Define Collector System

Define Collector System

If this topic seems to be a little bit difficult for the first reading, read it through to understand only what it is about. Then, after you become familiar with "solar" windows, return to it and reread it together with all other linked topics.

Use array-objects to define your system

Once you created the architectural environment of your solar project, it is time to define your collector system.

The "solar" windows of Shadow Analyzer interpret objects of the following object types as solar collectors:

"Arr RectInc" -- an array of the static solar collectors.
"Arr RectST" -- an array of the 2-axes sun-tracking solar collectors.

This mechanism provides a user with a flexible way to construct a collector system of different configurations composing a few array-objects of these types. These array-objects are rectangular like a matrix (static or sun-tracking collectors are organized in rows and columns, and occupy a rectangular area). To cover a non-rectangular area, you can combine a few rectangular arrays with different numbers of rows and columns.

In all aspects, objects of these types behave as usual objects. You can create and delete them, set their parameters, coordinates, parents, and children, as well as decorate them as any other objects. Only the "solar" windows of Shadow Analyzer react on them specifically.

The following screen shot shows two scenes with the "Arr RectInc" and "Arr RectST" objects. The Scene 1 shows both array-objects with the default parameter settings. Editing parameters, you can change the number of panels, distances between panels, the inclination angle of static panels, etc. Then, you can put the collector arrays into your architecture environment (left them on the ground, or install them on any platform, or attach them to roofs and walls of your buildings). The scene "s873_2Systems_Stat_and_STrack2.sa1" illustrates how it can be done. Find other examples in the folder "Examples". The scene files with solar collectors have the prefix "s" in their file names.

How Shadow Analyzer assembles a collector system

The "Solar Day" and "Solar Year" windows of Shadow Analyzer work with solar collectors of the active scene. The corresponding text line of these windows shows which particular objects are included in the collector system.

These "solar" windows use the same procedure to interpret objects of "Arr RectInc" or "Arr RectST" types as solar collectors. The "solar" window recognizes these objects among other scene objects and assembles a collector system from them using some specific rules. So you need to understand these rules to use Shadow Analyzer properly.

Practically it means the following. You can populate a scene with any reasonable number of "Arr RectInc" and/or "Arr RectST" objects. Shadow Analyzer will consider all of them as potential members of the collector system. However, it can exclude some objects from the system, considering them further as usual objects that can cast shadows, but do not work as collectors.

Assembling the collector system, Shadow Analyzer uses the following order of the evaluation of scene objects.

All objects of an active scene are being considered in the sequence, in which they appear in the SCENE list. If an array of one type "Arr RectInc" or "Arr RectST" is found, then all arrays of this type with the same dX-, dY-dimensions of the collector shields as the first one and with the same 3D orientation of the collector shields as the first one are considered an entire solar collector system. Other collectors are ignored, and further are considered as usual objects.

In other words, Shadow Analyzer assembles the collector system of geometrically similar solar panels of the same orientation. This rule covers most of the practical cases, and substantially accelerates the shadow calculations.

The following two screen shots illustrate this rule. Each screen shot shows the 3D View window and the "Solar Year" window of the same scene "s823_Static_PV_Shadowers.sa1". The scene contains two static array objects of "Arr RectInc" type (objects 4 and 5). The object 4 has 4 * 4 = 16 shields, and is selected in the first 3D view. The object 5 has 2 * 3 = 6 shields, and is selected in the second 3D view. Collector panels (shields) of both the objects have the same dimensions dX = dY = 1, and the same zero inclination angle iA = 0 relatively the roof plane, which the arrays are attached to.

Scanning the objects' list of the scene, Shadow Analyzer finds the object 4, recognizes it as an array of static collectors, defines the system type as "static", and then scans the rest of the list searching for static arrays. The object 5 is just the static array with the panels of the same dimensions and orientations as ones of the object 4. Therefore, the assembled system includes both the objects 4 and 5 (see the first text line inside each "Solar Year" window).

"Active" and "Inactive" collector arrays

In addition, Shadow Analyzer verifies whether or not the front faces of the collector array object are hidden. Collectors with hidden front faces are ignored as "inactive" collectors.

Use the toolbar COLOR and its button "h" to hide or unhide the front faces of the collector objects:

To make a collector array active, unhide its "surface" and its face group "zone 1".
To make a collector array inactive, hide its "surface" or its face group "zone 1".

Through this method you can change the order of evaluation of scene objects, and consequently can manage the contents of the collector system assembled by Shadow Analyzer.

