Solar ... In the news

Nicolai_Grenovski

I said : “You claimed 50 degrees was the optimum angle for solar - PVGIS completely disagrees with you.

You replied: ”Not true again I'm afraid, I was quite clear:"
And quote yourself saying: "... in reality it's probably the optimum pitch for south facing PV in the UK to best match supply and demand."

Unless you're claiming pitch and angle have different meanings I think you should make your mind up and not be so objectionable.

But, just to be clear, you've only introduced the issue of variable pitch after I pointed out that PVGIS supported a 50d pitch, before that you simply stated that 38d pitch was better.

The subject has only just come up from your "guardian troll" which I think means an imaginary friend - yes?

Back to the subject, it is pointless if you're grid connected and offgriders optimise their activity to fit the solar profile so they (with the option) optimise for summer in the summer and for winter in the winter.


38 degrees is the optimum figure from PVGIS for the latitude quoted and PVGIS does not recommend 50 degrees as optimum for any latitude.

I note that Heinbloed, a German who posts loads of excellent information on many forums has previously described you as a troll and an atom clown.

who?, what? ?????????????????
Anyone have any idea what he's on/talking about?

zeupater

Nicolai_Grenovski wrote: »

.... PVGIS does not know what area you are in - it assumes that the world is an oblate spheroid and cannot factor in a high 'horizon' caused by trees/buildings etc - even though theses may not pose a shadow over the panels, they limit the view of the sky unless you're on the side of a south facing hill or have your ground mount panels on the tallest building around ...

... it is the total radiance (what is called insolation) ...

Hi

More absolute rubbish ...do you really understand the industry you claim to operate in ??

.."PVGIS does not know what area you are in" ... yes it does, you've told it and from that the irradiation and insolation data which applies to the relevant ~2km grid location is applied to the calculation.

.. "it assumes that the world is an oblate spheroid" ... absolute rubbish - PVGIS takes account of latitude, turbidity and time-averaged weather conditions (cloud cover etc) which are applied on a GIS mapping basis. Far from the model basis being one "that the world is an oblate spheroid", PVGIS does, and always has, takes the elevation of the ground at the selected location into consideration and relates this to geographical features to virtualise a terrain based horizon using the SRTM-3 model, from that it calculates the effect of terrain shadowing on performance.

... "cannot factor in a high 'horizon' caused by trees/buildings etc " ... again, a misinformed assertion - PVGIS has the ability to override the default terrain horizon with a bespoke user designed representation of any site to do just that ... the effect of buildings, trees or any other feature can be modelled, it's simply a case of describing the feature elevations and direction to the model ....

... "it is the total radiance (what is called insolation)" ... a fundamental issue here which is as basic as understanding the difference between power & energy, Cardew will be able to help on this point, I seem to remember that he has a history of correcting newbies where the two are transposed! ... anyway, more important than that - the correct technical term is 'irradiance', not 'radiance'


As an aside can you also research the average US$/GB£ exchange rate over the 6 months immediately prior to the UK's referendum and compare it to the average for the last week ... you may possibly find that there's more misinformation based on overestimated assumptions in recent posts ...

Is there a chance that you can stop trolling this forum & return to fishing in a river where the water isn't so obviously flooding into your waders? ... (out of depth & all that!)

HTH
Z

Cardew

zeupater wrote: »

which is as basic as understanding the difference between power & energy, Cardew will be able to help on this point, I seem to remember that he has a history of correcting newbies where the two are transposed!


Z

Your memory is failing I believe: are you not thinking of grahamc2003?

If it is my memory failing, perhaps you can point out my posts on the subject; I am sure The Guru will help!

zeupater

Cardew wrote: »

Your memory is failing I believe: are you not thinking of grahamc2003?

If it is my memory failing, perhaps you can point out my posts on the subject; I am sure The Guru will help!

Hi

A couple of seconds ....
http://forums.moneysavingexpert.com/showpost.php?p=68187852&postcount=12

We need to get the terminology of kW and kWh and efficiency correctly defined.


The rating of an appliance in kW has little relevance to the kWh it will use; and it is kWh that we pay for.


For instance a washing machine might have a heater rated at 2.5 kW and some washing cycles take 2 hours or more to complete. However it doesn't use 5kWh as the heater is only on for a very short period in that 2 hours and a typical consumption on a 2 hour cycle might be 0.6kWh - and that is mainly for the motor and pump.


Your analogy of air conditioning efficiency is misleading. Efficiency in that case, would be the ability of a unit to keep a room of a specified size, at a specified temperature, with a known outside temperature.


You quote an example of an a/c unit of '2.6kw power using 1kw
energy' as an example of efficiency.


