{"id":2625,"date":"2026-10-21T02:04:24","date_gmt":"2026-10-21T02:04:24","guid":{"rendered":"https:\/\/willele.net\/heat-shrink-tubing-in-solar-pv-string-junctions-protecting-dc-connectors-for-25-year-service-life\/"},"modified":"2026-10-22T00:37:49","modified_gmt":"2026-10-22T00:37:49","slug":"heat-shrink-tubing-in-solar-pv-string-junctions-protecting-dc-connectors-for-25-year-service-life","status":"publish","type":"post","link":"https:\/\/willele.net\/ja\/heat-shrink-tubing-in-solar-pv-string-junctions-protecting-dc-connectors-for-25-year-service-life\/","title":{"rendered":"Heat Shrink Tubing in Solar PV String Junctions: Protecting DC Connectors for 25-Year Service Life"},"content":{"rendered":"

On a 50-megawatt solar farm in the Mojave Desert, the midday sun pushes module surface temperatures past 85\u00b0C, while DC string currents run at 1500 volts through hundreds of parallel-connected connectors. Every junction box, every MC4 coupler, every field-spliced cable termination represents a potential point of failure that, if left unprotected, can arc, corrode, or combust\u2014taking an entire string offline and slashing the plant’s revenue-generating capacity for the remainder of its 25-year design life. The difference between a junction that survives three decades and one that fails in year five often comes down to a few cents’ worth of polymer: specifically, the heat shrink tubing applied over the connector interface and cable insulation transition.<\/p>\n

Solar photovoltaic systems impose a uniquely punishing combination of stressors on DC wiring: continuous UV exposure, extreme thermal cycling from sub-zero winter nights to scorching summer noon peaks, moisture ingress from rain and condensation, mechanical loading from wind vibration, and the constant electrochemical threat of DC leakage current tracking across degraded insulation surfaces. In this environment, heat shrink tubing is not a cosmetic finishing touch\u2014it is a structural component of the weatherability system. This article examines how properly specified heat shrink tubing protects solar PV string junctions, what material properties matter most for 25-year outdoor service, and how engineering teams can select the right tubing grades for residential rooftop arrays, commercial carport installations, and utility-scale ground-mount plants.<\/p>\n

The Unique Demands of Solar PV DC Wiring Environments<\/h2>\n

Solar DC wiring operates under conditions that would rapidly degrade standard industrial cabling. Unlike AC distribution, where current reverses direction 50 or 60 times per second, DC current flows unidirectionally\u2014meaning any electrochemical migration, corrosion, or tracking that begins at a junction point will only intensify over time rather than self-correcting. A solar string connector carrying 10 amperes at 1500 VDC continuously for eight hours a day, 365 days a year, accumulates more than 43 million ampere-hours of charge transport annually. Any weakness in the insulation system will be found and exploited by that relentless electrochemical pressure.<\/p>\n

Thermal cycling is the second relentless aggressor. A rooftop installation in Arizona might see module junction-box temperatures swing from -5\u00b0C on a January dawn to +95\u00b0C on a July afternoon\u2014a 100-degree daily delta repeated thousands of times across the system’s life. Each cycle causes differential expansion and contraction between the copper conductor, the cross-linked polyethylene (XLPE) insulation, and the connector contact housing, creating micro-pumping action that draws moisture into any gap that isn’t hermetically sealed. Heat shrink tubing with an adhesive liner addresses this directly: the hot-melt sealant flows into and fills interstitial voids during recovery, then sets to a rubber-like consistency that remains compliant across the full temperature range, maintaining a moisture barrier even as the underlying materials expand and contract.<\/p>\n

UV radiation is the third critical factor. Standard polyolefin heat shrink tubing, while excellent for indoor and under-hood applications, will chalk, embrittle, and crack after 2\u20133 years of direct solar exposure unless it is specifically formulated with UV stabilizers. Solar-grade heat shrink tubing incorporates carbon black loading (typically 2\u20133% by weight) and hindered amine light stabilizers (HALS) that extend outdoor service life to 25 years and beyond. The difference between a generic and a solar-grade compound is not academic\u2014it is the difference between a tubing sleeve that still shows 80% tensile strength retention after 20,000 hours of accelerated weathering and one that shatters when touched after the equivalent of two summers of exposure.<\/p>\n

