Its Dropped Off...

[MicraShed]

Winter is on the way and the huge big oak tree on the fields behind me has started to affect PV output now the sun (that big orangey yellow ball in the sky, remember it?) is lower. During the summer months its high enough to shine on my PV panels from 8.00hrs to 15.00 hrs directly with no shade issues. But now Im lucky if I get 09.00 to 11.00 then the shadows creep across and PV output falls like a stone.

10.30hrs and the shade is creeping up - glad I didnt put another 6 panels on the extension now...

The shade doesnt completely cover the panels, but affects the two at the end of each string of 5 so the whole lot drops off.
Apart from changing the inverter and fitting optimisers (£££) I couldnt see any way round this, but Mrs Micrashed emailed the local council who sent a nice tree officer out and agreed that the oak is getting a bit out of hand and is rather close to a lot of properties so next spring its getting a hair cut!

Result! And a very unexpected one on my part really.

 

[Worcester]

Perhaps they should have designed the strings left / right instead of up /down me thinks..... But then we know that some installers don't think.

I guess it depends upon how long the transition took from just bottom row in shadow to both rows...

Chin up though, you'll generate more in April than you will November thru January anyway. - Do a quick system analysis on PVGIS and you'll get the nmonthly outputs PV potential estimation utility

 

[sedgy34]

Winter is on the way and the huge big oak tree on the fields behind me has started to affect PV output now the sun (that big orangey yellow ball in the sky, remember it?) is lower. During the summer months its high enough to shine on my PV panels from 8.00hrs to 15.00 hrs directly with no shade issues. But now Im lucky if I get 09.00 to 11.00 then the shadows creep across and PV output falls like a stone.

10.30hrs and the shade is creeping up - glad I didnt put another 6 panels on the extension now...

The shade doesnt completely cover the panels, but affects the two at the end of each string of 5 so the whole lot drops off.
Apart from changing the inverter and fitting optimisers (£££) I couldnt see any way round this, but Mrs Micrashed emailed the local council who sent a nice tree officer out and agreed that the oak is getting a bit out of hand and is rather close to a lot of properties so next spring its getting a hair cut!

Result! And a very unexpected one on my part really.

mr & mrs micrashed should invest in a log burner you will have free heating

 

[MicraShed]

I'd love one, Mrs Shed doesnt - so the pine bunk beds I broke up this morning (they were pretty knackered after 10 years of abuse by the kids and held together with carcassing screws and gorilla glue) are on the bonfire pile for next week).
Shame as there is a lot of seasoned untreated wood there (and screws).

 

[sedgy34]

was thinking about that tree thats having a haircut and mrs shed should be told and not have a choice lol

 

[Worcester]

Notice that you didn't cut off the stink stack in the end, - has leaving it caused any problems?

 

[MicraShed]

I dont think so. Ive kept an eye on the shadow cast by it and it really doesnt hit the panels.
It just catches them slightly for a little while early on in the morning sun.

 

[SolarCity]

Was this tree factored in to the PV output calculations? If it is having this kind of effect in October then it will have an even bigger impact over the next few months.

 

[MicraShed]

Nope, fraid not. The calculations said "no shading" and it wasnt factored in at all.

I suspected it might be an issue in winter months but didnt realise quite how much impact its having.

not a great quality picture Im afraid, but the green circle is the tree in question and you can see the extent of the shade across the garden even in summer months.
The yellow star is the location of the PV.

As I said, now the sun is lower its behind the tree. Bit of a bummer, but there you go. I just hadnt realised (or been told) just how much impact even a bit of shade was going to have on the output. But we live and we learn.

It is still making a difference to my electricity use and there is little doubt the ImmerSun is contributing to the hot water
The Immersun has put 19kWh into the immersion in October, and this table shows my Generation Vs Consumption - its not great compared with a lot of other installs but it is making a difference to us.

Just to illustrate - in June & July last year I was using 14kWh/day off the grid, this increases steadily during the winter months, in October I was using 17 to 19kWh (family of 5 or 6 depending on who is stopping in the house) and its only a 2.5kWp system.

