Patent Description:
A pyranometer is a measuring instrument that detects the radiation amount (e.g. the solar irradiance amount) incident on a surface.

According to the working principle for the measurement of irradiance, pyranometers can be grouped in two different categories, that is thermopile-based sensor pyranometers and silicon semiconductor-based pyranometers.

As to the thermopile-based sensor pyranometers, the irradiance is measured by a sensor based on thermopiles and designed to measure a substantially broad band of the radiation flux density, from about a <NUM>° field of view angle. The thermopile-based sensor is arranged below a transparent dome, particularly a dome made of glass, the latter limiting the spectral response from about <NUM> to about <NUM> nanometers, particularly from about <NUM> to about <NUM> nanometers, while substantially preserving about the <NUM>° field of view. At the same time, the glass dome has the function of protecting the thermopile-based sensor from the external environment.

Pyranometers can be used in conjunction with other systems, among others solar simulators, photovoltaic systems, and meteorological stations. In these systems, the radiation measured by the pyranometer is used for determining other parameters and/or performances of the system, for example the photovoltaic module effective power. Therefore, the measurement accuracy of a pyranometer is one outmost aspect of this measuring instrument. Particularly, the measurement accuracy of the pyranometer is even more one outmost aspect in climate applications where changes of parts of a percent over years are recorded.

During use, the dome of a pyranometer may be covered by a layer of dew or frost, especially during the early hours of a day, just before the sunrising. A layer of dew or frost may potentially prevent a large amount of radiation to reach the thermopile-based sensor. Additionally, a layer of frost or dew may also reflect a substantial amount of the radiation in a direction opposite to the thermopile-based sensor. Consequently, in the presence of dew or frost, the irradiance (e.g. solar irradiance) measured by the pyranometer may not correspond to the effective irradiance that may be measured in absence of a dew/frost layer. Thus, in order to accurately measure the incident radiation, the pyranometer response should not be affected by frost or dew.

In order to prevent the formation of a dew or frost layer, known pyranometers are heated. Specifically, known pyranometers are usually heated and simultaneously ventilated so as to defrost the dome, thereby resulting in a more precise measuring of the irradiance (e.g. solar irradiance). The heating is particularly performed by an electric fan arranged close to a heating element. The electric fan is configured to diffuse a warm air flow over the pyranometer body, and particularly in a cavity above the dome. The warm air flow diffused by the fan defrosts the glass dome.

The use of a heating/ventilation unit may result in a temperature offset in the pyranometer. In other words, the temperature measured by the sensor may be greater than the effective temperature that may be measured in absence of the additional heating. Consequently, the temperature offset resulting from the additional heating can substantially reduce the measurement accuracy. Additionally, a direct heating of the radiation sensor (thermopile-based sensor) is also not performed because of a thermal offset signal that may be produced.

Accordingly, there is the need to a heated pyranometer, wherein layers of dew or frost that may cover the dome outer surface can be efficiently removed, while not affecting the measurement accuracy of pyranometers.

Document <CIT> describes a device for measuring solar short-wave radiation energy. The device comprises a thermopile fixing device, a thin film thermopile is mounted on the thermopile fixing device; the thin-film thermopile comprises a substrate and at least eight pairs of thermocouple wires which are connected in series with each other and are uniformly distributed around the same circle centre and coiled into a disc shape in a divergent manner. The thermocouple wire is formed by vacuum copper plating on a polyester film through a first mask plate under vacuum. At the location where the polyester film is attached to the substrate, a black coating is arranged on the surface of a hot junction of the thin-film thermopile.

Document <CIT> describes a pyranometer comprising: a light sensor; a first lens arranged to face a light-receiving surface of the light sensor; and a light-shielding ring arranged between the light sensor and the first lens, the light-shielding ring having a light-transmissive region allowing transmission of light at some angles of incidence in the light passing through the first lens. Further prior art is disclosed in <CIT>.

It is an object of the present invention to provide a pyranometer for measuring the irradiance with a high accuracy. Particularly, it is an object of the present invention to provide a heated pyranometer whose measurement accuracy is not affected by weather conditions, for example by the formation of dew or frost layer.

The achievement of this object in accordance with the invention is set out in the independent claims. Further developments of the invention are the subject matter of the dependent claims.

These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and accompanying drawings. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments.

With reference to the above figures, the pyranometer according to the present disclosure is indicated in its entirety with the reference number <NUM>.

