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UK ROOFS NEED UK PV
- Published: Thursday, 15 September 2011 18:38
NHBC Foundations’ announcement that increased solar PV installations on roofs have led to more roofs leaking is not surprising.
There have been these concerns within the roofing industry for some time, especially with regard to ‘on top/roof’ solar PV systems and how they are fixed to roofs. Most common problems occur due to poor design, or suitability, of fixing mechanisms, problems that we have eliminated from our Redland range of PV
As a company, we have been making the argument that PV technology and installation methods imported from mainland Europe and further afield are just not suitable for UK roofs: A view shared by the NHBC.
We need solar PV technologies and installation procedures that are tailored to our construction and climate. After all, the UK has the strongest winds in Europe and some of the heaviest rainfall.
At Ecobuild earlier this year there were a number of manufacturers exhibiting solar PV systems. Many of these seemed to be imported direct from continental Europe or China, with fixings clearly not specifically designed and tested for the UK. It is vital that any solar PV product does not detract from the fundamental function of the roof itself, to provide reliable and durable protection to a homes’ internals from the elements.
A roof integrated solar PV system should by definition be better at maintaining weather-tightness. However, since the introduction of the FIT, the vast majority of PV systems installed have been of the ‘on top’ variety.
One of the biggest causes of leakage associated with these types of PV systems is where the tile immediately below the fixing hook cracks and breaks during its lifespan on the roof. This gives rise to an opportunity for water ingress. This is more often than not down to the actual design of the hook itself and how it integrates with the roof.
Other problems include fatigue loading on PV module fixings caused by gusting of wind over time. This results in the module fixings working loose on the roof, not ideal with such a valuable component. Again, this is commonly caused by poor design of the system itself and can be expensive to rectify.
The NHBC Foundation correctly make the point that there is currently no European or British Standard regulating the mechanical installation of solar PV on buildings to ensure prevention of these problems i.e. resistance to wind and rain.
Recognising this as such an important issue, the Microgeneration Certification Scheme (MCS) has developed some additional requirements for MCS-certified solar PV (and solar thermal) systems, in particular their mounting kits. The additional requirements relate specifically to weatherproofing and security against wind uplift, recently formalised in the new MCS012 standard, as well as external fire resistance.
MCS012 is set to come into force later this year and compliance with it should be the first point to check for anyone looking to specify solar PV systems for residential homes with pitched roofs. Long term, this should give assurance that houses built or re-furbished today with this technology should maintain weather-tightness for many years.
All Redland solar PV products have been designed with MCS012 in mind and are specifically designed and tested for this country. Dedicated training courses for their installation are also offered.
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