Direct Buried cables within a controlled area and what constitutes mechanical protection

The only law which applies to BS7671 is contract law, that which is written into the contract. Whilst one may attempt to say a PV array farm is not a HV generator, this is not true if the connection to the Grid is a HV one

Real generating stations operate with many generation voltages, there are numerous efficiency constraints that may suggest a particular generation voltage, but the power station transformers which connect to the metered grid often deliver at 132kV or more. This is the point, a generator would be very difficult to design which actually made power at 132kV, the first being the level of insulation required. Take a 600 MVA unit, it would need to deliver only 4545 amps at 132kV, but this is not a big current and would need a lot of turns. Much better from an insulation point of view would be 45 kA at 13.2 kV, and perhaps a single turn per phase. Cooling is the least of the problems here, insulation is both thermal and electrical, and a lightly insulated bar of a significant cross-section would cool best, or perhaps a number of smaller ones in parallel, giving more surface area. The voltage is then sorted by the transformer, which we need anyway for fault handling and protective purposes. At 1MVA the preferred generation voltage may be 3.3kV, but 400V is not unknown at this power level. If connected to the grid, this is still considered a generator, and G59 would apply, and the grid voltage would probably be 11kV. This kind of installation often has "differences" to BS7671. You seem to be implying that the reference to BS7671 is to use it as a safety case against the wiring. If one reads BS7671 it is quite clear that the safety is for consumers and users of wiring systems. To use it for 1.5kV DC wiring is pushing the scope quite a long way from its normal purpose, if it ended up in court a skilled Engineer would drive "a coach and horses" through the argument you are putting, simply asking why an IT system with inbuilt protection could be dangerous to anyone off-site, to which you control access and presumably maintenance operations? On-site, you as the operator simply need to set safe rules for staff, including such items as permissions to work.

The only law which applies to BS7671 is contract law, that which is written into the contract. Whilst one may attempt to say a PV array farm is not a HV generator, this is not true if the connection to the Grid is a HV one

Real generating stations operate with many generation voltages, there are numerous efficiency constraints that may suggest a particular generation voltage, but the power station transformers which connect to the metered grid often deliver at 132kV or more. This is the point, a generator would be very difficult to design which actually made power at 132kV, the first being the level of insulation required. Take a 600 MVA unit, it would need to deliver only 4545 amps at 132kV, but this is not a big current and would need a lot of turns. Much better from an insulation point of view would be 45 kA at 13.2 kV, and perhaps a single turn per phase. Cooling is the least of the problems here, insulation is both thermal and electrical, and a lightly insulated bar of a significant cross-section would cool best, or perhaps a number of smaller ones in parallel, giving more surface area. The voltage is then sorted by the transformer, which we need anyway for fault handling and protective purposes. At 1MVA the preferred generation voltage may be 3.3kV, but 400V is not unknown at this power level. If connected to the grid, this is still considered a generator, and G59 would apply, and the grid voltage would probably be 11kV. This kind of installation often has "differences" to BS7671. You seem to be implying that the reference to BS7671 is to use it as a safety case against the wiring. If one reads BS7671 it is quite clear that the safety is for consumers and users of wiring systems. To use it for 1.5kV DC wiring is pushing the scope quite a long way from its normal purpose, if it ended up in court a skilled Engineer would drive "a coach and horses" through the argument you are putting, simply asking why an IT system with inbuilt protection could be dangerous to anyone off-site, to which you control access and presumably maintenance operations? On-site, you as the operator simply need to set safe rules for staff, including such items as permissions to work.