Arrangement for determining the incidence angle of radiation and especially solar radiation

An arrangement for determining a first angle of incidence (α) in a first plane and a second angle of incidence (β) in a second plane perpendicular to said first plane, of incident light relative to said arrangement, comprising:

• an array of at least three respective light sensitive elements arranged successively one after another respectively along each one of mutually perpendicular first and second linear directions, wherein each respective one of said elements has an output adapted to provide a respective output signal responsive to light impinging on said respective element,
• a shadow mask that is arranged at a spacing (d) away from said array in a path of the incident light, and that includes two transparent quadrants and two non-transparent quadrants arranged alternatingly adjacent one another along said first and second directions in a checkerboard pattern, wherein said non-transparent quadrants are respectively separated from said transparent quadrants by a first linear mask boundary parallel to said first linear direction and a second linear mask boundary parallel to said second linear direction, wherein the incident light is incident on said shadow mask such that said two non-transparent quadrants cast two shaded regions respectively onto said array, the incident light passing through said two transparent quadrants projects two illuminated regions respectively onto said array, and the incident light passing by said first and second linear mask boundaries projects first and second shadow boundaries respectively onto said array between said shaded regions and said illuminated regions, wherein a position of said shaded regions, said shadow boundaries, and said illuminated regions on said array varies responsive to said first and second angles of incidence, and wherein some of said elements are completely shaded elements lying completely in said shaded regions, some of said elements are completely illuminated elements lying completely in said illuminated regions, and some of said elements are boundary elements located between said completely shaded elements and said completely illuminated elements,
• first means connected to said outputs of said light sensitive elements and adapted to receive said output signals, and from said output signals determine numbers and locations of said completely shaded elements, locations of said boundary elements, and fractional shading portions of said boundary elements that are within said shaded regions, and
• second means connected to said first means and adapted to determine said first and second angles of incidence from said numbers and said locations of said completely shaded elements, said locations and said fractional shading portions of said boundary elements, and said spacing (d).

A method of determining an angle of incidence of incident light falling on a detector arrangement including an array of at least three consecutively arranged light sensitive elements, and a shadow mask that has a transparent region, a non-transparent region, and a linear mask boundary therebetween and that is arranged at a spacing (d) away from said array in a path of said incident light, wherein said method comprises the following steps:

• a) allowing said incident light to fall on said detector arrangement so that said non-transparent region casts a shadow forming a shaded region on said array, said incident light passing through said transparent region projects an illuminated region on said array, and said incident light passing by said linear mask boundary projects a shadow boundary on said array between said shaded region and said illuminated region, wherein one or more of said elements are completely shaded elements lying completely within said shaded region, one or more of said elements are completely illuminated elements lying completely within said illuminated region, and one of said elements is a boundary element located between said shaded elements and said illuminated elements, dependent on and responsive to an angle of incidence of said incident light relative to said detector arrangement;
• b) evaluating respective output signals from all of said elements to determine a number of said completely shaded elements;
• c) evaluating respective output signals at least from said boundary element and from at least one of said completely illuminated elements for determining a fractional shading portion of said boundary element that lies within said shaded region;
• d) calculating a reference length (L) along said array to a point at which said shadow boundary crosses said array, using said number and said fractional shading portion;
• and
• e) calculating said angle of incidence using said reference length (L) and said spacing (d) to solve a trigonometric function.