Introduction
PV connectors are integral to every solar project: they are
the links through which DC solar power is transmitted from
PV modules through cables into inverters. For a system to
produce AC power safely and reliably, connectors must:
1. Provide low-resistance connections that minimize
resistive losses as electricity flows through the array.
2. Withstand 25+ years of environmental exposure with
minimal corrosion, degradation or current leakage.
However, the industry lacks a universal standard for
PV connector design. While the design details of these
electromechanical devices vary, they usually have a male
part, which is an internal plug that encloses a contact, and
a female part, which is a socket with an extended contact.
Tightly locking these two parts creates an electrical circuit.
Hot connectors, or connectors that have high operating
temperatures, are the most important indicator of latent
failure. Any other warning signs are usually hidden from
view because field-made connectors cannot be internally
inspected after installation without destroying them.
Inside a PV Connector
The inside of a PV connector is rarely seen. Many PV
connectors are field-made, which means their two parts are
pushed together in the field during installation. Once locked,
opening a field-made connector permanently destroys it.
PVEL's field testing team obtained the image shown to the
right using an advanced lab testing technique called X-ray
Computed Tomography, which yields a 3D image of the
inside of the connector.
Connectors and Fires
Connectors are a leading cause of fires instigated by PV
systems in many global solar markets. These rare events
pose severe threats to safety, property and even the public
image of solar power. While many are confidential, there are
documented cases of PV system fires and connector failures:
• In January 2022, SunPower initiated a >$30MM USD PV
connector replacement initiative due to a cracking issue
in third-party products it supplied.1
• In the U.K., 27% of 58 fires instigated by PV systems from
2010 to 2017 were caused by connectors.2
• In Germany, connectors were blamed for 24% of 180
fires caused by PV systems from 1995 to 2012.3
• Japan’s Consumer Safety Investigation Commission
recommended rooftop PV system inspections in a report
citing 127 fires from 2008 to 2017.4
A Growing Concern
As of December 2021, there were approximately 375M PV
connections in the U.S. and an estimated 3.5B PV connections
worldwide. Each of these individual connectors represents
a potential point of failure, but only a tiny fraction of them
are regularly monitored. Fires in operating assets with faulty
connectors are preventable, but only with the right inspection
and testing techniques.
Inside a PV Connector
The inside of a PV connector is rarely seen. Many PV
connectors are field-made, which means their two parts are
pushed together in the field during installation. Once locked,
opening a field-made connector permanently destroys it.
PVEL's field testing team obtained the image shown to the
right using an advanced lab testing technique called X-ray
Computed Tomography, which yields a 3D image of the
inside of the connector.
In order to operate properly, the male and female contacts of
connectors must be correctly matched, fully inserted and correctly
crimped as shown above.
Modern Connectors and Field Failures
Push-fit connectors accelerated the growth of the solar industry in the early 2000s by
simplifying PV system installation. The design allowed construction workers to make
electrical connections in the field instead of licensed electricians
Unintended Consequences
As technology improved, the slow pace of development for
connector standards and regulations led to confusion in the
market and failures in the field.
As a result, many solar installation professionals have
received incorrect training that specifies:
1. Uncertified, generic tools can be used for installation.
2. MC4-compatible connector parts produced by any two
different manufacturers can be paired.
These are myths that cause field failures.
The Signs of Connector Failure
The obvious signs of failure are: loose or disconnected
connectors; high temperatures; melted, discolored or cracked
casings; arc faults and ground faults; fires. But these field
observations are only the symptoms of deeper challenges:
• Uneven, insufficient or improper surface contact on
metal contacts.
• High resistance due to soiling, corrosion or foreign
particles.
• Moisture or water ingress that creates alternate
electrically conductive paths, typically resulting from a
broken seal and/or separated connectors.
• Material degradation due to environmental factors.
The conditions described above arise when fundamental
mistakes are made at the time of connector manufacturing,
procurement or installation, or due to a natural catastrophe
or force majeure event.
A mismatched MC4 and MC4-compatible connector in the
field at a site with extensive connector failures.
Why Failures Happen: The Most Common Root Causes are Simple Mistakes
-Improper installation
Contacts that are not inserted fully into housing is a
common issue.
-Improper installation tools
Uncertified tools may not meet product specifications and/
or damage components.
-Lack of training
Proper torquing technique and the use of end caps are often
overlooked.