Compare the following two screen shots that show the difference in how the "Solar Day" window works with two scenes "s873 ..." and "s874 ...". Both the scenes have the same contents and structures. In both scenes, the object 27 is the array of static collectors, and the object 28 is the array of sun-tracking collectors. The difference between scenes is that faces of the object 27 of the second scene are hidden.

Scanning the objects' list of the first scene, Shadow Analyzer finds the object 27, recognizes it as an "active" array of static collectors, defines the system type as "static", and then scans the rest of the list searching for static arrays only. Therefore, the assembled system includes only one object 27 (see the first text line inside the "Solar Day" window).

Scanning the objects' list of the second scene, Shadow Analyzer ignores the object 27 as an "inactive" array. Then it finds the object 28, recognizes it as an "active" array of sun-tracking collectors, defines the system type as "sun-tracking", and then scans the rest of the list searching for sun-tracking arrays only. Therefore, the assembled system includes only one object 28 (see the first text line inside the "Solar Day" window).

Note that although the faces of the static array are hidden in the second scene, we see their shadows on the roof as a set of dark red rectangles. To understand it, read further.

Notes about filters

Note that a collector array with the hidden front faces is still a shadower if its "surface" and all face groups (all zones) are marked as shadowers with the button "sr" of the toolbar Color. In this way, the "inactive" collectors take part in the shading calculations of "active" collectors.

Note that by the default settings all objects are shadowers until you explicitly switch this property by yourselves. The single exclusion from this rule is the "Arr Rect1s" objects that you can use as a decoration of plane surfaces of other objects.

See the topic Set Object Colors/Filters for more details about the three-level system of filters. The filters define the object properties and the way how objects are shown in the 3D View window. You need to understand the logic and the sense of these filters.

For your convenience (not to learn all from the very beginning), we remind you the following key rules:

Note the difference between the "property" filters (the first and second levels) that you set with the toolbar Color, and the "show" filters (the third level) that you manage with the toolbar Show. Note that the toolbar Color have several control elements that allow you to mange not only colors. The toolbar Color set the properties of objects individually for each particular object that is selected in the 3D View. In contrast, the toolbar Show concerns the entire scene, and defines which of the elements (points, edges, faces) and which of the properties (reflectivity, shadows, textures) will be shown in the 3D View window. Properties of objects exist even if they are not shown. So the property filters have the higher precedence than the show filters.

Rigorously speaking, a shadow is not an object property, it is an effect that is provided by the object. An opaque object has a property to cast shadows (to be a shadower). And a shadow casted by an object appears on the surfaces of other objects. You set the "shadower" property with the button "sr" of the toolbar Color. Then you decide whether you want to see shadows using the button "sh" of the toolbar Show.

Although in the reality the transparent objects do not cast shadows (they are transparent both for us and for the sunlight), we artificially separate the property "to be visible" from the property "to be a shadower" (to cast shadows). With this artificial technique, we can make an object transparent for us but not for the sunlight. In this way, we can see through a shadower object the shadows that it casts on the surfaces of other objects. This technique is useful for the visual analysis of shadows.

Shadow Analyzer also uses this double interpretation, when it assembles the collector systems, and then when it calculates its shading. Namely, it ignores the hidden collectors, when it decides, which of the array-objects should be included into the collector system. But after the collector system is assembled, Shadow Analyzer includes all the shadower objects of the scene in the shading calculations. In this way, the collector arrays that are excluded from the assembled collector system (but still are the shadowers) take part in the shading calculations regardless of whether they are hidden or not.

All this means that the assembling of the collector system and the shading calculations are based only on the object properties that you set with the Color toolbar, and do not depend at all on the show filters that you set with the toolbar Show. Note also that colors and textures are ignored by the shading calculations too. So you can manage the visualization independently from the shadow calculations.

In addition, the energy output of the collector system, which is calculated and displayed by the "solar" windows of the Shadow Analyzer, depends only on the parameter "Efficiency", and does not depend on colors that you choose for the collector faces. So you can set even the white color for the collector faces to display the shadows on them in a more contrast manner in the 3D View window -- unlike the reality, it will not impact the calculated energy output of the collector system. We will discuss the parameter "Efficiency" later in the topics devoted to "solar" windows.

Collector models with complex geometry

You can use the described mechanism of the collector system assembling to create the rather sophisticated but practically useful collector models. Consider two example scenes "s774_One_Stat_on_STrack2.sa1" and "s775_Complex_Stat_on_STrack2.sa1".

The scene "s774 ..." contains the static collector that is attached to the middle shield of the array of sun-tracking collectors.

