INSTALLATIONROOF MOUNTED
In agriculture or industrial installations things inevitably get more complicated – the installations are normally far larger and the roof types typically very different from a domestic house. From asbestos cement through fibre cement to metal sheet – corrugated or seam-crimped – to flexible membranes. All of these roof types/surfaces have their own challenges and when it goes wrong taking down tens of kWs of PV modules to fix a leak is no easy (or inexpensive) matter
roofs interacting with the PV mounting frame can lead to the roof sheets cracking (and cracks leak).
The only really viable solution to mounting PV onto fibre cement is to make a new support system above the existing roof with the absolute minimum of supports to minimise potential leaks. Here at The Solar Building Company we have designed a roof mounting solution that works and can be fitted to existing (and of course new) fibre cement roofs simply, quickly and without in any way compromising the roof warranty.
Maintaining excellence
The final challenge to any roof mounted PV installation is fitting the modules and, after that, maintaining them. What? I hear you say, I have to maintain them? But solar PV has no moving parts. Well, firstly, fitting them will require correct (and compliant) attention to HSE directives. Safety nets under certain roof types, guard rails, scaffolding etc. There is no “run up a ladder and plonk it down – as long as you are quick no one will notice” option.
Aside from the obvious risk to health (and potential liability on a building owner for allowing this to happen) the technology is expensive and has to be fitted with great care. Again, removing PV to rectify a bad installation (be that leaks or failure of the roof structure through overloading) is going to eliminate all the up-side expected from the FIT. After installation, routine maintenance (modules can fail) has to be considered and most importantly cleaning will be required. Any claim that modules “clean themselves” has to be taken against the backdrop of any other window you have seen left to its own devices over a year or more –especially roof lights. Nature steps in with
various contaminates from general dust/pollution through to bird droppings (which by their very nature stick and can cause significant module hot spots and output disruption). When you most need the modules clean is when it’s least likely to rain – ie in the summer. Routine cleaning of the PV installation is in reality not an option - it’s a necessity. Again this is not something one can do from a ladder with a long handled mop and soapy water. Proper access is needed to allow “hands on” cleaning, and must be considered at the design stage.
In summary, roof-mounted PV is financially attractive at present here in the UK. installations “North of Watford” do actually work and as far as Edinburgh and beyond are viable. Just make sure that your PV system stays on the roof and the roof continues to do its job. Don’t compromise your building when fitting PV – this needs to be done with care and by professionals with roofing skills - then your PV will be doings its job (and making you money) for 25 years and beyond.
© 2011 Angel Business Communications. Permission required.
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www.solar-pv-uk.com Issue III 2011
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