GB2458639A

GB2458639A - Solar alignment device

Info

Publication number: GB2458639A
Application number: GB0805326A
Authority: GB
Inventors: Roy Trevor Ince
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-03-25
Filing date: 2008-03-25
Publication date: 2009-09-30
Anticipated expiration: 2028-03-25
Also published as: GB2458639B; GB0805326D0

Abstract

A solar alignment device comprises a control box 12 with lens assemblies 2 and 14, and is secured to a solar panel 16. The sunbeam lens assembly 2 forms a thin planar beam of light which passes into a darkened chamber 10 and is detected by a light dependent resistor LDR 11, which in turn controls the motor aligning the solar panel with the sun. Each small angular movement will stop the sunbeam 13 passing through lens assembly 14 onto the LDR 11. This activates the circuit on light operated printed circuit boards LSPCB 9 to switch "on" motor 17 and then switch it "off" again when the panel faces the sun. The lens 14 is preferably a convex lens and two elongate convex shielding members may be provided to form the light from the lens 14 into a narrow slit. A daylight lens assembly 2 may be included such that when clouds block the sunshine the darkened side of a glass bulb 15 casts a shadow over light tube 3 and LDR 4 that activates LSPCB 7 to stop the panel just as it passes the brightest position in the sky. The panel is automatically readjusted to the sun when it shines again.

Description

SOLAR ALIGNMENT DEVICE

TECHNICAL FIELD OF THE INVENTION

This invention relates to solar alignment devices.

BACKGROUND

When a solar panel is fitted to a house, the best position for the absorption of the suns energy is on a south facing slope of a pitched roof If the panel is secured in this static position, it can only receive the full benefit the sun's power when the sun reaches its meridian. This means that at all other times the energy received by a statically installed solar panel is diminished and the temperature of the hot water will be considerably less compared to midday.

Using a solar tracking device to align a solar panel with the sun is not new. Slovenjan patent specification SI 21 861 A discloses a tracking device which includes two solar energy detectors mounted on opposite sides of a partition wall. When the wall is aligned with the sun the output of the sensors will be substantially equal, but mis-alignment causes a motor to move the panel until the two signals are equal again.

The present invention seeks to provide a new and inventive form of solar alignment device which is simple and inexpensive yet is capable of aligning a solar panel with the sun extremely accurately and smoothly, with little or no lag between movement of the sun and re-alignment.

SUMMARY OF THE INVENTION

The present invention proposes a solar alignment device having a sunbeam lens assembly which is arranged to form a thin planar beam of sunlight which passes into a darkened chamber to illuminate an electronic fight detector when the device is aligned with the sun, and the detector is arranged to control a motor which turns the device, such that the motor is deactivated when the device is aligned with the sun.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Ejqijre 1 is a somewhat diagrammatic representation of a solar alignment device in accordance with the invention shown in a Condition in which the device is aligned with the sun; Figure 2 is a similar diagram of the solar alignment device in a condition in which the sun has moved round to the west; figure 3 is another similar diagram of the solar alignment device under low light conditions;

A

Figure 4 shows a practical configuration of the solar alignment device and the position in which the device is mounted on a solar panel; Figure 5 is a general view of a solar panel which is controlled by the solar alignment device, mounted on a roof; Figure 6 is an end view of the solar panel as shown in Fig. 5; and Figure 7 shows three possible alternative configurations of the solar alignment device.

DETAILED DESCRIPTION OF THE DRAWINGS

The solar alignment device described below includes a control box and two lens assemblies which are configured to monitor the sun's position in the sky. The slightest movement of the sun as it arcs westwards above the lens assemblies wi!I change the level of light faHing on light sensitive electronic components. These variations operate a low voltage dc motor to keep the collecting face of a thermal solar panel aligned with the sun.

The device may be used to control solar panels of the kind used to provide a Supply of hot water, but they may also be used with other kinds of panel such as those which use photovoltaic cells to produce electricity.

During the year and especially in the summer the panel will begin to heat water not long after sunrise in the morning, right through to late afternoon arid continue to heat water in the evening. Absorption of the sun's energy in this way will increase the supply of hot water for domestic use.