The static collector has only one shield (nx = ny = 1). It has zero inclination angle (iA = 0), and a very small stage height (hZ = 0.01). Therefore its plane is very near to the plane of the middle shield of the sun-tracking array, to which it is attached. Although it is a static object, it is "static" only relatively to its parent object, and is rotating together with the parent following the Sun during a day.

Constructing the scene, we created the static collector object earlier than the sun-tracking array. So the static object stands before the suntracking object in the list of the scene objects. Therefore Shadow Analyzer identifies the static object as the single active collector, and consider the suntracking object only as a "passive" shadower.

This example is very useful for the optimization of distances between the collectors in a large sun-tracking array, because it simulates the characteristics of an average inner shield of a large-scale system abstracting from the boundary effects.

The scene "s775 ..." contains multiple static arrays that are attached to the shields of the sun-tracking array.

Here, the order of objects is not important, because the faces of the sun-trucking array are hidden. So Shadow Analyzer identifies the static objects as active solar collectors. Again, static objects behave actually like the sun-tracking objects, rotating synchronously together with their sun-tracking parents.

This example is useful for those engineers and designers who are developing the advanced sun-trucking solar collector systems with the refined shield geometry, which can decrease the shading effects.

The accuracy of the "similarity"

Working with the 3D model of your system, you can unintentionally destroy the identity of the orientation of solar panels of different array-objects due to the restricted accuracy of the parameter settings.

For example, let us assume that you plan to put two static arrays of identical solar panels both on the roof and on the wall of your house. Suppose you want to set the same slope for all the collectors relatively the horizontal plane. You do it using the parameter "iA" -- the inclination angle of the "Arr RectInc" objects. You precalculate the required "iA" values individually for each array, taking into account the slope of the roof itself. Then you set the calculated "iA" values into the Edit control of the combo box PAR. You do it with a restricted accuracy. So the slope of the roof panels can slightly differ from the slope of the wall panels. If it is so, the orientation of the collectors is not identical in the rigorous mathematical sense.

In this case, if the comparison of the orientation of solar panels of the different array-objects were too precise, then (in spite of your intention) Shadow Analyzer could detect that the collector system is combined of two separate parts with the differently oriented panels.

To avoid such inconsistent and senseless situations, Shadow Analyzer evaluate the geometrical similarity of dimensions and orientations of solar panels with the restricted accuracy too. After the first array-object (which defines the system type) is found, Shadow Analyzer uses it as an etalon: it compares all next array-objects with this first one. The panels of any next array-object are recognized as geometrically similar to the panels of the first array-object, if their dX- and dY-dimensions differ less than by 1% from ones of the first array-object, and if the directions of their X and Y axes differ less than by 0.01 radian from ones of the first array-object.

Systems with mixed geometry

What to do if your real system consists of the geometrically different solar panels, or if the panels cover a curved surface like a wall of a cylindrical building, or if your system is a mixture of static and sun-tracking collectors, and all of them are working together?

Sorry. In all such cases, you have to divide your system into several parts (consisting of panels of the same type, dimensions, and orientation), and analyze only one part at a time.

To divide your full system into parts, do the following:

Firstly, prepare the scene with the full model of your real collector system. Set the climatic data of your site (see the topic Climate & Irradiance for more details). Set also the parameter "Efficiency" if it differs from the default value.

Make the copy of the scene file, saving the scene under a different file name (the climatic data and the "Efficiency" are copied automatically).

Find the first collector object that is excluded from the collector system assembled by Shadow Analyzer in compare with your real full system. For this purpose, compare the object list of the combo box SCENE with the text line of the "Solar Day" window that shows the system contents.

Working with the copied scene, make all the collector objects that precede the excluded object "inactive". Note, do not delete the objects, make them "inactive" instead, because we need their shadows!

Make the next copy of the scene from its previous copy with already partly "inactivated" collector objects. Repeat the same procedure to find the new first excluded collector object, and "inactivate" all its predecessors.

Continue this process until you get the full nonintersecting set of collector subsystems that covers all the collector objects of your initial real full system.

Note that if the different parts of your real system have also different values of the parameter "Efficiency", you need to correct this parameter individually in each copy of the scene. We will discuss the parameter "Efficiency" later in the topics devoted to "solar" windows.

After you divide your system into parts of similar collectors (inside each part), analyze properties of the parts using "solar" windows. Use the data transfer options to unite your intermediate results somewhere in tables of MS Excel or in a working report document of MS Word (see the topic Data Transfer for more details). Then, calculate the characteristics of the entire full system summarizing the partial characteristics or averaging them according to their energy weights and their physics nature.