WO2022043880A2

WO2022043880A2 - A method for maximization of energy yield from a photovoltaic installation and a method of installing solar modules

Info

Publication number: WO2022043880A2
Application number: PCT/IB2021/057769
Authority: WO
Inventors: Ernest GRODNER; Jakub LEJA
Original assignee: Scanthesun Sp. Z O.O.
Priority date: 2020-08-24
Filing date: 2021-08-24
Publication date: 2022-03-03
Also published as: WO2022043880A3; PL435069A1

Abstract

The subject of the invention is a method for maximization of energy yield of a photovoltaic installation by planning the arrangement and orientation of solar modules on the roof surface of a building, ensuring the maximum energy yield with a minimum number of solar modules. The subject of the invention is also a method of installing solar modules including the aforementioned method.

Description

A method for maximization of energy yield from a photovoltaic installation and a method of installing solar modules

The field of technology

The invention relates to the field of photovoltaic (PV) installations, and more specifically to a method for maximization of energy yield of a photovoltaic installation by planning the arrangement and orientation of solar modules on the roof surface of a building, ensuring the maximum energy yield with a minimum number of solar modules, especially carried out automatically. The invention also relates to a method of installing solar modules including the aforementioned method.

Prior the art

The photovoltaic installations which are known in the art are designed arbitrarily, based on the individual knowledge of the installer. Installers typically use simplified design methods where the solar modules are arranged: i) within the roof plane (Fig. 1), or

II) with arbitrarily selected tilt with respect to the roof surface and arbitrarily selected spacing between modules, ill) based on the textbook data on the solar modules orientation and spacing.

These installations are made without science-based methods of spatial optimization aimed at the efficiency and energy yield maximization. The design processes of known installations, usually do not include measurement techniques or scientific methods to maximize the overall efficiency of the installations through spatial analysis. These processes also do not take into account the local weather conditions, the influence of shading from the building elements and the influence of shading resulting from the area around the building.

Designing the photovoltaic installations with prior art equipment used for spatial designing of PV installations on buildings does not include the optimization analysis related to spatial arrangement of the solar modules. It is not possible to obtain information about the best direction and location of solar modules on a building’s roof, wherein the term ‘the best’ here stands for the most efficient in terms of the amount of energy produced. Therefore, in state of the art, there is a need for methods allowing planning, preferably in an automatic manner, and installing the solar modules, in order to maximize the efficiency of the solar modules operation and the solar energy yield, while minimizing the number of modules used for this purpose.

Surprisingly it turned out that problems known in the prior art can be solved by the method of the present invention.

Advantages of the invention

The method according to the present invention consists in determination of how the geometry of the building and its vicinity affects the spatial distribution of the direct (direct irradiation) and diffuse (diffuse irradiation) solar energy flux at the installation site of each solar module, wherein the method is preferably carried out in an automatic manner.

This solution allows the determination of the roof sections with the greatest insolation and the determination of the best orientation for each solar module located on the building surface, wherein the mutual shading of the modules; and the shading caused by the building and its vicinity is taken into account.

This method allows, preferably in an automatic manner, to obtain spatial plan of the solar modules placement, i.e. their location and orientation on the roof; so as to ensure the highest energy yield with the minimum number of solar modules used, which provides the material savings, more efficient use of renewable energy sources and, consequently, the reduction of energy production costs from these sources. Subject of the invention

The subject of the invention is a method for maximizing energy yield from a photovoltaic installation with a minimum number of solar modules, characterized in that it includes:

(a) determining the influence of building geometry on the spatial distribution of direct solar radiation flux,

(b) determining the building geometry impact on the spatial distribution of diffuse solar irradiation, c) determining the best direction and arrangement of modules on the roof surface, d) planning the orientation and arrangement of solar modules on the roof surface.

Step a) of the method includes: a1 ) determining the trajectory (2) of the Sun movement in the sky for each day for a predetermined time interval, (a2) obtaining the data regarding atmospheric solar photon absorption and scattering at the geographic location of the installation, a3) determining the values and directions of solar energy fluxes corresponding to direct solar radiation reaching selected points (3) on the roof of the building and in the area surrounding the building based on the combination of the Sun trajectory data with data regarding atmospheric solar photon absorption and scattering,

(a4) performing geometric analysis of the impact of the building shape on direct solar irradiation and resulting shading,

Step b) of the method includes: b1) determining the reduction of the solid angle of the sky hemisphere at selected points on the roof of the building and in area surrounding the building, b2) determining the building geometry’s impact on the reduction of the energy yield from diffuse radiation,

Step c) of the method includes: c1) carrying out an overall analysis of the data collected in steps a) and b) for the selected time interval, c2) determining the course of the total solar irradiation and its spatial distribution in the selected time interval, c3) determining the impact of the building geometry and its vicinity on the distribution and course of solar irradiation, and c4) determining the orientation of at least one solar module at a given location on the roof surface that guarantees maximum energy yield,

Preferably the time interval is 12 months.

