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The bottom of 4.4.2.2 says

"If the earthing is for bonding requirements only then the array earth may be connected to
the installation earth via the PCE protective earth so long as removing the inverter for
maintenance:
(i) does not remove the earth connection; and
(ii) provided the PCE protective earth is of adequate cross-section according to the
requirement of Figure 4.3."

Am I reading this right that I may connect my earth to the protective earth in the cable that feeds the inverter? But I can only do so if the PEC in that cable also meets the minimum size requirements of Fig 4.3

So if I have a 4mm2 earth for the exposed conductive parts, I can only connect to the PEC at the inverter if it also was at least 4mm2?

Just to make things a little clearer, what standard are you referring to?

Hi Jamie, you are correct but in practice the installs I have inspected the installers use a 6mm earth wire as its cheaper than 4mm generally and take it from the switchboard and connected to the inverter in the same crimp lug then to the frame of the array. The earth wire is normally installed in the solar conduit with the DC cabling so it can connect straight to the inverter (same with the DC cables).

Sorry, 5033:2012

Further question, is the method of connecting to the PCE earth only permissable when it is for bonding? The clause indicates in the first line this method is only permitted when for bonding only. If it is for earthing does it have to go all the way back to the earth bar via PCE?

This would mean this method couldn't be used for an array above ELV because the frames require earthing?

Yes; the method is only permitted for equipotential bonding [4.4.2.1 (c)]; and not for protective earthing [4.4.2.1 (a)] or lightning protection [4.4.2.1(b)].

And yes, as per 4.4.2.1 para 3, this precludes it being used for arrays above ELV.