IMPROVED SOLAR PANEL AND AIR HEATING AND HEAT RECOVERY VENTILATION SYSTEM

Abstract: An air heating and heat recovery ventilation system comprise on or more solar panels (1, 1') for absorbing and collecting energy from the sun during daylight hours, an energy processing unit (50) for combining and distributing energy from different sources; a boiler (10) which is interlinked to the system via the energy processing unit (50), an air distribution system and air handling unit (105) which allows for heat to be distributed throughout a house via a network of conduits and a control means which provides a means for co-ordinating and controlling all the components and functions of the system. The solar panel (1) has a solar radiation transmitting cover (7) and a reflective base held in spaced apart relationship by side end members (1a, 1b), a solar radiation absorber (6) within the housing, inlet means enabling fluid to enter the absorber at one end of the housing, and outlet means enabling the fluid to exit from the absorber at an opposite end of the housing. The cover (7) is a sheet of glass, the underside of which has a "low E" coating. The cover (7) may also be spaced apart from the solar radiation absorber (6) and an air gap is provided between the cover (7) and absorber (6).

Description: IMPROVED SOLAR PANEL AND AIR HEATING AND HEAT RECOVERY VENTILATION SYSTEM The present invention relates to improved solar panels and an air heating and heat recovery ventilation system. The invention relates particularly to solar panels of the type which comprise a housing, a cover on the housing which transmits incident solar radiation into the housing, a solar radiation absorber in the housing, and air inlet and outlet ports to enable air to be circulated through the panel to collect heat from the panel. Known solar panels are of the type described in EP-A-0 384 787. An object of the present invention is to provide a more efficient solar panel and a more efficient air heating and heat recovery ventilation system. The features of the invention will be apparent from a consideration of the attached Claims 1 to 13. The present invention accordingly provides a solar panel, comprising an elongate housing including a solar radiation transmitting cover and a reflective base held in spaced apart relationship by side end members, a solar radiation absorber within the housing, inlet means enabling fluid to enter the absorber at one end of the housing, and outlet means enabling the fluid to exit from the absorber at an opposite end of the housing; characterised in that the solar radiation transmitting cover comprises a sheet of glass, the underside of which has a "low E" coating (i.e. a coating which has a low emittance value). Preferably, the cover is spaced apart from the solar radiation absorber and an intermediary layer is located therebetween, the intermediary layer including an air gap spaced from the cover. Preferably, the intermediary layer includes a layer of polytetrafluorethene (PTFE) . The present invention also provides an air heating and heat recovery ventilation system comprising (a) one or more solar panels for absorbing and collecting energy from the sun during daylight hours; (b) an energy processing unit for combining and distributing energy from various different sources; (c) a boiler (typically a gas, oil, solid fuel or electric boiler) which is interlinked to the system via the energy processing unit; (d) a control means which provides a means for co-ordinating and controlling all the components and functions of the system; (e) an air distribution system which allows for heat to be distributed throughout the house via a network of conduits. The invention will now be described more particularly with reference to the accompanying drawings in which are shown, by way of example only, two embodiments of the invention. In the drawings: Figure 1 is a sectional view of a solar panel of the present invention; Figure 2 is a sectional view of a second embodiment of the solar panel of the present invention; Figure 3 is a schematic view of the components of an heating and heat recovery ventilation system of the invention including a solar panel as shown in Figure 1 or Figure 2 shown operating in "solar" mode; Figure 4 is a schematic view of the air heating and heat recovery ventilation system shown operating in semi-solar mode; Figure 5 is a schematic view of the air heating and heat recovery ventilation system operating in "boiler" mode; Figure 6 is a schematic view of the heat recovery and ventilation unit used in the air heating and heat recovery ventilation system shown in Figures 3, 4 and 5; Figure 7 is a schematic view of the air handling unit used in the system shown in Figures 3, 4 and 5; Figure 8 is a schematic view of the heat recovery and ventilation system in a second embodiment of the invention; and Figure 9 is a detailed schematic view of the heat recovery and ventilation system in the second embodiment showing the energy processing unit (EPU). In the drawings, like features are identified by like numerals. Referring to Figure 1 of the drawings, the solar panel 1 of the invention fits within a rectangular space frame constructed from timber members 1a, lb. A sheet of plasterboard 4 with a foil backing is provided beneath the timber frame. Next is a layer of long strand fibreglass 