Preferably determining the orientation of at least one solar module in step c4) comprises determining its tilt angle with respect to the roof of the building and azimuth. Preferably the step d) of the method comprises:

(d1) planning the solar modules arrangement and their orientation over the entire roof area taking into account the tilt angle of each solar module relative to the roof and the spacing between the solar modules, d2) assigning the tilt angle relative to the roof surface to each solar module that guarantees the highest energy yield, taking into account the influence of other solar modules.

In another preferred embodiment the step (d) of the method further comprises: d3) selecting a starting and the ending point of the time interval.

Preferably, after step b) the method of the invention comprises the additional step: (e) determining the areas on the roof surface suitable for the solar modules installation.

In preferred embodiment the step e) of the method comprises:

(e1) performing an analysis of the entire roof surface, taking into account obstacles such as chimneys, window openings and the like, and e2) determining at least one flat area suitable for installation of at least one solar module and areas where installation of solar modules is precluded or hindered. Preferably at least one step or sub-step of the method is performed automatically.

In another preferred embodiment each step and sub-step of the method is carried out automatically.

The subject of the invention is also a method of installing solar modules, characterized in that it comprises the method for maximizing energy yield from a photovoltaic installation as defined above.

Preferably the method of installing solar modules comprises changing the tilt angle of the solar modules relative to the roof depending on the season.

Drawings

Embodiment of the subject of the invention is shown in the drawings in which Figure 1 shows the arrangement of solar modules in the roof plane according to the methods known in the prior art,

Figure 2 shows the step in which the influence of the building geometry on the spatial distribution of direct solar irradiation (direct solar energy flux) is determined, Figure 3 illustrates the step in which the influence of the building geometry on the spatial distribution of the diffuse solar irradiation (diffuse solar energy flux) is determined.

Figure 4 illustrates the step where the orientation and arrangement of the modules on the roof surface is planned.

Figures 5A and 5B show the orientation and arrangement of the solar modules depending on the season,

Figure 6 illustrates the step of determining the regions on the roof surface in which solar modules can be installed,

Figure 7 illustrates the roof of a building on which the method of the invention was tested in accordance with Example 1 ,

Figure 8 shows the roof of the building as of Figure 7 with a layout plan for solar modules resulting from the method of the invention, Figure 9 illustrates the roof of a building on which the method of the invention was tested in accordance with Example 2,

Figure 10 shows the solar modules as of Figure 9 with information on the total energy yield for individual modules. Detailed description of the invention

A solar module, herein also referred to as "module", "photovoltaic panel" and "panel", generally means a device capable of converting solar energy into usable electric energy. The term therefore covers any type of solar collector, any type of photovoltaic module (commonly referred to as a photovoltaic panel), any type of PVT hybrid collector (commonly referred to as a hybrid panel).

In a first aspect, the subject invention relates to a method for maximizing the energy yield of a photovoltaic installation.

The method according to the first aspect of the invention allows to maximize the energy yield of the photovoltaic installation by using a minimum number of solar modules. This method is preferably carried out automatically and consists in carrying out the following steps on the basis of the building’s geometry plan:

Step a)

Determination of the influence of a building geometry on the spatial distribution of direct solar irradiation (Fig. 2).

Direct irradiation is the part of solar radiation reaching a given surface (especially the Earth's surface) that passes through the atmosphere without interactions such as, the photon absorption, scattering, reflections, etc.

In this step the trajectory 1 of the Sun's movement in the sky is determined for each day of the year based on the geographic location of the building. The trajectory of the Sun's motion in the sky as a function of time for any day of the year is preferably determined numerically with a time step not longer than one minute. The geographic location of the building (e.g. in the form of longitude and latitude values) defines the trajectory 1 of the Sun's movement in the sky as the azimuth and elevation angles of the Sun over the horizon plane as a function of time, for each day of the year. The trajectory 1 of the Sun's motion determines the direction of the direct solar irradiation as a function of time. This direction together with the terrestial or satellite data (such as e.g. NASA

containing the values of the direct solar

irradiation at the ground level determine the vector

of direct solar energy flux reaching the Earth's surface at the location of the building 2 (Formula 1):

where

is the value of the direct solar radiation flux (expressed in W/m² units) as a function of time fitted to satellite or terrestrial data, which takes into account the flux reduction due to the atmospheric absorption or scattering, and

denotes the direction as a function of time from which the direct irradiation arrives.

