Technical field: The present invention relates to an arrangement and a method at solar panels, heat carrying wall sections and the like primarily intended for use as light permeability and solar energy absorbing wall and roof element sections for green houses where the arrangement also has been adapted to give shadows for the plants which are culti¬ vated in the greenhouses. The invention is however suit¬ able also for use within other areas as for example as heat carrying wall sections in offices and as solar energy absorbent enclosures for swimming-pools and the like.

Background of the invention:

Conventional greenhouses of glass have a small or no heat isolation. A substantial amount of energy is therefore used to heat the greenhouses during the dark and cold period of the day. This heating is traditionally carried out by means of oil or electric heating. This means that large greenhouses have substantial heating costs. In greenhouses there is further a need to protect the culti- vated plants from some radiation wave lengths in the sun radiation. Each type of plant has consequently an indi¬ vidual need of sunshine which is advantageous for the plant and having short and long wave radiation. Traditionally shadowing is made by so called chalking of the transparent surfaces of the greenhouse with chalk mud. The chalking is however an inconvenient method which

i.a. requires cleaning of the surfaces in question one or several times each year. Another and a better solution compared to the chalking is shadowing by means of special shadowing curtains which often are made from aluminium paper. It is, however, circumstantially to control the solar radiation into the greenhouse by means of such shadowing curtains as these usually have been suspended in more or less difficultly actuated rope systems. Said actuating difficulties are further increased when the curtains are used in large greenhouses having large glass surfaces. A common and deciding disadvantage with both the chalking method and the curtain method is that the shadow obtained without selection excludes radiation of the types which are necessary for the plants. All known shadowing systems being present on the market have this disadvantage. To bring about acceptable plants in spite of this the problem is today attacked from another point namely y more or less extended gene manipulation of the plants. Such gene manipulation is however extremely expensive and it requires also substantial research work.

Technical problem:

The problem with the present types of greenhouses is acc¬ ordingly that they need a very costly heating by electricity or oil during the dark period of the day and that by means of known arrangements for the shadowing of unwanted radiation wave lengths of the solar light also the necessary radiation wave lengths for the plants are shadowed which brings about an unsatisfactory cultivation product.

Object of the invention:

The object of the present invention is to solve the above problem by bringing about an arrangement of the type men- tioned in the preamble so that the greenhouse is heated during the whole day of absorbed and stored solar energy

and that the light transparency of the transparent sur¬ faces of the greenhouse can be adapted freely so that the need of the plant of short- and long-waved sun radiation is sufficiently brought about whereas non-desired radi- ation wave lengths are shadowed. The invention can also advantageously be used in other applications such as for example heat carrying wall sections and enclosure sections for swimming-pools.

Conclusion of the invention:

The above mentioned object is obtained by the character¬ izing part in the following claims of the arrangement and the method according to the invention.

The invention is thus mainly characterized in that in the greenhouse application a wholly transparent plate section comprising a number of parallel channels in which a heat absorhing fluid is circulated, which contains pigment particles for both heat absorbtion and limitation of the light permeability of the plate. The solar energy thus absorbed is thereafter stored within the greenhouse for heating of it.

Further as appears from the claims the arrangement according to the invention can advantageously be used in applications such as heat carrying wall elements in offices where the heat permeability of the plate can be freely chosen by regulating this pigment particle amount of the circulating fluid and as solar energy absorbing enclosures for swimming-pools where the absorbed heat content from the solar energy in the fluid is used for heating the water of the swimming-pool and the light- permeability of the plate can be freely chosen by regu¬ lating the amount of pigment particles in the circulating fluid.

Solar energy panels as such are of course earlier known through for example the US patent 4 082 082 and US patent 4 625 711. These teach, however, only wholly conventional solar panels provided with solar energy absorbing liquid filled pipes which are covered by a protecting cover and behind which there is an absorbing opaque layer which has been attached to an isolating disc which has been mounted to the structure. Both examples relate however to only just solar panels and are by means of their construction completely unusable within the areas of the invention. They do neither solve any of the technical problems men¬ tioned above.

