Andy Champ wrote:
On 27/11/2011 01:38, Bill Wright wrote:
We are committed to pay a feed-in tariff of 45p/kWh for 25 years on
this. But these particular photovoltaic panels shouldn't cost us too
much, since they face slightly north of east!

That's very odd, since it would suggest that they'd work better on the
other side of the roof. I'm also not quite sure about the NE, looking
at the sat dishes. Where is this?

Andy
It's South Yorkshire. I agree the dishes look as if the building isn't
aligned north-south. But Multimap says it is. I took the picture at
11.55am, and the front of the building is in shadow, which agrees with
multimap (I'm making the assumption that the sun will be due south at 12.)
The dish angle is 30deg east of south of course. And I have to say that
looking at aerial and dish directions can be very misleading.
If you want to look on maps yourself the road is Hepworth Drive,
Swallownest. To get your bearings the big white building is the health
centre, which is brand new. Might not be on some maps actually.

Bill

Bill Taylor wrote:

Not all people interested in renewables are cowboys; there's a lot of
reliable, well researched information out there.
I've been reading the ******** put out about our new local windfarm, and
frankly it's a ludicrous travesty. They really must think the public is
entirely composed of imbeciles.

Bill

On 27/11/2011 22:14, Bill Taylor wrote:
On Sun, 27 Nov 2011 19:23:59 +0000, Bill
wrote:

Steve Thackery wrote:
Bill Wright wrote:

I actually find that very hard to believe, especially since the whole
renewables industry pumps out lies and half truths all the time.

I think it's the sort of thing we could work out. At least in theory,
which should get us in the right ball park.

The physics behind the light incident on a panel must be relatively
straightforward, I would think.

Apart from the reduced effective surface area when the light is arriving
at an angle, does anyone know if the photovoltaic material is in any way
directionally sensitive? For instance, does the light have to travel
down tiny tunnels, or through little lenses?

Incidentally, I don't understand why tilting the panel backwards helps
when it is facing east or west (rather than south). Surely the sun will
be, on average, lower in the sky when an east-facing panel can "see" it,
which suggests an east or west facing panel should be a bit more
upright, not a bit more laid back.

Possibly the idea is that the closer the panel is to horizontal the less
'directional' it is. In other words it will get more incident light from
the directions it isn't 'pointing at'.

When the panels have to be on a roof that faces other than south, why
not lift the north sides of each panel a bit? That would effectively
align them more to the south.

Does anyone know how long these panels are expected to last, by the way?
Since the thing seems to be now largely in the hands of the 'get rich
quick' sort of trader I wouldn't be surprised if there are lots of
problems regarding moisture ingress (of panel and roof) and all sorts of
other snags, in the years to come. There's going to be some right old
barneys.

Bill


Reputable modules will be "guaranteed" to still produce at least 80%
of their original output after 25 years. As crystalline panels have
been in reasonably large scale production for 40 years or more, there
doesn't seem to be any particular reason to expect large numbers of
failures.

Roof problems would be down to the installers and they'ld probably be
long gone by the time it becomes apparent.

Someone gave me half a dozen or so PV cells in about 1970.
Each one came in it's own little envelope with the test data of the cell
hand written on it.

The guy told me they were destined for spacecraft use and were not
available to buy, and were effectively priceless.

Soldering wires to them was very difficult, the glass was very thin.
Each time I cracked one I pondered on how much poorer I had become!



--

Graham.

%Profound_observation%

Graham. wrote:

Soldering wires to them was very difficult, the glass was very thin.
Each time I cracked one I pondered on how much poorer I had become!

I bought some. They were 3x1 feet. The problem was soldering wires onto
them. I had to chip away at the glass to reveal a lead. They did work. I
think I got 12W max out of each.

Bill

Bill Wright wrote:

the dishes look as if the building isn't
aligned north-south. But Multimap says it is
If you want to look on maps yourself the road is Hepworth Drive,
Swallownest.

