Verification of Solar Installations in the UK

Spot checks on solar installations by MCS inspectors are increasing, with the installer having to cover the cost of re-inspection if the installation is sub-standard, according to Deks UK, the supplier of flashing products to the roofing industry.

In line with the Government's Microgeneration Installation Standards (MIS), all solar installations have to be carried out by MCS registered installers.

MIS 3001 2.1a for solar thermal and MIS 3001 2.1 for PV state that in 'all circumstances the building's weather tightness must be maintained. Holes sealed with mastic or silicone sealant are not considered durable.' The standard also emphasises that 'all roof penetrations (eg for the collector, pipe work, cables or bracketry) must be durably sealed using purpose made products capable of accommodating movement and temperatures to which they may be subjected.'

David Jones, divisional manager of Deks UK, said: "Many of the on-roof installations we see do not have appropriate seals around roof penetrations or protection for PV cables, creating problems for the future - or in the shorter term a serious risk of failing the spot checks we hear are currently being carried out by MCS inspectors."

He added: "If installers fail their MCS accreditation assessments or substantiated complaints are received, then the certificate holder is liable to carry the additional costs of re-inspection which at current daily rates will be an eye-watering minimum of £600 plus VAT."

NHBC Foundation research shows that an increasing number of roof leaks are being caused by faulty solar installations which could lead to reduced customer confidence in renewables.

Deks believes that lack of training or understanding how to carry out best practice weatherproofing of pipes and cables is more likely to be the cause than poor installation of the collectors themselves. Failure to adequately protect cables from damage can easily reduce the effectiveness of the system and create a possible electrical danger.

Mr Jones said: "Under the MIS regulations just because you may not have designed the system you are installing it doesn't mean that you won't be held responsible if the roof leaks. As an installer or sub-contractor you still have to be competent enough to review and verify that the design would meet the MIS standards set out, so lack of knowledge isn't a valid excuse."

"Responsibility for fixing solar panels often falls between two trades, roofers and plumbers. By using specialist flashings that have been designed for use with solar panels, fixing couldn't be easier and all of the problems created by DIY solutions are eliminated," he concluded.