With reference to <FIG>, the pyranometer according to the present disclosure is indicated in its entirety with the reference number <NUM>. The pyranometer <NUM> comprises a dome <NUM>. The dome <NUM> may be an outer dome of the pyranometer <NUM>. In other words, when mounted on the pyranometer <NUM>, the dome <NUM> may form the outermost dome <NUM> of the pyranometer <NUM>. If the dome <NUM> is an outer transparent dome <NUM> of the pyranometer <NUM>, an outer surface <NUM> of the dome <NUM> substantially faces an environment <NUM> external to the pyranometer <NUM>. In contrast, an inner surface <NUM> of the dome <NUM> substantially encloses a cavity <NUM>. Particularly, the cavity <NUM> is an air cavity underneath the dome <NUM>. Thus, the inner surface <NUM> of the dome <NUM> substantially faces the cavity <NUM>. The cavity <NUM> substantially corresponds to the space underneath the inner surface <NUM> of the dome <NUM>. Particularly, the cavity <NUM> has a shape that is substantially complementary to the shape of the inner surface <NUM> of the dome <NUM> that encloses the cavity <NUM>. The cavity <NUM> may have a substantially hemispherical shape and includes a bottom opening having a substantially circular shape. The dome <NUM> may comprise an edge <NUM>. The edge <NUM> may be a perimetric edge substantially forming the rim of the dome <NUM>. The edge <NUM> may have a substantially annular shaped surface. Particularly, a difference between the external radius, that is the radius of the outer surface <NUM>, and the internal radius, that is the radius of the inner surface <NUM>, substantially corresponds the thickness of the dome <NUM>.

The dome <NUM> is at least partially transparent to a radiation (e.g. solar light). Particularly, the radiation may be solar radiation. Particularly, the dome <NUM> is configured to limit the spectral response from about <NUM> to about <NUM> nanometers (nm), specifically from about <NUM> to about <NUM> nanometers (nm), while particularly substantially preserving the <NUM>° field of view. The transparency of the dome <NUM> may be particularly such that at least about <NUM>%, more particularly at least about <NUM>% of the incident radiation (e.g. solar radiation or light) in the relevant spectral range may pass therethrough. In other words, the dome <NUM> is configured to allow at least a portion of the radiation spectrum to be transmitted from the external environment <NUM>, through the outer surface <NUM>, through the material forming the dome <NUM> and through the inner surface <NUM>, into the cavity <NUM>. In the cavity <NUM>, the radiation can be measured as will be described in more details hereafter.

The dome <NUM> may be made of any suitable at least partially transparent material that allows the transmission of a radiation (particularly solar radiation or light) therethrough. Particularly, the dome <NUM> may be made of any material having such physical/chemical characteristics so as to physically protect the measuring surface of the pyranometer <NUM> yet at the same time being transparent to (most) of the light (at least partially transparent for a spectrum of radiation (e.g. solar radiation) the pyranometer <NUM> is intended to detect). For example, the dome <NUM> may be made of glass, quartz or sapphire. Alternatively, the dome <NUM> may be made of a transparent thermoplastic polymeric material, i.e. poly(methyl methacrylate) (PMMA) also known as acrylic, acrylic glass, or plexiglass.

As shown in <FIG> and <FIG>, the pyranometer <NUM> comprises at least one radiation sensor <NUM>. Particularly, the pyranometer <NUM> may comprise one, or more radiation sensors <NUM>. The radiation sensor <NUM> is a measuring sensor configured to measure the radiation (particularly the solar radiation) impinging the pyranometer <NUM>. Particularly, the radiation measured by the at least one radiation sensor <NUM> may include any type of radiation in the electromagnetic spectrum, including radiation in the ultraviolet (UV), visible, and infrared spectrum (IR), and more particularly it may include solar radiation.

Particularly, the radiation sensor <NUM> comprises a receiving surface <NUM>. Particularly, the radiation sensor <NUM> is arranged such that the radiation external to the pyranometer <NUM> impinges on the receiving surface <NUM>. Particularly, the radiation impinging the pyranometer <NUM> is at least partially transmitted through the dome <NUM> and/or diffused on or toward the receiving surface <NUM> of the radiation sensor <NUM>, by means of at least one diffusor <NUM>. The diffusor <NUM> is specifically arranged to diffuse the radiation passing through the dome <NUM>, on the receiving surface <NUM> of the radiation sensor <NUM>. Particularly, the radiation sensor <NUM> and the diffusor <NUM> may be stacked one on top of the other, particularly with a distance or air gap therebetween. As shown in <FIG>, the radiation sensor <NUM> comprises a second opposite (bottom) surface <NUM>.

The radiation sensor <NUM> comprises a thermopile-based sensor. The thermopile-based sensor may be based on thermopiles particularly suitable to measure the broad band of the radiation flux density specifically from a substantially <NUM>° field of view angle. A thermopile specifically is an electronic device that converts thermal energy into electrical energy and comprises several thermocouples connected in series or in parallel. The thermopile works on the principle of the thermoelectric effect of generating a voltage when its dissimilar metals or thermo-couples are exposed to a temperature difference. Thermocouples operate by measuring the temperature differential from their junction point to the point in which the thermocouple output voltage is measured. Once a closed circuit is made up of more than one metal and there is a difference in temperature between junctions and points of transition from one metal to another, a current is produced as if generated by a difference of potential between the junctions being at different temperatures. In other words, the pyranometer <NUM> of the present disclosure particularly may be a thermopile pyranometer (also referred to as thermo-electric pyranometer).

