How to install solar panels

How to install solar panels

John, DIYer & IT developer, Brighton

Guide written by:

John, DIYer & IT developer, Brighton

Solar panel roof installation varies based on the accessories used. PV panels on a tile or slate roof can be installed over roofing underlay or a special integrated framework and solar flashing can be made of various materials including zinc, lead or plastic. Read on for the basic steps to installing solar panels.
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Solar panels: different methods of installation

Solar panels: different methods of installation

Solar panels are usually installed on roofs. Ideally, they should be south-facing with a tilt angle of 30 to 35 degrees. However, the system used to install the panels can differ and this will impact how easy the panels are to fit, the accessories required, the length of the job, and the skills and tools required to complete the installation. From fitting rails over roofing to removing roof tiles or slates and fitting a waterproof integrated framework or roofing underlay, the cost of installation varies considerably. Installing solar panels allows you to generate electricity. The type of installation you choose depends on several factors. These factors will also determine the type of solar panels you can install. It is important to plan carefully in advance in order to work out the precise requirements of the installation and/or the home.

Steps

  1. Remove roof tiles or slates

  2. Fit roof flashing

  3. Install roofing underlay/integrated framework system

  4. Secure the mounting rails and panels

  5. Connect the inverter

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Installing solar panels in five steps: the basics

The following guide provides a general outline of how to install solar panels. At the end of this guide, you'll find a few tutorials showing different configurations which will provide a more detailed look at installation possibilities.

1. Remove roof tiles or slates

Installing solar panels in five steps: the basics

There are a couple of different scenarios here. If your roof is covered with interlocking roof tiles or slates, you will need to remove part of the roof covering. Start by marking out the exact spot where you want to install the solar panels. You will then need to remove the tiles over a slightly larger area than the solar panels will take up themselves. Once this is done, you will have a gap in your roof: this hole will be used to fit your solar panels after careful preparation.

Be sure to wear protective gloves when removing tiles or slates as these materials are abrasive and could injure your hands. Any work on the roof must be performed with the appropriate fall protection equipment (e.g. temporary fencing or a fall arrest lanyard and harness. If you are removing tiles close to the roof ridge, be careful not to damage your ridge or hip tiles: do not walk close to these tiles and remove all tiles with care.

If you don't have a traditional roof frame with rafters (e.g. a roof truss), do not walk between the battens nor on the roof underlay to prevent the risk of falls.

2. Fit roof flashing

Installing solar panels in five steps: the basics

Roof flashing is used to connect roof materials (in this case roof tiles or slates) to any protruding elements (here, the solar panels and mounts). Flashing is used to prevent water ingress. It comes in a wide range of designs to match any model of tile or slate in terms of shape and colour. Slate roof flashing is made of slate-coloured sheet metal or traditional zinc.

Installation consists in fastening the flashing to existing or additional battens using screws. To insert the screws, you will need to use a drill driver and tape measure to mark out precise measurements. The roof hooks should also be secured using screws.

You can fit an additional batten along the length of the solar panel and behind the first row of tiles to add height and provide more support for the flashing. Flashing can be made of plastic and can come as a kit. It can also consist of lead roll designed to be unwound over a pre-fitted batten and the first row of tiles. Lead rolls vary in width and are secured in place using a silicone-based adhesive applied using a silicone gun. The lead roll should be shaped by hand to mould to the contours of the tiles. Battens will need to be cut to size using a circular saw.

3. Install roofing underlay/integrated framework system

Fitting roofing underlay

Installing solar panels in five steps: the basics

When fitting a roof, you must lay roofing underlay. This layer of protective plastic is used to create a water-resistant yet breathable barrier. It is recommended to leave a gap between the underlay and insulating materials to prevent mould growth. The underlay is generally stapled onto the battens in a traditional roof structure. If you are unable to leave a gap and the underlay has to rest on the insulation, choose a vapour permeable, or VP, underlay. Water vapour is able to pass through this material to reduce the risk of condensation building up in the insulating materials. If condensation is allowed to reach the insulation, it will become less effective and can even start to rot. Any overlap between strips must be sealed using a special adhesive. Use the adhesive recommended by the manufacturer and apply it following their instructions.

