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Solar Energy Systems installation UK - lack of skills

Rob Tes

As I researched Solar Energy systems for over a year now I discovered how little I understood the dangerous realities of Solar installations even though powered at ELV level <50Vdc.  The difference being that you are dealing with a constant current of 50 - 100's A dc.  Average Joe, maybe used to Auto/Truck 12/24Vdc  systems probably sees the system as safe - you dont get a shock (boat owners will disagree).  So the hazards of installing a dc distribution system  within a domestic house and the potential to cause disastrous fires are totally underestimated.  Even the average tradesman electrician will not have sufficient training in such matters in his CPD scheme.

To make matters worse, as a result of a question by a neighbour who want to suggest to his lad that he follow an Electrician apprenticeship, I discovered that my area (SE UK) has no regular Technical College Route pursuing CnG courses.  Apprenticeships are very rare and as a rule focus on training junior managers. 

In short, a young person cannot readily find his way in to becoming and electrical tradesman ( I have to make a distinction between the concept of a Technician here)

When you aggregate the complete installation identifying all physical components, the SLD suddenly becomes quite complex.  ie Going from Panel Arrays > optomisers > cables > marshalling boxes > Fuse links > Isolators > Master Circuit Breaker > Inverter (s) > Battery Bank > Domestic Consumer Unit > Grid resale meter > Master Isolator > standby generator > Auto Transfer Switch, Control and monitoring systems, Emergency shutdown scheme.

When you seen the numerous wannabee hopefuls going offgrid and often their lack of formal technical training they dont realise how dangerous their rough and ready installation is

I can post links to many sources of my concern here if there is sufficient interest

Robin 

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  • gkenyon said:
    Yes, arc flash energy at 12 V may well be low,

    and of course the arc flash is therefore not sustained for long enough for it to be what we know of as a "full blown flas" ... This particular point raises something very  interesting and important, in that if the voltage is sufficiently low, the model of "fault of negligible impedance" isn't always applicable ... the results are either:

    • More risk of arcing at the "higher end of ELV" in DC systems - possibly risk of arc flash if there's sufficient current (although "sufficient" here may well be surprisingly low).
    • More risk of a high resistance fault  at the "lower end of ELV" (say 30 V AC or DC, or less ... only a finger in the air) leading to fire - importantly, this is a possibility  with AC or DC. Having resistance in the fault may cause overcurrent protective devices to fail to operate.
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  • gkenyon said:
    Yes, arc flash energy at 12 V may well be low,

    and of course the arc flash is therefore not sustained for long enough for it to be what we know of as a "full blown flas" ... This particular point raises something very  interesting and important, in that if the voltage is sufficiently low, the model of "fault of negligible impedance" isn't always applicable ... the results are either:

    • More risk of arcing at the "higher end of ELV" in DC systems - possibly risk of arc flash if there's sufficient current (although "sufficient" here may well be surprisingly low).
    • More risk of a high resistance fault  at the "lower end of ELV" (say 30 V AC or DC, or less ... only a finger in the air) leading to fire - importantly, this is a possibility  with AC or DC. Having resistance in the fault may cause overcurrent protective devices to fail to operate.
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