MicroSolar Energy
The Risk of Solar Mounting System

It is the responsibility of both installer and designer to choose a qualified mounting system. As you know, mounting system is a basic truss structure system; the joints and fasteners are considered to be the most important parts within a structure. This is the reason why Australian government and councils insist to design solar mounting systems according to Australia Building Standard.

Conforming to the standard, AS1170.1.2, that fasteners constructed within buildings must use stainless steel or carbon steel with galvanised as its materials (see graph below). Any material that is not within this list will count as substandard comply with Australia Building Standard. However, it is clear that the evidence shows their fasteners are against the Australia Building Standard. Products, they’ve produced, only comply to their own company’s standard and disregards AS1170.1.2 or any other related government solar mounting standards.  

As a good example, to follow the Australia Building Standard, MSS Ezquik solar mounting system uses stainless steel bolt and nut/threads as its fasteners.

There are some solar mounting systems out there using aluminium nut/threads; and they should create their own special certification to approve that the products works on the mounting systems, and at the same time there will be huge question mark on the side asking ‘Does this really comply with AS1170.1.2?’

Material and treatment Chemical composition limits
(check analysis) % (m/m)
min. max. max. max. max. min.
3.6 b Carbon steel - 0.20 0.05 0.06 0.003 -
4.6 b - 0.55 0.05 0.06 0.003 -
4.8 b
5.6 0.13 0.55 0.05 0.06 0.003 -
5.8 b - 0.55 0.05 0.06
6.8 b
8.8 c Carbon steel with additives (e.g. B, Mn or Cr)
quenched and tempered
0.15 d 0.40 0.035 0.035 0.003 425
Carbon steel quenched and tempered 0.25 0.55 0.035 0.035
9.8 Carbon steel with additives (e.g. B, Mn or Cr)
quenched and tempered
0.15 d 0.35 0.035 0.035 0.003 425
Carbon steel quenched and tempered 0.25 0.55 0.035 0.035
10.9 f Carbon steel quenched and tempered 0.25 0.55 0.035 0.035 0.003 425
Carbon steel with additives (e.g. B, Mn or Cr)
quenched and tempered
0.20 d 0.55 0.035 0.035
Alloy steel quenched and tempered g 0.20 0.55 0.035 0.035
12.9 f h i Alloy steel quenched and tempered g 0.28 0.50 0.035 0.035 0.003 380

a. Boron content can reach 0.005% provided that non-effective boron is controlled by addition of titanium and/or aluminium.
b. Free cutting steel is allowed for these property classes with the following maximum sulfur, phosphorus and lead contents; sulfur 0.34%, phosphorus 0.11%; lead 0.35%.
c. For nominal diameters above 20 mm the steels specified for property class 10.9 may be necessary in order to achieve sufficient hardenability.
d. In case of plain carbon boron steel with a carbon conten below 0.25% (ladle analysis), the minimum manganese content shall be 0.6% for property class 8.8 and 0.7% for 9.8, 10.9 and 10.9 .
e. Products shall be additionally identified by underlining the symbol of the property class (see clause 9). All properties of 10.9 as specified in table 3 shall be met by 10.9 , however, its lower tempering temperature gives it different stress relaxation characteristics at elevated temperatures (see annex A).
f. For the materials of these property classes, it is intended that there should be a sufficient hardednability to ensure a structure consisting of approximately 90% martensite in the core of the threaded sections for the fasteners in the "as-hardened" condition before tempering.
g. This alloy steel shall contain at least one of the following elements in the minimum quantity given: chromium 0.30%, nickel 0.30%, molybdenum 0.20%, vanadium 0.10%. Where elements are specified in combinations of two, three of for and have alloy contents less than those given above for the two, three or four elements concerned
h. A metallographically detectable white phosphorous enriched layer is not permitted for property class 12.9 on surfaces subjected to tensile stress.
i. The chemical composition and tempering temperature are under investigation.


Steel fastener connections shall be referred to Australian Standard 4100. According to Australian Standard, if other material were used, such as aluminium as fasteners, special detailed design report and evidence is required.
Table 2 - Steels
Table 2 (page 5) specifies steels and tempering temperatures for the different property classes of bolts, screws and studs.
The chemical composition shall be assessed in accordance with the relevant ISO standards.
According to AS/NZS 4291.1

According to AS/NZS1252


The materials and mechanical properties of high-strength steel bolts shall be as given in AS/NZS 4291.1 for property class 8.8.

According to AS 4100



The use of other high stregth fastners having special features in lieu of bolts to AS/NZS 1252 shall be premitted provided that evidence of their equivalence to high strength bolts complying with AS/NZS 1252 and installation in accordance with this standard is available.

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