SOLAR PV PANELS

All the brands favoured by EvoEnergy in photovoltaic installations are solar cells encased in a solid aluminium frame, the same material used in aircraft manufacture, and used for the same reasons - it is light and strong.  This gives the panels a rigid shell and allows them to be screwed or clamped in various manners.

Panels vary in weight between 13 and 50kg depending upon their size and manufacturer.  The Sharp polycrystalline ND series panel to the right is 16kg and 1.3 x 1m in size.  Further details can be found in the solar panel section of this website.

Roof Anchors For a Solar PV Installation

These are aluminium or steel components that screw directly into the rafters.The type of roof anchor used is determined by the type and dimensions of the roof tile and the height and spacing of the batons.  The majority of the anchor fits under the tiles with only a portion of its tail visible. It is to this tail that the aluminium frame is attached.

To the right is simply a selection of the roof anchors that we use. One of the most important purposes of the site visit is to determine the system that we will use.

Mounting Frame For a Solar PV Installation

Once the roof hooks are secured in place the frame is attached to them.  This attachment is made using a specially engineered locking system to ensure that there is no movement and then tightened using conventional bolts. The frame consists of two parallel aluminium bars for each row of panels.  The panels sit directly on the frame attached by the clamps.

Clamps Needed For A Solar PV Installation

The panels are attached to the frame using clamps. There are two varieties of clamp, end-clamps, and mid-clamps. End-clamps are situated at the end of a row of panels, thereby helping to secure one panel, mid-clamps are used between two panels, thereby helping to secure two panels. The other function of the mid-clamp is to ensure equal spacing between each panel (usually 20mm) so that they look good aesthetically. The specific clamps used are determined by the solar panel being attached. At least four clamps are used to hold each solar panel to the frame.

The pictured clamp is a mid-clamp showing the bolt and the especially designed mechanism to attach to the frame and hold the panels in place.

Scaffold for a Solar PV Installation

The scafford comes right up to the eaves of the roof and ensures the safety of those working on the roof and compliance with all relevant Health and Safety codes.  Ladders from the scaffold across the roof are used when the roof tiles are slippery or fragile.

Placing the Roof Anchors for a Solar PV Installation

The measurements made on the site survey are checked and small marks are made on the roof in chalk to indicate the planned positions of the panels. The chalk washes off with the first bit of rain.

The location of the rafters under the tiles is found. Roof anchors will soon be screwed into these rafters, and it is important that these anchors are placed in the correct position. The anchors are placed on top of the tiles where they will eventually be positioned and measurements are taken to ensure that the aluminium frame will sit 'straight'.

Once the position of the anchors is determined they are screwed into the rafters so that they remain 'straight' across the entire roof.  The tiles are then replaced on top of the anchors so that the roof remains watertight.  It is important that the correct type of anchor is used; this would be determined during the site survey.

Mounting the Alumium Bar for a Solar PV Installation

The aluminium bars that make up the frame are then locked into the roof hooks and screwed into place. Each bar is checked to make sure that it is straight and that all the bars are parallel to each other. This is the single most important step in ensuring that the panels will look correct.

If the length of the frame is longer than the aluminium bars supplied then they are spliced together using specially designed strips of aluminium and further bolts.

PV Panel Installation

With the bars in place, and the frame complete the panels can start to be attached and clamped to the frame. A minimum of four clamps is used per solar panel, though in some cases extra clamps are used to aid the alignment of the rows.

The panels are either placed by row or by column depending upon which is the easiest in the specific situation. In the photo to the right the panels are being placed by row. In this case the top row is placed and the alignment of each row thereafter is taken from it.

Wiring for a Solar PV Installation

Panels are wired by the manufacturer, meaning the rooftop connection is straightforward.  The specific voltage, ampage and power of the system determines how the panels are connected; smaller systems have a single series to a single inverter, larger systems have several parallel series into a single inverter with the largest systems requiring multiple series into multiple inverters. Shading and panel positioning can also influence the design of the wiring.

Installing the final PV Panel

Once the top row of solar panels is correctly clamped the rows beneath are secured to the frame in the same manner, taking their positioning from the row above.

The parallel alignment to the panels above is extremely important to the aesthetics of the system.  This is easy if the original frame is well placed, but difficult otherwise.  EvoEnergy only accept payment when you're happy with the look of the system, not just its performance.

Final Wiring of a PV Installation

Once all the panels have been installed and the final alignment checked the DC wiring is complete are then run into the building.  In some cases this is achieved by running the wire under the eaves and directly into a loft.  In others, such as that pictured, a hole has to be made into the mounting building which is then sealed.

This completes the rooftop section of an installation!