3; and a solar radiation absorber 6, comprising a matrix of glass fibre which is bonded by a phenol formaldehyde resin or melamme resin. A housing cover 7 is fitted to the top of the unit and comprises a sheet of toughened glass, with a coating applied on its underside. The coating has a low emittance ("low E") value. The solar panel also has a cover retention means comprising aluminium extrusions and silicone gaskets (not shown) and a series of air inlet ports (not shown) across one end of the panel, and a series of air outlet ports (not shown) across the other end of the panel to allow for circulation of air through the solar panel. Referring now to Figure 2, the solar panel in an alternative embodiment the invention is indicated generally by the reference numeral 1 ' . The solar panel 1 ' includes the features of the solar panel 1 in addition to a layer of PTFE 10 over the absorber 6, an air gap 11 preferably in the range 15-40 mm, between the PTFE layer 10 and the housing cover 7, thus in effect creating a "double glazed" solar panel. In operation, during daylight hours, direct or diffuse solar radiation falling on the housing cover 7 is transmitted through the housing cover 7 with the "low E" coating provided on the underside thereof, through to the solar radiation absorber 6. The absorber 6 is of very open construction and the radiation passes down through the volume of air which permeates the absorber, and undergoes multiple reflections off the surface of the absorber material and also off the upper surface of the foil backing on the plasterboard and the "low E" coating on the undersurface of the housing cover 7. in this manner the radiation gives up its energy, warming the volume of air with the solar panel 1, 1'. Air enters the inlet ports at one end of the solar panel 1 , 1 ' passes through the absorber 6 where it is heated, and leaves through ports at the other end of the solar panel 1 , 1 ' . The air passing along the solar panel is widely and evenly distributed across the full width and height of the panel, resulting in uniform flow which gives maximum heat collection, and minimum pressure drop. In operation, during night hours, when there is no incident solar radiation, the solar panel 1 , 1 ' may be operated in an alternative mode in which air at a temperature lower than the ambient outdoor air temperature is circulated through the solar panel 1 , where it is heated by thermal conduction through the housing cover 7, and the heat thus collected may be transferred to a heat store. Referring specifically to the solar panel 1 ' of the second embodiment, the advantage of including the air gap 11 is that it results in the provision of a "double glazed" solar panel 1 ' which has an extremely low coefficient of thermal conductivity value. An equation for indicating the overall effectiveness of a solar panel is as follows: Total heat loss = U τ collector efficiency The typical value for the prior art solar panels is 11 whereas the typical value of the double glazed solar panel 1' is 4.5. This indicates that the solar panel 1 ' is much more effective than the prior art type of panel. The solar panel 1 has a level of effectiveness between these two values. Referring now to Figure 3, the air heating and heat recovery ventilation system including the solar panels 1 will be described. The system includes solar panels 1 or 1 ' for absorbing and collecting energy from the sun during daylight hours and an energy processing unit indicated generally by reference numeral 50. The energy processing unit 50 comprising an air handling unit 105 and a heat recovery ventilation unit 110 is usually located in the attic of a house and combines and distributes energy from various different sources. The system also includes a boiler 100 which is interlinked to the system via the energy processing unit 50. A control means (not shown) provides a means for co-ordinating and controlling all the components and functions of the system. An air handling un t, indicated generally by reference numeral 105 is also provided which allows for heat to be distributed throughout the house via a network of conduits. The air handling unit 105 comprises a four chamber housing 106, the first chamber 111 being the fresh air intake chamber and has a damper 171 to control and stop the intake of fresh air, a second chamber 112 being the chamber which directs air to the solar panel 1 and housing the fan 153 to force air through the system; a third chamber 113 being the chamber which receives air returning from the solar panel 1 and has a damper 170 to control and stop the flow of air from the solar panel 1 ; and a fourth chamber 11 being the chamber which directs heated air to the house and having the air-to-water heat exchanger 151. The damper 171 is movable between an open and closed position. In the closed position it blocks the air intake into the unit and allows communication between the first and fourth chambers 111 and 114 through orifice 130. The damper 170 is movable between an open and closed position. In the closed position, it blocks the air flow from the solar panel 1 and allows communication between the second and third chambers 112 and 113 through orifice 135. The heating system includes a high output radiator or booster 180 which can be used when a high heat output is required in a short