Specifically, a thermopile pyranometer particularly detects light of about <NUM> to about <NUM> with a largely flat spectral sensitivity. Specifically, if the radiation sensor <NUM> is a thermopile-based sensor, the receiving surface <NUM> substantially corresponds to, or comprises, a black coating which absorbs (particularly all) radiation (e.g. solar radiation or modified solar radiation modified e.g. in its spectral composition by the optical elements in front of it such as the dome <NUM> and/or the diffusor <NUM>) impinging thereon. The active (hot) junctions of the thermocouples are located beneath (or in correspondence with or adjacent to) the black coating surface and are heated by the radiation absorbed from the black coating. The passive (cold) junctions of the thermocouples are (particularly fully) protected from radiation and in thermal contact with a pyranometer housing <NUM>, which particularly serves as a heat-sink. Particularly, the passive (cold) junctions of the thermocouples are in contact with a radiation sensor housing <NUM> that may be in thermal contact with the pyranometer housing, so as to substantially dissipate the heat to or through the pyranometer housing. This advantageously reduces or prevents any alteration from yellowing or decay when measuring the temperature in the shade, thus impairing the measure of the irradiance by the pyranometer <NUM>.

The radiation sensor <NUM> is located in a radiation sensor housing <NUM>. The radiation sensor housing <NUM> may be provided with a window <NUM> that allows to expose the receiving surface <NUM> of the radiation sensor <NUM>. The radiation sensor housing <NUM> may have a cavity configured to integrally at least partly contain the radiation sensor <NUM>. In other words, the radiation sensor <NUM> is included into the radiation sensor housing <NUM>.

The housing <NUM> specifically may be a TO (transistor outline) housing: particularly, the housing <NUM> of the radiation sensor <NUM> comprises or is made of, a metal. More particularly, the metal material of the housing <NUM> is a thermal and electrical conductor.

The window <NUM> of the housing <NUM> may be arranged to substantially face, but not in direct contact with, the receiving surface <NUM> of the radiation sensor <NUM> on its bottom side. Particularly, a gap may be present between the receiving surface <NUM> and the window <NUM> in order to prevent thermal leakage which may degrade the sensor performance. The window <NUM> of the housing <NUM> may be arranged to substantially face, but not in direct contact with, a second (bottom) surface <NUM> of the diffusor <NUM> on its upper side. Particularly, a gap may be present between the second (bottom) surface <NUM> of the diffusor <NUM> and the window <NUM>. In other words, the window <NUM> of the housing <NUM> may be substantially arranged between, but not in contact with, the second (bottom) surface <NUM> of the diffusor <NUM>, and the receiving surface <NUM> of the radiation sensor <NUM>.

The window <NUM> of the housing <NUM> is at least partially transparent to the radiation (light). Particularly, the window <NUM> of the housing <NUM> may have a transparency such that at least about <NUM>%, more particularly at least about <NUM>% of the incident radiation (e.g. solar radiation or light) in the relevant spectral range may pass therethrough. If the radiation sensor <NUM> is located into the housing <NUM>, the second surface <NUM> of the radiation sensor <NUM> corresponds to a bottom surface of the housing <NUM>. The housing <NUM> of the radiation sensor <NUM> may comprise, or be made of, thermally conductive material, for example metallic material. More particularly, the metal of the housing <NUM> may be Aluminum, Aluminum alloy, steel or steel alloy.

As shown in <FIG>, the pyranometer <NUM> comprises the at least one diffusor <NUM>. Particularly, the pyranometer <NUM> may comprise one or more diffusors <NUM>. The diffusor <NUM> is configured to diffuse radiation (light) external to the pyranometer <NUM>, and passing through the dome <NUM>, toward the receiving surface <NUM> of the radiation sensor <NUM>. Accordingly, the radiation impinging the receiving surface <NUM> the radiation sensor <NUM> (particularly of the thermopile-based sensor <NUM>) can be measured by the radiation sensor <NUM>.

The diffusor <NUM> is an optical element that has an incident first or top surface <NUM> substantially facing the cavity <NUM> of the dome <NUM>, particularly when the diffusor <NUM> is mounted on the pyranometer <NUM>. In other words, the diffusor <NUM> is arranged such that the incident surface <NUM> substantially faces the inner surface <NUM> of the dome <NUM>, in the cavity <NUM>. Particularly, the diffusor <NUM> may be located in a through-opening provided in the pyranometer housing <NUM>, particularly in a through opening <NUM> provided in an upper surface <NUM> of a first portion <NUM> of the pyranometer housing <NUM>, such that the incident surface <NUM> of the diffusor <NUM> substantially faces the inner surface <NUM> of the dome <NUM>.

