GB2563306A - A ladder apparatus for maintenance of a solar array - Google Patents

Abstract

A ladder 300 is provided for maintenance of a solar module or array of solar modules. The ladder has a pair of parallel rails 10 joined by rungs 20. The rails are adapted to receive at least one sliding bracket (40, fig 5C). Each sliding bracket supports a hook 50 that extends from the sliding bracket to permit engagement of the hook with part of a solar module so as to locate the ladder on the solar module. A locking means (41, fig 3) is provided to fix each sliding bracket in position on a rail. The hook may be coated by a non-conductive, typically rubber or plastic coating, to prevent risk of electrocution in case of damaged cables and to protect the solar panel. A sheet of plastic material 70 may be arranged underneath the rungs to catch dropped items. Also provided is a trolley for the ladder.

Description

A LADDER APPARATUS FOR MAINTENANCE OF A SOLAR ARRAY

Field of the Invention

The present invention relates to a ladder apparatus for maintenance of a solar array; in particular apparatus for allowing access to maintenance of a solar array; such as but not exclusively an array formed of multiple photovoltaic modules.

Background

Increasing numbers of properties and users are using photovoltaic cells or solar cells to supply electricity. Frequently the photovoltaic cells or solar cells are arranged in arrays of multiple modules, all being tilted towards the sun at a fixed or an adjustable angle.

For a number of years there has been a problem when installing and maintaining solar modules as well as a need to clean and repair damaged modules. There has been no way to carry out this work without standing on the solar modules.

This maintenance has caused users high costs in replacing brand modules after construction often because of cracked glass. In most circumstances only hairline cracks were created by standing on the modules. In other cases modules have cracked completely and required replacement.

Prior Art CN 204 960 775 (LU) discloses a climbing device for a photovoltaic module. CN 204 002 517 (LI et al) discloses an anti-slip ladder for mounting and maintaining components in a photovoltaic plant. JP 2000 145 130 (KAWAKAMI) discloses a maintenance ladder for a roof equipped with a solar battery by which maintenance work was able to be efficiently carried out.

The present invention arose in order to overcome problems suffered by existing devices.

Summary of the Invention

According to the present invention there is provided a ladder apparatus for maintaining a solar module comprising: a pair of substantially parallel rails joined by a plurality of rungs; the rails are adapted to receive at least one sliding bracket; each sliding bracket is associated with at least one hook that extends downwards from the rail to permit engagement of the hook with part of the solar module so as to locate the ladder apparatus on the solar module; and a locking means fixes each sliding bracket in position on a rail.

In this way the apparatus can be deployed so that it spans over one or more solar modules thereby permitting maintenance without causing damage to the module(s).

Advantageously the ladder apparatus can be arranged for use with solar module arrays so as to allow a user to gain access to a large solar module which may comprise many panels or arrays without standing on glass in the panels or the arrays.

In one embodiment the apparatus forms a ladder that extends across an upper face of a solar module so that a user can climb across the modules. The apparatus is adapted to fit to the module such that the solar cells and covering layers are protected whilst access over the module is permitted safely.

Typically the weight of the apparatus is borne by the frame upon which the solar module is arranged. The ladder apparatus is adapted to engage with the frame so as to locate the apparatus on the module.

The apparatus forms a ladder that extends across the face of a solar module so that a user can climb across the modules for maintenance, repair and cleaning. The apparatus is adapted to fit to the module such that the solar cells and covering layers are protected whilst access over the module is permitted safely.

Typically the weight of the apparatus is borne by the frame upon which the solar module is arranged. The ladder apparatus is adapted to engage with the frame so as to locate the apparatus on and over the module.

The ladder apparatus is adjustable so as to provide a universal device that can be adapted to fit solar modules of different shapes and dimensions. For example, the ladder apparatus can be configured to allow use over module arrays in portrait and in landscape orientations.

The ladder apparatus has a pair of sliding brackets arranged on the pair of substantially parallel rails.

