The SANS 10142-1-2 draft standards (for PV Installations) have yet to be published.

Many South African standards are thus, also based on IEC and NEC standards.

Here’s what you need to know…

 

# 1 – DC Cabling

 

This is the system that carries the sun’s energy from the PV panel to the people.

It should be easy to understand your system so the PV source, its output, the combiner box and inverter circuits should be labelled. This includes all termination points, connections and splices.

  • DC cable should not be readily accessible or in a conduit.
  • When routed inside a building cables must be in a metal raceway or metal clad cable or conduit.
  • Raceways must be labelled “Warning : Photovoltaic Power Source”.

 

#2 – DC Voltage

You need to do a whole lot of math when attempting a solar installation.

Code and Standards require that calculations for derating and correction factors must be done as the environment affects how the system will perform.

System should operate according to how the designer or Installer has intended.

  • Calculate the correct (maximum) voltage known as VOC (Voltage Open Circuit) for the COLDEST expected ambient temperature. Yip, you read right – voltage increases with temperature decrease. You could damage your inverter if you do not plan accordingly.
  • Check the VOC for the warmest expected ambient temperature. Your inverter might actually not start if the voltage is too low.
  • Ensure that all equipment is rated for the voltage:
    • The cables 
    • All disconnectors
    • Overcurrent devices such as fuses and breakers need to be rated correctly

#3 – DC Ampacity

The circuits (cables) must be able to carry the maximum PV source-circuit currents that the runs carry.

  • Check the Isc (short circuit current) rating of the panel.
  • Multiply that by 1.25 – this is to cater for edge of cloud effects.
  • Multiply that answer again by 1.25 for continuous operation rating.
  • The wiring should be able to carry these currents.

#4 – AC Ampacity

Solar panels produce DC but the house and the grid use AC.

You will have to understand both in order to “keep the lights on” and this may include feeding energy back into the grid.

The inverter will have a continuous current rating on the nameplate and datasheet. This cannot be exceeded.

  • Determine whether the AC panel you have will pass inspection.
  • Ensure that the back-feed breakers are located correctly.
  • Verify compliance with the interconnection requirements of IEC, SANS 10142-1 and SANS 10142-1-2

 

#5 – Ground Fault Protection

Safety is what it is all about !!!

As the SANS codes and Safety regulations state, People, Property and Animals must be protected.

Anyone coming into contact with the system should be protected from shocks, and also cut the risk from lightning or other power surges.

  • All grounded PV systems must have ground fault protection.
  • Ungrounded systems must also have ground fault protection or other system that meets the requirements of GFP.
  • Labels are required at the location of the ground-fault indicator or on the inverter.

 

#6 – Arc Fault Circuit Protection

Where there is power, there is a potential for a fire.

Arc fault protection helps prevent veld fires where there are ground mounted arrays, and building fires with roof-top installations.

  • NEC codes state that DC PV systems operating at greater than 80 volts must have DC protection.

 

#7 – Rapid System Shutdown

Ensure that first responders can shut down solar systems when the seconds count.

  • NEC code changes in 2014 state – A rapid system shutdown mechanism is required on all PC systems installed on buildings with DC conductors more than four metres inside a building or more than 8 to 10 metres from the array.
  • SANS 10142-1-2 section 5.2.5.1 states that each individual embedded generator shall have its own dedication disconnection device.
  • The disconnection device shall not be of the standard load plug-type installation.

#8 – Listing

All equipment that comprises the system is listed and labelled irrespective if it is powering a single building, multiple buildings or other structures such as a pole for security lighting.


  • Equipment for use in PV power systems shall be identified and listed, including:
  • Photovoltaic panels
  • Combiner boxes
  • Chargers / Charge controllers
  • Disconnectors
  • Inverters
  • Generating sets etc.
  • All equipment testing laboratories must test to the applicable standards

#9 – Equipment Grounding

All electrical equipment is to be grounded by means of a direct attachment to a recognised equipment grounding conductor.

  • Exposed non-current carrying metal parts of PV module frames, electrical equipment, and conductor enclosures shall be grounded
  • Structures – the racking, can be used for grounding if listed with the brand of modules used
  • Devices used for equipment grounding must be listed according to the applicable standards
  • Grounding conductors must be of sufficient size and generally not less than 6mm2

 

#10 – Grounding Electrode System

“An electrode in the vicinity of the array provides a short path to the ground in the event of a lightning strike. Secondly, it provides a low resistance path to ground and offers additional protection for people should they come into contact with a module frame that might be inadvertently energised by a failed wiring system or damaged module” – Bill Brooks, solar consultant.

  • An AC system must have a grounding electrode
  • A DC system must have a grounding electrode
  • If a system has both AC and DC requirements then
    • Bond DC grounding electrode to the AC grounding electrode system OR
    • Install a common grounding system

The contents of this article are credited to Hellermann Tyton, our preferred supplier of photovoltaic combiner boxes. For more information on Hellermann Tyton, their products and services, visit their website here.

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