Key Junction Points Where Heat Shrink Tubing Is Critical<\/h2>\n

In a typical utility-scale PV plant, there are several distinct junction points where heat shrink tubing plays a protective role, each with different mechanical and electrical requirements:<\/p>\n\n\n\n\n\n\n\n\n
Junction Point<\/th>\nTypical Location<\/th>\nPrimary Failure Mode Without Protection<\/th>\nRecommended Tubing Type<\/th>\n<\/tr>\n
MC4 Connector Coupling<\/td>\nString-level, between module cables<\/td>\nWater ingress \u2192 contact corrosion \u2192 arc fault<\/td>\nAdhesive-lined polyolefin, 3:1 ratio<\/td>\n<\/tr>\n
Extension Cable Splice<\/td>\nHome-run wiring from string to combiner<\/td>\nMoisture tracking \u2192 insulation breakdown \u2192 ground fault<\/td>\nDual-wall adhesive-lined, 4:1 ratio<\/td>\n<\/tr>\n
Junction Box Penetration<\/td>\nCombiner box or re-entrant entry<\/td>\nVibration loosening \u2192 connector unseating<\/td>\nSemi-rigid polyolefin, 2:1 ratio<\/td>\n<\/tr>\n
Bifacial Module Edge Seal<\/td>\nModule-level, rear-side cable exit<\/td>\nUV embrittlement \u2192 insulation cracking<\/td>\nUV-stabilized polyolefin, 3:1 ratio<\/td>\n<\/tr>\n
Tracker Motor Cable<\/td>\nSingle-axis tracker drive harness<\/td>\nFlex fatigue \u2192 conductor fracture<\/td>\nFlexible polyolefin, 2:1 ratio<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Each of these applications demands a different balance of shrink ratio, wall thickness, adhesive presence, and mechanical stiffness. A one-size-fits-all approach to heat shrink tubing in solar PV is a guarantee of premature failures at the weakest junction in the system\u2014often the one least accessible for repair, such as a rooftop combiner box or a tracker harness routed through a torque-tube cavity.<\/p>\n

UV Resistance and Weathering: The 25-Year Survival Test<\/h2>\n

The International Electrotechnical Commission’s IEC 61215 and IEC 61730 standards mandate that PV modules survive 25 years in the field, and by extension, every component connected to the module must meet the same service life expectation. For heat shrink tubing, this means passing accelerated weathering tests that simulate decades of UV exposure, thermal cycling, and moisture freeze-thaw. The most commonly referenced protocol is ASTM G154, which uses fluorescent UV lamps to deliver a spectrum closely matching solar UV output, combined with condensation cycles to simulate nighttime moisture. A tubing grade suitable for solar applications should survive a minimum of 7,000 hours of G154 exposure (roughly equivalent to 20\u201325 real-world years in a temperate climate) while retaining at least 50% of its initial elongation at break.<\/p>\n

Carbon black is the workhorse UV blocker for polyolefin heat shrink tubing, but it comes with a trade-off: it limits the available color palette to black and dark gray, which is acceptable for most solar applications where aesthetics are secondary to function. For installations where visual identification of string polarity (positive vs. negative) is required\u2014common in residential rooftop arrays where inspectors need to quickly verify wiring\u2014tubing manufacturers offer UV-stabilized colored compounds using HALS additives rather than carbon black. These typically achieve somewhat shorter outdoor lifespans (15\u201320 years) and should be paired with periodic visual inspection programs in long-life installations.<\/p>\n\n\n\n\n\n\n\n
UV Stabilization Method<\/th>\nTypical Outdoor Service Life<\/th>\nColor Availability<\/th>\nBest Fit for Solar Application<\/th>\n<\/tr>\n
Carbon black loading (2\u20133%)<\/td>\n25+ years<\/td>\nBlack only<\/td>\nUtility-scale ground-mount, commercial rooftop<\/td>\n<\/tr>\n
HALS additives (colored compounds)<\/td>\n15\u201320 years<\/td>\nRed, blue, green, yellow<\/td>\nResidential rooftop, string polarity marking<\/td>\n<\/tr>\n
Non-stabilized polyolefin<\/td>\n2\u20133 years<\/td>\nFull color range<\/td>\nIndoor\/inverter cabinet only\u2014not for outdoor solar<\/td>\n<\/tr>\n
Fluoropolymer (PVDF\/FEP)<\/td>\n30+ years<\/td>\nClear, black<\/td>\nHigh-voltage DC (1500V+), extreme environments<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

For utility-scale plants operating at 1500 VDC, fluoropolymer heat shrink tubing\u2014particularly PVDF (polyvinylidene fluoride)\u2014offers an even longer service life and superior dielectric strength, though at a significantly higher cost per meter. The decision between carbon-black polyolefin and PVDF typically comes down to voltage class: for 1000 VDC systems, UV-stabilized polyolefin is sufficient; for 1500 VDC systems, the higher dielectric strength and tracking resistance of PVDF (comparative tracking index above 600 V versus 250\u2013300 V for polyolefin) justifies the premium for critical junctions.<\/p>\n