In some embodiments the rails may be have a shallow arch so as to span the module. The shallow arch limits the degree of flexion towards to module so that the rails do not sag during weight bearing such that the rails become too close to the module.

The sliding brackets includes a locking means for fixing the bracket at a desired location on the rail. In some embodiments the sliding bracket includes apertures through which a fixing such as a bolt can be passed through in order to lock the sliding bracket to the rail.

In another embodiment the bracket may include a grub screw or a knob bolt that can be tightened so as to come into contact with the rail and lock the sliding bracket to the rail by means of friction.

The sliding brackets support hooks or are associated with a structure that support hooks so that the position of the hooks can be adjusted by sliding the sliding bracket along rails so that the hooks can be positioned to correspond with the frame of the solar module.

Preferable the sliding brackets, or associated structure that supports the hooks are arranged, and sized and dimensioned, to allow the hooks to fit in between the solar modules when arranged in an array and transfer the weight of the ladder and user(s) onto the structure of the frame underneath the solar modules. As the brackets slide they can be moved to accommodate different frames or gaps between modules.

In a preferred embodiment the pair of sliding brackets is adapted to receive an elongate member extending therebetween from which a pair of hooks suspend. In this way the sliding bracket is associated with a structure (elongate member) from which the hooks are suspended.

The elongate member is arranged to slide beneath the rails and rungs such that the elongate member is suspended from the sliding brackets a distance that permits the elongate member to slide freely between the ladder apparatus and the solar module.

Preferably the sliding bracket is adapted to receive an elongate member such that is the elongate member is anchored in position below the rungs. Ideally the sliding bracket is adapted so that the elongate member can be attached to or removed from the ladder apparatus. In this way the assembly and disassembly is permitted.

Preferably the hooks are supported by and suspended from a connector mounted on the elongate member. Ideally the connector is moveable long the length of the elongate member so that the distance by which the hooks are spaced apart can be adjusted to correspond to the width of a solar module and/or the frame upon which the solar module is arranged. It is appreciated that the elongate member extends beyond the rails of the ladder such that the hooks can be positioned at a width greater than the ladder.

In this way the ladder apparatus can be adjusted to the length of the solar module by positioning the sliding bracket along the rails, and adjusted to fit the width of a solar module by moving the connector along the elongate member to the desired position.

The connector is also adapted to permit connection of a hook. Typically the connector provides a clamp in which a hook is mounted and secured. The hook is attached to the connector so that hook extends downwards towards the solar module.

Preferably the hook can be added to and removed from the connector. This permits assembly and disassembly. For example the connector may be a clamp assembly that removably receives the hook.

In some embodiments each hook may be arranged on a pivot so that the that hook can be displaced, for example when being slid along the rails so as not to catch on a part of the frame that the hook is not intended to connect.

The hook is typically provided at a distal end of an arm such that the length of the arm determines the distance by which the rails are separated from the solar module.

The hooks may be provided in different shapes such as T-shaped (one hook) or F-shaped (two hooks). The hooks may be formed from plates cut using water-jet technology into T- or F-shapes.

In some embodiments the brackets may comprise a plurality of hooks, or displaceable hooks, such that the hooks may be hooked onto or over more than one part of the frame, or so as to permit connection to different parts of a frame by one hook.

In some embodiments a hook with a plurality of hook portions may permit the ladder to be set different distances from the solar module depending upon the work to be carried out.

Typically the hook is received by the solar module frame into a recess or channel. For example often a solar array frame may be formed from C-section. Ideally the hook is arranged to engage with the C-section. In this way the hook permits the ladder apparatus to hang from the solar module at a fixed position and to bear weight as the hook bears on a recess defined by the C-section of the frame.

In some embodiments the hook is coated with a non-conductive material so as to prevent conduction through the ladder if part of the module accidentally became electrified, such as due to damaged cables.

Additionally the costing may be formed from a resiliently deformable material so as to prevent damage to the surface with which the hook is in contact.