The diffusor <NUM> comprises a second (bottom) surface <NUM> that is substantially opposite to the incident first or top surface <NUM> and at least one side surface <NUM>. The diffusor <NUM> is arranged such that the second surface <NUM> is substantially opposite to the incident surface <NUM> and substantially faces the receiving surface <NUM> of the radiation sensor <NUM>. The incident surface <NUM> may be a flat circularly shaped surface, a conically shaped surface, a convex surface, a concave surface, or an inverted conical surface.

Particularly, the diffusor <NUM> may be axisymmetric, that is symmetric about a longitudinal axis X3 of the diffusor <NUM>. In other words, the diffusor <NUM> may be a rotationally symmetric body having a longitudinal axis X3. For example, the diffusor <NUM> may have a substantially cylindrically shaped side surface <NUM> and/or comprise a conically shaped incident first or top surface <NUM>.

As shown in <FIG>, the diffusor <NUM> may be arranged such that the second surface <NUM> substantially faces toward the receiving surface <NUM> of the radiation sensor <NUM> (particularly of the thermopile-based sensor <NUM>), whereas the incident surface <NUM> substantially faces towards the inner surface <NUM> of the dome <NUM>.

Accordingly, the radiation or light (e.g. solar radiation) external to the dome <NUM> enters the cavity <NUM> through the dome <NUM>. In the cavity <NUM>, the radiation or light impinges the incident surface <NUM> of the diffusor <NUM> and it is at least partly transmitted through the diffusor <NUM> and the second surface <NUM>, towards the receiving surface <NUM> of the radiation sensor <NUM>. The radiation or light (e.g. solar radiation) reaching the radiation sensor <NUM> can be thus measured by the latter.

The diffusor <NUM> may comprise or be made of any material that allows a light incident thereon to be diffused and transmitted through the diffusor <NUM>. For example, the diffusor <NUM> may comprise, or be made, of at least partially porous material, such as quartz, particularly bubble quartz.

As shown in <FIG>, the pyranometer <NUM> may comprise at least one control unit <NUM>. The control unit <NUM> may be operatively connected to the radiation sensor <NUM>. The control unit <NUM> may be a controller, particularly a micro controller. The control unit <NUM> may be located in a pyranometer housing <NUM>.

The pyranometer housing <NUM> may comprise the first portion <NUM>. Particularly, the first portion <NUM> may be configured to, at least partially, enclose the radiation sensor <NUM>.

As shown in <FIG>, the first portion <NUM> may comprise a cavity <NUM>. Particularly, the cavity <NUM> may be configured to, at least partially, contain the radiation sensor <NUM>. More particularly, the cavity <NUM> may be configured to integrally contain the radiation sensor <NUM>. In other words, the cavity <NUM> may be dimensioned so as to at least partially, or integrally, enclose the radiation sensor <NUM>.

Specifically, the cavity <NUM> may have a cylindrical shape. As shown in <FIG>, the cavity <NUM> may be surrounded by a perimetral wall <NUM>. The perimetral wall <NUM> may be part of the same first portion <NUM>. The perimetral wall <NUM> may have a cylindrical shape, that is it may correspond to a cylindrical outer surface of the first portion <NUM>. The cavity <NUM> may be further delimited by the first (upper) surface <NUM> of the first portion <NUM> and by a second (upper) surface <NUM>. The first surface <NUM> and the second surface <NUM> may be seamlessly coupled to the perimetral wall <NUM>. Particularly, the first surface <NUM> may have a circular shape. Additionally, the first surface <NUM> may include a through opening <NUM> in connection with the cavity <NUM>. The second surface <NUM> may be configured as a flange portion of the first portion <NUM> of the pyranometer housing <NUM>. That is, the first surface <NUM> and the second surface <NUM> substantially may lie on parallel planes.

As shown in <FIG>, the pyranometer housing <NUM> may comprise a second (outer) portion <NUM>. The second portion <NUM> may have a substantially cylindrical shape. The second portion <NUM> may comprise at least one through opening <NUM> arranged on an upper surface <NUM> of the second portion <NUM>.

Particularly, the second portion <NUM> may be configured to substantially, integrally, enclose the first portion <NUM>. Particularly, the second portion <NUM> may have a cavity <NUM> that is configured to integrally contain the first portion <NUM> of the pyranometer housing <NUM> therewithin. Specifically, the second portion <NUM> may be an outer carter of the pyranometer <NUM> configured to protect the first portion <NUM>, as well as the radiation sensor <NUM> and/or a control unit <NUM> from the environment external to the pyranometer <NUM>. The second portion <NUM> may be made of, or may comprise, a metallic material. Specifically, the metallic material may be an Aluminum alloy, aluminum, steel or brass.