Adhesive-Lined Tubing for Moisture Seal at DC Splices<\/h2>\n

Field-spliced DC cable extensions\u2014necessary when home-run distances from the string to the combiner box exceed the standard module lead length\u2014represent one of the highest-risk junction points in a solar array. The splice must maintain electrical continuity, dielectric insulation, and a moisture seal for the full 25-year design life, despite being buried in a shallow trench, encased in a cable tray, or exposed to weather on a rooftop. Standard single-wall heat shrink tubing, even when correctly recovered, does not create a hermetic seal at the splice interface: capillary action can draw moisture along the conductor strands and into the crimped connection, where it initiates corrosion that propagates invisibly until resistance rises enough to cause thermal runaway.<\/p>\n

Adhesive-lined dual-wall heat shrink tubing solves this problem definitively. The inner layer is a meltable hot-melt adhesive (typically an ethylene-vinyl-acetate or polyamide compound) that softens during the heat-gun recovery process, flows into all voids around the splice and between conductor strands, and then cools to form a rubber-like, moisture-impermeable seal that adheres tenaciously to XLPE insulation, copper, and the tubing’s own outer wall. A properly recovered adhesive-lined sleeve over a DC splice will withstand immersion testing at 1-meter water depth for 1,000 hours per UL 486D with no detectable moisture penetration\u2014a test protocol that single-wall tubing fails within hours.<\/p>\n\n\n\n\n\n\n\n\n\n
Property<\/th>\nSingle-Wall Polyolefin<\/td>\nDual-Wall Adhesive-Lined Polyolefin<\/td>\n<\/tr>\n
Moisture sealing<\/td>\nNone (capillary gaps remain)<\/td>\nFull hermetic seal<\/td>\n<\/tr>\n
Water immersion test (UL 486D)<\/td>\nFails within hours<\/td>\nPasses 1,000 hours<\/td>\n<\/tr>\n
Typical wall thickness after recovery<\/td>\n0.25\u20130.40 mm<\/td>\n0.60\u20131.20 mm<\/td>\n<\/tr>\n
Vibration resistance<\/td>\n\u30b0\u30c3\u30c9<\/td>\nExcellent (adhesive dampens micro-motion)<\/td>\n<\/tr>\n
Cost relative to single-wall<\/td>\n1.0\u00d7<\/td>\n1.5\u20132.0\u00d7<\/td>\n<\/tr>\n
Recommended for solar DC splices<\/td>\nNo<\/td>\nYes\u2014mandatory for outdoor field splices<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

For Willele’s solar industry customers, the recommendation is straightforward: every field-spliced DC junction in a PV string should be sealed with adhesive-lined heat shrink tubing with a minimum 3:1 shrink ratio to accommodate the diameter transition from the splice crimp to the unspliced cable insulation. The small cost premium\u2014typically 50% more per sleeve than single-wall tubing\u2014is negligible compared to the cost of a single string-level fault that takes the array offline and triggers a warranty claim.<\/p>\n

Shrink Ratio Selection for Solar Connector Geometries<\/h2>\n

Solar DC connectors present a challenging geometry for heat shrink tubing: the transition from a 6 mm\u00b2 or 10 mm\u00b2 PV cable (typically 5\u20137 mm outside diameter over XLPE insulation) to a MC4 connector coupling (typically 13\u201318 mm outside diameter at the coupling nut) creates a diameter step of 2:1 or greater. A heat shrink sleeve with an insufficient shrink ratio will either not fully recover over the larger connector diameter, leaving a loose, unsealed sleeve, or will be overstretched during installation, causing wall thinning and reduced dielectric strength. The correct shrink ratio ensures that the tubing recovers fully over both the cable and the connector, maintaining consistent wall thickness and\u2014when adhesive-lined\u2014a continuous seal across the diameter transition.<\/p>\n

For MC4 connector sealing, a 3:1 shrink ratio is the industry standard minimum. A 3:1 tubing with an expanded inside diameter of 18 mm will recover to approximately 6 mm, perfectly accommodating the transition from the connector body to the cable. For larger connectors\u2014such as the Amphenol H4 used in some commercial systems\u2014or for splices that incorporate a crimped copper ferrule alongside two cable diameters, a 4:1 shrink ratio provides the additional recovery range needed to seal the full geometry without leaving gaps. In all cases, the recovered wall thickness should be measured after installation to confirm it meets the minimum specified by the tubing manufacturer\u2014typically 0.8 mm for adhesive-lined grades used at DC string voltages.<\/p>\n