Data on the atmospheric absorption and dissipation of solar energy at the installation location are available online, e.g. at

These data can also be obtained from any other source

(e.g. textbook / tabular data) for the given latitude and longitude of the photovoltaic installation site.

Obtaining a direct solar energy flux vector may require aggregation of satellite or terrestrial insolation measurements data, containing (often implicitly) the value of this vector, with the trajectory of the Sun's movement in the sky specifying the direction of this vector.

The geographic location data can be entered manually or obtained from a locating systems such as GPS or services such as Google Maps.

Finally, a geometric analysis of the influence of the building shape on the direct irradiation and the resulting shading is performed 4. At a (any) given point

on the building surface or in any spatial position around the building, the vector of the

direct solar energy flux as a function of time determines the time interval

in which this vector intersects the surfaces of building elements 4 or the obstacles around the building visible from point r.ln the time interval , the direct solar irradiation does

not reach the selected point

.

The effect of shading by a building element on direct irradiation at a selected point r is given by setting

in the time interval in which the direct

solar energy flux does not reach the point .

As a result of this step, vectors of direct solar energy flux which reach

the selected points on the building surface or in the building's vicinity, as a function of

time t are obtained, where shading by obstacles visible from point ? is taken into account.

Preferably, the determination of the building impact on the direct solar energy flux at a given point r on the building surface or its vicinity is based on the determination of the Sun's trajectory in the sky with the use of a computing machine with a step not longer than 1 minute. The position of the Sun in the sky as a function of time allows to determine whether at a given time t it is behind the obstacles in the form of building elements represented by a digital model of the building geometry. As indicated above, in this case, the influence of the building on the direct solar energy flux is reflected by taking = 0, i.e. the building's impermeability to sunlight.

Step b)

Determination of the influence of a building geometry on the spatial distribution of diffuse solar irradiation (Fig. 3).

Diffuse solar irradiation accounts for almost a half of the available solar energy and reaches solar modules from all directions within the solid angle of the visible part of the sky. Diffuse solar irradiation is a result of phenomena such as scattering and reflection of the sunlight in the atmosphere..

In the absence of shading, the diffuse solar irradiation reaches any selected location from all directions contained in the hemisphere above the horizontal plane on which the building is located.

The reduction of the solid angle of the sky hemisphere is required in order to determine the reduction of energy yield from the diffuse irradiation caused by the building geometry.

The angular distribution of the diffuse solar irradiation as a function of time

j_S determined by the terrestrial or satellite measurements of the diffuse solar irradiation on the ground surface at a given geographic location (such as the NASA and/or COPERNICUS data mentioned above). Such angular distribution where is any direction (e.g. defined by azimuth and elevation angles) and

t is time, does not take into account the shading caused by the building geometry.

The effect of shading on solar diffuse irradiation at a given point on the

building surface 5 or at any position around the building is determined by excluding from the sky hemisphere the solid angle (Ω) 6 corresponding to all obstacles 7 (such as a chimney, antennas, etc.) visible from a given point. This exclusion is realized by assuming that for all directions contained in the solid angle (Ω).

Preferably, the exclusion of the solid angle (Ω) 6 corresponding to all obstacles (such as, for example, a chimney, antennas, etc.) visible from a given point from the sky hemisphere is performed digitally by scanning all directions

originating from a given point with a step not greater than one angular degree for the elevation and the azimuth angles.

If the direction

in a given step intersects any of the building elements 4 or any obstacle in the building vicinity which are visible from the point

, the exclusion angle is preferably incremented by a solid angle of 1 degree elevation and 1 degree azimuth in this direction.

As a result of this method step, a spatial distribution of the diffuse irradiation at selected points r on the surface or in the vicinity of the building is obtained, taking into account the shading by obstacles visible from points

Initially, the solid angle 6 shaded by the obstacles 7 is determined at any spatial point 5 in building vicinity,. Then, based on this solid angle, the impact of the building geometry on the reduction of the energy yield from the diffuse irradiation is determined..

