Photovoltaic Cabling Systems
Solar cables are for use in all photovoltaic systems for cabling of solar modules among themselves as a connection to the DC/AC inverters.
Our double insulated Electron Beamed Cross-linked Cables meets the highest requirements for Solar Cables in the most important photovoltaic markets of Europe and the USA.
North American Requirements for PV Module Interconnecting Cable
The National Electrical Code (NEC), 2008 Edition, Sec. 690.31(B) specifies that single-conductor Type USE-2 service entrance cable and single-conductor photovoltaic (PV) wire are suitable for installation in exposed outdoor locations for photovoltaic module interconnections within the photovoltaic array.
Since PV modules operate at elevated temperatures and are exposed to a variety of environmental conditions, the insulation of the module interconnection conductors are required to be sunlight resistant and rated for wet locations at a temperature rating of 90ºC or above.
The UL standards used for investigating USE-2 wire (TYLZ) and PV wire (ZKLA) are UL 854 and UL Subject 4703 respectively.
PV wire comes with a thicker insulation or jacket to provide additional mechanical protection against the physical abuse that USE-2 wire is typically protected from.
PV wire has to employ stranded copper conductors to make it flexible for the intended application. On the contrary, USE-2 wire can employ either solid or stranded conductors made of copper, copper-clad aluminum or aluminum because it is typically installed in locations not subject to movement or mechanical damages.
The minimum conductor size for USE-2 wire is 14 AWG but PV wire can employ a smaller conductor size down to 18 AWG.
Insulation and Jacket Materials
Both PV wire and USE-2 wire use thermoset insulation and jacket typically made of XLPE or EPCV. Nevertheless, other thermoset materials such as CP over EP, CP over EPCV, SBR/IIR/NR and EP are also available. PV wire may also be constructed similar to type UF but using an additional 15 mils more of 90ºC wet and dry rated integral PVC insulation and jacket.
Considering USE-2 wire is typically installed underground or in similar locations where a flame may not propagate but PV wire can be installed exposed, a flame test is only required for PV wire.
On the other hand, the overload test and the mechanical abuse tests including crushing resistance and impact resistance are just applicable to USE-2 wire. As for sunlight resistance and flexibility at low temperature tests, PV wire has to comply with more stringent requirements. It has to undergo 720-hour weatherometer and -40ºC cold chamber conditioning respectively.
The requirements for USE-2 wire are 300-hour weatherometer and -25ºC cold chamber conditioning. In summary, PV wire has superior sunlight resistance and low-temperature flexibility when compared to USE-2 wire, in addition to a thicker insulation or jacket and a proven level of flame resistance.
Given PV wire can facilitate the use of ungrounded PV arrays as well as transformerless inverters, it is anticipated to become popular for module interconnections soon.
Differences Between PV Wire and USE-2 Wire
Whereas USE-2 wire has long been accepted for PV module interconnections, PV wire is newly introduced in the 2008 edition of NEC.
Though their construction and performance requirements are similar, some variations do exist due to their unique installation conditions.
Below is a comparison of these two types of wires, based on their usage, construction and testing requirements.
PV wire, with 90ºC wet rating and up to 150ºC dry rating, is dedicated for interconnecting PV modules.
USE-2 wire is designated as underground service entrance cable typically for connecting to the terminals of service equipment. It is limited to installations in maximum 90ºC wet and dry conditions.
Both USE-2 wire and PV wire can be rated 600 V. However, PV wire can also be rated 1000 V and 2000 V to accommodate photovoltaic modules intended for use in systems with a system voltage greater than 600 V.
Per the NEC, USE-2 wire is suitable for use in grounded PV arrays only but PV wire can be used within both grounded and ungrounded PV arrays.
- Conductor : IEC 60228 Class 5
- Insulation: Dytron XL
- Operating voltage: 600/1000V AC – 1000-1800V DC
- Test Voltage: 4000 V, 50Hz, 5 min.
- Operating temperature: -40 to +125C
- Ambient temperature: -40 to 90C
- 25 year life expectancy guarantee
- Max Short circuit temp: 280C
- Bending radius: >4 times OD
- Flame/fire performance: IEC60332-1 – UL 1581 VW-1
- Smoke density: IEC601034
- Smoke emission: IEC601034
- Fire load: DIN51900