For the angular movement of the solar panel, two specially designed lens assemblies, the daylight lens assembly and the sunbeam lens assembly, are assembled into a purpose built control box which is secured to the frame of the solar panel so that the lens assemblies are facing the sun.

Each lens assembly activates its own electronic module, fitted inside the control box, and this activation switches the electric motor on and off to "step" the rotation of the motor, this ensures that the solar panel stays accurately in line with the sun as it moves westwards. The modules, which are printed circuit boards (PCBs), have separate light dependant resistors (LDRs) which are also mounted on their own miniature circuit boards. This enables the LDRs to be in a different position to the main PCBs so that they can be operated remotely and more importantly for present purposes, function independently. These light sensitive modules are normally used to switch on lights in the dark but for this circuit their wiring has been modified to make one of the modules switch on in the light for the correct alignment of the solar panel.

Referring firstly to Fig. 1, the solar alignment device includes a control box 12 mounted on a solar panel 16. The control box 12 contains two light sensing printed circuit boards (LSPCBs) 7 and 9 which are modified light detector modules originally designed to switch on lights when it is dark. However the operation of the modules is changed as described below to enable the alignment device to follow the sun very accurately.

Each modules has a miniature light dependent resistor (LOR), 4 and 11, which are each soldered to a small printed circuit board (PCB) allowing the LDRs to be located remotely from the main LSPCBs 7 and 9. Lens assemblies 2 and 14 mounted on the control box 12 are arranged to monitor the sun's angular movement, and this movement varies the amount of light shining on LDRs 4 and 11. LDRs are passive devices. A change of light intensity affects their resistance. In bright light their resistance is small, but in the dark or shade their resistance is high.

These variations operate the circuits on the main LSPCBs 7 and 9, to switch respective relays 28S arid 28D on and off, as described below.

The relays are arranged to control a 12 volt dc motor 17 which may be powered from a bank of trickle-charged batteries. The motor turns the solar panel 16, Fig.s 5 and 6, on very strong and substantial bearings 42 and 43 to rotate about longitudinal axis 44 in order to face the sun. The axis of rotation 44 is aligned generally in a north-south direction. Fig.s 5 and 6 also show how the solar panel 16 is secured to a south facing roof 47 and the gearing of the 1800 rack and pinion 48 which achieves the alignment rotation.

The LDRs 4, 11 and LSPCBs 7 and 9 are all mounted inside the control box 12 as shown in Fig. 4. LDRs 4 and 11 are mounted on top of partition 8 which forms a separate internal compartment 10 which is blackened to absorb reflected light. LSPCBs 7 and 9 are shown separately in Fig. 4 for clarity, but when mounted in the box 12 they are inverted through 1800 as inthcated by arrows R and mounted on the underside of the partition 8. Lens assemblies 2 and 14 are mounted on the top of the control box 12, with mirror faces 36 and light tube 3 positioned inside the enclosure. The LSPCBs 7 and 9 have various electronic components operated by a 12 volt dc supply 30 but for the purposes of this description the main components are LORs 4 and 11 and operational amplifiers (OPAMPS) 29S & 29D which are configured as fast-switching comparators to activate the switching relays 28S & 28D. An important characteristic of the OPAMPs is their ability to switch the relays on and off rapidly. This important feature, Iri Conjunction with the design of lens assemblies 2 and 14, prevents the 12 volt dc motor 17 from turning the solar panel 16 too far past the position of the sun as it travels in an arc across the sky.

