Roof Mounting.
When it comes to mounting solar PV panels there are three general types of system that we use, depending on the roof structure.
On-Roof
This is the most common installation, and the one you will see on many homes around the UK. It usually provides the best cost benefit of any mounting system. Rails, normally aluminium, are bolted into the roof structure. We take special care to ensure that these penetrations are then sealed effectively, to prevent water ingress that could cause problems in the future. PV panels are then clamped onto the rails in either portrait or landscape aspect as required making this the most flexible mounting system on offer. It is worth noting that although many installers claim to install systems appropriate for the roof in question, isoenergy has an established track record of working with period properties. If you are concerned about the way the panels will look on your roof, take care to select an installer who will go the extra mile to ensure you are satisfied with the final outcome.
Flat-roof
Maintaining the water tightness of a flat roof should be of paramount importance when considering PV. Therefore isoenergy’s preferred method of installation is using ballasted moulded pods, onto which individual panels are securely fastened. This method allows us flexibility in our design, working round skylights, pipes, shading caused by parapets and any other obstacles that may manifest themselves to leave you with the largest, most efficient system possible without any penetrations through the roof for mounting the panels.
In-roof
For those who would like a more aesthetic look to their panels, isoenergy has experience of installing in-roof mounting frames. Once mounted, your PV panels lie almost flush with the surface of your roof. Extra attention needs to be paid with this type of mounting to ensure that water penetration does not become a problem. Only consider in-roof mounting systems if you are confident your installer can get it right first time. Retrospective sealing and repairs are costly.
Ground-mounted arrays
isoenergy also has experience of designing and installing ground-mounted arrays, most commonly used for larger PV systems. Mountings are designed appropriate to each project, but normally take the form of a properly laid frame, onto which all panels, cables and inverters can be securely and safely mounted. No two arrays are ever the same, so our design team will take into account all factors to ensure that you have the most efficient system that will generate maximum benefit for the space you have available. It is worth noting that ground mounted arrays do require planning permission, but the first array installed at a property is normally considered permitted development provided your property is not listed and does not sit in a conservation area. Consult your local planning authority before committing to a ground mounted array to avoid potential disappointment and costly delays.
East-West arrays
For large areas of flat roof, there is an alternative to pod mounted systems in the form of east-west mounting systems. East-west array panels generally lie flatter than south-facing ones, and consequently they have a lower peak power. However, they are able to work for a longer period throughout the day, making the most of morning and evening sunshine to generate their electricity. As the panels on an east west array cover a present a larger surface area than pod mounted options, you can fit more panels on which easily offsets the loss in generation from the low angle the panels sit at. The east-west mounting system installed by isoenergy is a self-ballasting system meaning the weight of the panels attached to each other helps hold them all down. This means the system can normally be installed without penetrating the roof to lash it down.
Source; Renusol
Shading
Aside from orientation and pitch, shading will have the largest impact on the performance of a PV system. Trees, chimneys, satellite dishes and moving clouds will all adversely affect the output of a PV system. Some area easier to predict than others and some have a greater impact on performance. The simplest way to counter this is to design a system where the panels are placed to minimise shading effects, or even mitigated altogether. However, if shading cannot be avoided, there are technological options available to maximise performance. Trackers, power optimisers and even micro-inverters can mitigate the string performance drop effect by tracking the output of individual panels as opposed to monitoring the entire string, as a typical inverter would. It is claimed that power optimisers can improve the overall efficiency of a whole string by as much as 20%.
Wind loading and safety
In our experience, the vast majority of roofs are more than able to cope with the weight and wind loading added by the introduction of solar PV panels. If there is any doubt then a structural engineer will perform a survey prior to any installation. We adhere to the MCS standards in all respects and take manufacturers guidelines seriously. Whilst some installers may bend the rules to a few fit extra panels on, we are not prepared to compromise the safety of your property or of those that maintain the system in the future. Therefore, all roof mounted systems are installed using safe access and the appropriate exclusion zones around the edges of the array. The most common cause of problems with PV is sub-standard installation so please consider if you want your home’s safety to be entrusted to the lowest bidder.
Gallery