The first portion <NUM> may be removably coupled to the second portion <NUM>. Particularly, the first portion <NUM> may be arranged to directly contact the second portion <NUM>. Specifically, by arranging the first portion <NUM> to (particularly directly) contact the second portion <NUM> a thermal coupling between the first portion <NUM> and the second portion <NUM> can be obtained. More particularly, when the first portion <NUM> may be coupled to the second portion <NUM>, the first (upper) surface <NUM> and/or the second (upper) surface <NUM> of the first portion <NUM> may be in direct contact with an inner surface of the second portion <NUM>, e.g. an inner surface of the cavity <NUM>.

Particularly, the first surface <NUM> of the first portion <NUM> is configured to be at least partially located in the through opening <NUM> arranged on an upper surface <NUM> of the second portion <NUM>, when the first portion <NUM> is coupled to the second portion <NUM>. Accordingly, the diffusor <NUM> that is supported by the first portion <NUM> may be also located in the through opening <NUM>. The first surface <NUM> of the first portion <NUM> may contact an inner bottom side of the upper surface <NUM> of the second portion <NUM>. The second (upper) surface <NUM> of the first portion <NUM> may also contact the inner bottom side of the upper surface <NUM> of the second portion <NUM> and/or the inner surface of the second portion <NUM>, e.g. an inner surface of the cavity <NUM>.

As shown in <FIG>, the dome <NUM> may be coupled to the second portion <NUM> of the pyranometer housing <NUM>, particularly to the upper surface <NUM> of the second portion <NUM> of the pyranometer housing <NUM>. The dome <NUM> may be arranged to particularly directly contact the upper surface <NUM> of the second portion <NUM> of the pyranometer housing <NUM>. Accordingly, the dome <NUM> may be thermally coupled to the second portion <NUM> of the pyranometer housing <NUM>.

As shown in <FIG>, when the dome <NUM> is coupled to the upper surface <NUM> of the second portion <NUM> of the pyranometer housing <NUM>, the through opening <NUM> of the first portion <NUM> is also in connection with (arranged below) the cavity <NUM> of the dome <NUM>. Particularly, the diffusor <NUM> may be arranged in the through opening <NUM> of the first portion <NUM>, as shown in <FIG>.

In summary, as shown in <FIG>, the dome <NUM> is connected to the pyranometer housing <NUM>, particularly to the upper surface <NUM> of the second portion <NUM> of the pyranometer housing <NUM>. Particularly, the dome <NUM> is configured to contact the pyranometer housing <NUM>, particularly the surface <NUM> of the second portion <NUM>. By means of this arrangement, the dome <NUM> and the pyranometer housing <NUM> are thermally coupled. Particularly, the dome <NUM> is (specifically directly) thermally coupled to the second portion <NUM> and (specifically indirectly) to the first portion <NUM> of the pyranometer housing <NUM>. That is, the dome <NUM> may be thermally coupled to the first portion <NUM> by means of the second portion <NUM>. As a result, the dome <NUM> may be directly heated by thermal contact, particularly by means of the pyranometer housing <NUM> being heated, as described below.

The first portion <NUM> may comprise, or be made of, a thermally conductive material. Specifically, the thermally conductive material may be a metallic material. For example, the first portion <NUM> may be made of a Aluminum, aluminum alloy, steel or steel alloy.

The pyranometer housing <NUM> comprises at least one supporting element <NUM>. The supporting element <NUM> may substantially be a plate or plate-like. Particularly, the supporting element <NUM> substantially may be a plate having a circular shape.

The supporting element <NUM> may include a first (upper) surface <NUM> and a second (bottom) surface <NUM> that is opposite to the first surface <NUM>. The supporting element <NUM> is coupled to the pyranometer housing <NUM>, particularly to the first portion <NUM> of the pyranometer housing <NUM>.

Specifically, the supporting element <NUM> is removably coupled to the pyranometer housing <NUM>, particularly to the first portion <NUM>. For example, the supporting element <NUM> may be removably coupled to the first portion <NUM> by a mechanical connection, i.e. one or more screws, rivets and/or clamps, and/or by adhesive.

Particularly, the supporting element <NUM> may be configured to at least partially, or integrally, close a bottom opening of the cavity <NUM>, when assembled to the first portion <NUM> of the pyranometer housing <NUM>. In other words, when the supporting element <NUM> is coupled to the first portion <NUM>, the cavity <NUM> becomes a substantially closed cavity and it integrally contains the radiation sensor <NUM> therewithin. Therefore, the cavity <NUM> is substantially delimited by the supporting element <NUM> on its bottom side, by the perimetral wall <NUM> on its lateral perimetral sides, and by the first surface <NUM> on its upper side. The cavity <NUM> may be in communication with the cavity <NUM> of the dome <NUM> by means of the through opening <NUM> provided on the first surface <NUM>.