For frames that do not include recesses or channels for receiving a hook, or for which the alignment of the recess or channel does not correspond to the hook the ladder apparatus includes an anchor bracket that is arranged on the frame for receiving the hook.

The anchor bracket has an attachment means for connecting the anchor bracket to the frame and a channel for receiving the hook. Preferably the attachment means comprises clips that define a channel for hooking over the frame so as to be quickly and easily deployed and attached to the frame. In this way the at least one anchor bracket may thereby be enabled to clip over horizontally arranged parts of the solar module frame by being hung by the clips.

Preferably the rails are formed from a metal extrusion to provide a strong, lightweight structure suitable for supporting a user. Ideally the rails are in the form of an I-beam or strut. In some embodiments the rails are formed from box section.

In some embodiments the ladder may comprise more than one set of rails, for example so as to define a side depth to the ladder.

In a preferred embodiment there is provided an outer set of rails, and an inner set of rails. The rail sets may be spaced apart by a body, which body may comprise diagonal braces.

It is appreciated that an extrusion may be drawn to include an inner and outer section with a body arranged between.

Rungs are arranged between the rails to form a ladder.

The rungs may be removably connected to the rails, for example being connected with bolts. This permits the ladder apparatus to be compacted when not in use or modified for use with non-standard solar panels. In other embodiments the rungs may be welded or bonded to the rails.

In some embodiments the rungs of the ladder may be doubled, for example wherein rungs may be provided on both outer and inner faces of the ladder. In other embodiments rungs may be substantially central extending from the body.

In some embodiments the rungs or sets of rungs of the ladder may be offset on the rails, for example having some rungs on a lower rail and some rungs on an upper rail.

The lower rungs may be arranged intermittently further along the rails than the top rungs. In this way the sets or rungs may be arranged to provide support for a user when climbing the structure, and the sets of rungs may provide a substantially horizontal alignment when the structure is provided at a known photovoltaic array angle horizontally and vertically.

The rungs may be shaped a dimension to provide a surface that is horizontal in use, in this way items such as tools can be rested on the rungs to provide a work surface at height.

The rungs may include lips to prevent items from falling from a rung.

In some embodiments the rungs may comprise one or more coaxial or telescopic portions so as to enable adjustment of a width or length of the ladder.

In some embodiments the rungs may be coloured so as to be clearly visible to a user, for example the rungs may have black and yellow stripes.

In preferred embodiments the ladder includes an elongate sheet of material arranged below the rungs. The elongate sheet provides a protective layer between the user and the solar module and serves to prevent dropped items from damage the solar module.

Preferably the ladder apparatus may include attachment means for receiving the elongate sheet of material. For example the rails may include projections upon which the elongate sheet rests in use.

In another embodiment the projections may be provided on the sliding bracket. In this way the elongate sheet is located between the rails.

In some embodiments the projections may be attached at a pivot so that the projections can be moved in order to engage with and secure the elongate sheet in place.

Ideally the elongate sheet of material is formed from a strong, lightweight material such as a synthetic plastics material.

In a preferred embodiment the sheet may include a strengthened edge, such as metal, or metal alloy edging to provide improved rigidity. Ideally the edge is provided along the elongate parallel sides of the sheet. The edging, for example, may be attached to the sheet by adhesive or may be bolted to the sheet. A solar module or array of solar modules may be arranged in a plurality of orientations or arrangements, but typically at set angles to the horizontal. It is common for solar modules to be arranged at an angle of 22 degrees, therefore the ladder apparatus is arranged on an angled surface and as such a user maintain solar modules is often working at height.

To ensure safety of a user each rung may include a harness anchor for receiving a safety line. The harness attachment point has an aperture through which a safety line, or clip attached to a safety line can be secured.

In this way a user can move the safety line from rung to rung as the move up and down the ladder.

In preferred embodiments the ladder apparatus has a handle provided at each end of the rails. The handle enables the ladder part of the ladder apparatus to be moved to and positioned over a solar module.