 

[MicraShed]

Well, its dropped further. The whole of November produced just 42kWh - I produced more than this in my first live week in July.
Last week I managed an average of just 1kWh/day which is a bit depressing, the only chap nearest to me that I can find entering data on PVoutput.org managed not much less than that a day last week (albeit with a system twice the size of mine) so why am I not managing at least 3kWh/day?

Probably the over cast sky and location of the trees on the playing fields at the back of me. The attached diagram shows how little of a window I have before the sun is obscure by trees - from about 9am now to 11am then because its so low in the sky it vanishes behind the trees, the neighbours tree isnt large enough yet to cause any issues, but the main culprit is the oak at the bottom of the diagram.


apart from hoping the council prune this (which Im not holding my breath over) I dont think there is a lot else I can be doing - according to my PV calculations I should be hitting 60-70Kwh this month.

Or am I being pessimistic and should I just be grateful for anything it produces?

Perhaps having the arrays re-wired from the current top & bottom strings to a left string and a right string might help prolong the output?

 

[FB.]

Well, its dropped further. The whole of November produced just 42kWh - I produced more than this in my first live week in July.
Last week I managed an average of just 1kWh/day which is a bit depressing, the only chap nearest to me that I can find entering data on PVoutput.org managed not much less than that a day last week (albeit with a system twice the size of mine) so why am I not managing at least 3kWh/day?

Probably the over cast sky and location of the trees on the playing fields at the back of me. The attached diagram shows how little of a window I have before the sun is obscure by trees - from about 9am now to 11am then because its so low in the sky it vanishes behind the trees, the neighbours tree isnt large enough yet to cause any issues, but the main culprit is the oak at the bottom of the diagram.

View attachment 15829
apart from hoping the council prune this (which Im not holding my breath over) I dont think there is a lot else I can be doing - according to my PV calculations I should be hitting 60-70Kwh this month.

Or am I being pessimistic and should I just be grateful for anything it produces?

Perhaps having the arrays re-wired from the current top & bottom strings to a left string and a right string might help prolong the output?

Losing 20kWh in the whole month of November (and presaumably December and again January before the sun starts to get higher in the sky again) and for the whole three months you've lost 60kWh.
I don't know the size or orientation of your system, but 60kWh for my 3.75kWp ESE system (SAP estimate 3000kWh/yr) it amounts to just a 2% loss in annual production.
If your system is half the size of mine, it's a 4% reduction in annual generation. Like having 20p FiT instead of 21p FiT.

For my system, just three decent sunny summer days will claw back a loss of 60kWh - and I feel that I missed out on those in summer 2012; I reckon the bad weather in peak summer cost me a loss of 5-10% in total generation for the year - more than the effect of low-level winter shading.

 

[MicraShed]

I was never in this for the Fit (though that is attractive thank you and makes the pay back a bit quicker than it would otherwise be).
It was always for me, about how much it can reduce my energy consumption off grid - this week, not a whole lot :-(

 

[FB.]

I was never in this for the Fit (though that is attractive thank you and makes the pay back a bit quicker than it would otherwise be).
It was always for me, about how much it can reduce my energy consumption off grid - this week, not a whole lot :-(

The weather has been poor recently too - all the flooding around the UK testifies to that.
From mid-October, due to heavy dark clouds and this ongong heavy rain, my outputs suddenly dropped - the following chart shows my daily generation, along with a red two-week-rolling-average line.
Array is 3.75kWp, Aurora 3.6, ESE-facing, 40-degree slope, no shading, Cambridgeshire.

.

 

[Gary K]

Apart from changing the inverter and fitting optimisers (£££) I couldnt see any way round this, but Mrs Micrashed emailed the local council who sent a nice tree officer out and agreed that the oak is getting a bit out of hand and is rather close to a lot of properties so next spring its getting a hair cut!

Result! And a very unexpected one on my part really.

Nip out one night and cut the bark off in a complete ring-in a couple of years the tree will be down. You can always blame rabbits or Deer if anyone asks.

 

[zeljuga]

3 Y x (r2 x3.14 x -20%shade) = + - similar Co2 footprint with ring of bark on or of.