time. The air heating and heat recovery ventilation system can be operated in several different modes, namely, "solar" mode in which the system can rely on solar energy and can be used to deliver hot water with or without heating the house; "semi-solar" in which the system can be operated in the solar mode when there is sufficient solar energy for it to do so and in which heat can be added to from the boiler; and "boiler" mode in which the system relies entirely on the boiler to supply the required heat to the house as well as hot water in the domestic hot water supply. Referring to Figure 3, the operation of the system in "solar mode" will now be described. This mode is applicable m Spring, Summer and Autumn. In the summer, when there is an abundance of solar energy, the system of the invention can be used to provide hot water from the domestic hot water supply without actually heating the house. The electronic control system ensures that when the house has reached a desired pre-set temperature, the system delivers no more energy to the house. During late Spring and early Autumn when the house requires moderate amounts of energy to heat it, the system will operate in solar mode, as shown in Figure 3, transferring heat into the house and also heating water m the domestic hot water cylinder 120. When the system is operated in solar mode, air is forced to flow over the solar panel 1 under the action of the fan 160 in the heat recovery ventilation unit 110. This results in the temperature of the air increasing from 20°C to 70°C This heated air is forced to flow to the air handling unit 105, where with damper 170 open, the heated air passes over the air-to-water heat exchanger 151 This results in the heat being transferred from the heated air to the water in the heat exchanger 151 so that heated water emerges from the heat exchanger 151 Th s hot water, at 60°C, is pumped to the coil in the domestic hot water cylinder 120 which results in the provision of a cylinder of hot water. In the meantime, the warm air exiting from the heat exchanger 151 is forced throughout the house under action of fan 153 in the air handling unit 105, provided the house requires heat The warm air is fed through the ducting system into all of the rooms via air diffusers 57a, 57b in the ceilings. Air is also removed from the house and is forced to flow over the heat recovery ventilation unit 110 (see Figure 6) under action of fan 160 in order to transfer its heat to the fresh air being brought into the house via conduit 155 (air-to-air heat exchange). This fresh air is forced by fan 153 in the heat recovery ventilation unit 110 to the solar panels 1 to start the cycle again. The system of the invention can also be operated in semi-solar mode. This will be described with reference to Figure 4 During winter the air heating and heat recovery ventilation system of the invention can be operated so as to take advantage of whatever solar energy is available. On very bright Winter days the system will operate in "solar" mode as described above with reference to Figure 3 while there is sufficient solar energy available for it to do so. In bright but cloudy conditions, the system will operate in a semi-solar mode as will be described below. In the semi-solar mode, the house is heated partially by way of solar energy and this can be supplemented by an oil or gas fired boiler 100. This semi-solar mode would only be operational if the boiler 100 is switched on during the day-time. If the boiler 100 is not switched on, the system will attempt to keep the temperature in the house as close as possible to the pre-set temperature which has been programmed into the control panel. In this mode, the air is circulated in the same route as in the solar mode described above except that in the semi-solar mode, heat is added to the air by way of hot water from the boiler 100 which is pumped to the air to water heat exchanger 151. When the system is operating in this "semi solar" mode, the solar collectors 1 are only raising the temperature of the air from 20°C to 30°C. It is the boiler 150 that makes the air hotter i.e. to 55°C. In this mode the water in the domestic hot water cylinder is also heated. The system of the invention can also be operated in "boiler" mode. This will be described with reference to Figure 5. In Winter, particularly during late November, December and January, there will be very dark, dull days during which the system relies on the boiler 100 to supply the required heat to the house as well as hot water. The "boiler" mode is also used at night time to supply heat to the house if it is required. In "boiler" mode, no air is directed by fan over the solar panels 1. Fresh air from the outside atmosphere, is fanned over the heat recovery ventilation unit 110 to remove heat from the "stale" air being fanned out of the house. The fresh air is then directed to the air handling unit 105 from which it is fanned to the air to water heat exchanger 151. The air-to-water heat exchanger 151 is being heated by hot water pumped from the boiler 100. The air leaves the heat exchanger at about 55° typically - it can be hotter or cooler depending on the water temperature setting of the boiler 100. This warm air is then fanned through the ducting system to each air diffuser in every room of the house. Stale air is fanned over