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EcoDirect.com offers cables for use in photovoltaic systems at competitive prices. We carry the newest MC4 locking cables, as well as the older MC3's and we even offer Rennsteig tools so that you can make your own professional-quality solar PV cables. For more information on solar panel cables, see our
Solar PV Cable FAQ
What is a PV adapter and what type do I need?
PV adapters allow a user to connect a module to an inverter equipped with a different type of end connector system. This allows the user to connect different brands of solar modules to another manufacture’s equipment, for example, an inverter.
It is essential that adapters not only have the physical format to attach the module to the inverter, but they must have the appropriate polarity.
An adapter plugs into the module's original cable and then provides the connection appropriate for the polarity of the original cable. They will usually have a positive (+) or connector on one end and a negative (-) on the other.
An important consideration is the terminology used to describe the physical connector at each end of the adapter.
In most electrical industries, connectors are described as “Male” and “Female” but this applies to the metal contacts themselves, not the plastic insulator that houses them. For some manufacturers of solar equipment, such as Amphenol, Tyco SolarLok, Multi-contact, and Radox connector systems, the housing of the connector pins appear opposite from standard electrical industries.
The male pin has housing with a relatively large opening in the end and the pin itself is recessed within. The female pin has housing that has a long narrow tip that fits into the male housing when they are mated. This appearance is just the opposite of what the terms “Male” and “Female” usually bring to mind and is the biggest source of problems in ordering exactly what you, the customer, needs.
When ordering adapters for your PV cables, it is vital to specify the physical type of connector for each end as well as its polarity.
Enphase Energy Application Note - Mating Microinverters with PV Modules for Correct Polarity:
The following helpful brief was prepared as an application note by Enphase Energy in October 2010 to provide clear guidance for mating microinverters with various DC connector types with PV modules (or adapter cables) and to ensure correct polarity between the microinverter and the PV module:
Microinverters are manufactured with two types of DC connectors for mating with PV modules. For example, microinverters ship with the following connector types:
- MC-4 compatible locking connectors (part number suffix S12)
- Tyco style locking connectors (part number suffix S13)
The polarity of the DC connectors on the microinverter varies with the type of connector.
When your microinverters are built with MC-4 compatible (S12) connectors:
When your microinverters are built with Tyco (S13) connectors:
Positive DC output of the PV module (+) connects to microinverter connector labeled positive (+)
- As we see above, connector labels do not always map to the corresponding positive or negative input of the microinverter.
- PV module connector labels may not map to the corresponding output of the PV module either.
- Microinverters should be ordered with the correct connectors for your PV modules.
- But if re-termination of your module’s connectors is required, it is critical that the positive output of the module be identified from labeling on the PV junction box. Connector labels can be misleading.
It is critical to follow these guidelines to avoid reversing the polarity between your PV module and the microinverter.
How do I determine what is a male or female connector?
The pictures below illustrate the differences.
Definition of Products
|Solar PV Cable: || This cable is precut and assembled with a connector at each end. |
|Connector: || There is one connector at each end of EcoDirect's solar PV cable. These are also sold separately so that you can make your own custom-length cable. |
|Adapter: || Adapters convert one type of connection into another so that two products with different connectors can be attached (for example, converting an MC3 connection into MC4). |
|Extension: || If your cable isn't long enough, use an extension so that it can reach. |
Which inverters require double insulated PV wire?
Double Insulated PV wire is required on transformer-less inverters, here is a short list of the inverters that require PV Wire:
- SMA Sunny Boy 8000, 9000, & 10,000W
- Power-One Aurora inverters 3kw to 12kW
- Solar Edge – entire line
The industry is moving to standardize on the PV Wire. Consensus is that the double jacket will last much longer in the sun on a hot roof.
What are the differences between PV wire and USE-2 wire?
Whereas USE-2 wire has long been accepted for PV module interconnections, PV wire is newly addressed in the 2008 edition of the NEC. Though their construction and performance requirements are similar, some variations between PV wire and USE-2 wire 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.
PV wire comes with a thicker insulation or jacket to provide additional mechanical protection against the physical abuse that USE-2 wire typically receives. PV wire employs stranded copper conductors to make it flexible enough 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 since 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 uses an additional 15 mils of 90ºC wet and dry rated integral PVC insulation and jacket.
Because USE-2 wire is typically installed underground or in similar locations where a flame may not propagate but PV wire can be exposed in an installation, a flame test is required only for PV wire. On the other hand, an overload test and mechanical abuse tests including crushing resistance and impact resistance are applicable only to USE-2 wire.
As for sunlight resistance and flexibility at low temperature tests, PV wire must comply with more stringent requirements. It undergoes a 720-hour weatherometer and -40ºC cold chamber conditioning. The requirements for USE-2 wire are 300-hour weatherometer and -25ºC cold chamber conditioning.
In summary, when compared to USE-2 wire, PV wire has superior sunlight resistance and low-temperature flexibility in addition to a thicker insulation or jacket and a proven level of flame resistance. Given that PV wire can facilitate the use of ungrounded PV arrays as well as transformerless inverters, it is anticipated to grow in popularity for module interconnections.