Ideally each handle is attached at a pivot so that the handle can pivot relative to the rails. The handle may be connected to the rails by a pin and hole arrangement. The pin may be provided on a tether to prevent the pin being separated from or falling from the apparatus.

In some embodiments the handle may be associated with a means of locking movement of the handle with respect to the rails. In this way the handle can be arranged to extend at a different angle relative to the rails.

Typically the handles fold downwards towards the ground when the ladder apparatus is in position. In some embodiments the ladder may provide addition rungs that enable a user to more easily step up to the solar module. The portions of the handle that are stepped on may be coloured so as to be clearly visible to a user. These portions may also have a grip surface to prevent a user slipping during use.

It is appreciated that the handles may be used to arrange the ladder at the desired angle so that the structure can be walked over a solar module or arrange of solar modules.

In some embodiments the rungs have a grip surface so that a user is less likely to slip when using the ladder apparatus.

In some embodiments the rungs may include padding for increased comfort during use. For example a user may need to rest against the rungs whilst maintaining the solar module and if the run is padded this may prevent or reduce the likelihood of the user being bruised. The padding may extend over part or substantially the entire rung.

The ladder allows a user to climb or walk up the array and access the solar modules for installation of/maintenance or replacement purposes. In particular the user is enabled to access the modules on large ground mount or rooftop commercial solar farms without placing pressure on the glass or the modules, advantageously removing need for persons to stand directly on the glass/modules.

The apparatus may be assembled on site wherein users carry and lift the ladder into place over the desired area of the array to be worked on.

Once placed into position the array can be accessed from ground level by stepping up onto the first stepping bar whilst holding on for extra safety. The user can manoeuvre all the way to the top of the module array to install panels or carry out maintenance as desired.

In this way the apparatus provides a valuable tool for operations and maintenance (O&M) of solar farms. The apparatus solves the problem of maintenance by allowing users to gain access onto the solar array without transferring any weight of the frame or user(s) onto the solar modules.

In preferred embodiments the ladder apparatus is provided with a trolley adapted to receive the ladder apparatus and transport it to the location of use.

Preferably the trolley is adapted to securely hold the assembled ladder apparatus.

Advantageously the trolley is sized and dimensioned so as to be suitable for rolling over the solar module, or array of solar modules, so that the assembled ladder apparatus can be rolled to the desired location on the solar array and then deployed.

Typically the trolley has wheels suitable for rolling over a face of a module, for example wheel with pneumatic tyres.

Ideally the trolley includes a set of wheels mounted in an alternative orientation for running along the top, side edge of the solar array such that the trolley is prevent from slipping down the solar array.

The trolley includes buckets for receiving the distal end of the hooks. In this way the ladder is secured in the trolley, the hooks are spaced apart from the solar module, or array, during transport.

In some embodiments the trolley may be suitable for rolling the ladder over the ground to reach the solar module. It is appreciated that the trolley may be adapted for different uses, for example having wheels suitable for the ground and wheels suitable for a solar module.

Preferred embodiments of the invention will now be described by way of example only and with reference to the Figures in which:

Brief Description of Figures

Figure 1 shows a perspective view of an embodiment of the apparatus in use on a solar module array;

Figure 2 shows a detail view of a second embodiment of the apparatus according to the present invention;

Figure 3 shows a detail view of the embodiment as shown in Figure 2;

Figure 4 shows a detail view of the embodiment as shown in Figure 2;

Figure 5 shows a second embodiment of the ladder apparatus;

Figure 6 shows an end view of the second embodiment of the ladder apparatus;

Figure 7 shows a side view of the third embodiment of the ladder apparatus;

Figures 8 show handles of a ladder apparatus;

Figure 9 shows various views of a rung;

Figure 10 shows various views of a safety line attachment point;

Figure 11 shows a rung section and a rail section;

Figure 12 show side view of a pair of rails;

Figure 13 shows an anchor bracket;

Figure 14 shows a trolley and ladder arranged on the solar module; and

Figure 15 shows an alternative embodiment of the sliding bracket including a projection for receiving the elongate sheet.

