Installer Requirements - Steve Pester Library/Presentations/S-Pester... · • In daylight, there...
Transcript of Installer Requirements - Steve Pester Library/Presentations/S-Pester... · • In daylight, there...
Installer Requirements
Steve PesterPrincipal Consultant
BRE
Scope of MCS Installer scheme
MCS Installer Technical Standards (e.g. MIS3002 for PV):
“specifies the requirements of the MCS for contractors undertaking the– supply– design– installation– set to work– commissioning and – handover
of Photovoltaic microgeneration systems for permanent buildings”
MCS Installer scheme stands on 3 pillars
MCS
QualityManagement
SystemMCS 001
Consumer Code(OFT*-approved)
e.g. REAL Code
PV TechnicalStandardMIS 3002
*OFT = Office of Fair Trading
Documented Quality Management System – why?
• Consistent quality of installations – there’s a lot to remember if you want to be a good installer!
• Business interruption due to illness/injury
• Staff training and new staff induction
• Auditable and accountable (esp. when things go wrong, can’t blame rogue engineer)
Consumer Code of Conduct
• Members of the REAL Assurance Scheme agree to abideby the REAL Assurance Scheme Consumer Code.
• Covers contractual elements of installation…
REAL Assurance Scheme cont..
• Acceptable sales and marketing techniques • Details of the conditions of business that apply • Guarantees, and any maintenance and after-sales
services needed • What action will be taken to deal with any problems
MCS Technical Standards (MIS 3xxx)
MCS Tech. standard
MIS3xxx
Existing Industry Guides and Standards
BuildingRegulations
MCS-specificrequirements
Regulations & Guides called up in PV technical standard
Stages of an MCS Installer Assessment
Assessment:• Quality Management System (QMS) assessment• System Design and Technical documentation of installation(s)• Technical assessment of physical installation(s)
All Non-Conformances must be rectified before an installer is certificated
BRE certificated installers are listed on the BRE green products sourcing site: www.greenbooklive.com
Typical small PV systems in the UK -practicalities
Typical Domestic Installation - schematic
Inverters
Inverters transform the DC electricity produced by your PV modules into the alternating current (AC) electricity
commonly used in most homes (they do other things too!)
DC Disconnect Requirements
Ø Double Pole
Ø Rated for DC
Ø Rated in excess of the expected current
Ø Labelled
AC Disconnect Requirements
Ø Double Pole
Ø Lockable in OFF position
Ø Rated in excess of the expected current
Ø Labelled
The Consumer Unit - AC Disconnect & Labelling
Commercial Buildings use 3-Phase Power
Micro-inverters
• DC – AC conversion on roof
• No high DC voltages
• Possible control & monitoring of individual modules
• Over-temperature shutdown
Photo: Enecsys
Safety – Why PV has Special Safety Issues:
• Beware High Voltage DC Electricity – Dangerous!
• The PV modules cannot be switched off (upstream of the DC isolator)
• Fuses are not likely to blow under short circuit conditions
• PV modules produce DC electricity – few electricians familiar
• For installers: combination of hazards: Working at height with high voltages and heavy modules
Earthing – Array Frame
Earthing of the array is NOT mandatory1) Must be earthed if:§ Any part of the frame is touchable from a window, attic
space, etc§ Also if positioned close to a solar thermal system
2) AC Side is normally earthed
Lightning Protection
Lightning protection of the array is only required if:
• there is a particular risk of lightning or• the array is near to a lightning protection system on the
same building
Protection can consist of:• Lightning conductors to earth• Surge Arrestors (usually small electronic components in
the junction box) • Spark gaps (unusual on small systems)
Array Mountings vary widely
• Installers must demonstrate static and dynamic load calculations and roof structure assessment
• Further info on mountings– New NHBC Guide
– DG495 - Mechanical installationof roof-mounted photovoltaicsystems
Common PV Installation issues:
• Some Installers have limited knowledge leading to poor design or installation
• Manuals, warranties, test certificates, grid connection docs not supplied to owner/operator
• Labelling not present or incorrect
• Earthing requirements often misunderstood
• Most operators have limited knowledge!
Fortunately poor DC connections are not very common!
Food for thought….• In daylight, there are high voltage DC electrics power on
roof and inside building• Not possible to completely isolate the DC electrics with
standard systems. Panels down to DC isolator remain live• DC is more dangerous than AC at the same voltage• 200-600V DC is common• Under fault conditions, shorts can occur, producing very
hot arcs, both inside panels and between shorting conductors
• Glass can fall from PV panels when broken
However, fires caused by PV appear to be rare at present!
Summary
• Installers - MCS requirements are tightening but still some way to go
• Safe practices and products are well-understood thanks to early German market and a few pioneers in UK
• DC high voltages and arcs are main dangers• Micro-inverters may offer some higher level of safety,
although they do not yet have much track record
• Questions?