Fig. 4 shows the LDR 11 positioned centrally on partition 8 at the bottom of compartment 10 The sunbeam lens assembly 14 has a convex lens or curved window 34 having a light-collecting face which is convex in a longitudinal direction. The convex tens 34 is surrounded by two side and two end plates which form a weatherproof cover, with inner mirrored surfaces, mounted over a strip lens (window) 35. Below the strip lens and within the compartment 10 are mounted two elongate shields 36, on opposite sides of the strip lens. The shields have convexly curved opposing mirrored surfaces, which mutually converge towards a narrow slit. This assembly is set centrally and upright on the top wall of the control box 12 to generate a narrow planar sheet of light 13 (a sunbeam) which is directed downwards inside the enclosure 10. As shown in Fig. 5, the control box 12 is mounted on the solar panel 16 with the sunbeam lens assembly 14 extending perpendicular to the collecting face of the panel and parallel to the axis of rotation of the panel, and preferably as close as possible to the axis of rotation. Fig. I shows the condition in which the LDR 11 is illuminated by the sunbeam lens assembly 14 when the lens assembly is aligned with the sun S. The sun light shining on LOR 11 minimises its resistance, OPAMP 29S deactivates relay 28S to the normally closed NC terminal 33. This opens the circuit through terminals 31 and 32 and stops the motor 17 so that the solar panel will stay in this position until the sun moves to the west. Fig. 2 shows the condition which occurs when the sun S has moved westwards. (The control box 12 has been omitted from Fig.s 2 and 3.) Since the sun is no longer on the plane of the lens assembly 14 the inside of enclosure 10 becomes darkened. The plate covering the right hand side plate (west) of the convex lens 34 has cast a shadow over LDR 11 To prevent any stray illumination of the LDR the blackened interior of compartment 10 absorbs any reflected daylight.

This shadow instantly maximises the resistance of LDR 11, so that OPAMP 29S activates relay 28S and switches from terminal 33 to the normally open (NO) position 31. This closes the circuit between terminal 31 and the common terminal 32 so that the motor 17 turns the solar panel 16 to face the sun The condition described in relation to Fig.s I and 2 is repetitive, enabling the sunbeam lens assembly 14 to track the sun very accurately These operations can only occur when the sun is shining, because sunbeam lens assembly 14 and its associated LSPCB 9 switches on the motor 17 as the enclosure 10 darkens. When the sun light is poor obscured by clouds or haze, it will tend to make the circuit run on", continuously trying to locate the sun in order to switch off. Fig. 2 shows that LSPCB 7 is incorporated in the motor circuit to prevent this "run on" occurrence The associated LDR 4 is also mounted inside the darkened enclosure 10 of control box 12 but is completely enclosed and isolated from the enclosure by light tube 3. Light entering by the daylight lens assembly 2 is collected by a circular concave reflector 24 mounted at the top of the light tube pointing vertically upwards. Above the reflector 24 is mounted a magnifying lens 23 and, above that, a flat lens (window) 22.

To the left hand side of the flat lens are two further reflectors 1 enclosed inside a weather protecting glass bulb 15 Both of the reflectors I are concave. The reflectors are arranged such that one of the reflectors faces to the west W. The other reflector faces down but will also face to the west when the panel is inclined towards the east. This arrangement ensures that on occasions when there is early morning cloud cover the daylight lens assembly will receive sufficient light for re-alignment of the panel to occur when light Conditions improve.

The daylight lens assembly 2 reactivates the motor circuit as the sun moves west, not only on a sunny day but also on a bright but cloudy day or when there is only light cloud cover over the sky. To obtain the correct operation of LSPCB 7 the 12 volt dc supply is connected to normafly closed (NC) terminal 27 of relay 28D. As shown in Fig. 2, during daylight, terminal 27 is connected to common terminal 26. By reversing the relay connections relative to LSPCB 9 the operation of relay 28D is changed such that it is deactivated to make the motor circuit in daylight and activated to break the motor circuit in the dark. Terminal 26 is connected to terminal 31 of relay 28S on LSPCB 9, and this link between the two modules controls this "run on" occurrence. "Run on" will cause the motor 17 to turn the panel westwards until a shadow forms over the top of light tube 3, created by the blackened east half of protective bulb 15, as illustrated in Fig. 3 The shadow on LDR 4 activates OPAMP 29D on LSPCB 7 to switch the relay 28D to the NO terminal 25. However because of the reversed connections this switches off the 12 volt dc supply to the motor 17. The accuracy of the daylight lens assembly 2 is not perfectly precise because the blackened east half of the protective bulb 15 (as the solar panel "runs on" westward) must pass the best source of light to throw a shadow over daylight lens assembly 2. However this operation is quite adequate due to the snap action of OPAMP 29D and the influence of the long shadow generated by the configuration of daylight lens assembly 2. In addition, LSPCB 7 is set to be extremely sensitive to a change of light. This sensitivity will also close down the motor circuit when light fails, but once the light improves the westward facing reflectors I of the daylight lens assembly 2 will reactivate the motor circuit causing the panel to follow the sun once again. Some time after sunset an electro mechanical circuit (not shown) rotates the solar panel to the east so that the alignment process will recommence as the sun rises in the morning. This system is fully automatic and operates throughout the year.