-Mismatched connectors
Design differences may prevent complete, watertight
locking.
-Counterfeit connectors
Untested, uncertified products may be unsafe and degrade
quickly.
-Faulty Faulty materials
Some polymeric materials degrade rapidly after contact
with oil or sunscreen.materials
Some polymeric mater
What Happens When Connectors Fail?
Some connector failures are worse than others. Catastrophic incidents that jeopardize
safety and property are more likely to occur when faulty connectors continue
operating in the field over time.
-Compromised Connectors Can Be Time Bombs
Connectors that are left unplugged and uncapped during
construction are often exposed to moisture and foreign
particulates, such as dirt or other organic matter. Without
connector caps, the metal pins of the connectors will be
exposed to moisture and begin to corrode.
Then, once the connector is closed, the corrosion continues to
propagate, increasing connector resistance until the connection
eventually fails. These connectors can become time bombs
waiting to ignite to the field.
-Poor Sealing Causes Nuisance Tripping
When connectors are not properly sealed against the
environment, current can leak to ground. Inverters have
sensitive circuits to detect the isolation of the system from
ground during start up. In PVEL and HelioVolta's experience,
inverter nuisance tripping during periods of high humidity (e.g.
from morning dew) is frequently traced back to the combined
ground leakage current from many poorly sealed connectors.
Connectors and Personal Safety
The safety of personnel and consumers cannot be overlooked in any discussion of connector failure. Silent,
non-detected or non-flagged ground faults can be lethal for technicians and other personnel, as well as the
customers of solar-powered businesses and homeowners with PV systems.
The Spectrum of Connector Failures
Initial symptoms of failure may go unnoticed, such as minor reductions in energy yield caused by resistive losses. The chart below
describes the spectrum of failure modes and range of potential impacts for asset owners
| Field Observations of Failure | Performance Impacts
| Commercial Impacts
|
Power Loss | Visible signs of failure may or
may not be apparent
• Disconnected, loose or
connectors
| 0.3% to 1% power loss
• Resistive losses may go
unnoticed
| Up to a few thousand dollars
per year in financial losses
|
Ground/
Arc
Faults
| Compromised enclosures
• Melted connectors
• Sparks
• Frequent inverter tripping
| Periodic downtime and/or
inactive strings are possible
• Major underperformance and
power losses can occur
| Up to a few thousand dollars
per day in financial losses
• Safety risks to personnel
• Equipment damage
|
| Fires | Extremely hot connectors that
ignite system components
• Explosions
• Destroyed equipment
| System failure
• Total power loss
• Repairs may require extended
system downtime
| • Severe safety risks to staff and
general public, for which asset
owners may be legally liable
• Total or near-total financial
losses possible due to property
and equipment damage
• Business closures for repairs
and restoration
|
Analysis assumes the following initial conditions: 5 MW commercial project; $0.15 PPA rate; 1400 kWp/kWh production; 425W modules; 588 strings; 10 A
module current; 42.5V module voltage; 1000 V string voltage. Connectors with resistance of 150mΩ affect 10% of the project. 1% of field made connectors
are open, rendering six strings inactive
Diagnosing Connector Failure
There are many ways to make mistakes when creating a PV connector, but few ways
to validate their quality after installation.
4
Assessing connector quality in the field is challenging. While these devices can safely be unplugged when they are not under
load, they cannot be disassembled without compromising their integrity: assembly is irreversible. Visual inspection of the
connector’s exterior can reveal some errors but it does not validate the quality of the internal connection
Failing Connectors are Hot
Compromised connectors have a higher resistance than
properly made connectors. That resistance decreases energy
yield and produces heat. As a result, high temperature is the
primary warning sign of looming connector failure:
• If major issues are present at the time of installation,
thermal identifiers may be present when the system is
commissioned.
• When latent defects are present, thermal identifiers may
not emerge until the system has operated for some time.
Thermal imaging on the ground can identify latent connector
reliability issues before they become catastrophic failures.
However, drone thermal imaging does not adequately
identify hot connectors because they are typically positioned
underneath modules that hide their heat signatures.
Identifying Failures with Thermal Imaging
There are no specific standards for on-site thermal imaging
of PV connectors, but HelioVolta’s data-driven approach has
proven successful in the field. Their process establishes pass/
fail criteria that includes two categories:
• Absolute temperature failure, which is defined according
to manufacturer specifications, typically 85°C to 95°C. All
connectors that display a temperature above this limit are
considered failures.
