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Solar DC connectors
Wednesday, January 20, 2021
As a licensed electrical worker...
All electrical work is covered by applicable standards and or guidelines and under Section 45 (1) of the Electricity Safety Act 1998 there is a requirement for a person who is responsible for the carrying out of prescribed electrical installation work to:
- Ensure the work is inspected by a licensed electrical inspector (LEI),
- Ensure this happens before the electrical installation is connected to the electricity supply
Remember, solar is classed as a prescribed electrical installation.
*Note: This excludes the testing requirements of Regulation 245 of the Electricity Safety (General) Regulations 2019.
DC connectors; like with like. (Is it a ‘shall’ or a ‘should’?)
Since July 2012 it has been a requirement in Australia and New Zealand within solar installations to only mate d.c. connectors of the same type from the same manufacturer. This is from AS/NZS 5033:2014 clause 4.3.7 Plugs, sockets and connectors which states:
Plugs, sockets and connectors shall- [...] (k) only be mated with those of the same type from the same manufacturer
This means the requirement is definitely a shall!
So there won't be any issues, right?
According to this October 2020 ESV Guide: in 2019, 30 percent of PV systems installed in Victoria contained mismatched DC connectors; and in 2020 this figure was still 18-20 percent — a good 6 years after the current 5033 standard came into effect.
Failure in many solar installations was the result of different brands of d.c. cable connectors mated together.
ESV’s take on this?
Now, ESV sees installing or certifying a solar system with mismatched DC connectors as a breach against section 44(1)(a) of the Electricity Safety Act 1998. Enforcement action may be taken if there is a proven breach.
What are the dangers?
The connectors carry significant d.c. energy and can operate at high voltages there is a risk of fire or smoke inhalation from mismatched d.c connectors. In addition bad crimping can lead to arcing and while the sun shines, this arcing will continue, a real issue for emergency service workers.
This is an issue with all electrical work as covered in AS/NZS 3000 clause 188.8.131.52.2 and all the connections should use a tool designed for the purpose and techniques specified by the manufacturer.
Different connector types
There are a range of different DC connector types used by the various PV panel manufacturer's around the world. Some of the more common connector types, with an example of a panel brand/model that uses them are:
When checking or designing PV systems you must:
- Check/identify the type of connectors used on the solar panels being looked at,
- Make sure you have the exact male and female connectors in your kit,
- Always use the right crimping tool for the connectors you are using,
- Be aware of the correct torque when cable connector back/screw cap is secured,
- Always follow manufacturer’s guidelines.
And do not energise a solar installation prior to the work being inspected (apart from during testing by a suitably qualified person).
Different ‘O’ rings and body shapes
What to look for with DC connectors
There are several identifying characteristics on DC connectors that need to checked and these include:
- Colour of the ‘O’ ring on the male + connector
- Different shaped screw nuts on cable gland
- Body contour shape. + and - are the same from same manufacturer
- Look for logo or symbol, see that they match
It is the responsibility of the designer/installer to make sure that ‘like’ components are being used.
The tools required
Pliers/cutters to cut solar cable:
Assembly and unlocking tool:
All components that require tightening, bolting, screwing have a manufacturer’s correct setting and in the case of tightening DC connectors this is measured in Nm, (Newton metre).
In America all solar electricians use calibrated torque wrenches when assembling DC connectors, while this is not a requirement in Australia at this point in time it could be considered best practice.
Some do’s and don'ts
Correct bending radius of cable exiting connections:
Correct crimping methods:
Tightening of the connectors:
Mated solar DC connectors must be like-for-like, i.e. same manufacturer and this is a 'shall', not a 'should'. Always use the correct tools and techniques as specified by the manufacturer as bad crimping can lead to arcing and while the sun shines, this arcing will continue.
As with everything in the electrical field there are standards and guidelines that must be adhered to and it is the responsibility of the designer/installer to not only know what is correct but to ensure that all times the correct materials are used and processes and procedures followed.