Fig. 7 shows possible alternative configurations of the control box and lens assemblies with the front of the box removed for clarity. In both the centre and left hand detail of the control box the sun beam lens assemblies 14 and the daylight lens assemblies 2 are mounted in the top-centre and west side of the control box respectively. A vertical partition isolates the darkened enclosure 10 from a light enclosure L which receives light from the daylight lens assembly 2. This enables the LDRs to function in exactly the same way as explained in the preceding paragraphs. The taller control box shown in the centre will be considerably more accurate than the shorter left hand control box, as indicated by the shadows M and N which are made with the sun S at the same angle. The longer shadow N wlI form very rapidly and will improve the operation of this taller box. A significant disadvantage of this design is that ai of the lens assemblies are exposed to the weather allowing rain drops to form over the lens assemblies and hinder their function. The right hand control box shows a similar arrangement with the LDR compartments and the LSPCBs mounted in separate boxes. The signal wires WS require very robust weather protection and must be well sealed to prevent moisture affecting the delicate electronics of the PCBs.

It will be appreciated that the configuration of the lens assemblies means that the forms of solar alignment device described above will not be sensitive to the height of the sun (the solar angle) which changes throughout the year. Seasonal variations in the height of the sun can have a large effect on the operation of a solar panel in the northern hemisphere so north-south alignment needs to be considered for even greater efficiency. The equipment required to adjust a solar panel to this solar angle would need to follow the sun up as well as down every six months, On the solar panel shown in Fig.s 5 and 6, the solar angle is adjusted every month using a manual switch and operated by a separate motor, but this function can be made to operate automatically using the same principle but with an additional circuit and motor to adjust the panel during the mid summer and mid winter periods.

Using LDRs in a circuit to track or follow the sun is not a new idea.

However a fundamental feature of this invention is that the solar panel, instead of turning to catch up with the sun, is kept in line with the sun due to the precise function of the lens assemblies. In the situation where a solar panel lags behind the sun and has to be actuated to catch up each time, energy is lost. This is because it spends time waiting to face the sun.

In the summer months the energy loss would not be significant; but it is not the same situation in the waning heat of the winter. During this time of the year it is imperative to absorb all of the sun's energy to maximise efficiency. The design of the two special lens assemblies intensifies the light or darkness passively this will instantaneously change the resistance of the LDRs to activate the components fitted to the PCBs. As a consequence this makes the LDRs extremely sensitive to each small angular change, as the sun arcs westwards, Instantly the level of the light changes the LDRs and this will the make the LSPCBs respond immediately, keeping the solar panel and the "shining sun" extremely well aligned.

So the function of this device is that of "a sun alignment circuit" rather than a sun following circuit. It achieves this because the LDRs are electrically wired to remotely control their own light sensitive printed circuit board (LSPCB) and are fitted inside a separate compartment in the purpose built control box. An LDR's electrical resistance changes; in the dark or shade the resistance is maximised, in the light the resistance is minimised. Changes to the resistance activate electronic components on the PCBs for the low voltage dc rotating motor to switch on and off very rapidly. Then the realignment makes sure that the solar panel is sharply positioned at 900 to face the sun (excluding the solar angle of the sun) all the time.

The control box is attached to the solar panel so that the two lens assemblies are positioned on the same plane as the face of the panel. A small angular movement of the sun prevents the sunlight passing through the sunbeam lens assembly, this darkens the inside of the control box and the rotating motor switches on to align the panel to the sun. Immediately the motor is switched off, because the sun lights up the control box. This last function occurs directly the sun shines through the lens assembly to ensure that the movement of the sun is monitored with exceptional accuracy from sunrise to sunset. In real time this motion is barely perceptible; it can be likened to the sweep of an hour hand on a clock.