• Differential temperature failure, which is project-specific.
Some connectors that operate below the threshold for
absolute temperature failure will measure at higher
temperatures than others at the site. These connectors
still present performance and safety risks.
The criteria for differential temperature failure is established
using baseline average connectors temperatures at specific
temperature and irradiance conditions. The threshold for
failure is based on the deviation from that baseline average.
The images above show differential temperature failures.
One of the connectors in the bundle (left) has an operating
temperature that is 15°C higher than the others, as indicated
by the thermal image (right).
The sample of failed connectors above melted due to high
temperature operation in the field. PVEL removed the devices
from the field for testing and root cause failure analysis.
Advanced Lab Testing for Root Cause Analysis
Determining the root cause of connector failure typically
requires sophisticated destructive testing conducted in
a laboratory setting. Neither thermal imaging nor visual
inspection reveal the inner workings of connectors. PVEL
recommends the following techniques for advanced analysis:
• X-ray computed tomography (XCT) to create a 3D
image of the connector, including metal and plastic
components.
• Scanning electron microscopy (SEM) and energydispersive x-ray spectroscopy (EDX) to identify metal
corrosion and arcing biproducts.
• Cross-sectioning the connector at the position of the
crimp to evaluate crimp quality.
• Subjecting connectors to accelerated stress testing in
high temperature/humidity conditions and/or thermally
cycling in a laboratory environment to accelerate
failure of suspected bad connectors.
The above XCT cross-section images show the difference
between a correct (left) and poor (right) connector crimp
found by PVEL in an active PV installation.
Inside a Root Cause Failure Analysis
Connectors regularly melted and caught in fire in a >150 MW
project in California.
The owner contracted PVEL to conduct a root cause analysis
that determined why the failures occurred and identified the
EPC as the party at fault. PVEL evaluated 1,500 of the nearly
100,000 field-made connectors at the site with a combination
of visual inspection, infrared thermography and XCT.
Installation error was identified as the overarching root cause
of connector failure:
• Critical connector installation errors were extensive,
including under- and overtorqued nuts, poor placement,
improper crimping, and improperly seated contacts.
• 40% of the connectors evaluated with XCT had
installation issues, and 20% had incomplete insertion
of the contact, which suggests issues are widespread
throughout the site.
• Persistent inverter nuisance tripping based on insulation
resistance faults could be due to the widespread poor
sealing of connectors due to under-torqued back nuts.
PVEL recommended further inspection and/or total
replacement of all field-made connectors in the project due
to significant installation errors
Inspecting Rooftop PV Systems
More than 70% of the commercial and industrial projects
inspected by HelioVolta have serious connector issues.
HelioVolta is usually contracted by the asset owner after a
safety event occurs. Several trends have emerged:
• Connectors can be difficult to locate and poor wire
management is common. Inspectors often crawl on their
knees with hand-held thermal cameras.
• Cross-mated connectors are frequently found on
homerun cables. This classic problem usually occurs
because modules come with a connector type that the
EPC does not have readily on-hand.
• Poor installation practices are often to blame for
failures. Connectors may be exposed to the elements,
resting on roof membranes, have a tight bend radius, or
poorly torqued backnuts, among other issues.
• Hot connectors are the most obvious indicator of
underlying issues. These connectors have higher
operating temperatures than other connectors installed
on-site, which indicates a higher electrical resistance.
Unfortunately, failure is only a matter of time for connectors
that are time bombs. To prevent future safety issues,
HelioVolta advises asset owners to:
• Ensure that connector quality assurance/control
protocols are in place for construction and
commissioning.
• Mandate proper field-made connector training for
personnel.
• Include connector inspection requirements and pass/fail
criteria in operations and maintenance contracts.
A single overheated connector caused this catastrophic failure.
Per PVEL's testing, installation error is likely the root cause.
These XCT images show two
poorly installed connectors. The
top image reveals incomplete
insertion and the left image zooms
in on a channel for water ingress
due to an undertorqued nut.
