“Wind energy is able to make a bigger impact on reducing carbon than almost any other
technology” Stephen Bradley, UrbanWind, p28
Opinion
By guest columnist Bill
Wright, head of energy
solutions, Electrical
Contractors’ Association
A burning issue
Steve Pester summarises some
of the real fire risks seen on PV
installations
he BRE
National Solar
Centre has
recently been
called out to sites and
been sent photos of PV
installations with melted or
burnt-out DC components.
It goes without saying
that this type of failure
carries significant fire risk
to life and property. The
main culprits appear to
be DC connectors and
DC isolators. Whilst good
product design is essential, the limited (often anecdotal)
evidence that exists seems to point to installation practices
being a significant factor.
Recent examples include IP-rated DC isolators mounted
outside with cable glands that are either incorrect for the type
of cable, or pointing upwards, so that any seepage through
the glands allows water into isolator casing. A short circuit
inevitably follows, often culminating in a fire.
Another concern is ‘MC4-compatible’ DC connectors
– to the casual eye, one ‘MC4’ looks much like another and
connectors from different suppliers are often all assumed to be
compatible. They are not. Slight variations in design, materials
and dimensioning means that it can be dangerous to mix
and match these connectors if they are not from the same
manufacturer and of the same product range.
The MCS guide for PV installers requires laboratory
proof of compatibility, where connectors from different
manufacturers have been mated together. The forthcoming
IET Code of Practice for Grid-connected Solar PV Systems is
even stronger on the subject and bans the practice of mixing
and matching different manufacturers’ connectors altogether –
even if they are apparently ‘MC4-compatible’.
Installers often need to make up (or buy) DC cables for
linking strings etc – what connectors will you use for this if
you have no idea what type are fitted to the modules? Insist on
knowing – your supplier can find out.
The NSC will be offering training on the CoP this summer.
T
W
e have to accept that nothing is
going to happen until the new
energy minister is in post but the
message that has to be given to whoever
takes that position is that the industry needs
stability and long term incentives. The current
‘stop–starts’ are no good for the industry.
The solar farm tariffs are a prime case.
Solar farms were first encouraged with a 1.4
ROC subsidy for those ‘ farms’ over 5MW.
This encouraged many applications and the
countryside in some areas has many such
solar arrays. This has now been curtailed
and the encouragement is being given to
rooftop solar. Rooftop solar is good in itself and
recent announcements by M&S that they had
constructed the largest single roof solar power
system is encouraging. The government is
saying that they have insufficient funds to
keep this level of subsidy. In the rush to beat
the deadline over 1GW of solar farms were
completed. Does this remind you of another
subsidy rush a few years ago?
The list of stop start policies goes on –on
and offshore wind farms, is another example
where local councils have policies against
them in many areas whilst central government
tries to encourage them but the system ends
in an impasse.
The message for the new minister must
be stability, long term polices and sensible
incentives so that long term investment in
renewable technology can be made.
16 | www.renewableenergyinstaller.co.uk