East-West or East-South or what!

[andrewindevon]

We're looking at a total revamp and have a large area of 45 degree, unshaded, east facing roof along with enough west facing roof for about an array.  So an E/W array should be simple...but on the West side there is a large south facing dormer roof, large enough to put a 30 tube panel (at least).  Obviously it is shaded to the east by the roof, and there is some tree cover to the south reducing low sun production and trees to the west as well!

So would an East/South split system be better than an East/West? Or indeed do I need to worry about the east bit at all and just bung on a south panel accepting the lower production?  Hopefully the small picture attached should show what I mean!  Vertical mount on the south wall isn't an option for various reasons.

Cheers

[brackwell]

Andrew,

I think i am understanding your words but the poor quality of the photo is not helping me.

E/W systems can work fine producing say 80% of a S facing but depending on roof angles.

The biggest factor to consider by far when it comes to PV is that a little bit of shading has a HUGE effect on output. This will probably dictate the solution.

This may help http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php

Ken

[shajazzi]

Hi, The image is obliviously a google image and was taken in the morning and shows plenty of sun on your dormer, I would be interested in the trees on the left of the image and how much shading they cast on to the west side throughout the afternoon.

It looks like they could be  evergreen.



shajazzi

[andrewindevon]

Well yes it is a google image, not having access to my own fleet of satellites. That's a morning summer picture, the trees to the west aren't evergreen but there is a big oak not to far away, the south facing dormer is getting sun by 10am now. 

Brackwell, looking at a thermal system , already have PV on a south facing outbuilding (not on the picture)

[Summerdays]

You could look on Bing maps to see if it covers your house and if so if the photo was taken at a different time of day to look at potential shading issues?

[andrewindevon]

I'd forgotten about Bing... brand new photo on there...looks to be just before mid-day in summer.  I'm beginning to lean towards east/south... East to capture the morning sun to replenish from showers etc then south to sustain tank temps during the day after washing and so on...

[JohnS]

Shading is much less of an issue for Solar Thermal compared to Solar PV.

[mikey9]

Just an aside - it is always wotth looking at Bing vs Google as the imagery they use is captured by Getmapping (who have National Cover Contracts - across the UK).

It appears that both Bing and Google negotiate contracts to include more current data in their offerrings - however the age of the photos varies dependent on when they do their updates/capture dates. There is of course much more value in <2 year old imagery than >5 year.

We currently have 2008 imagery (pre PV showing on both Bing and Google) - this is the most current for the area (I licence the same data directly for use at work) as Scotland gets a 5 yearly refly.....