Determining the reduction of the energy yield from the diffuse irradiation due to the building geometry requires including the impermeability of obstacles to diffuse solar energy flux for each angular step of azimuth and the elevation angle, i.e. by taking

for directions

within the solid angle Ω.

Solid angle measurements are made by any method known to a skilled person or known in the prior art

Determination of the building impact on the diffuse solar energy flux is preferably carried out by means of a computation machine by scanning all directions of the sky hemisphere with a step not larger than one degree of elevation angle and one degree of the azimuth angle. The use of the digital model of the building geometry allows to determine whether a segment of the sky hemisphere in a given direction is behind obstacles in the form of building elements. In such a case, the impact of the building geometry on the diffuse solar energy flux coming from this direction is reflected by assuming i.e. by assumption of the building’s impenetrability to diffuse

sunlight.

Stage c)

Determination of the best direction and arrangement of modules on the roof surface.

In the first step (c1), an overall analysis of the data collected in stages a) and b) is performed for the selected time interval (e.g. for the entire year), taking into account variations of the direct solar irradiation as a result of the Sun’s trajectory changes during the year, the changes in the diffuse solar irradiation as a result of a variable Sun elevation angle in the sky hemisphere during the year, the atmospheric photon absorption and scattering based on satellite measurements. The course of total solar irradiation over a selected time interval (e.g. 12 months) and its spatial distribution are then determined based on said analysis.

The analysis requires the repetition of steps from at) to b2) for each day within the selected time interval and recording the results obtained in these steps for each day separately.

The overall analysis takes into account the impact of the building’s geometry and its vicinity on the distribution and course of the total solar irradiation.

The direct solar energy flux as well as the angular distribution of the

diffuse solar energy flux , both taking into account the effects of shading,

determine the amount of solar energy hitting the solar modules. Getting the amount of the modules output energy and output power requires additionally the efficiency of the modules and its dependence on the sunlight incidence angle

to be taken into account, where

is the direction of incidence of sunlight in the reference frame of the solar module. The direction of sunlight incidence

depends on the direction of the module , as well as the direction , from which the direct or diffuse solar irradiation

arrives at the panel surface (Formula 2):

In the case of a flat-plate modules, their direction is determined by e.g. the

azimuth and elevation angle of the normal to the module surface. In the case of non- planar modules, is additionally a function of the parameters related to the module

rotation (twist) around the axis normal to their surface.

The output power produced by solar modules per unit area at a selected point ? on the module surface is given by Formula 3:

where

is the output power per unit area produced from the direct irradiation as a function of time and module orientation, and

is the output power per unit area produced from the diffuse irradiation as a function of time and module orientation. The output power per unit area produced by the module from the direct irradiation is determined by the product of the direct solar energy flux value

hitting the module and the module efficiency

as a function of the incident sunlight direction

(Formula 4):

where shading is taken into account as described above by taking

in the time interval [t₁, t₂], in which the direct solar energy flux hits obstacles and does not reach the point r on the module.

In turn, the output power per unit area of the module produced from the diffuse irradiation is determined by the angular distribution of the diffuse solar energy flux

For any point r on the solar module surface the contribution

to the total diffuse solar energy flux incident on the module is (Formula

5):

where

is the value of the angular distribution of the diffuse solar energy flux at a selected point

for the direction defined by infinitezimal solid angle dΩ from

which the diffuse irradiation arrives at the module surface.

The contribution of the diffuse solar energy flux

incident on the module surface determines the contribution to the module output power

from the diffuse irradiation through the modules efficiency as a function of the light incidence angle

(Formula 6):

where

denotes the module efficiency as a function of incidence light direction in the reference frame associated with the solar module, depending on both the direction

of the module orientation and the direction from which the diffuse sunlight arrives at the module surface .

The output power per unit area of the module produced from diffuse irradiation is the sum of all contributions to the output power coming from all solid angles dΩ (solid angles for all selected points) and thus from all directions (Formula 7):

where shading is taken into account as described above, by taking for directions of all obstacles visible from the selected point

within

the solid angle.

The output power per unit area of solar modules at a selected point

on the module surface given by Formula (8):

determines the amount of energy produced per unit time and unit area of the module at any time (t) at the given point

on the module surface.

