Renewables: "talking 'bout my generation"

Martyn1981

Oscargrouch wrote: »

whoops, cannot compete with the statistics of the other
Anoraks’ here but here goes:-
5.6 today
Total for May 324
Average for this Month 10.61 :rotfl:

No probs Oscar, we offer a free trial on our anoraking services. If at the end of the trial you wish to continue, there's still no fee, but you do have to listen patiently to all the train numbers we've written down that day!

Well you beat me:

324kWh / 2.5kWp = 129.6kWh/kWp

Mart.

jackieblack

Here's how we ended up....
Total Gen for May 12 = 272kWh, 110% of predicted/target
This slightly reduces our overall % of gen since installation to 123%

Oscargrouch

Martyn1981 wrote: »

Well you beat me:

324kWh / 2.5kWp = 129.6kWh/kWp

Mart.

Having a 'thick' moment; what is the relevance of the above Mart?

sly_dog_jonah

Oscargrouch wrote: »

Having a 'thick' moment; what is the relevance of the above Mart?

It gives a better way of comparing your array's performance compared to other's by adjusting the generation to account for the size of the array. By dividing generation in kWh by panel size in kWp(eak) this means you can compare a 1kWp system to a 3.9kWp system to see how the two systems fared in a given period. For example a 4kWp East facing system might perform less well per kWp than a South facing 2kWp system.

sly_dog_jonah

Martyn1981 wrote: »

System: 3.58kWp

Slope 27°, 110° (South -70°), Lat: 50.5

Total generation: 443kWh

Target PVGIS Climate: 395kWh

Daily average: 14.29kWh

Generation per kWp: 123.74kWh

Daily average per kWp: 3.99kWh

Mart.

Edit: SDJ - You beat me by 0.4 Grumble, grumble, grumble!

But to illustrate the point in my previous post, you beat us on kWh/kWp by 3. Probably chiefly attributable to your orientation I imagine.

EricMears

Oscargrouch wrote: »

Having a 'thick' moment; what is the relevance of the above Mart?

I suppose it can be thought of as one way of comparing two different installations. However, it lumps together panel performance & inverter performance and also doesn't allow for different aspects or shading effects. Anyone tempted to go for brand X panels because MSE member X's 'performance' is better than anyone else's could make a dreadful mistake when their local conditions are completely different.

sly_dog_jonah

jimjames wrote: »

You can see the difference from the peak and panel potential in this graph.

http://uk-solarpanels.blogspot.co.uk/2012/05/solar-panels-low-peak-output.html

Is that your own blog jimjames?

Martyn1981

sly_dog_jonah wrote: »

But to illustrate the point in my previous post, you beat us on kWh/kWp by 3. Probably chiefly attributable to your orientation I imagine.

Actually my orientation is badly written, I'll amend it next time (changing it now will only confuse these posts).

It's ESE, or 110deg from North, or -70 azimuth, so little worse than yours.

I assume I snuck the kWp win, due to roof pitches, with 2/3 on 30 deg and 1/3 on 20 deg. I've definitely noticed that my generation is improving when compared to others now, though the ESE bit will always pull it down a tad (10% ish).

Mart.

PS Addendum to what Eric pointed out about comparisons. As above, roof pitch will also need to be taken into account (Edit: Oops, sorry Eric, I read 'aspects' as 'angles', should have known better than to doubt you!), so drawing any strong conclusions on performance would be unwise - too many variables. Just chill in the sun instead. M.

KevinG

jimjames wrote: »

I'd say base it on the panels. In most situations you won't be achieving the output near the panel total so the inverter won't be limiting the generation

I'd agree with that. After all, if I were to adjust my PVGIS estimates by using the maximum inverter output rather than peak panel power, it would reduce them considerably and I would have exceeded PVGIS by an even larger amount than I already have!

Fruit_and_Nut_Case

Martyn1981 wrote: »

It's ESE, or 110deg from North, or -70 azimuth, so little worse than yours.

My roof is WSW (-68 degrees) so like yours is far from the "ideal" orientation. When I was first researching solar PV I was concerned about this and assumed that it wouldn't be worthwhile; even some installers were dubious.

I'm glad I investigated more thoroughly and took the plunge. I think the "south-facing" roof requirement is over-emphasized sometimes.