As shown in <FIG>, the radiation sensor <NUM> is supported by the supporting element <NUM> on the pyranometer housing <NUM>. Particularly, the second surface <NUM> of the radiation sensor <NUM> (or the bottom surface of the radiation sensor housing <NUM> of the radiation sensor <NUM>) at least partially contacts the first surface <NUM> of the supporting element <NUM>. Particularly, the radiation sensor <NUM> and the first surface <NUM> of the supporting element <NUM> may be in direct contact, or indirect contact to each other The second surface <NUM> of the radiation sensor <NUM> may be directly connected to the first surface <NUM> of the supporting element <NUM>. More particularly, the second surface <NUM> of the radiation sensor <NUM> may be coupled to the first surface <NUM> of the supporting element <NUM> by adhesive.

The supporting element <NUM> is configured to electrically isolate the radiation sensor <NUM> from the pyranometer housing <NUM>, particularly from the first portion <NUM> of the pyranometer housing <NUM>. Simultaneously, the supporting element <NUM> is configured to thermally couple the radiation sensor <NUM> to the pyranometer housing <NUM>, particularly to the first portion <NUM> of the pyranometer housing <NUM>. In other words, the radiation sensor <NUM> is connected to the pyranometer housing <NUM> by means of a supporting element <NUM>. The supporting element <NUM> is specifically configured as electrically isolating element, that is the supporting element <NUM> does not allow any direct passage of electrical current between the pyranometer housing <NUM> and the radiation sensor <NUM>. At the same time, the supporting element <NUM> is specifically configured as thermally coupling element, that is the pyranometer housing <NUM> (particularly the first portion <NUM>) is thermally coupled to the radiation sensor <NUM> (or to the housing <NUM> of the radiation sensor <NUM>) by means of the supporting element <NUM>. Accordingly, a heat flow can be exchanged between the pyranometer housing <NUM>, particularly the first portion <NUM> of the pyranometer housing <NUM>, and the radiation sensor <NUM> by means of the supporting element <NUM>.

In summary, the radiation sensor <NUM> is electrically isolated from the pyranometer housing <NUM> and simultaneously thermally coupled to the pyranometer housing <NUM>, particularly to the first portion <NUM> by at least one supporting element <NUM>, wherein the supporting element <NUM> is connected to the pyranometer housing <NUM> and it is configured to support the radiation sensor <NUM>. Accordingly, the supporting element <NUM> is configured to support the radiation sensor <NUM> (or the radiation sensor housing <NUM> containing the radiation sensor <NUM>) on the pyranometer housing <NUM>.

Particularly, the supporting element <NUM> may comprise, or it may be at least partially made of any suitable material having electrically isolation properties and simultaneously having thermal conduction properties. Particularly, the supporting element <NUM> may comprise, or it may be at least partially made of, any suitable metallic or nonmetallic electrically isolating and thermally conducting material.

Specifically, the supporting element <NUM> comprises or is at least partially made of, a ceramic material. For example, the ceramic material may be aluminum nitride. Specifically, the supporting element <NUM> may have at thickness of about <NUM>. The supporting element <NUM> may have a heat conductivity equal to, or greater than, about <NUM> W/(mK).

According to an aspect, the supporting element <NUM> comprises, or is a printed circuit board (PCB). The printed circuit board may be thermally coupled to the radiation sensor <NUM> through the same supporting element <NUM>.

Particularly, the supporting element <NUM> may mechanically support and electrically connect to each other one or more electrical or electronic component(s) <NUM>. The one or more electrical or electronic component(s) may be arranged on the second (bottom) surface <NUM> of the supporting element <NUM>, that is the electrical or electronic component(s) may be arranged on the surface opposite to the first surface <NUM> of the supporting element <NUM> where the radiation sensor <NUM> is supported.

Specifically, the supporting element <NUM> may comprise on the second surface <NUM> one or more conductive track(s), pad(s) and other features etched from one or more sheet layers of conductive material (i.e. copper) that is laminated onto and/or between sheet layers of a non-conductive substrate. The one or more electrical or electronic component(s) of the printed circuit board may be operatively connected to the radiation sensor <NUM>.

At least one temperature sensor, particularly a thermistor, may be located on the second surface <NUM> of the supporting element <NUM>. The temperature sensor may be in direct contact with the supporting element <NUM> so as to be thermally coupled to the radiation sensor <NUM> that is located on the first surface <NUM> of the supporting element <NUM>.

As shown in <FIG> and <FIG>, the pyranometer <NUM> may comprise a centering element <NUM>. The centering element <NUM> may be configured to substantially, at least partially, enclose the radiation sensor <NUM>. Particularly, if the radiation sensor <NUM> is enclosed into a radiation sensor housing <NUM>, the centering element <NUM> may be configured to substantially, at least partially, enclose the radiation sensor housing <NUM>.

Particularly, the centering element <NUM> may include a through opening <NUM> provided in supporting portion <NUM> of the centering element <NUM>. The through opening <NUM> may have a shape that is substantially complementary to the external shape of the radiation sensor <NUM> (or of the external shape of the radiation sensor housing <NUM>), so as to enclose the radiation sensor <NUM> within the through opening <NUM> of the supporting portion <NUM>. For example, the through opening <NUM> may be circularly shaped, particularly if the radiation sensor <NUM> has a substantially cylindrical shape.

