Renewables: "talking 'bout my generation"

Oscargrouch

zeupater wrote: »

Hi All

I'd propose that the only relevant comparative measure between systems, if this is the requirement, is to quote %age achieved against individual system PVGIS target, this is the only way that orientation, roof angles and location can be accounted for.

Of course, the version of PVGIS and the associated losses would need to be standardised and it would need to be recognised that any change to the database would need everyone to adopt rebased targets in order to standardise comparisons for new members, but .....

.... then again, I'll just keep spot-checking MPPT1 DC generation against MPPT2 to see if the panels are all working and then see how our weekly/monthly averages compare to target and some very local systems, even though we automatically collect masses of data. The reason for this, well, whether the system is performing well or disappointingly, if it's working properly it's where it is and pointing the way that it does, so seeing that I can't do anything about the weather, why worry ? .... :cool:

HTH
Z

At the end of the day this is a social thread not a scientific chore......:) Even though most people, myself included have learnt a lot from the info posted here....i.e. my sytem performs better than Shafeeq's, irrespective of the 'TREE'.....

Oscargrouch

3.4 O's today, may have been 3.5 O's if the roof pitch was better, and/or whatever else comes into the equation. The Gen Meter reading still boiled down to 3.4 O's despite all else. (In kWh just times it by 2.5 .... please)

shafeeq

Oscargrouch wrote: »

Even though most people, myself included have learnt a lot from the info posted here....i.e. my sytem performs better than Shafeeq's, irrespective of the 'TREE'.....

Are you sure Oscargrouch? :mad: If that is the cause then get your system checked out...

13.21 kwh / 4.40 O's :rotfl: you thought you going to have a laugh at me think again :eek: :T

Martyn1981

13.8kWh's here, or 2.47 O's, so slowly slipping down, but still a little ahead of target thanks to week 1. Looks like week 3 could be as bad as week 2, but week 4 looking good according to the long range forecast - but we all know how accurate they are!

Fingers still crossed for 2 consecutive '+' months, even if the magic 700 is slowly fading out of sight.

Mart.

csh_2

Averaging 4.15 O's for the last 3 days. Wall to wall cloud. I can't remember having a June so dry and hot, yet cloudy.
Last June we had about 3 dry days and this year although rain forecast every second day it's only rained twice and it wasn't very convincing.

sly_dog_jonah

Martyn1981 wrote: »

I would suggest the order of importance would be, size, orientation, location, pitch. Weather is also very important, but depends on size of sampling period.

Don't forget every PV system's 2nd worst enemy (after clouds): shading!

Kernel_Sanders

Martyn1981 wrote: »

So, yes I agree it's a crude measure, but it's certainly not flawed or irrelevant, it's step one and both accurate and relevant, but the comparison data needs expanding if you want greater accuracy.Mart.

OK gentlemen, I wasn't expecting my tongue-in-cheek post to spark discord in the thread! In truth, the only thing that annoys me about Os is some people's tendency to use an apostrophe when pluralizing
I think Mart's point is valid, in fact the system capacity is surely more important than all the others put together. It's certainly better than nothing, although I also agree with Eric that the proposed Zs have much more validity.

jimjames wrote: »

ALL the variables would also include temperature and sun/cloud cover.

Eric only meant the variables between people's systems. The whole point, surely, of reporting daily production is to inform others about the cloudiness and temperatures in your locality. If these drawbacks were somehow incorporated into a formula, wouldn't that mean everybody having the same values as yesterday or tomorrow?

sly_dog_jonah wrote: »

Don't forget every PV system's 2nd worst enemy (after clouds): shading!

Do you mean every one apart from those that have no shading, or only slight shading?

Actually clouds aren't the no.1 enemy; that would be...........this!

Martyn1981

Kernel_Sanders wrote: »

OK gentlemen, I wasn't expecting my tongue-in-cheek post to spark discord in the thread! In truth, the only thing that annoys me about Os is some people's tendency to use an apostrophe when pluralizing
I think Mart's point is valid, in fact the system capacity is surely more important than all the others put together. It's certainly better than nothing, although I also agree with Eric that the proposed Zs have much more validity.

Don't worry Kernel, this is a very friendly thread, I was only playfully 'poking' Eric (apologies if it came over differently).

Regarding importance I agree, and was going to suggest that generation is 50% of the story, gen/kWp (Os) 75%, and all the rest making up the difference. But then I realised that gen itself is actually almost worthless, (2kWh's from a single sunny panel, or from a fog bound 50kWp install) but we get away with it here as the nature of the thread (and site) means installs are largely in the 2 to 4kWp range. Without those 'boundaries' the gen figure would be almost 0% of the story, but the Os (kWh/kWp) still 75% (perhaps?).

I totally agree with Eric that it takes a month to average out the weather enough for some comparisons, and that's why I try to post monthly figures for both ESE and WNW gen in kWh's and Os. But Os become ever more crucial. My systems might average 4,250kWh's pa, similar to Mysterons 4,460kWh's (who hasn't posted (here) for some time). But in Os the story is much different as I get 761.65 Os pa v's his 1,115 Os (5.58 v's 4kWp).

I also agree about the Os and O's, I settled on O's simply because I realised posting without an ' could look like an extra decimal place eg 3.215 O's or 3.215 Os. Looking again, I was probably overthinking it (now there's a surprise!)

Lastly can I state that this detailed look at Os is also very much tongue-in-cheek, but the sun is shining and I'm back in shorts, so I'm feeling a little playful.

Mart.

EricMears

Martyn1981 wrote: »

Don't worry Kernel, this is a very friendly thread, I was only playfully 'poking' Eric (apologies if it came over differently).

I realised that - no offence taken.

Kernel_Sanders wrote: »

The whole point, surely, of reporting daily production is to inform others about the cloudiness and temperatures in your locality. If these drawbacks were somehow incorporated into a formula, wouldn't that mean everybody having the same values as yesterday or tomorrow?

Quite so.

But unless you're considering moving and want to pick the best place to go, even that isn't really helpful !

But there is another useful reason for monitoring performance of other SP installations. Monitoring your own and comparing it with pvgis predictions would alert you to any unusual drop in performance (or of course unexpected improvements but maybe they're not so worrying). If your own drop coincided with that of others, it might set your mind at rest a bit and save you getting out your ladders to see if panels need a clean. e.g. I think most of us had a pretty bad March (and I in particular knew there had been several days with snow sitting on panels) so ladders stayed in the shed.

The crude calculation of dividing daily generation by system size ignores so many variables as to become virtually useless.

John_Pierpoint

http://www.guardian.co.uk/commentisfree/2012/jul/27/greenland-ice-sheet-melt