the heat recovery ventilation unit 110 where its heat is recovered and conducted to the incoming fresh air prior to being extracted out of the house. The fresh air, with the recovered heat from the stale air, is fanned to the air handling unit 105 to begin the cycle again. Referring now to Figure 8, an alternative air heating and heat recovery ventilation system including the solar panels 1 will be described. The system comprises solar panels 1 , an energy processing unit indicated generally by reference numeral 50', a boiler 100', a control means (not shown) which provides a means for co-ordinating and controlling all the components and functions of the system and an air distribution system indicated generally by reference numeral 105', which allows for heat to be distributed throughout the house via a network of conduits. The heating system includes a high output radiator 180' which can be used when a high heat output is required in a short time. Referring now to Figure 9, the energy processing unit 50' and its operation in the second embodiment of the system of the invention will be described in more detail. The energy processing unit comprises a conduit 55 for bringing warm air from the solar collectors 1 to the energy processing unit, an air/water heat exchanger 51, a conduit 56 for carrying water from the energy processing unit to around the house, dampers 52,54 for controlling the direction of air flow, a conduit 57 for carrying air to supply the house and a conduit 58 for carrying air extracted from the house to the fan 53 and a conduit 59 for carrying air from the energy processing unit back to the solar collectors 1. The energy processing unit also includes a heat recovery unit 60 which comprises an air/air heat exchanger. The heat recovery unit 60 is linked to the energy processing unit via conduits 61,62 and air from atmosphere can enter the unit 60 via conduit 63 and air exits from the unit 60 to atmosphere via conduit 64. The air/air heat exchanger is a cross flow type heat exchanger made up of aluminium plates across which heat exchange occurs between warmer and cooler air streams. Heated air collected by the solar panels 1 is pumped into the energy processing unit 50' via conduit 55 and enters an air/water heat exchanger 51 where the heat energy from the air is transferred to the cooler water in the heat exchanger 51, thereby warming the water in the heat exchanger 51. Depending on the direction in which the damper 52 is open, the air emerging from the heat exchanger may (a) when the damper 52 is in the horizontal position as shown in Figure 9 be directed towards conduit 57 which leads to two vents 57a and 57b through which warm air emerges to supply the house; or alternatively, (b) when the damper 52 is in the vertical position as shown in Figure 9 it will result in the warm air stream emerging from the heat exchanger 51 being directed towards the fan 53. The fan 53 directs the air stream towards the damper 54. Again, depending on the direction in which the damper 54 is open, the air stream may be directed either (c) when the damper 54 is in the horizontal position as shown in Figure 9, towards conduit 59 leading from the energy processing unit 50' to the solar collectors 1 ; or (d) when the damper 54 is in the vertical position as shown in Figure 4, no air is being supplied to the solar collector 1 , therefore no significant heat is being collected from the collectors 1. In this case, the heat exchanger 51 may be used to heat air which is directed through conduit 57. The direction of the dampers 52,54 respectively effectively controls the temperature of water and air supplied to the house since for example in option (c), warm air entering from the solar collectors 1 will obviously result in warmer water emerging from the heat exchanger 51. When the fan 53 is operating, air in the system is continuously being refreshed through conduits 63 and 62 with a feed of fresh air, with approximately 10% of air being dumped to atmosphere through conduits 61 and 64 which provide the bleeding of air from the system at generally the same rate as the feed of air. Warm water which emerges from the heat exchanger 51 is carried from the energy processing unit 50 via conduit 56. This warm water can be pumped to the standard household hot water cylinder 120 via conduit 106. Water emerging from the cylinder 120 is carried via conduit 107. Alternatively, if the water emerging from the energy processing unit 50 is not hot enough for household use, it can be pumped to the boiler 100 where it is heated and then subsequently pumped to the cylinder 120. Air is extracted from the house via extractor unit 58a and enters the fan 53 in the energy processing unit 50. The control means used to or-ordinate and control the components and functions of the embodiments of the invention is not described in detail as it can be one of a number of control devices currently available on the market for heating and ventilation systems. Typically, it will include a control panel for use by the user, one or more thermostats throughout the house, a programmable logic controller, various transducers and relays for opening and closing valves and dampers and generally controlling the electrically operated components of the system. It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the appended claims.

