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Is E/W orientation of panels OK?

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Posted by Neil on November 6, 2007, 10:58 pm

I'm looking at specifying a solar heating package for my house which is
around 52 Deg N close to London, UK

The roof pitches are 90/270 Deg with gable ends.

Companies who have provided quotes so far tell me that the E/W
orientation is fine with one panel on each pitch.

I'm not convinced this would be viable because, from now 'till about
March, the sun rises and sets so far south of E/W that the pitches are
virtually shaded for a good part of the day,

I have an option to hang the panels on the South facing gable end but
they would need to be vertical - Is this a major problem?

So, which would be my best option?




Posted by Mark Schofield on November 7, 2007, 1:03 pm
if you hung them vertically on the south wall, you might pick up allot more
during the winter months, when the sun is lower and the arc of it's travel
is less.  hopefully some engineering or design pros will pipe in. do some
serious research/calculations before they go up.

Posted by gary on November 7, 2007, 3:14 pm
You can download Radiation On Collector (free), and do the calc for
both orientations -- its very easy to use.
When you look at the tabular output table for the year, you are
interested in the last column labeled "total".
Just compare an ideal south facing collector titled at around your
latitude to the gable one and the east/west one.
email me if you have any trouble with it.

I did one of these recently, and at a somewhat lower latitude than
yours, the winter collector for the east or west facing collectors was
down about 60% from an ideal south facing collector.  East or West doe
does work pretty well through the summer.

I think you might be better off with the gable hung south facing -- if
you could get a little tilt in that would help.  Like the first one in
this section:

Could you put the collectors on the ground?


Posted by Neil on November 7, 2007, 8:57 pm

gary@builditsolar.com wrote:


Thanks Gary, that's exactly what I needed :-)

The initial calculations show that, as expected, the South facing
collectors would be 33% more effective over the year (478 kBTU V 357 kBTU).

However, between April and August, the E/W facing collectors become more

As this coincides with the period we turn the heating off, it would seem
more effective to site the collectors on the roof pitches and accept
that during the winter months, when the boiler is on for heating anyway,
the additional DHWS load may add to its efficiency!!

I'd be interested in your analysis of my logic . . . . . !

What a fantastic resource Builditsolar is!! I've got lots of reading to
do now. . .

Many thanks



Posted by daestrom on November 11, 2007, 9:31 pm


Guess I don't understand this.  You say during April to August you don't
need heating, yet you want to put the panels such as to maximize their
output for those months?  If you don't need the boiler those months, why
would you care about solar collector output those months?

While south facing may be more effective over the year by 33%, how much more
effective is south-facing for those months when you actually need heat?
Seems like *that* is the real question, to maximize collector output those
months when you need heating.


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