The centering element <NUM> may comprise a base portion <NUM>. Particularly, the base portion <NUM> may substantially be shaped as a flange. The base portion <NUM> may be configured to directly, or indirectly, contact the supporting element <NUM>, particularly the first surface <NUM> of the supporting element <NUM>.

The centering element <NUM> may be connected to the radiation sensor <NUM> and to the pyranometer housing <NUM>. Particularly, the base portion <NUM> of the centering element <NUM> may be removably coupled to the supporting element <NUM> of the pyranometer housing <NUM>, and/or the supporting portion <NUM> of the centering element <NUM> may be removably coupled to the radiation sensor <NUM>.

Particularly, the radiation sensor <NUM> may be tightly fit in the through opening <NUM> of the supporting portion <NUM> of the centering element <NUM>, while the base portion <NUM> of the centering element <NUM> may be configured to directly contact the first surface of the supporting element <NUM>. Particularly, the base portion <NUM> of the centering element <NUM> may be coupled to the first surface <NUM> of the supporting element <NUM> by adhesive.

Specifically, the centering element <NUM> may be configured to substantially center the radiation sensor <NUM> or the first portion <NUM> of the housing <NUM> with respect to a longitudinal axis X1 of the dome <NUM> of the pyranometer <NUM>, and/or with respect to a longitudinal axis X3 of the diffusor <NUM>. In other words, the centering element <NUM> is configured to align a longitudinal axis X2 of the radiation sensor <NUM> (or a longitudinal axis X41 of the first portion <NUM> of the housing <NUM>), with the longitudinal axis X3 of the diffusor <NUM>, and/or with a longitudinal axis X1 of the dome <NUM>.

The centering element <NUM> may be provided with a centering groove <NUM>. The centering groove <NUM> may be configured to enclose a corresponding centering protrusion <NUM>, the latter provided on the radiation sensor <NUM>. Particularly, the centering protrusion <NUM> may protrude, substantially in a radial direction, by the radiation sensor <NUM> (or by the housing <NUM>) and it may be dimensioned so as to match with or correspond to the centering groove <NUM>. In other words, the centering protrusion <NUM> may be integrally enclosed in the centering groove <NUM>. Specifically, the matching between the centering groove <NUM> and the centering protrusion <NUM> provides a guidance to the alignment, and subsequent coupling, between the centering element <NUM> and the radiation sensor <NUM>.

The centering element <NUM> may be configured to electrically isolate the radiation sensor <NUM> from the pyranometer housing <NUM>. In other words, the centering element <NUM> may be specifically configured as electrically isolating element, that is the centering element <NUM> does not allow any direct passage of electrical current between the pyranometer housing <NUM> and the radiation sensor <NUM>.

The centering element <NUM> may comprise, or it may be at least partially made of any suitable material having electrically isolation properties. Particularly, the centering element <NUM> may comprise, or it may be at least partially made of, any suitable metallic or nonmetallic electrically isolating material.

More particularly, the centering element <NUM> may comprise, or may be at least partially made of, a resilient material. Further particularly, the centering element <NUM> may be made of a thermoplastic, or thermosetting, polymeric material.

As shown in <FIG>, the pyranometer <NUM> may comprise at least one heating element <NUM>. The heating element <NUM> may be arranged to heat the pyranometer housing <NUM>, particularly the first portion <NUM> and/or the second portion <NUM> of the pyranometer housing <NUM>.

Particularly, the heating element <NUM> may be arranged to at least partly contact the perimetral wall <NUM> of the first portion <NUM> of the pyranometer housing <NUM>. Accordingly, the first portion <NUM> of the pyranometer housing <NUM> may be heated by contact by means of the heating element <NUM>.

Alternatively, or additionally, the heating element <NUM> may be also arranged to at least partly contact an inner surface of the cavity <NUM> of the second portion <NUM> of the pyranometer housing <NUM>. Accordingly, the second portion <NUM> of the pyranometer housing <NUM> may be heated by contact by means of the heating element <NUM>.

The heating element <NUM> may comprise at least one thermal conductive foil. The thermal conductive foil may be made of polyamide. Particularly, the heating element <NUM> may be arranged in and/or coupled to an inner cavity of the pyranometer housing <NUM>, particularly the an inner cavity <NUM> of the second portion <NUM> of the pyranometer housing <NUM>, and/or on the perimetral wall <NUM> of the first portion <NUM> of the pyranometer housing <NUM>.