A 2.6kW rated unit will use 2.6kW and over a certain period of time will use 1kWh. That period of time is determined by how long the A/C unit runs.


A 12kW unit will also use 1kWh over a certain period of time. Neither is a measure of efficiency; the 12kW a/c unit could be more or less efficient than the 2.6kW unit.

More? ... or will you withdraw and not politely help to correct a newbie on a fundamental energy related measurement issue in line with past practice in order to reduce misinformation and misunderstanding ? ....

HTH
Z

Cardew

zeupater wrote: »

Hi

A couple of seconds ....
http://forums.moneysavingexpert.com/showpost.php?p=68187852&postcount=12



More? ... or will you withdraw and not politely help to correct a newbie on a fundamental energy related measurement issue in line with past practice in order to reduce misinformation and misunderstanding ? ....

HTH
Z

I withdraw!

Albeit in my defence I thought you were referring to something on solar PV and that quote is dealing with terminology.

zeupater

Cardew wrote: »

I withdraw!

Albeit in my defence I thought you were referring to something on solar PV and that quote is dealing with terminology.

Hi

No problem ... I just thought that you'd be interested in the use of correct terminology, after-all, if we were to expect an electrical or electronics engineer to know the difference between power & energy, shouldn't we equally expect someone in the PV industry to know the difference between radiation, irradiation and insolation ?

HTH
Z

Martyn1981

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Nicolai_Grenovski

"... in reality it's probably the optimum pitch for south facing PV in the UK to best match supply and demand."

50 degrees... less import, and reduce the highest month by 6.5%, less export.

Apologies, I thought it was simple and clear, but obviously not. I wasn't challenging the wording of pitch nor angle, I was pointing to my very specific wording that it's the optimum for ..... wait for it ...... here it comes ...... to best match supply and demand.

I mentioned that 50d was optimum as per the supply/demand issue.

So you do dispute PVGIS when it gives 38 degrees optimum for your location.

Here's a clue - possibly the most notable thing about being off grid is that they are not connected to the grid.

So there is no import or export to optimise - only consumption.


And if you ARE grid connected then the cost of electricity at mid day is the same winter or summer and if you have an export tariff/payment then all you have done is lose some of your efficiency in exchange for a lower income.

Or are you claiming to have a export tariff that pays more in winter than summer and you got confused as to what offgrid meant?

Nicolai_Grenovski

I find that hard to believe for several reasons.

No, I just think you find it hard to accept - that's different.

1. Surely given the ability, they would want to optimise (with a mid point) for Spring and Autumn too.
2. The cost and complexity of even a simple adjustment, would outweigh the cost of adding 1 more panel, which would make up for any summer loss, whilst leaving the whole setup in a single, simple demand/supply optimised pitch of 50d.
3. That's what those I've chatted with, who have ground mounts have done.

4. (and just for fun) If we are really going to analyse it, and have the space and choice, then I'm sure you'll agree with me that something along the lines of 45d pitch with 50% SE and 50% SW would be best to help optimise the generation curve*. Certainly worth an extra panel or two for a wider/flatter generation curve.

1./ Yes, if you have the means of adjustment then you could adjust 4 times a year but most people running at that level have a specific issue with space and are far more likely (circumstances allowing) to track the suns azimuth (horizontal) - we recently re-sold a used array of 14 (12% efficency) panels to someone who builded a tracked system that tracked the azimuth (horizontal) track of the sun that he had made out of some bits of old farm machinery.
He planned to automate it but every morning he manually set it E, then south then west to track the sun - three times a day - so once a quarter is nothing to the dedicated offgrider..
2./ Panels are considerably less expensive than they used to be - a lot of offgrid community is working to a budget (as 1.) and use home made frames.
3./ any pictures of panels at 50 degrees?
4./ Again, it is space, needs and budget dependent.

But go ahead and google solar pv groundmount tracking - there is a large community and all sort of inventiveness such as the satellite actuator I mentioned earlier.
.. and just for fun, click the 'image' search and see if you can find any systems working at more than 42 degrees, even to the north of the UK..
You may find one or two, but I doubt you'll find any working at (an intentional) 50 degrees unless they're in really special circumstances.

Nicolai_Grenovski

No need, I already chat with many folk about trackers, and one who has built his own and published the documents, free of charge.

And?
That is precisely what I described - So why all the complaining about the idea of the off-grid community setting between summer and winter if you knew about it all along as you are now saying?

However, I think you'll find that most now agree that due to the incredibly cheap cost of PV now, it's simply far cheaper to just deploy 20% more kWp, and hence why they choose 45d-50d pitch as the optimum angle to best match supply and demand.

It is still space and as I said before, it is also windage based - however, see you've dropped from 50 as UK optimum to 45-50

That's some progress - well done champ!