Drilling Down on Connector Inspection Techniques
Different types of connector inspections can reveal different issues. The table below describes the types of connector failure
modes that can be identified through visual inspection, thermal imaging and advanced lab testing
Failure Mode
| Root Cause | Failure Mode | Visual Inspection - Connected* | Visual Inspection - Disconnected* | Thermal Imaging | Advanced Lab Testing |
Lack of Trainingor Improper Installation Practices | irty contacts or contamination by
foreign particles | No | Yes | Somewhat likely | Yes |
| Corroded by exposure to water during installation | No | Yes | Somewhat likely | Yes |
| Contact not seated in housing | No | Yes | very likely | Yes |
| Cross-threaded | YEs | Yes | Not likely | Yes |
| Incorrect choice of contact for wire gauge or strand count | No | No | Likely | Yes |
| Incorrect choice of plastic housing for wire insulation outer dimension | No | No | Likely | Yes |
| Connectors exposed to elements | Yes | Yes | Not Likely | No |
| Wire nicks during stripping | No | No | somewhat Likely | Yes |
| Lost wires during stripping | No | No | somewhat Likely | Yes |
| Wires too bent going into connector | Yes | Yes | Not Likely | No |
| Low point location (water dripping) | Yes | Yes | Not Likely | No |
| Not fully seated (plastic pins do not click) | Yes | Yes | Likely | Yes |
| Too much tension | Yes | Yes | Likely | No |
| Counterfeit Products | Many failure modes are possible due to lack of certifications and testing | Maybe | Maybe | Somewhat Likely | Maybe |
| Improper Tools | Improper torque | Maybe | Yes | Not Likely | Yes |
| | Bad crimp | No | No | Likely | Yes |
| | Incorrect stripping length | No | No | Somewhat Likely | Yes |
| Mismatched Parts | Disimilar contacts and couplers specifications | Yes | Yes | Somewhat Likely | Yes |
Faulty Materials / Manufacturing Defects | Fast degradation of polymer materials | Maybe | Maybe | Somewhat Likely | Maybe |
| Propensity for fretting corrosion | No | No | Somewhat Likely | Yes |
*Non-destructive visual inspection can be conducted on connectors that remain connected; i.e., the male and female parts are
locked together. It can also be conducted on connectors that have been disconnected, so long as they are opened safely and are
not under load. Removing the back nut and opening the plastic housing of a connector to inspect its interior will compromise it.
**Thermal imaging is presented by probability of detection because this technique can only identify issues that cause resistance
rise to the point that the connector causes significant resistive losses and is close to failure. While thermal imaging does identify
hot connectors, it typically does not reveal the specific issue or root cause of failure.
Insights from Non-Destructive Visual Inspection
During O&M inspection, thermal imaging is the primary tool for identifying PV connector issues. However, there are also visual
cues that can identify the longer-term connector issues soon after commissioning, before they are apparent in a thermal scan.
These cues are also helpful if irradiance conditions are below a minimum threshold for inspection.
Connectors may be unconnected,
loose, or improperly connected. If the
connector is not pushed in all the way,
the connection is not perfect and can
lead to increased resistance over time.
 |
Signs of overheating ("shine effect"
or thermal deformation). Materials in
connectors change appearance when
they degrade due to operation outside
of specified temperatures.
 |
Cross-threaded back nuts. When
torquing back nuts, threads can bite
in the wrong channels, or crossthread.
This can compromise the connector's
watertight seal.
 |
Over-torqued back nuts. Torquing
specifications vary by manufacturer
and must be followed. Over-torquing
compromises the seal and integrity of
the connector body.
 |
Under-torqued back nuts.* This error
is usually caused by skipping a step
or using plastic installation wrenches.
Some manufacturers specify the
number of visible threads.
 |
Inconsistent back nut visible threads.
This can indicate a mistake because
all connectors in a single array are
usually made with the same tools and
conditions. They should match
 |
Exposure to sunlight and water.
Connectors should be protected from
moisture and direct UV rays as they
will degrade the material over time.
This is often manufacturer-specified.
 |
Insufficient bend radius or too much
tension on the leads. These conditions
can compromise the integrity of the
seal at the back nut or even damage
the internal crimp.
 |
Crossmated connectors. The term
"compatible" refers to the shape of the
termination and does not guarantee
safety. Parts from different brands are
not usually tested/certified together
 |
Additional Notes
• Connectors should not be located at a low point in cabling. This allows water to seep along their cables and interact with
the backing nut. If the back nut seal is compromised, moisture ingress may create an alternate path for electron flow.