Short description of the drawings: The invention will further be described more in detail by means of an embodiment example in connection with the attached drawings in which the same denotiations in the different figures relate to corresponding parts.

Fig. 1 shows an embodiment example of an arrangement according to the invention. Fig. 2 is a broken sectional view along the line II-II in fig. 1 showing a pipe-connection mounted on a plate according to the invention. Fig. 3 is a sectional view along the line III-III in fig. 1 showing the channels of the plate contain¬ ing fluid. Fig. 4 is a schematic picture of a greenhouse equipped with the arrangement according to the invention.

Description of embodiment examples:

In fig. 1 the denotiation 1 means generally a continuous wholly transparent plate. The plate 1 comprises a plural¬ ity of parallel transparent channels arranged in the same plane. The plate has been made in transparent polycarbonate plastics having the product-name "Makrolon

SDP Long Life" so that unwanted cracking of the material is avoided. The ends 3 of the channels 2 are connected to inlet 4 for supply of heat absorbing fluid to all the channels 2. In the same way the opposite ends 5 of the channels 2 are connected to an outlet 6 for discharging of said fluid. The fluid contains pigment particles for limiting of the light-transparency of the plates 1 for absorbing of heat. To attain this it has according to the invention been chosen an extremely suitable fluid called "Dowcal 20" which is based on propylene glycol and is manufactured by Dow Chemical AB, Stockholm. The fluid chosen contains pigment particles which can circulate freely within the system according to the invention with¬ out discolouration and covering of the plastics material in the plates 1.

As further appears from fig. 1 an edge list 8 has been arranged at both the inlet 10 of the plates 1 and its outlet 11. The edge list 8 is glued to the plate 1 as will be described later in connection to fig. 2. The edge list 8 has been provided with pipe connections 12 at the inlet 4 and at the outlet 6 to which pipes 14 have been connected.

With reference to fig. 2 the inlet 4 and the outlet 6 shall now be more closely described. The figure is a sec¬ tional view along the line II-II in fig. 1 and shows the transparent plate 1 at the end of which, in this case the outlet 11, the edge list 8 has been glued by means of longitudinal sealing glue joints 15. The gluing can be carried in a convenient way as the edge list 8 has side- parts 16 having an angular deviation as appears from the figure. The edge list 8 has preferably been made in the same material as the plate 1. To the edge list 8 has fur- ther been attached for example by gluing one in the example cylindrically shaped pipe connection 12. The pipe

connection 12 has means as for examples threads for con¬ nection to a pipe 14, here an outlet pipe. In connection with the pipe connection 12 there is preferably a circu¬ lar hole 19 in the edge list 8. Thus the pipe connection 12, the pipe 14 and the hole 19 of the edge list 8 form together a penetrating opening 20 to the plate 1. To have said opening 20 to communicate with all the channels 2 in the plate 1 recesses 22 have been made in connection with the edge list 8 in the partitions 23 of the channels 2. The recess 22 has in the example been made as a semicir¬ cular recess which is favourable from a stability point of view.

In fig. 3 is shown a sectional view of the channels 2 of the plate 1 from along the line III-III in fig. 1 containing said liquid. Herewith it appears that the outer walls 24 of the channels 2 have a slightly concave shape which assists in the stability of the plate 1.

According to the invention the arrangement is manu¬ factured in an economically highly advantageous way by extruding said channels 2 into the continuous plate element 1. The material is the earlier mentioned poly¬ carbonate plastics "Makrolon SDP Long Life". The extruded plate 1 is thereafter cut to the desired length transversly at the inlet and outlet ends 10, 11 whereafter the recesses 22 are milled at ends 10, 11 in the partitions 23 of the channels 2. Hereafter the edge- lists 8 are attached by means of for example gluing at the ends 10, 11. At this stage the holes 19 in the edge- lists 8 have already been made and pipe connections 12 have been attached directly in front of them.