Claims: CLAIMS : 1. An air heating and heat recovery ventilation system comprising one or more solar panels for absorbing and collecting energy from the sun during daylight hours; an energy processing unit for combining and distributing energy from different sources; a boiler which is interlinked to the system via the energy processing unit; a control means which provides a means for co-ordmatir.g and controlling all the components and functions of the system; and an air distribution system which allows for heat to be distributed throughout a house via a network of conduits. 2. An air heating and heat recovery ventilation system according to Claim 1 , characterised in that the energy processing unit includes an air handling unit which comprises an air-to-water heat excr.anger and means for forcing the heated air from the solar panels through the heat exchanger, thereby transferring heat to water in the domestic hot water supply system; and forcing warm air emerging from the heat exchanger to flow around the house. 3. An air heating and heat recovery ventilation system, as claimed in Claim 2, in which the air handling unit includes an air-to-air heat exchanger for extracting heat from air returning from t÷he house. 4. An air heating and heat recovery ventilation system as claimed in Claim 3, m which the air returning from the house flows through a conduit which is separate from the conduit conducting heated air to the house and means are provided to expel all the air returning from the house after it has passed through the air-to-air heat exchanger. 5. An air heating and heat recovery ventilation system as claimed in Claim 3, in which the air returning from the house flows through a conduit which provides for mixing with fresh air entering the system and means are provided to expel a portion of the mixed air after it has passed through the air-to-air heat exchanger. 6. An air heating and heat recovery ventilation system as claimed in any one of Claims 2 to 5, in which the energy processing unit comprises a four chamber housing, the first chamber being the fresh air intake chamber and having means to control and stop the intake of fresh air, a second chamber being the chamber which directs air to the solar panel and having a fan to force air through the system; a third chamber being the chamber which receives air returning from the solar panel and having means to control and stop the flow of air from the solar panel; and a fourth chamber being the chamber which directs heated air to the house and having the air-to-water heat exchanger. 7. An air heating and heat recovery ventilation system as claimed in Claim 6, in which the control means in the first chamber comprises a first damper movable between an open and closed position, the damper in the closed position blocking the air intake into the unit and allowing communication between the first and fourth chambers, and in which the control means in the third chamber comprises a second damper movable between an open and closed position, the damper in the closed position blocking the air flow from the solar panel and allowing communication between the second and third chambers. 8. An air heating and heat recovery ventilation system as claimed in Claims 6 and 7, in which the boiler is operable to provide hot water to the air-to-water heat exchanger in the fourth chamber of the energy processing unit, whereby the air being directed to the house can be heated by the heat exchanger. 9. A solar panel, comprising an elongate housing including a solar radiation transmitting cover and a reflective base held in spaced apart relationship by side end members, a solar radiation absorber within the housing, inlet means enabling fluid to enter the absorber at one end of the housing, and outlet means enabling the fluid to exit from the absorber at an opposite end of the housing, characterised in that the solar radiation transmitting cover comprises a sheet of toughened glass, having a coating applied on its underside, the coating having a low emittance ("low E") value. 10. A solar panel according to Claim 9, characterised in that the cover is spaced apart from the solar radiation absorber and an intermediary layer is located therebetween, the intermediary layer including an air gap spaced from the cover. 11. A solar panel according to Claim 10, in which a layer of transparent sheeting is spaced from the cover to define the said air gap, so as to provide a "double glazed" solar panel collection. 12. A solar panel according to Claim 11, in which the layer of transparent sheeting comprises a layer of polytetrafluorethene (PFTE) . 13. An air heating and heat recovery ventilation system as claimed in any one of Claims 1 to 8 and including a solar panel as claimed in any one of Claims 9 to 12.

Inventors: QUIGLEY WILLIAM, QUIGLEY, WILLIAM
Applicants: KOLLECTAIRE TECHNOLOGY LIMITED, QUIGLEY WILLIAM, QUIGLEY, WILLIAM
Application year: 1996
Main classification: F24D19
IPC codes: F24D5, F24D19, F24J2