Detailed Description of Figures

The pictured embodiment of the ladder apparatus 100 comprises two rails 10 comprising square box tube sections welded together in parallel with rungs 20 running between.

The rails 10 comprise two vertically spaced apart tube sections 11 A, 11B with diagonal bracing 12 therebetween to give the rails 10 a rigid strength over a long distance.

Preferably the rails and rungs are formed from aluminium so as to be strong, durable and lightweight.

In Figure 1 the top face of the ladder further comprises a plurality of rungs 20 periodically spaced apart and consisting of box section tube aluminium welded onto rails 10 to create steps which the user uses to access to the top of the array in use.

As shown in the second embodiment shown in Figures 2 to 4 the lower rail 11B may have a plurality of basal rungs 20B arranged less frequently between the rails 10, so as to provide a sturdy construction. Such basal rungs may be offset so as to provide a substantially horizontal alignment with the upper rungs in use.

The rungs 20, as shown in the first embodiment (Figure 1), may have a foam or rubber coating or padding 21 for comfort and to protect the knees. The padding 21 is arranged proximate the rails 10, providing approximately a third coverage at each end wherein a central part of the rungs 20 are not covered. In this way the user is enabled to stand on the central part of the rung 20 without risking slippage of feet or padding.

The rails 10 comprise an outer rail 11 A, and an inner rail 11B, wherein the bracing 12 is arranged to extend in a zigzag arrangement at 45 degrees to the top and bottom rails 11 A, 11B.

The apparatus further comprises a handle 30 at each end of the ladder. The handle 30 secures to both rails 10 when in use. Once the ladder has been carried to the location of use the handles can be folded downwards to the ground to provide legs. The legs may be variable in angle with respect to the rails 10.

The legs may also be telescopic so as to variable with regards to height.

The handle 30 on the top enables the ladder 30 to be carried and positioned carefully into place where required, wherein the top handles may be large so as to allow the apparatus to be lifted up around 2-3 meters high dependant on the array. Such handles may also be rubber/plastic coated for comfort and health and safety reasons. The coating is also preferably non-conductive.

The apparatus comes in two parts and will be assembled on site when needed so as to be easier to transport.

Figure 2 shows a second embodiment of the ladder apparatus with a hook 50 suspended from a sliding bracket (not shown) extending downwards between adjoining solar modules 500. The hook 50 is F-shaped with a distal hook below the solar module and a second hook visible.

Figures 3 shows a hook 50 extending from a sliding bracket 40. The hook 50 is welded to the sliding bracket 40. There are two hooks 50A, 50B extending from the arm 51. In use the hook 50 rests on the frame of the solar module (not shown) so as to space the ladder apparatus from the solar module 500.

The sliding bracket 40 has a grub screw 41 for locking the sliding rail in place.

The hooks 50 are formed of 10mm aluminium plate which is small enough to fit in between the lateral gaps between modules 500 and make contact with the sturdy structure frame system underneath the solar modules 500.

In Figure 3 there are two hooks 50 that are spaced apart appropriate the depth of the solar module and are radiused to limit damage to the array. In some embodiments the sliding brackets 40 may include a plurality of hooks, or displaceable hook, so as to adjust to different depths.

In the pictured embodiment there are envisaged to be eight of these hooks 50 on the ladder, arranged four to each rail 10, so as to allow points of support on and contact with the array frame underneath the modules 500.

As shown in Figure 4 the bracing 12 provided between the upper and lower rails 11 A, 11B further includes orthogonal bars 13 and bars 14 parallel to the top and bottom rails 10.

The rails 10 provide a body along which a sliding bracket 40 can slide. The sliding brackets 40 extend from and below the bottom rail 11B. The sliding bracket 40 is adapted to fit about the rail 11B.

