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Weird panel orientation of the Cestas solar farm

PostPosted: Tue Dec 15, 2015 2:07 pm
by mkitch
Hi all, I would appreciate some comments from the gurus here that know a lot more about panel orientation than I do. I was looking at the Renew Economy article on the Cestas solar farm in France, and then went hunting for further details, I found that the panels are all oriented in an east-west manner like little low pitched shed roofs. Like in the picture linked below.
http://en.clemessy.com/uploads/RTEmagic ... _1.jpg.jpg
What would be the benefit of doing this? I know that this would flatten the daily production as per Gordon's past postings, but why have then at such a shallow angle? Surely this would result in less generation. Or are the panels so cheap now that close to 100% ground cover outweighs the lower performance of this orientation?
Matt

Re: Weird panel orientation of the Cestas solar farm

PostPosted: Tue Dec 15, 2015 9:46 pm
by Tracker
East and west..

That means that you get power from dawn to.dusk..

Point them just north and your peak is at noon, and sfa in the AM and worse in the PM, which is just when you need the greatest power

Point them just north and you will likely have. Far more power than you can actually use (at that time).. = wasted

Were I starting again, I would likely install 1/3 Ease and 2/3 west..

And.. I just looked at the image.. and I think that in this case, it is just logical. They are almost using the panels.as a.roof surface.. as such, flat would be best..
But flat is seriously bad because it hold all dirt.. so inclining allows some flushing during.rain, and.the, east/west will give a small.am/pm benefit
..
.

Re: Weird panel orientation of the Cestas solar farm

PostPosted: Tue Dec 22, 2015 7:50 pm
by mkitch
OK, so I was on the right track. The panels are at a price point that allows the economics of jamming in as many as possible, with the benefit of AM/PM boosted and overall flattened production, ie the ability to load match. At the expense of maximal production in the middle of the day by spacing them out and orienting the panels to get a normal incidence angle at the time of year needed for maximum annual K(M)Whr production. It apparently makes better economic sense to install the panels tin this orientation now. I wonder what orientation we will see in the next bunch of large solar installations? Perhaps sites with a relatively steep sun-facing slope, and than east-west orientation? For Australia, hot, dry north facing hillsides now well shaded by east west pleated panels looking like a segment of 1950's lamp shade?

I looked at the Desert Knowledge data for the East/North/West/Horizontal installation. The mounting angle is nowhere near as shallow as the Cestas Farm mounting angle, but there is an obvious advantage if you cram the panels in together like the Cestas Farm as the AM and PM production peaks are higher than the midday peak, temperature effect?

I wonder what the engineering challenges would be in Australia to implement this arrangement? I suspect good solar sites in Australia may be dustier than Southern France, and with less rainfall, and with the probability of higher wind speed. This suggests a steeper panel angle, as well as more frequent washing. I can also foresee a panel design that has no lower end lip, because I know that I have to clean a heap of mud off the bottom 10 cm of my panels every 6 months, due to the pooling created by the frame damming water (with dust) every time it rains, and then this splashes up the panel and dries (at a normal tile roof pitch in Melbourne).

It will be interesting to see whether the Cestas design is implemented in other new farms.

Matt

Re: Weird panel orientation of the Cestas solar farm

PostPosted: Wed Dec 23, 2015 2:27 am
by Privatteer
The cost of land would also come into it. Here we can afford to have nice spaced out rows if we built them in low cost country areas. I would assume the per meter cost of land there would be quite high.

I initially though they had used the roof of some sort of intensive farming sheds setup but looking at some other pics they are only about a meter off the ground.

Re: Weird panel orientation of the Cestas solar farm

PostPosted: Wed Dec 23, 2015 11:54 am
by tom rickard
That picture is pretty cool! I'm thinking my next lot of panels may well be laid out on ground poles instead of on my roof. That way I can collect the rainfall from my array as well as my roof. I do think I would put them on a steeper angle though, I have the same problem with a layer of dust accumulating on the lower frame (at 14degrees).

Re: Weird panel orientation of the Cestas solar farm

PostPosted: Wed Dec 23, 2015 9:34 pm
by Tracker
I removed a garden shed, and replaced it with a solar.shed.. a solar man-cave, where the solar panels ARE the actual.roof..
..
.