Long after sunset the electro mechanics and a 12 volt dc power supply from a bank of batteries (for example) turns the solar panel 1800 to the east to be in position for the sunrise every morning. Electronics of the LSPCBs and the electra mechanics of the power supply will automatically repeat the alignment procedures every day Thick clouds covering the sun will switch on the electronics associated with the sunbeam lens assembly; this means that the rotating motor will -12 -try to turn the panel further westwards. During this occurrence the daylight lens assembly's electronics will control the alignment of the panel.

Although the operation of the daylight lens assembly is not quite instantaneous nor as quick as the sunbeam lens assembly, its relatively delayed response will position the solar panel slightly ahead of the sun, a shadow has to be formed over the daylight lens assembly by the panel turning westwards. As a result of the modification to the wiring the daylight lens assembly now switches the rotating motor off However if the daylight conditions are reasonably good, the electronics will continue to adequately turn the panel to the brightest part of the sky; suitably positioning the solar panel for the sunbeam lens assembly to resume control, once the sun shines again. Very poor daylight will close down all of the electronic circuit as the daylight lens assembly is preset to a level that is extremely sensitive to the lack of good light. Improvements to the light will reactivated the electronics of the daylight lens assembly and it will realign the panel to face the sun for the operating procedure to continue.

The light lens assemblies that are mounted to the control box have been deliberately designed so that long shadows are formed. Long shadows ensure that the angular movement of the sunlight can be followed instantly. A slight shift will form a shadow which is immediately registered by the lens assemblies, primarily by the sunbeam lens assembly and this is how it achieves the best possible accuracy. The alternative of recessing the lens assemblies into the top and west side of the box's casing would not achieve the same accuracy because the shorter shadows formed would delay the activation. Making a longer box in this way is quite feasible but this design is very cumbersome by comparison with the first design. Another solution is to make two control boxes, one to contain the lens assemblies and LDRs and the other the LSPCBs. The box containing the lens assemblies and LDRs would be on the top side of the solar panel and the box containing the LSPCB's and their components, attached to the rear This design would certainly operate well and be less obtrusive, but it would detrimentally expose the signal wires of the LDRs and be far more difficult to make durable and to manufacture.

The main emphasis of this design is its simplicity; it is simple sun alignment system. Making the parts for the control box and lens assemblies is very easy, the materials and components are readily available. There is absolutely no complicated assembly or electronic work because the modules are all ready pre assembled. The innovation is how the circuit and control box are put together, how the lens assemblies affect the light and it's considered use for operating the solar panel that is its success Aligning a solar panel to face the sun all day is undoubtedly better by far in comparison to a static installation; it will be in the best possible position to absorb all of the available energy. Consequently the temperature and the amount of hot water produced increases because the energy of the sun is avaiiabie for a much longer period of time.

It is in the winter and during the colder times when the demand for hot water is at its peak, that the design of this system will prove its worth.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