Typically the sliding bracket has a channel that corresponds to the rails 10. The channel may include a return 43 (see Figure 5C) so as to secure the sliding bracket about the rail during sliding.

The sliding bracket 40 has apertures 44 that correspond to apertures on the rails 10. In Figure 11A the lower rail 11B has an aperture through which a fixing can be arranged. In this way the sliding bracket 40 can be locked to the rail in a fixed position, for example by a nut a bolt or similar fixing means.

In some embodiments the sliding bracket does not include a return and is held in position by a fixing means.

The sliding bracket 40 can be locked in place by a screw threaded locking means 41. Other locking mechanism may be used, for example a pin and hole arrangement.

In Figures 3 and 4 there is shown a grub screw arrangement in which when the grub screw is tightened by turning the grub screw 41 causes contact of the grub screw with the lower rail 11B to provide a friction lock.

By release of this friction lock the sliding brackets 40 can slide up and down the frames to fit different solar module framing systems.

The ladder apparatus thereby transfers the weight of the ladder and user(s) onto the subordinate array frame underneath the modules to leave zero pressure on the solar modules and the glass of the solar modules.

The hooks 50 have a non-conductive coating (not shown), typically rubber/plastic coating to prevent the flow of electric in case of damaged cables for health and safety reasons. The costing also protects the frame from damage by the hooks.

Figure 5 shows a third embodiment 300 of the ladder apparatus. The rails 10 are formed from a metal extrusion with the lower section of the extrusion adapted to receive a sliding rail 40.

The sliding rail 40 is adapted to hold an elongate member 60. The sliding bracket 40 has an opening 42 for receiving the elongate member 60. The elongate member 60 extends between a pair of sliding brackets 40. The elongate member hangs below the rails 10.

The elongate member 60 also receives connectors 61 which are slidably mounted on the elongate member and are also adapted to receive the hooks 50.

The connectors 61 shown in Figure 5 have square sections 62 that corresponds to the elongate member 60. The connectors 61 can be slid on the elongate member 60 to adjust position of the hooks 50.

The connectors have a clamp 63 for receiving a hook 50. The arm 51 of the hook 50 is sandwiched between the clamp 63. Corresponding apertures (not shown) are aligned and a bolt is passed through the aligned apertures in order to form a connection.

Each rung 20 has a safety line attachment point 22 for securing the safety of user climbing the ladder apparatus. The safety line anchor point has an aperture 22A for receiving a line or clip.

The ladder apparatus 300 in Figure 5 also has an elongate sheet 70 that prevents dropped items from contacting the solar module.

Figure 6 shows an end on view of the third embodiment of the ladder apparatus.

Figure 7 shows a side view of the third embodiment of the ladder apparatus.

Figures 8A and 8B shows an example of a pair of handles 30A, 30B and indicated preferred dimensions. The larger handle 30A shown in Figure 8A is intended to enable the ladder apparatus to be lifted over the highest part of the solar module. Close up image C shows how two box sections weld together such that part of the handle can slide inside another part. Close up B shows a close up of two box sections welded together and then welded to the outside box allowing the internal frame to slide inside. This is also a crimp box bracket with a hole and a rivet nut fitted.

The smaller handle 8B is arranged in use at the lowest part of the solar module and may also serve to provide additional steps to the ladder. Close up A shows two box sections welded together to the outside box allowing the internal frame to slide inside. This is also a crimp box bracket with a hole and a rivet nut fitted.

Figure 9 shows different views of a second embodiment of a rung 20. The rung 20 as a triangular cross section and includes an internal rib. The rung ends includes a plate 23 that is for joining the rung to the rails. The rungs 20 can be bolted to the rails 10.

Figure 10 shows different views of the safety line attachment point 22. A first portion of the safety line attachment point 22B has an aperture 22A. The first portion is angled with respect to the second portion 22C that attaches to the rung 20. This angle makes it easier to connect the safety line to the aperture 22A without the rung interfering. Typically the angle between the portion 22B and 22C is 146 degrees.