Due to the thermal contact between the heating element <NUM> and the first portion <NUM> and/or the second portion <NUM> of the pyranometer housing <NUM>, the first portion <NUM> and/or the second portion <NUM> may be heated by contact by the heating element <NUM>. The dome <NUM> can be also heated by the heating element <NUM> as a result of the thermal coupling between the second portion <NUM> of the pyranometer housing <NUM> and the dome <NUM>. The radiation sensor <NUM> is also heated by the heating element <NUM> by means of the supporting element <NUM>, the latter being thermally coupled to the first portion <NUM> of the pyranometer housing <NUM>. In other words, the radiation sensor <NUM> may be also heated through the supporting element <NUM>. The latter thermally couples the radiation sensor <NUM> to the pyranometer housing <NUM>, e.g. the first portion <NUM>, that is (particularly directly) heated, by contact, by the heating element <NUM>.

Additionally or alternatively, the dome <NUM> may be heated by the heating element <NUM>, particularly as a result of the thermal connection (thermal contact) between the dome <NUM> and the pyranometer housing <NUM>, e.g. the second portion <NUM>.

The heating element <NUM> may be or comprise at least one heating foil and/or flexible heater. The heating foil may be a heating foil comprising, or being made of, a polymeric material. For example, the heating foil may comprise, or it may be made of Polyester or Polyamide. The flexible heater may be a chemically etched, screen printed and/or wire wound heater which can be flexed or bent or deformed to substantially conform to the contours of the surface of the pyranometer housing <NUM> which is to be heated. The flexible heater may be or comprise a silicone rubber heater (etched and/or wire wound), a Polyimide/Kapton® Film heater, a carbon printed heater, and/or a transparent heater.

Specifically, the heating foil may be arranged to at least partly, specifically substantially completely wrap or cover the perimetral wall <NUM> of the first portion <NUM> of the pyranometer housing <NUM>. The heating element <NUM> may be controlled by the control unit <NUM>.

Particularly, the pyranometer <NUM> may further comprise at least one thermal conductive foil (not illustrated). The thermal conductive foil may be arranged between the radiation sensor <NUM> and the pyranometer housing <NUM>.

According to an aspect, a method of assembling a pyranometer <NUM> is disclosed.

The method of assembling the pyranometer <NUM> comprising a step of providing a pyranometer housing <NUM>. The method further comprises a step of mounting a radiation sensor <NUM> to the pyranometer housing <NUM> such that the radiation sensor <NUM> is electrically isolated from the pyranometer housing <NUM> and thermally coupled to the pyranometer housing <NUM> by means of at least one supporting element <NUM> configured to support the radiation sensor <NUM>.

The method of assembling the pyranometer <NUM> may further comprise a step of mounting a diffusor <NUM>, particularly mounting a diffusor <NUM> on the pyranometer housing <NUM> (specifically on the first portion <NUM> of the pyranometer housing <NUM>), wherein the diffusor <NUM> is arranged to diffuse light external to the pyranometer <NUM> on the receiving surface <NUM> of the radiation sensor <NUM>.

The method of assembling the pyranometer <NUM> may further comprise a step of locating the radiation sensor <NUM> into the radiation sensor housing <NUM>, and mounting the radiation sensor housing <NUM> on the supporting element <NUM>.

The method of assembling the pyranometer <NUM> may further comprise a step of mounting a dome <NUM> on the pyranometer housing <NUM> such that the dome <NUM> and the pyranometer housing <NUM> are thermally coupled.

The method of assembling the pyranometer <NUM> may further comprise a step of mounting a centering element <NUM> on the radiation sensor <NUM>, and mounting an assembly formed by the radiation sensor <NUM>, the supporting element <NUM> and the centering element <NUM> on the pyranometer housing <NUM>, specifically in the cavity <NUM> of the first portion <NUM> of the pyranometer housing <NUM> such that the longitudinal axis X2 of the radiation sensor <NUM> is substantially aligned with a longitudinal axis of the dome X1 and/or with a longitudinal axis X3 of the diffusor <NUM>, and/or with a longitudinal axis X41 of the first portion <NUM> of the pyranometer housing <NUM>.

Claim 1:
A pyranometer (<NUM>) comprising:
a pyranometer housing (<NUM>);
a radiation sensor housing (<NUM>); and
at least one radiation sensor (<NUM>) located in the radiation sensor housing (<NUM>), wherein the at least one radiation sensor (<NUM>) comprises a thermopile-based sensor, and wherein the radiation sensor housing (<NUM>) comprises, or is made of, a metallic material;
wherein the at least one radiation sensor (<NUM>) is electrically isolated from the pyranometer housing (<NUM>) and thermally coupled to the pyranometer housing (<NUM>) by at least one supporting element (<NUM>),
wherein the supporting element (<NUM>) is connected to the pyranometer housing (<NUM>) and is configured to support the radiation sensor housing (<NUM>), wherein the radiation sensor housing (<NUM>) is configured to at least partially contact a first surface (<NUM>) of the supporting element (<NUM>), wherein the supporting element (<NUM>) comprises, or at least partially is made, of a ceramic material to enable electrical isolation and such that a heat flow is exchanged between the pyranometer housing (<NUM>) and the radiation sensor housing (<NUM>) by means of the supporting element (<NUM>).