• Exposure to mechanical interference can also damage connectors and lead to electrical problems. For example, connectors
may be pinched due to tracker movements or affected by vibrations from heating and cooling systems
The Solar Industry's Most Common Torquing Myth
It is a common misconception that the plastic wrenches used for installation slip when there is sufficient
torque on the back nut. This is false. Plastic wrenches may be used to initially make the connection, but
then the nut must immediately be torqued properly with the manufacturer-approved torque wrench.
Torque on the back nut cannot be checked post-commissioning. It is imperative that asset owners are
confident in their installation teams and the quality of the connectors in their projects
Best Practices to Ensure Connector Reliability
Connector failure creates safety risks and causes underperformance in PV assets, but
these negative outcomes are avoidable. Take action throughout the project lifecycle
to prevent connector failure by following these five steps:
1. Specify Connectors
Specify certified connectors by manufacturer and exact product type in both module
supply agreements and EPC contracts. Mandate and validate product authenticity to avoid
counterfeits.
2. Install the Right Connectors
Do not allow cross-mated connectors unless they are tested and certified together as a single
component. Obtain new connectors from module manufacturers if necessary.
3. Install Connectors Properly
Use manufacturer-provided crimping tools. String modules immediately to prevent
environmental exposure and use end caps when necessary. Document the status and location
of all field-made connectors at the time of installation.
4. Validate Connector Installation
Include third-party as-built inspection and verification requirements in EPC contracts. Ensure
connectors are covered under EPC warranties.
5. Regularly Inspect Connectors
Periodically inspect connectors throughout the project lifecycle using SolarGrade software and
an acceptable quality level (AQL) sampling approach. Always conduct inspections after force
majeure events because they can compromise the integrity of well-made connectors
Next Steps
Connectors are not complicated when they are installed correctly and functioning properly – but when they fail, the
ramifications can be enormous. While field inspections can prevent costly fire incidents, the root causes of connector
failure are more fundamental and must be addressed
 |
Standardize Connector Design
The industry lacks a clear, consistent standard for connector design. MC4 has emerged as the de facto
connector standard, but it is a proprietary design. Product marketing that promotes “MC4 compatibility” has
resulted in widespread and dangerous assumptions about connector intermatability. The best way to prevent
compatibility-related failures is to standardize connector design.
|
 |
Improve Installer Training
Solar training programs do not always provide accurate guidance for connectors. In our experience,
problematic practices that lead directly to connector failure are widespread and deeply ingrained. A concerted
industry-wide effort to improve training programs is necessary, especially as the solar installation workforce
grows. The best way to prevent installation-related failures is to require robust, accurate installer training.
|
 |
Conduct More Research
The industry will benefit from new tools and more test methods that enable frequent, low-cost connector
inspections on a regular basis. The humble PV connector should be prioritized by researchers precisely
because it is easy to overlook in the field. With the right technology, connector inspections can become a
standard operating procedure for solar PV systems instead of a reactive response to obvious signs of failure.
We urge those interested in joining PVEL and HelioVolta’s research and development efforts to reach out.
|
Staubli MC4 Connector
MC4 & MC4-Evo 2 connectors
Maximum Isolated Voltage 6000V
1500 V, 100 A and 10 mm²/8
Water and Wheather Proof
Maxim System Voltage 1500V
IEC 61984:2008, UL 1977
Maximum Pulsa Voltage 8000V
Max System Voltage
Max DC Current
Cable Size
0-1500V DC
30-100A
4-10mm²
Custom ,Gümrük Tariffe GTIP Number:8536690000
32.0018 PV-AZB4 Female+Female=Male (Pozitif+Pozitif=Negative)
32.0018 PV-AZS4 Male+Male=Female (Negative+Negative=pozitive
MC4 Branch plug PV-AZS4 connector for a safe and simple parallel or serial parallel connection of PV-modules
Product features
-Safe and simple parallel or serial parallel connection of PV-modules
-Pluggable with single-pole Stäubli PV-cable coupler MC4. Unmated connections must be protected by sealing caps
-Plug-and-Play: no crimping or torquing necessary
-Versatility and compact dimensions
-Mating compatibility with original MC4 and MC4-Evo 2 cable connectors
-DC 1500 V according to IEC 62852 and UL 6703 PV-AZB4-EVO 2-UR PV-AZS4-EVO 2-UR
-Resistance to salt mist spray
-Proven MULTILAM Technology with high long-term stability which ensures consistently low performance loss throughout the entire service life of the connector
-The Original MC4 is the world’s leading PV connector designed and engineered by our in-house experts more than 20 years ago. As the most installed PV connector worldwide, the MC4 continues to set new industry benchmarks thanks to our drive for excellence and innovation.