The total energy yield

at a given point

during an arbitrary time interval [to, to + At] per unit area of modules oriented in the direction

is given by the sum of products of the instantaneous output power and the short time intervals

dt covering the entire interval [to, to + At] (Formula 9):

In turn, the total energy yield of a solar module oriented in the

direction

between to and t₀ + Δt is the sum of the products of the energy yield per unit area of the solar module and the small areas

covering the

whole module surface and is expressed by Formula (10):

The value of the energy yield of the solar module in the selected time interval depends on the direction of orientation of the module

. In order to find the best module direction it is necessary to determine the energy yield values

for all directions

on the sphere, with the step not larger than one angular degree. This method allows to determine the direction of the module for which the energy yield

in the selected time interval is the highest, with an accuracy of one angular degree.

This direction also determines the tilt angle of modules with respect to the roof surface that guarantees the highest energy yield in selected time interval where shading caused by the building geometry and its vicinity is accounted for. The determination of the best orientation of the solar module for selected time

interval and amount of the energy yield for module oriented in this

direction and placed in selected position on the roof surface is the result of this stage.

In this way, the orientation of at least one solar module at a given location on the roof surface that guarantees the maximum energy yield is determined.

This operation should be performed with computing machine using digital data obtained in steps at) to c3) and the digital model of the building geometry.

Step d)

Planning the modules orientation and placement on the roof surface (Fig. 4 and 5a/5b).

The aim of step d) is to guarantee the maximum energy yield with the minimum number of solar modules.

In this step, a layout plan of solar modules is made on each roof surface, taking into account all parameters obtained previously, in particular the tilt angle 8 of solar modules with respect to the roof and the solar modules spacing 9. Then the tilt angle that ensures the maximum energy yield, where the impact of other modules is accounted for, is assigned to each solar module.

The layout plan is made according to the following procedure:

First, the energy yield produced by the solar module is

determined for the best possible direction of the module for the selected time interval with various location points / of the module on the roof surface. The / points form a grid on the roof surface with a constant spacing not larger than 1 cm. This provides a map of the highest energy yield E_I and the best direction on the grid points /. The best

common direction

for all solar modules on the roof surface is given by the average of the best directions on the grid points weighted by the energy yields El at the grid

points according to Formula (11):

The common direction

determines both the common direction and the common tilt angle for all solar modules placed on a given roof surface that guarantees the highest energy yield for the selected time interval. Since it is the direction common to all solar modules, it determines the direction of entire rows of solar modules on the roof surface. The row spacing 9 is determined by the effect of shading of the preceding row on the energy yield

for the current row. The value of

is determined repeatedly for increasing (with a step not larger than 1 cm) row spacing. The value of

increases with increasing spacing due to decreasing shading from the preceding row of solar modules.

The largest spacing between solar modules rows is attained when the energy reduction due to shading decreases to about 1%. In this way, a layout plan of rows with the minimum number of solar modules is obtained that guarantees the highest energy yield on a given roof surface for a selected time interval where shading is accounted for.

Preferably, for a given solar module placed at a point / all possible directions of this module arrangement are scanned digitally using a computing machine (e.g., computer/smartphone), preferably with a step of 1 angular degree. In this way, the best direction

is found, i.e. the direction for which the energy yield in a given time interval is the highest. This operation is preferably repeated for successive / points on the grid. At each grid point, the best direction

and the maximum energy yield

are obtained. In order to layout (parallel) rows of solar modules on the roof, one best common direction v should be determined. For this purpose, according to Equation 11 , the average over the grid points / is calculated and weighted by the maximum energy yields in grid points. Thus, the modules

with higher energy yield have a greater impact on the average giving the best common direction v.

This operation should be done by computing machine using the numerical data obtained in steps at) to c4) and the digital-model of the building geometry.

The roof of any building may consist of many different flat surfaces with different tilt angle and azimuth. Performing step d2) requires repeating step d1) for each flat surface that makes up the geometry of the entire roof of the building.

The basic criterion for the placement of solar modules is the volume of the energy yield that can be obtained from solar radiation at a given location on the roof over a pre-determined time interval, taking into account the parameters mentioned above. Additional criteria may include the type of solar modules to be installed (i.e. their size, energy efficiency, etc.).

The layout plan containing the orientation and placement of the modules is made for a specified time interval, therefore this step of the method may also take into account the selection of a start and end month of a given season (i.e., the starting point to and the ending point to + At of the time interval), e.g., in the form of a calendar starting day and a calendar ending day, to guarantee a maximum energy yield with a minimum number of modules for a given season, e.g., winter or summer. For this purpose, steps d1) and d2) are carried out for all days included in this time interval.

In this embodiment of the invention, the solar module mounting parameters (e.g., direction, tilt angle, etc.) may vary with the season as shown in figs 5a and 5b - such as the tilt angle of the solar modules in winter 10 and the tilt angle of the solar modules in summer 11.

