Photo voltaic PV methods – DC cable sizing with examples

The right sizing and correct set up of cables for grid-connected PV methods is crucial to make sure the efficiency, reliability and security of the system.

A PV system has each DC and AC cabling. The DC cabling connects the PV modules to the inverter whereas the AC cabling connects the inverter to the connection level of the grid.

The 4 standards for cable choice which apply contains:

1. Present-carrying capability – relies on the conductor measurement, working temperature restrict of the cable, overcurrent safety, technique of set up and the presence of exterior influences. The present carrying capability could also be taken from the present tables of requirements together with AS/NZS 3008.1, BS 7671 or IEC 60364-5-52. Alternatively they are often precisely calculated utilizing software program based mostly on the IEC Commonplace 60287.

2. Voltage drop (voltage rise for DC cables) – relies on the impedance of the conductor of the cables, the magnitude of the load present and the load energy issue.

3. Quick-circuit temperature restrict – the power of the cables to face up to the short-circuit currents with out sustaining everlasting injury, relies on the conductor kind and measurement in addition to the insulation properties similar to short-circuit temperature limits.

4. Financial optimisation – the optimum financial cable measurement is discovered by minimising the lifetime prices of the cable which incorporates each its preliminary price and the working prices (i.e. prices of {the electrical} I²R  losses).

The cable sizing calculations herein focusses on the present score and voltage rise calculations of the DC facet of PV methods and have been carried out in response to AS/NZS 3008.1.

The DC cable has two segments are thought of: the PV string to the array junction field (AJB) and the AJB to the inverter.


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