-Stäubli connectors are crafted with Swiss precision, offering optimal efficiency and long-term performance for small to large-scale PV systems. When selecting connectors, trust the original to rest assured that your operations will be safe and perform sustainably for decades to come.
• In accordance with NEC 2023, requires a tool to open.
• Proven MULTILAM technology with high
long-term stability, which ensures consistently low performance loss throughout the entire service life of the plug connector.
• Approved for DC 1000 V (IEC) and DC 1500 V (UL).
• Tried and tested plug connectors, over 25 years of experience in the field.
• Available for assembly with cross-sections up to 10 mm².
• Also available as ready made leads according to customer‘s specification.
• To be used with suitable mated connectors from the MC4 product family and
suitable lead
long-term stability, which ensures consistently low performance loss throughout the entire service life of the plug
connector.
By selecting the premium-quality MC4 PV connector of Stäubli for your PV projects, you are creating a solid foundation for success while minimizing risks and ensuring efficiency and profitability.
Constantly low contact resistance of the PV connectors is key for efficient operation and safe energy feed-in. Increasing contact resistance, e. g. due to deficient material characteristics, can weaken the efficiency of the entire PV system
-The core of the Stäubli PV connectors is the innovative MULTILAM contact technology. This unique contact principle stands out due to multiple contact points that improve connection quality and energy transfer thanks to its constant spring pressure and unique design. This results in constantly low contact resistance, ensuring safe and long-life operation and reduces downtime and service cost significantly.
-This differentiating contact technology minimizes the risks of power loss, downtimes, hotspots, or even a fire that could lead to enormous reconstruction costs. The original Stäubli PV connectors of the MC4 connector portfolio are very stable in terms of temperature and show no heat accumulation.
The following information describes possible cable types
on which the connectors might be used in low-voltage DC
applications regarding cable stranding, diameter range and
limiting temperatures. Further, current ratings with respect
to ambient temperature (derating diagrams) are given. The
products’ assembly instructions (as listed above) are valid for
non PV cables as well and have to be followed.
For general low-voltage DC applications the products fulfill
the requirements of IEC 61984:2008 (Connectors – Safety
requirements and tests).
Further, the technical performance of the connectors is TÜV
certified according to IEC 62852:2014 (Connectors for DCapplication in photovoltaic systems - Safety requirements and
tests). At UL, the connectors are certified according to UL
6703:2014 (Standard for Connectors for Use in Photovoltaic
Systems). This high-level PV certification outperforms the
general industry level requirements of IEC 61984:2008, UL 1977
and is beyond most known general industry level standards
(UL 2237, UL 2238, UL 486A/B, etc.). These TÜV and UL
certifications, however, are only valid when the respective
PV cables are mounted. Also the UR sign on the connectors
is only valid for certified PV cables attached as described in the
assembly instructions (MA231, MA275, MA273, MA285).
Summary:
■ The connectors are suitable for use with other cable types in
lieu of PV cables
■ For the use in systems outside of photovoltaics, no
PV-specific certification is applicable
■ In this case connectors perform according to IEC 61984:2008
(Connectors - Safety requirements and tests)
Bankability - a matter of trust Gain the trust of investors and build the foundation for long-term economic growth
Cross-Connections Gain knowledge in optimizing your PV system and avoiding technical failures caused by cross-connecting components.
Market Leadership With over 2 billion PV connectors installed worldwide, Stäubli connects more than 50% of the world’s cumulative PV capacity
What are The Parts of Solar Connectors?
A few different parts that make up each solar connector:
Male or Female Connector: Solar connectors come in matched pairs — one male and one female. The male connector features a rod, while the female connector has a corresponding receptacle.
Contact Pins: There is a metal pin inside each connector (both male and female). These contact pins are usually made from tinned copper, providing excellent electrical conductivity and corrosion resistance.
Housing: This is the outer part of each connector, often made from durable black plastic. The housing should be resistant to UV light and weather. The plastic housing features a locking mechanism that prevents accidental disconnections.
Sealing Glands: The sealing glands are located at the bottom end of the connector where the cable enters. They provide a weather-proof seal.
Cable Gland Nut: This nut secures the connector and cable together. It provides strain relief for the cable and adds another layer of weather resistance.