The method according to the invention may also comprise the optional step e) in which areas on the roof surface not suitable for installing photovoltaic panels are specified (Fig. 6). This step is preferably carried out between steps c) and d) of the method according to the invention.

In this step, in order to determine the areas not suitable for installing photovoltaic panels, an analysis of the entire roof surface is first performed, taking into account obstructions such as chimneys, window openings and similar elements. The term similar elements includes, for example, vents, antennas, transmitter masts and other transmitters, lightning rods, off-limits areas such as helipads etc.

Based on such an analysis, at least one flat surface 12 suitable for the installation of at least one solar module and areas 13 in which the installation of solar modules is excluded or difficult are determined. Installation of the modules may be difficult due to, for example, proximity to roof edges, presence of joints of different materials within the roof, difficult access to potential installation sites, etc.

The surfaces 12 and areas 13 may be used in step d) of the method according to the invention.

This operation requres to determine the position of obstacles on the roof surface using any method known to a skilled person or known in the prior art e.g.:

- physical measurement of the location of the obstacles by a person on the roof surface,

- use of aerial photography, - use of drone photography,

- use of satellite image of a building, and then entering (automatically or manually) the position and shape of the obstacles into a digital model of the building geometry.

Preferably, at least one of the steps of the method according to the invention is carried out in an automatic manner. In another preferred embodiment of the invention, all the steps of the method are realized in an automatic manner. The term "automatic", "machine" or digitally used alternately in the present description in the context of the method of the invention means that the process is performed by computing machine and proceeds without direct human intervention. Preferably, the process can be automated, for example, by using a computer algorithm which, after feeding with the input data such as, the building geographic location data, satellite data, solid angle data, information regarding obstacles blocking the sunlight, data describing the roof surface, etc., performs at least one, preferably all, of the steps of the method according to the invention, yielding as a result a layout plan of solar modules on the roof of the building, including all parameters necessary to maximize the energy yield with the minimum number of modules.

The individual technical steps constituting the stages and sub-stages of the method according to the invention may also be performed manually or automatically, preferably automatically.

The implementation of the steps of the method is preferably carried out using any computing machine (e.g., a numerical machine, a computer, a smartphone) by digital implementation the formulas contained in the description of the method, most preferably using a smartphone equipped with measurement sensors facilitating the data input, such as a compass, a gyroscope, an accelerometer, a gravity sensor, a GNSS, a camera.

The term "computing machine" means any device known in the prior art which enables the above-described formulas for performing the steps of the invention methodology to be programmed and the necessary input data to be entered (manually, automatically or by means of onboard sensors), and which enables at least one step of the method to be performed. Preferably, the computing machine is provided with at least a processor, a memory for storing therein said formulae, input data and output data, means for the machine programming, as well as for feeding input data, and means for sharing the output data with a user, e.g. a screen, a printer, a portable memory slot, means for wired or wireless communication, etc.

Thus, in yet another preferred form of the invention, the method may be implemented using a computer program which, when run by a computer (processor) and fed with the necessary input data, performs at least one, preferably all, of the steps of the method according to the invention.

The terms "time interval" or „period” as used herein means the time interval over which the maximum energy yield of the solar modules resulting from method of the invention is desired. The time interval may be of any duration calculated in days and may be from about 1 month to about 12 months (1 year), preferably from about 6 months to about 12 months, even more preferably from about 9 months to about 12 months, and most preferably is about 12 months.

The points

on a roof surface of the building and in the buildings vicinity may be arbitrarily selected depending on the roof structure and the objects located on it and its vicinity (e.g. other buildings, trees, power and telecommunication poles, etc.). Preferably, the points are selected with a spacing ranging from about 0.1 to about 100 cm, especially preferably from about 1 to about 50 cm, even more preferably from about 1 to about 25 cm, for example from 5 to 10 cm.

The term "building vicinity" used herein means the area on the surface of the building , the area directly around the building and the area directly above the building where sunlight can be used to produce energy from the solar modules. Preferably the building area means an area located within a radius of about 10 m, more preferably about 50 m, even more preferably about 100 m, for example about 20 m.

The term "building vicinity" or “area surrounding the building” as used herein means the area around the building containing objects that influence or may influence the solar radiation energy fluxes, e.g. other buildings, trees, power and telecommunication poles etc. Preferably the "building vicinity" or “area surrounding the building” is an area within a radius of about 20m, more preferably about 50m, even more preferably about 100m, for example about 40 m.