Google maps agrees with multimap, it's only slightly on the **** from
N-S. From streetiew, a quick count of bricks in the gable end shows the
roof is a pretty normal 35 degrees.

"Victor Delta" wrote in message ...

"Doctor D" wrote in message
o.uk...


"Bill Wright" wrote in message ...

We are committed to pay a feed-in tariff of 45p/kWh for 25 years on
this. But these particular photovoltaic panels shouldn't cost us too
much, since they face slightly north of east!

The roof pitch is quite shallow so they will never even properly face
the low sun as it rises.

The main pic was taken at 11.55am.

The inset is from Multimap, and I assume straight up is north.

http://dl.dropbox.com/u/11023364/ele...0money%203.jpg

Bill

Assuming the sat dishes are facing SE, are the PVs not facing south? Or am
I missing something fundamental?

Surely if the dishes in the photo are pointing SE, the PVs must be facing
east - which is what the noon shadows also indicate...???

V

Could be!

D.

On Sun, 27 Nov 2011 09:16:49 +0000, Bill Taylor
wrote:

There's a useful estimator, which is pretty accurate at
http://re.jrc.ec.europa.eu/pvgis/.

Using Doncaster as a location

There are some that would dispute that figure, Doncaster being in an
area of above average sunshine (for the North) and below average
rainfall. It'd be interesting to see if Sheffield or Barnsley gave
similar figures as they are both cloudier and wetter.

Doncaster was also the hottest place in the country the other month
(September or October I can't recall which) but as its weather
station, despite being perfectly good for aviation purposes, is no
longer recognised by the Met Office the record went to somewhere down
south.

--

The Other Mike wrote:

Using Doncaster as a location

There are some that would dispute that figure

Giving the actual location Bill coughed up, and the roof angle of 35
degrees (as counted by the bricks) and using the CLIMATE-SAF data, it
came out at 636kWh/year/kW.

So for a typical 4kW domestic install, it will average electricity worth
70p/day at retail prices, but cost "us" £1140/year on our bills.

I wonder if the local kids might be handy with a catapult?

Bill Taylor wrote:

On Sun, 27 Nov 2011 14:56:53 +0000, Bill Wright
wrote:

Bill Taylor wrote:

There's a useful estimator, which is pretty accurate at
http://re.jrc.ec.europa.eu/pvgis/.

Using Doncaster as a location and the default roof slope of 35
degrees, a south facing roof should yield 909kWhr per year (per kW
peak of installed capacity). Facing 10 degrees N of E yields 678 kWhr
per year, but dropping the slope to 20 degrees increases the output
slightly to 718 kWhr per year.

The output is lower than a south facing roof, but not as low as you'ld
think.

I actually find that very hard to believe, especially since the whole
renewables industry pumps out lies and half truths all the time.

The amount of enrgy falling on a surface is fairly straightforward to
calculate and module efficiency and other losses can be estimated
well, so you could work it out yourself if you doubt the industry.

Not all people interested in renewables are cowboys; there's a lot of
reliable, well researched information out there.

I'm more in favour of renewable energy than Bill, and think that there's
as much or more unscientific rubbish coming from the sceptic side than the
advocate side, but I have to say that it doesn't sound right to me either.
And anyway, for photocells, shallower angles of incident light give worse
results than you'd expect from the light-per-unit-area calculation due to
greater reflection and other direction-specific construction-issues.

Andy Burns wrote:
Bill Wright wrote:

the dishes look as if the building isn't
aligned north-south. But Multimap says it is
If you want to look on maps yourself the road is Hepworth Drive,
Swallownest.

Google maps agrees with multimap, it's only slightly on the **** from
N-S. From streetiew, a quick count of bricks in the gable end shows the
roof is a pretty normal 35 degrees.
Ah! Look at the pictures I posted of the wallbox. The bricks are the
1970s hollow ones that are larger than normal. Although their aspect
ratio might be the same, I dunno.

I'd certainly believe 35deg.

Bill