-Rated voltage : 1000 V DC
-Rated current (30 °C) :2.5 mm²/14 AWG: 39 A , 4.0 mm²/12 AWG: 51 A , 6.0 mm²/10 AWG 65 A ,10.0 mm²/8 AWG: 104 A
-Rated surge voltage :12 kV
-Ambient temperature range: -40 °C…+85 °C
-Upper limiting temperature :105 °C
-Mating cycles :100 plug+unplug
-Degree of protection, mated IP65
-unmated :IP2X
-Overvoltage category/Pollution degree :CATIII/3
-Contact resistance of plug connectors: ≤ 0.35 mΩ
-Locking system snap-in/locking type :Safety class II
-Contact system :MULTILAM
-Type of termination:Crimping
-Contact material :Tin-plated copper
-Warning Do not disconnect under load Insulation material PC/PA
-Flame class: UL94-V0
MC4 connectors are single-contact electrical connectors commonly used for connecting solar panels. The MC in MC4 stands for the manufacturer Multi-Contact (now Stäubli Electrical Connectors) and the 4 for the 4 mm diameter contact pin. MC4s allow strings of panels to be easily constructed by pushing the compatible connectors from adjacent panels together by hand, but require a tool to disconnect them to ensure they do not accidentally disconnect when the cables are pulled. The National Electric Code (NEC) and the UL6703 standard for PV connectors specify that connectors have to be from the same type and brand to avoid the dangers of cross-mating.[1][2] In addition, IEC 62548 ‘design requirements for PV Systems' require PV connectors to be of the same origin.Originally rated for 600V, newer versions of the MC4 connector are rated at 1500V, which allows longer series strings to be created.
The MC4 system consists of a plug and socket design. The metal contacts of the plugs and sockets are inside plastic insulators; the plug's metal contact is inside a cylindrical insulator that looks like a socket, and the socket metal contact is inside a square probe that appears as a plug. The socket has two plastic locking tabs that have to be pressed toward the central probe slightly to insert into holes in the front of the plug connector. When the two are pushed together, the fingers slide down the holes until they reach a notch in the side of the plug connector, where they pop outward to lock the two together.
For a proper seal, MC4s must be used with cable of the correct diameter. The cable is normally double-insulated (insulation plus black sheath) and both UV and higher temperature resistant (most cables deteriorate if used outdoors without protection from sunlight). Connectors are typically attached by crimping, though soldering is also possible.
What are The Advantages of Solar Connectors?
Modern solar connectors have several inherent advantages when compared with older and proprietary types of solar plugs:
Weather Resistance
Solar connectors are designed to withstand years of harsh outdoor conditions, including UV radiation, rain, and snow. They usually have an IP67 or IP68 waterproof rating, meaning that they are exceedingly resistant to moisture and dust. You should never use connectors that are rated below IP67 or IP6* for water/dust resistance, as you open yourself up to issues when your system inevitably experiences harsh weather.
Safety
Solar connectors have a secure locking mechanism that prevents accidental disconnections. They are also designed to accommodate the high DC voltages present in residential solar power systems. Polarity protection is another critical safety feature of solar connectors. Since they have both male and female versions, reverse polarity is nearly impossible, which reduces the risk of system damage from wiring mistakes.
Industry Standard
Most modern solar panels and portable power stations use solar connectors that are universally compatible. When you use a standard solar connector, you can swap out other panels and components without any hassle. Most solar panel manufacturers utilize the same solar connectors, and the technology is poised to be the standard for years to come.
How and When To Use a Solar Connector?
Solar connectors are most commonly used to connect solar panels together in series or in parallel. They are sometimes used to connect solar panels to junction boxes and other solar components. They are easy to use — just plug the male connector into the female connector until you hear the locking mechanism click. Always ensure the power is disconnected when working on a solar power system.
To disconnect solar connectors, just squeeze the clips on the side using a solar cable disconnect tool (or your fingers). Exercise caution when working with solar panels, and never work on your system while it is under load.
Easy to Use
Solar connectors are known for their simplicity — connecting and disconnecting only takes seconds. This makes the solar installation process accessible to DIY-savvy homeowners and allows for easy maintenance if ever required.
They are not hardwired in, so you can always unplug and swap out components as needed. If you make a mistake in your initial installation, you can quickly adjust and make layout or wiring changes.