* * * * * * * *

Claims

-14 -CLAIMS1. A soiar alignment device having a sunbeam lens assembly which is arranged to form a thin planar beam of sunlight which passes into a darkened chamber to illuminate an electronic light detector when the device is aligned with the sun, and the detector is arranged to control a motor which turns the device, such that the motor is deactivated when the device is aligned with the sun.
2. A solar alignment device according to Claim 1 in which the sunbeam lens assembly includes a convex lens of planar shape having a light-collecting face which is convex in a longitudinal direction, 3. A solar alignment device according to Claim 2 in which the convex lens is enclosed between two side plates having opposing reflective surfaces.4. A solar alignment device according to Claim 2 or 3 in which the convex lens is mounted over a strip lens opposite to the light-collecting face.5. A solar alignment device according to Claim 2, 3 or 4 in which the sunbeam lens assembly includes two elongate shields which form light from the convex lens into a narrow slit.6. A solar alignment device according to Claim 5 in which the shields have convexly curved opposing surfaces.7. A solar alignment device according to Claim 5 or 6 in which the shields have mirrored opposing surfaces.8. A solar alignment device according to any preceding claim in which the electronic light detector associated with the sunbeam lens assembly is arranged to control the motor via a fast-switching operational amplifier and an electromagnetic relay.9. A solar alignment device according to any preceding claim which includes a daylight lens assembly arranged to collect daylight from one side of the sunbeam lens assembly (directed towards the west in use) and illuminate an electronic light detector which is arranged to prevent the motor from operating under low fight conditions.10. A solar alignment device according to Claim 9 in which the daylight lens assembly includes a reflector arrangement mounted inside a transparent weather-protecting housing.11. A solar alignment device according to Claim 10 in which the daylight lens assembly includes a pair of reflectors, one facing towards the side which is directed towards the west in use and another facing downwards.12. A solar alignment device according to Claim 9, 10 or 11 in which the daylight lens assembly includes a magnifying lens.13. A solar alignment device according to Claim 12 in which the daylight lens assembly includes a concave reflector arranged to collect light from the magnifying lens.14. A solar alignment device according to any of Claims 9 to 13 in -16 -which the daylight lens assembly includes a flat lens.15. A solar alignment device according to any of Claims 9 to 14 in which the daylight lens assembly includes a tube which conducts light to the electronic light detector.16. A solar alignment device according to any of Claims 9 to 15 in which the electronic light detector associated with the daylight lens assembly is arranged to control the motor via a fast-switching operational amplifier and an electromagnetic relay 17. A solar alignment device which is substantially as described with reference to the drawings.* * * * * * * * Amendments to the claims have been filed as follows 1. A solar alignment device having a sunbeam lens assembly which is arranged to form a thin planar beam of sunlight which passes into a darkened chamber to illuminate an electronic light detector when the device is aligned with the sun, in which the sunbeam lens assembly includes a lens of planar shape enclosed between two side plates having Opposing reflective surfaces and having a light-collecting face which is convex in a longitudinal direction and the detector is arranged to control a motor which turns the device, such that the motor is deactivated when the device is aligned with the sun. * S. *.S.2. A solar alignment device according to Claim I in which the *5*.i Convex lens is mounted over a strip lens opposite to the light-collecting face.
3. A solar alignment device according to Claim 2 in Which the sunbeam lens assembly includes two elongate shields which form light from the convex lens into a narrow slit.
4. A solar alignment device according to Claim 3 in which the shields have convexly curved Opposing surfaces.
5. A solar alignment device according to Claim 3 or 4 in which the shields have mirrored Opposing surfaces.
6. A solar alignment device according to any Preceding claim in which the electronic light detector associated with the sunbeam lens assembly is arranged to control the motor via a fast-switching operational amplifier and an electromagnetic relay.
7. A solar alignment device according to any preceding claim which includes a daylight lens assembly arranged to collect daylight from one side of the sunbeam lens assembly (directed towards the west in use) and illuminate an electronic light detector which is arranged to prevent the motor from operating under low light conditions.
8. A solar alignment device according to Claim 7 in which the daylight lens assembly includes a reflector arrangement mounted inside a transparent weatherprotecting housing. * **9. A solar alignment device according to Claim 8 in which the daylight lens assembly includes a pair of reflectors, one facing towards the side which IS directed towards the west in use and another facing * * * 10. A solar alignment device according to Claim 7, 8 or 9 in which the daylight lens assembly includes a magnifying lens.11. A solar alignment device according to Claim 10 in which the daylight lens assembly includes a concave reflector arranged to collect light from the magnifying lens.12. A solar alignment device according to any of Claims 7 to 11 in which the daylight lens assembly includes a flat lens.13. A solar alignment device according to any of Claims 7 to 12 in which the daylight lens assembly includes a tube which conducts light to the electronic light detector. 0\14. A solar alignme device according to any of Claims 7 to 13 in which the electronic light detector associated with the daylight lens assembly is arranged to control the motor via a fast-switch ing operational amplifier and an electromagnetic relay.15. A solar alignment device which is substantially as described with referenco to the drawings.* * * * * * * * * .* * S S * ** **S* * * ** * * * * * S. S..... * I * .. * . .