point would the inverter shut down,would it keep producing with only 1 panel in the sun?

I'd consider swapping it if thats how the solar edge works as it can be 2 hours from one end to the other meaning another 2-3kWh's per day.

Any advice?

Tunnel

Martyn1981

tunnel wrote: »

Energetic,

Would swapping the inverter to a solaredge and adding all the gubbings that goes with it to each panel make a difference. ie,would the power reduce accordingly as each panel shades, for arguements sake say...8x panels 1600w,7 panels 1400w,6 panels 1200w etc etc and at what point would the inverter shut down,would it keep producing with only 1 panel in the sun?

Tunnel

Sorry to interrupt, but if it's any use I can recall some actual numbers from my SE system back in early Aug.

I have a chimney to the south of my panels, in fact one panel SS (Slim Shadey) almost touches it. Using the SE monitoring portal, I was interested to scroll through daytime generation, which is available on a panel by panel realtime Watt basis, as well as on a cumulative or time (Wh) basis.

When the sun is coming around the chimney, approx noon to 2pm, SS is in massive shade. On one sunny day I recall it was generating about 23W, whilst the other 7 were generating around 170W (+/- 5W). Later in the year a second, then third panel became more shaded as the chimney shadow becomes longer.

I've just taken a quick look at the cumulative panel totals, which are (in kWh) 51.51(SS), 53.49 & 54.04, then for the other 5 56.24 rising to 58.99.

Also, and assuming your inverter is a SB2000HF, then the SE inverters should be approx 2% more efficient.

(I've priced up exactly what you're describing for my ESE systems, even down to the possible 2nd hand value (on Fleabay) of my SB1200 & SB2500HF)

Not sure if this helps.

Mart.

tunnel

Martyn,

How many panels are there on that string with your mate "slim"? Was you told at what point the inverter may stop generating at from shading? Or was it not an issue.

As stated mines 8 and they do get progressively shaded. The shade doesn't move around,it just starts at one end and continues along.

What i'm asking is when would the inverter stop working,will the power output just get progressively less as each panel falls into shade and at what point will it stop producing(will it continue with only 1 in 8 panels in full sun)

When mine was installed the installer said that as the sun was going down i wouldn't lose too much generation,but i'm not so sure now(constant checking showed power output drop from 1600w to 300 in space of minutes) and wish i'd looked into it a little more prior to installation.

As you know,with my good fortune with the FIT,it really is worth investigating and the sooner the better for me now the days are supposidely drawing out.

edit,DOH, just seen you've got 8 panels on it

Tunnel

grahamc2003

tunnel wrote: »

Energetic,

I have a system installed,2.04kWp,consisting of 8 x 255W panels(can't remember for the life of me what make they are). The inverter is an SMA 2000,problem i have is late afternoon the house next door progressively shades the panels from one end to the other. In winter its not so much a problem(sun doesn't go far enough round) but in summer i can be producing 1600-1700w an hour ,then when the shade hits it drops dramatically.

Would swapping the inverter to a solaredge and adding all the gubbings that goes with it to each panel make a difference. ie,would the power reduce accordingly as each panel shades, for arguements sake say...8x panels 1600w,7 panels 1400w,6 panels 1200w etc etc and at what point would the inverter shut down,would it keep producing with only 1 panel in the sun?

I'd consider swapping it if thats how the solar edge works as it can be 2 hours from one end to the other meaning another 2-3kWh's per day.

Any advice?

Tunnel

I'd see if you can get the software upgrade for their Optitrac system on your Inverter model. All it is is a better tracker, which searches for all the peaks in the Power v Voltage curve instead of stopping at the first local peak. If you have shading, then you have several local peaks (or rather points where dP/dV is zero), and Optitrac seeks out the peak peak, iyswim. Should give similar results to the solar edge system, without the expensive hardware and fitting. But you may have to go that way if Optitrac isn't available on your inverter, which it isn't on mine (SB1800). I decided not to go down the solar edge route due to the risk of increased problems in the future, but it depends on how much generation you are losing due to the shading.

Martyn1981

Hiya Tunnel, yep 8 panels single string. If I'm understanding an SE system correctly, then you have a single string of PO's (power optimisers) in series, but each PO is connected in parallel to a single panel.

I've seen my system running at about 20W (on the TGM LED flasher monitor), but that doesn't really answer your question if 7 panels were in full shade, could the eighth carry on. I suspect it would carry on, as even the shaded panels (like SS @23W v's 170W) will still be producing a bit.

Anyways, I'll shut up now with my guesses, and leave it to the man that actually know's what he's talking about. Assuming he doesn't run away when he sees all the requests for free advice - Oops!

Mart.