Renewables: "talking 'bout my generation"

Martyn1981

EricMears wrote: »

But when you ignore major differences in the two systems the 'comparison' becomes completely meaningless. Where's the 'fun' in that ?

Again*. The 'major' differences aren't being ignored, they are included in the totals. So the comparison remains valid. 6ft is taller than 5ft, is it not?

You keep confusing 'comparison' with 'explanation'. We are not trying to explain the differences, just compare them. I believe it was put to you, very succinctly some time back - if we adjusted our generation figures to take account of (explain) all and every factor that makes them different, then we will all just report a big fat 1 each and every day. No fun in that, is there.

*Remember when you used to say that O's didn't take account of the weather!!!! Since O's are just generation divided by system size, and generation can't ignore any factors that influence it (it is the sum of all parts), then neither can Os.

Mart.

zeupater

Martyn1981 wrote: »

Not missing anything.

If we're comparing fuel economy, is 75mpg bigger/better than 10mpg? Yes it is.

So the smartcar (during that comparison period) operated more efficiently than the Bentley.

You can make this as complicated as you want, (and come up with a thousand reasons for the difference between any 2 Os) but it doesn't prevent comparisons.

I suspect you are so 'stuck' trying to explain the reason for the differences, that you've missed the point entirely, we just want to compare the results ......... and have a bit of fun doing so ......... please?

Mart.

Hi Mart/Eric /All

The issue being missed in these examples is pretty major.

Simply saying that one vehicle is more efficient than another based purely on mpg is similar to comparing the generation of a 2kWp system with a 50kWp system ... it needs to have a baseline calculation to work a more realistic comparison on.

The above figures (2 vs 50) were not selected at random. Let's say that Eric's Smartcar averaged 75mpg and Mart's Bentley averaged 20mpg ... does this mean that a simple 75/20 represents a true reflection of the relative economies ? .... in that case, how would you ever be able to compare a Smartcar with a bus averaging 5mpg or an airliner achieving 0.2mpg ?

In order to perform any form of comparison you'd need to align the potential of each mode of transport, with the obvious solution being to bring the number of seats into play (let's say seat miles per gallon) ... so Erics's 2 seat Smartcar achieves 150smpg(75x2), Marts 5 seat Bentley 100smpg(20x5), the 50seat bus gets 250smpg(5x50) and an Airbus A380 with 850 seats (full economy seat configuration) comes in at 170smpg(0.2x850) ....

Note, we now have a comparison of relative efficiency which would work for any form of passenger transport which uses liquid fuel, so simply changing gallons to the reflect the specific energy of the fuel consumed you could compare any form of fuelled passenger transport, so something like smpkWh would work for batteries, petrol, rocket fuel, coal, gas, biofuels, nuclear or anything else ....

Any form of efficiency comparison needs to work from a standardised baseline in order to work ... the calculation kWh/kWp gives that efficiency comparison baseline for solar pv, it's just a case that someone with a less than ideally situated system must recognise and compensate for it .... which brings us around to the reason why PVGIS targets and MetOffice anomaly comparisons are also used by some ...

If you're going to compare, as the above mpg example demonstrates, you must somehow take relative sizes into account ...

HTH
Z

tunnel

Wow, so many posts over the O.
Well after a wet start I still managed just over 3 O's = me happy

Dodo0808

tunnel wrote: »

Wow, so many posts over the O.
Well after a wet start I still managed just over 3 O's = me happy

Ditto.....12.5 kWh. Much better than expected, thought today was gonna be a washout.

Oscargrouch

zeupater wrote: »

Hi Mart/Eric /All

The issue being missed in these examples is pretty major.

If you're going to compare, as the above mpg example demonstrates, you must somehow take relative sizes into account ...

HTH
Z

Hi Z, Could you explain that again in Ltrs please.....:rotfl:

tunnel wrote: »

Wow, so many posts over the O.
Well after a wet start I still managed just over 3 O's = me happy

A Hawaii +0.12 O's here and today; I will settle Martins bet with a 'Mere' confession from Eric that comparison of kWh or O's does not take all parameters into consideration; although, O's do actually take more than kWh..

zeupater

Oscargrouch wrote: »

Hi Z, Could you explain that again in Ltrs please.....:rotfl:

Hi

Would that be in Ltrs of Uranium235 or petrol ? ...

We're really talking about quite a difference ... Uranium would work out at somewhere around 18.9kg/l, which would have a potential of 22.6GWh/kg, so around 427GWh/litre ... against petrol around 0.74kg/l with a potential of ~9kWh/litre .... that's enough information to start to compare the relative litre/litre efficiencies/seat of something like an American nuclear aircraft carrier to a Smartcar, if anyone could be bothered :cool: ... but I'm pretty happy with sticking to kWh/kWp for our pv ....

Z

Martyn1981

zeupater wrote: »

Hi Mart/Eric /All

Any form of efficiency comparison needs to work from a standardised baseline in order to work ... the calculation kWh/kWp gives that efficiency comparison baseline for solar pv, it's just a case that someone with a less than ideally situated system must recognise and compensate for it .... which brings us around to the reason why PVGIS targets and MetOffice anomaly comparisons are also used by some ...

HTH
Z

Got fed up yesterday with the claims that O's are meaningless, and that's why I dug my feet in. Hopefully, we've finally got to the bottom of this, and the 'dispute' revolves around the crossover point between comparison and analysis.

Some time back (10th April) we got some interesting data,

generation in kWh for 2013:

Mart 4,413 (expressed in Os on thread)
jackieblack 2,288
jimjames 3,137
Mysterons 4,421 (Dec to Nov)

Relatively meaningless, but in Os, we get:

Mart 791
jackieblack 1,031
jimjames 1,046
Mysterons 1,105 (Dec to Nov)

Now, in my little world, that is where the comparison ends (and we can compare performance over the given timescale) and analysis (for the differences) begins.

Don't get me wrong, if I said I wasn't interested in the analysis, you guys would (quite rightly) rip me to pieces within seconds, as I'm always pondering such stuff. But there is a difference between a baseline comparison and an analysis to determine the reasons for those differences.

So Os aren't meaningless, they allow a comparison between any 2 (or more) systems, of any size, anywhere in the world over a given time period*. Though the analysis/explanation for the resulting difference(s) may be long, complicated and dare I say interesting.

*Time period, generally in multiples of 24hr, to account for the differing sunrise/sunset times around the world. A 12hr comparison with, say Australia, could result in some 'unusual' results.;)

Mart.

Martyn1981

theboylard wrote: »

I have thought about the chimney - no we don't use it! Need to find out what the costs are likely to be?

Hiya TBL. I had a chat with a builder friend, who thought my £250 suggestion might not be too far off, if the job could be done by ladder, and clean up/material removal was handled by the customer. But suggested a more reasonable price/quote would probably be £500, taking 1 day (2 workers) including site cleanup and removal of materials.

But, but, but, would depend on access, and the use of ladders. Tower/scaffolding hire would bump the cost up.

I mentioned the PV, and risk of damage, but as he pointed out, it would always be done carefully anyway, as dropping bricks onto a roof, and them possibly rolling down and dropping onto other roofs etc is very serious, regardless of PV.

Mart.

legoman62

Keep taking your O's I say:D

3.37 of 'em yesterday:T

The_Green_Hornet

I don't know too much about Os but reading through this thread recently is giving me a distinct case of the ZZZZZZZZZZZZZZZZZs.

Wake me up when something interesting is being discussed.