Integrated frameworks

Depending on the model, solar panels may come with their own waterproofing system. This type of system tends to be made of flexible plastic and is designed to be integrated into the roof. You will therefore need a rigid support made up of battens. These framework systems are then screwed into the rafters and/or battens where the panels will be installed.

4. Secure the mounting rails and panels

Installing solar panels in five steps: the basics

Solar panel mounts must be secured firmly to the rafters using roof hooks or rafter brackets. To secure the fasteners, you will need a cordless screwdriver or drill driver, and specially designed screws. Bear in mind that solar panels are heavy and exposed to windy conditions. Some complex mounting systems are designed to adapt to the shape of roof tiles and can therefore be secured through the roof covering itself. In this case, you do not need to remove any tiles or slate since the mount structure is installed over the roof.

It is particularly important to pay attention to the maximum gap allowed between two mounting rails, as indicated by the manufacturer. Similarly, you need to study the maximum distance allowed between two fastening points in the rafters. If the mounting rails are not long enough or you need to overlap rails, you can use various rail joiners or cross rail connectors. Please note that solar panels can be rotated a quarter-turn so the long side is set vertically. In this case, it may also be necessary to fit mounting rails vertically. The PV panels must then be fastened to the rails using hooks or bolts. Once all the panels are in place, you can fit an overlay before replacing the missing tiles or slates.

If you are fitting solar panels over a special framework system, the mounting rails can be installed directly over the system.

5. Connect the panels to the inverter

Installing solar panels in five steps: the basics

A solar inverter is an electronic device used to turn direct current supplied by the solar panels into 230 V alternating current with a frequency of 50 Hz (for UK mains electricity). The inverter is connected to the solar panels on one side and a solar energy meter and consumer unit on the other. The solar meter is used to inform energy suppliers of how much electricity is being delivered to the National Grid by a domestic solar panel system. For this step, it is essential that you know how to read a wiring diagram.

Some solar panels must be wired in series and others in parallels to meet the minimum operating requirements of your inverter in terms of voltage and amperage. This will help to ensure a long service life. Solar panels with the same characteristics are wired in series if the positive (+) terminal of one is connected to the negative terminal (-) of another. In this case, the voltage of the panels adds together.

Therefore, if each panel has a rated voltage of 12 V, two panels in a series will have a rated voltage of 24 V. If you connect the positive terminal of one panel to the positive terminal of another, they are wired in parallel. When mounting solar panels in parallel, the voltage remains the same but the amperage produced by each panel adds together. Be careful – if you connect two groups of panels in series in parallel, the voltage of each group must be equal to protect the panels and maximise their production.

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Tape measures

Tutorial 2. Fitting solar panels over a concrete tile roof

Tutorial 3. Installing solar panels on a new build roof

How to install solar panels

Required skills

Required skills

If you plan on installing your own solar panels, you must be comfortable working at height and have an understanding of how to waterproof a roof to prevent water ingress. You must be able to securely fit the solar panels to the rafters or battens using roof hooks, or rafter brackets, and mounting rails to ensure they can withstand harsh weather conditions. It's also important to be able to read instructions, follow a wiring diagram, follow safe working practices (particularly involving electricity), installing and connecting an inverter, connecting wiring and securing it to the wall. You also need to be comfortable using a drill driver and circular saw. Depending on the solar panels and the fastening system required, you may have to fit a roofing underlay or integrated framework; the first can be stapled into place while the second must be screwed in. You also need to be in good physical condition to work on a roof and handle the PV panels.

Time required

Required time

6 hours minimum (depending on installation)

Number of people required

Number of people required

2 people

Tools and equipment

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More information

 
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Guide written by:

John, DIYer & IT developer, Brighton

John, DIYer & IT developer, Brighton

Since I was a child, I was always interested in manual and technical work. Always fascinated by woodworking, I took advantage of my first flat as a playground. On the cards: electricity (of course, safety first!) and some partition walls; but also decorating with the help of the missus, made-to-measure furniture and little tricks to optimise the space, all the while remaining as original as possible. When the little one arrived, I started building bits and pieces for him! Lacking space, I have not got a permanent workshop and certain tools I dream about are not part of my collection. Not to worry, I already know a lot about DIY and I have a high-tech profile that I hope will guide you in your decisions!

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