I recently read a short piece that caught me up short, and I quote:
“The fast dropping cost of solar, while a huge boon to the adoption of solar
PV, has counter-intuitively altered design parameters. No longer is the
north-facing roof considered unusable because limited application in less-tha
WrenchesI see this working south of the tropic of cancer but at 1000 watts per
meter squared tilted north might work for a month a year but I don't think the
tax credits were proposed for poor performance module installations. I see
enphase annual readings prove the point. Jerry
Sent fr
Within the last year a fairly large (~100-130kW?) system was installed on a
4-sided building in Alberta that had PV installed on all four vertical
walls. Each side's PV system operating independently, of course.
We were not involved in this project and i'm not totally up to speed on the
why's, how
I think the point of view Peter shared has more to do with lower sloped
North facing or other non-ideal orientations. The proof is in the pudding –
just simulate the production and utility bill offset and see if the
proposed orientation makes sense financially. We haven’t done any North
facing arra
We get this question all the time, mostly due to aesthetic concerns. The
location is obviously a huge factor in this decision, but the mounting
pitch is also very important. I did a PVWATTS-based study recently based on
our local area, and the results are here:
http://floridasolardesigngroup.com/s
I did a slide on the effect of North facing modules. For even a fairly
aggressive rotation North as shown, the effect is "only" a 50% reduction.
The questions of whether or not to do it, are,
- is the mounting structure simpler, lower cost
- security against wind
- can I put a larger array on t
Maybe I'm a bit slow, but I don't understand this slide at all. This might
make sense for expected momentary power output at a particular static sun
position (perpendicular to the south panel face) under test conditions, but
it doesn't relate to real world energy output with weather and sun positio
Jarmo,
The sun’s geometry is not nearly that simple. To understand the impact of
north-facing arrays, you have to perform a simulation. PV:WATTS does this just
fine and it is easy to show that a 18-degreed North-facing tilt produces 75% of
a perfect 30-degree south-facing array. Far more than
In Yuma, AZ, north facing modules will have direct sunlight for small part of
the year. In the picture, look at the yellow area above the East-West line.
Thats direct sunlight from the north. The green top line in the picture shows
summer solstice showing sunlight from sunrise to about 0930 and
The analysis of 50% of south facing production is too simplistic; running
some modeling shows that, depending on the latitude, the difference can be
much smaller, approaching 25% less for the north facing. I think this
layout could become more common especially on low slope commercial roofs,
where
Hi:
Granted that the description is very simple, but that is the intent.
The essence of it is that the "loss" for small variations in angle of
incidence is approximately bounded by, (less than), the sin of the angle
between the orientations of two panels/arrays in question.
10 degrees ---> m
In the Caribbean, low tilt roofs that face North can work very well, we (16
degrees) are below the Tropic of Cancer (23 degrees) and the sun is in the
North for much of the year.
On Tue, Jul 28, 2015 at 12:24 PM, wrote:
> Jarmo,
>
>
>
> The sun’s geometry is not nearly that simple. To understand
I did a quick simulation using PV Watts for a small system in Western Mass.
Here’s what I found:
Azimuth Roof Pitch kWH/year % of optimum
180 40 2593
100%
0 40
Jarmo,
Unfortunately, simple is wrong in this case—and detrimental to the PV industry
that needs all the roof real estate it can find.
Bill.
Bill Brooks, PE
Principal
Brooks Engineering
From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf
Of jarmo.venalai.
Larry and Peter,
You are too old-school to think outside the box. It’s not about direct
sunlight—it’s all about kWh/m^2/day and those numbers don’t lie. Your analysis
is not correct and this is why simple analyses will always give you a wrong
answer.
North-facing arrays have been financial
The intent of the simple example was to show that production is not
severely affected by unusual orientations.
I will clarify my message.
JARMO
_
Jarmo Venalainen | Schneider Electric | Xantrex Brand
Bill and Wrenches,
I have been battling this issue for a while. Our sales folks are up against
fierce competition and want to design a system that has the best return on
investment. So, they will choose a reverse tilt system over a North facing
array unless there is a strong deterrent to going
This assumes 180º is optimum, which it may be for you, but 170º is actually
closer to modeled optimum in my area. Bill Brooks nailed it by clarifying
that it's all about the kWh/m^2/day, or more accurately kWh/m^2/year for
netmetered customers without TOU metering. My research at the link below
cov
I am paying close attention to this thread, but for different
reasons. I have designed and will install next month an off grid
system for a high-elevation research hut. At 14,242' I believe this
will be the highest elevation
off grid system in the continental US (Alaska t
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