The term "best direction" used herein means the direction of a solar module for which the energy yield over a given time interval is highest.

The term "best common direction to all modules on a given roof surface" used in this document means the average of the best directions taken over a solar module locations on grid points on a roof surface and weighted by the highest energy yield at each grid point.

The term " digital model of the building geometry " used herein means the numerical representation of the building body taking into account: the shape of walls, the shape of the roof where location of flat surfaces and elements such as chimneys, antennas, window openings, etc. are accounted for; as well as the tilt angles of individual roof fragments and the geographical location of the building. The digital model of the building geometry may be created by any means known to skilled person, for example by using aerial photography, drone photography, satellite images, architectural plan of the building in paper or digital form, as well as direct measurements of the building and its elements, and suitable software. In a second aspect, the invention relates to a method of installing solar modules employing the above-mentioned method of maximizing the energy yield of a photovoltaic installation.

The method according to the second aspect of the present invention, in addition to the maximization method (i.e. the steps at to d2, and preferably including the steps e1 and e2) for determining the best common direction and spacing of the rows of modules on each roof plane, will include steps for mounting the solar modules on the roof of the building.

In the case of an embodiment in which the method of maximizing the energy yield of the photovoltaic system includes determining different mounting parameters of the modules depending on the season, the method of installing will include the use of mounting means that will allow modifying the mounting parameters of the individual solar modules (tilt angle, direction, etc.). In this way, it will be possible to change these parameters with changing season.

Changing these parameters may be performed manually or automatically.

In the latter case, the change may preferably be carried out by means of a programmable control unit into which the necessary data is entered and set of actuators or other components for enabling the programmed operation to be carried out.

The method of installing modules according to the present invention may preferably be implemented by any mechanical method for mounting the solar modules on the roof known to a skilled person or known in the state of the art, that allows to attain:

- the best direction of the modules, i.e. the direction for which the energy yield in the selected time interval is the highest - the distance between solar modules rows resulting from the method according to the invention.

According to the invention, the word "about" as used above and below is to be understood as a deviation of +/- 10% from a given value, reflecting measurement inaccuracies which may arise in the course of carrying out the method according to the invention.

Examples Example 1

The method according to the invention was tested on a building where 12 flat roof surfaces (12₁ - 12₁₂) were determined . There was additionally a complex arrangement of chimneys and window openings on the roof. (Fig. 7). Data on the geographical location of the building and its geometry were obtained from satellite imaginary (Google Maps) and a complementary physical measurement on site.

Digital satellite imaging was used to create digital model of the building geometry. Satellite imaging allows to obtain two-dimensional topology of the roof in two dimensional space. A complementary physical measurement on site allows to get the roof topology in three-dimensional space including the heights of all edges of each roof surface. The complementary measurement is not part of the invention, and may be performed in any manner known to a skilled person, such as:

- direct measurement,

- use of an architectural plan of the building in paper or digital form,

- the use of measuring instruments such as a theodolite,

- the use of smartphone sensors to perform the height measurement using Augmented Reality (AR).

The value of the direct solar energy flux

as a function of time as well as the angular distribution of the diffuse irradiation

_{as a} function of time were determined for the geographical location of the building based on NASA measurement data for direct and

diffuse solar irradiation components. For each mentioned roof surface J, the best direction of the solar modules

common to all modules on a given flat roof surface was determined for a time interval of one year (t₀=1 , Δt= 365 days),.

All roof planes were determined by manual marking on a digital satellite image leading to creation of a digital model of the building geometry. The complex layout of chimneys and window openings was also determined using the satellite image and introduced into the digital model of the building geometry .

The directions together with the azimuth and tilt angles of each roof surface /

were used to determine the tilt angle of the solar module rows with respect to each roof surface J and the spacing between those rows. The data are collected in Table 1 Table 1 - Summary of the tilt angles and spacing of the solar module rows determined for the entire building roof

The determined layout plan of solar modules rows on all roof surfaces (12i - 12i₂> is shown in Fig .8.

For each module mj on roof surfaces / the module energy yield was determined.

Then, using Formula 12

10

where

N_j is the number of modules on roof surface J , the average energy yield per module on roof surface / was calculated.

The average energy yield per solar module for the best common direction was

compared with the average energy yield per module for the standard, known in the prior art, direction of modules placed within the roof surface. The data were collected

in Table 2.

