PV ELECTRICAL ANCILLARY EQUIPMENT

When installing PV systems the ancillary equipment is usually provided as part of the equipment.

The way that this equipment is specified is important to system safety and performance.

All equipment supplied by NuVision Energy meets the MCS standards and are CE marked.

AC switches: The rotary switch has to be lockable to comply with MCS regulations and suitable for 240 volt (single phase) or 415 volt (three phase) operation but importantly, the correct current rating (Amps) for the particular inverter. Common rotary isolators have 3 poles and are usually specified with single phase inverters whereas for three phase inverters 4 poles will be required to isolate the three live wires and the neutral.

DC Switches: These are usually denoted by a different colour from the AC switch by a black rotary knob. DC switches should be rated for DC current and voltages and not AC. The voltage rating of DC switches should be noted as this can vary depending on the number of modules in a string and the type of inverter being installed. Most common domestic PV installation comprise of 1 or 2 strings of panels at around 30 volts each. String these together can give voltages of up to 500 volts DC @ 8 amps. This changes with commercial installations where 20 – 25 modules are possible giving voltages of up to 800 Volts DC. Therefore the correct switch for the system is important.

FIT Meters: These meters come with pre-registered numbers from the manufacturers to simplify the system registration. The single phase units are simple meters but can be supplied with additional pulse output terminals for ancillary monitoring systems if required. Three phase meters come with this option too and both can be supplied with remote GPRS connection if required. Where system go over 100 Amps per phase then standard practice is to have a meter with a set of CT sensors that are fastened around the phase wires, which makes installation simpler. It is important to specify the current in this case in order to make certain that the CT leads are suitable.

TYPE 4 PV plugs: These are now standardised across much of the PV system and while there are a few manufacturers who make non universal units (particularly when crimping) it is important to have correct tool for assembling PV plugs. Many installations have failures caused by poor assembly.

PV Wire: It is important that complies with the relevant regulations for MCS and that the power rating is suitable for the application. For larger strings and longer runs, it may be necessary to increase the wire size from the standard 4mm² to 6mm².