With reference to fig. 4 one example shall be described where the arrangement according to the invention is used as a light permeable and solar energy absorbing wall- or

roof-section for greenhouses. In the figure a greenhouse 30 has been schematically drawn, the roof of which con¬ sists of 6 pieces of connected elements 1 according to the invention. The connected elements 1 make thus together a roof unit 31 (one roofside of the greenhouse 30) . To the inlet 4 of the roof unit 31 has via a pipe- connection 12 an inlet pipe 32 been connected. In a cor¬ responding way an outlet pipe 33 has been connected to the outlet ends 6 of the roof unit 31.

The basic principal for the function on the arrangement in the greenhouse application described is that the light permeability of the different plates 1 is adapted to the light need of the cultured plants by regulating the amount of pigment particles in the earlier described cir¬ culating fluid. Further the heat content absorbed from solar energy in the fluid is used for heating the cultur- ing space of the greenhouse 30 during the time period of the day vhen sunlight does not exist.

The heatabsorping fluid is circulated within the green¬ house 30 according to the circuit which appears from fig. 4. The fluid is pumped by means of a circulation-pump 35 in through the inlet pipe 32 of the roof unit 31 and thereafter it passes through the different plates 1 and their transparent channels 2 , which are subjected to the solar radiation. The pigment particles in the fluid absorb the solar energy supplied and transport thereafter the resulting heat content out through the outlet pipe 33 of the roof unit 31. The fluid continues in said pipe 33 for transportation to storing tanks 37, 38 under the floor of the greenhouse 30, which tanks contain heat- exchangers (not shown). Via said storing tanks 37, 38 heating of the greenhouse 30 can accordingly occur for example by letting the heated fluid circulate in the heat carrying floor 40 and possibly also culturing shelves 41.

The plate 1 according to the invention can than advantageously also make said floor 40 and shelves 41. By such a use the plate 1 has, however, of course no solar energy absorbing effect anymore but is here instead used as a genuine heat carrying construction element making a very economically attractive solution.

With the object to adapt the lightper eability of the plate 1 to the need of light of the cultured plants and accordingly influencing the morphology of the plants the amount of pigment particles in the circulating fluid can according to the invention be freely regulated. This can for instance occur by storing fluid having different amounts of pigment particles in a number of tanks 43. By the action of regulation means fluid can in this way be chosen from that tank having fluid containing an amount of piαment particles which gives the optimal light per¬ meability in the roof unit 31 with regard to the plant type cultured in the greenhouse. Within the scope of the invention the light permeability can accordingly be conducted to different levels for different parts of the greenhouse in case of having different plants with dif¬ ferent radiation needs in the same greenhouse.

In the above mentioned greenhouse application the arrangement according to the invention offers a very easily controlled shadowing system for plants by which the radiation need of the plants can be exactly satisfied at the same time as the heating demand for the whole greenhouse 30 can be satisfied by using solar energy. The need for growing-suppressing agents and gene manipulation of the plants can accordingly be eliminated.

A further application area for the arrangement according to the invention is as heat carrying wall panel for offices and the like. Such a wall panel can for example

be made as the plate-element 1 in fig. 1. Light- permeability is the plate 1 can then be varied freely by regulating the amount of pigment particles in circulating fluid. The need of separate heating elements is then eliminated and one gets an extremely attractive wall panel where for example the colour of the fluid can be varied according to what is desired and where also advanced light-effects can be obtained by the light con¬ ducting ability of the fluid.

The present invention can also be used as a solar energy absorbing enclosure for swimming-pools and the like. Then the heat content of the fluid absorbed from the solar energy is used for heating the water of the pool. At the same time the light permeability of the plate 1 can be freely varied by regulating the amount of pigment particl 2s in the circulating fluid.

The present invention is not limited to the examples shown in the drawings and described but can be freely varied within the scope of the succeeding claims. For example the plate 1 can also be used as a conventional solar energy panel located on conventional roofs and so on. In such a way an effective solar energy panel is obtained at an appreciably lower manufacturing cost than what is the case with common more complicated solar energy systems.