Fostertom, here is a page with links to PV software, some that will calculate the shadows from a pananoramic photo of your site, might be helpful to you.


http://www.pvresources.com/en/software.php

Panorama master - with "Panorama master" you can make exact matched set of photos - base for panorama picture (see also "Horizon" below).

Horizon - software simulates sun path diagrams for arbitrary latitude.



Shadows - Shadows is a program used to design sundials and astrolabes and it is very useful also in solar energy engineering. Key points of Shadows:

Free of charge in its entry level
Calculates and prints the drawings at real scale
Simulates, displays and animates the shadow of the style
Exports drawings as BMP, JPG, EMF and DXF (AutoCAD)
Offers complete ephemeris of the Sun and draws the Solar Diagram
Supports plane sundials with polar style of any orientation and reclination, analemmatic sundials, cylindrical and bifilar sundials.

Languages: fr gb de it es pl


GOSOL - Das solar + energetische Simulationsprogramm für städtebauliche Planungen.

Comprehensive tool intended for detailed site analysis, included building shape and vegetation shading analysis. Suitable for urban planning and detailed architecture studies (german language only).

Tom

Are you talking Solar Thermal here, I think you are.
Leaves, trees or other obstructions can be calculated a number of ways. The reduction in solar input, a reduction in the time at a given input or a combination of both. As most software/models use historic data for the inputs it is almost certain that a mean average is used for the input. Or another way a simple percentage reduction.

To predict what is really happening is virtually impossible because of the stochastic nature of the weather, but finding out the monthly means is pretty accurate.

To give an example the 5 charts below are all based on identical data. Just different methodologies.

More

Last

Posted By: SteamyTeaLeaves, trees or other obstructions can be calculated a number of ways. The reduction in solar input, a reduction in the time at a given input or a combination of both

That's right, and with a wide-area 3D model, comprising both the 'target' building, the distant horizon (350m distant x 85m high above GrdFl of the building) and closer obstructions (e.g. trees at 50m distance), Tas can run the sunpaths day after day as the season progresses, to see just what duration, elevation and bearing of direct sun radiation the building 'sees', when the sunpath rises above the obstructions.

Within that, the upper band of the distant (forest) horizon and the whole of the nearby trees are partly transparent while leafless, during most of the time of greatest interest, the heating season. When you say

Posted By: SteamyTeaAs most software/models use historic data for the inputs it is almost certain that a mean average is used for the input. Or another way a simple percentage reduction

you're not referring to historic leaf-fall/leaf growth data/dates? I don't think Tas does that, tho why not?

Your following graphs are interesting, but I'm missing how they apply to %age transparency of bare-branch trees?

Thanks Chris.

The answers look encouraging - same over on AECB -

Posted By: fostertomsimple %age of bare-branch sky area obstructed by branches and twigs

it is then, or even a bit better if they're shiny silver birches!

Amy other comments?

Posted By: jonCompared to the variability of the cloud cover it's almost an irrelevant consideration

But no - it's a major bonus, if what I took to be the skyline (distant forest treetops-in-leaf) is in fact about 3.5o lower in elevation (the hard ground brow, seen thro bare-branch trees).

Then the sunpath 'sees' the target building considerably earlier in the day, as it rises, albeit partly obstructed by branches and twigs, and albeit weaker in intensity because at lower elevation (longer airpath thro the atmosphere). Especially in the depth of winter, when direct-sun duration is effectively tripled.