Figure 11 shows a cross section of the rung 20 (Figure 11 A) and a cross section of the rail 10 (Figure 11B). Preferred dimensions are indicated.

Figure 12 shows side views of the rails 10 indicating preferred dimensions.

Figure 13 shows an anchor bracket 80 that may be hung from the frame of a solar module. The anchor bracket 80 is for receiving the hooks 50 of the ladder apparatus 100, 200, 300, if the frame of the module does not provide a suitable mounting position for the hooks.

The anchor bracket 80 has two clips 81 that hook over part of the frame, in use, so as to provide a channel 82 in the correct orientation for receiving a hook 50.

Figure 14 shows a trolley 90 arranged on a solar array 500. The trolley 90 has a frame 93 with six wheels 92 arranged on the face of the modules 500 and a pair of wheels 94 arranged on a top, side edge of the solar module (See Figure 14B).

The frame 93 is formed from tubular sections.

The wheels 92 are spaced to correspond to the edges of the solar modules 500.

The wheels 92 that contact the face of the solar module 500 have pneumatic tyres. The wheels 94 that travel along the side edge of the module 500 are smaller and may not be pneumatic, for example having solid tyres.

The trolley 90 has four buckets 91 for receiving the hooks of the ladder. The buckets 91 locate the hooks and ensure the ladder stays in position as it is rolled over the solar array. The buckets 91 are mounted on the frame 93.

The position of the buckets 91 can be adjusted to correspond to the position of the hooks.

Once the desired location is reached the ladder 100 can be lifted from the trolley 90 and position of the solar array 500.

Figure 15 shows an alternative embodiment of the sliding bracket 40 including a projection 45 for receiving the elongate sheet 70. The projection 45 provides a ledge on which the sheet is positioned in use.

The invention has been described by way of examples only and it will be appreciated that variation may be made to the above-mentioned embodiments without departing from the scope of invention as defined by the claims.

Claims (16)

Claims

1. A ladder apparatus for maintenance of a solar module, comprising: a pair of substantially parallel rails joined by a plurality of rungs; the rails are adapted to receive at least one sliding bracket; each sliding bracket is associated with at least one hook that extends downwards from the rail to permit engagement of the hook with part of a solar module so as to locate the ladder on the solar module; and a locking means to fix each sliding bracket in position on a rail.

2. A ladder apparatus according to claim 1 wherein a pair of sliding brackets arranged on the pair of substantially parallel rails are adapted to receive an elongate member extending therebetween from which a pair of hooks suspend.

3. A ladder apparatus according to claim 2 wherein the hooks are supported by and suspended from a connector mounted on the elongate member.

4. A ladder apparatus according to any preceding claim wherein the substantially parallel rails comprise a metal extrusion.

5. A ladder apparatus according to any preceding claim wherein the hook is coated in a resiliently deformable material so as to protect the solar module from damage.

6. A ladder apparatus according to any preceding claim including an elongate sheet of material arranged below the rungs.

7. A ladder apparatus according to claim 6 including an attachment means for receiving the elongate sheet of material.

8. A ladder apparatus according to claims 6 or 7 wherein the elongate sheet of material is formed from a synthetic plastics material.

9. A ladder apparatus according to any preceding claim where’re in each rung includes a harness anchor for receiving a safety line.

10. A ladder apparatus according to any preceding claim including a handle provided at each end of the rails.

11. A ladder apparatus according to claim 10 wherein each handle is attached at a pivot and includes a means for locking movement of the handle with respect to the rails.

12. A ladder apparatus according to any preceding claim including a receiving element arranged on the solar module for receiving the hook.

13. A ladder apparatus according to any preceding claim wherein the rungs have a grip surface.

14. A ladder apparatus according to any preceding claim wherein the rungs include padding.

15. A ladder according to claim 14 wherein the padding extends over part of the rungs only.

16. A trolley adapted to receive the ladder apparatus according to any of claims 1 to 15.