Table 2 - Comparison of average energy yield per module on roof surfaces for the standard direction of solar modules arrangement in the roof surface (prior art) and for the best common direction of solar modules rows arrangement according to the invention

Example 2 The method of maximizing the energy yield from a solar installation according to the invention was used in the design and implementation of a photovoltaic installation on a single-family building (Fig. 8).

The installation was realized on one roof surface with 70 degrees azimuth and 20 degrees elevation angle. The best direction T, common to all solar modules on the roof surface, was determined using the method of maximizing the energy yield according to the invention: = 130 degrees azimuth elevation angle = 61 degrees.

Two rows of six solar modules each were installed on the roof surface with the tilt corresponding to the determined best direction i? (14). Four other modules (15) were installed in a standard way according to the method from the prior art in the roof plane to verify the effectiveness of the method of maximizing energy yield according to the invention.

The energy yield was monitored for three years using an inverter tracking the energy yield from each individual solar module. The average energy yield per solar module positioned according to method from the prior the art in the roof plane E(n) was compared with the average energy yield E(v) per solar module positioned in the best common direction v determined according to the method for maximizing energy yield of the invention.

The results of these measurements, shown in Fig. 9, confirmed the effectiveness of the method for maximizing the energy yield according to the invention. The energy produced by the modules (14) positioned according to this method was on average 19.3% higher than the energy produced by the modules (15) positioned in the roof plane according to the method of the prior art.

Claims

Patent claims

1. A method for maximizing energy yield from a photovoltaic installation with a minimum number of solar modules, characterized in that it includes: (a) determining the influence of building geometry on the spatial distribution of direct solar radiation flux, comprising: at ) determining the trajectory (2) of the sun's movement in the sky for each day for a predetermined time interval,

(a2) obtaining the data regarding atmospheric solar photon absorption and scattering at the geographic location of the installation, a3) determining the values and directions of solar energy fluxes corresponding to direct solar radiation reaching selected points

(3) on the roof of the building and in the area surrounding the building based on the combination of the Sun trajectory data with data regarding atmospheric solar photon absorption and scattering,

(b) determining the building geometry impact on the spatial distribution of diffuse solar irradiation, comprising: b1 ) determining the reduction of the solid angle (6) of the sky hemisphere at selected points (5) on the roof of the building and in area surrounding the building, b2) determining the building geometry’s impact on the reduction of the energy yield from diffuse radiation, c) determining the best direction and arrangement of modules on the roof surface, c1) carrying out an overall analysis of the data collected in steps a) and b) for the selected time interval, c2) determining the course of the total solar irradiation and its spatial distribution in the selected time interval, c3) determining the impact of the building geometry and its vicinity on the distribution and course of solar irradiation, and c4) determining the orientation of at least one solar module at a given location on the roof surface that guarantees maximum energy yield, d) planning the orientation and arrangement of solar modules on the roof surface.

2. The method according to claim 1, characterized in that the time interval is 12 months.

3. The method according to claim 1 or 2, characterized in that determining the orientation of at least one solar module in step c4) comprises determining its tilt (8) with respect to the roof of the building and azimuth.

4 The method according to any of claims 1 to 3, characterized in that the step d) of the method comprises:

(d1) planning the solar modules arrangement and their orientation over the entire roof area taking into account the tilt angle (8) of each solar module relative to the roof and the spacing (9) between the solar modules, d2) assigning a tilt angle relative to the roof surface to each solar module that guarantees the highest energy yield, taking into account the influence of other solar modules.

5 The method according to claim 4, characterized in that step (d) of the method further comprises: d3) selecting a starting and the ending point of the time interval.

6. The method according to any of claims 1 to 5, characterized in that after step b) it comprises the additional step:

(e) determining the areas on the roof surface suitable for the solar modules installation.

7. The method according to claim 6, characterized in that step e) of the method comprises:

(e1) performing an analysis of the entire roof surface, taking into account obstacles such as chimneys, window openings and the like, and e2) determining at least one flat area (12) suitable for installation of at least one solar module and areas (13) where installation of solar modules is precluded or hindered.

8. The method according to any of the preceding claims, characterized in that at least one step or sub-step of the method is performed automatically.

9. The method according to claim 8, characterized in that each step and sub-step of the method is carried out automatically.

10. A method of installing solar modules, characterized in that it comprises the method as defined in any one of claims 1 to 9, and mounting the solar modules on the roof of the building.

11. The method of installing solar modules according to claim 10, characterized in that it comprises changing the tilt angle of the solar modules relative to the roof depending on the season.