Thermal Cycling and Long-Term Mechanical Integrity<\/h2>\n

The 25-year service life of a solar PV plant translates to approximately 9,000 daily thermal cycles, 300 seasonal freeze-thaw cycles, and 18,000 UV exposure hours (assuming 8 hours of meaningful solar radiation per day). Over this period, the materials comprising a DC junction\u2014copper conductor, tin-plated brass contact, XLPE insulation, connector PBT housing, and heat shrink tubing\u2014each expand and contract at different rates. The tubing’s job is to hold everything together, maintain dielectric insulation thickness, and prevent moisture ingress despite these differential movements. This requires a material with sufficient flexibility to follow the dimensional changes without cracking, sufficient rigidity to resist mechanical unseating of the connector, and sufficient adhesion to prevent the seal from peeling away during thermal contraction.<\/p>\n

Cross-linked polyolefin, the most common base material for solar-grade heat shrink tubing, achieves this balance through its semi-crystalline morphology. The crystalline regions provide mechanical strength and dielectric barrier properties, while the amorphous regions provide flexibility and crack resistance. After cross-linking (achieved via electron-beam or peroxide methods), the material exhibits excellent recovery memory\u2014returning to its pre-expansion dimensions when heated above the crystalline melting point\u2014along with good low-temperature flexibility down to -40\u00b0C and long-term thermal stability up to 125\u00b0C continuous. These properties are precisely what the solar application demands: a material that remains elastic across a 165-degree operating range while maintaining its dielectric and mechanical integrity.<\/p>\n

Compliance with IEC 61215, IEC 61730, and UL 1703\/61730 Standards<\/h2>\n

Solar PV installations are governed by a matrix of international standards that set minimum requirements for safety, performance, and durability. While these standards focus primarily on the modules themselves, the wiring systems\u2014including heat shrink tubing used at junctions\u2014must be compatible with the overall system certification. The key standards and their relevance to heat shrink tubing selection are summarized below:<\/p>\n

IEC 61730-1 and -2 specify construction and safety requirements for PV modules, including requirements for the junction box and its cable exit. Heat shrink tubing applied at the module-level cable exit must be compatible with the module’s fire class rating and must not introduce materials that compromise the module’s overall thermal or electrical performance. UL 1703 (now harmonized with IEC 61730 in the US) similarly requires that all materials used in the module-cable interface meet specific flame ratings\u2014typically UL 94 V-0 or V-1\u2014and demonstrate resistance to UV and thermal aging per UL 746C protocols. For installers and EPC contractors, the practical takeaway is that heat shrink tubing used in module-level applications should carry its own UL recognition (Yellow Card) with a suitable UL 94 flame rating, a temperature index appropriate for outdoor solar use (RTI of 90\u00b0C or higher), and documented UV resistance per UL 746C or ASTM G154.<\/p>\n

In Europe, the EN 50618 standard for PV cabling specifies that all outdoor cable accessories must meet the same 25-year design life as the cables themselves, with accelerated aging tests that include 1,000 hours of damp heat at 85\u00b0C\/85% RH (per IEC 60068-2-30) and UV exposure per EN 50281. Heat shrink tubing specified for European solar projects should carry documentation of compliance with these protocols, typically verified by the tubing manufacturer’s third-party test reports. Willele provides material certifications and test data sheets for all solar-grade tubing products to support installer compliance with these requirements.<\/p>\n

Installation Best Practices for Solar Field Technicians<\/h2>\n

Even the best-specified heat shrink tubing will fail to protect a junction if it is installed incorrectly. The most common installation errors observed in solar field commissioning inspections are: insufficient heating leading to incomplete recovery and unsealed sleeves, overheating causing polymer degradation and wall thinning, failure to pre-position tubing before making the electrical connection, and using tubing with an incorrect diameter range for the actual connector geometry. A simple field protocol can eliminate most of these failure modes.<\/p>\n

First, always pre-cut the tubing to the required length and slide it onto the cable before making any crimp or connector coupling. This seems obvious, yet field failure reports consistently list “forgot to put tubing on first” as a primary error. Second, use a calibrated gas torch or electric heat gun with a spreader nozzle\u2014never an open flame directed at the sleeve\u2014to apply heat evenly, starting at the center of the sleeve and working outward to each end. This technique ensures that the adhesive (in dual-wall grades) flows outward and fills the full sleeve length rather than being trapped in the center. Third, after cooling, verify recovery by visual inspection: the sleeve should be uniform in color with no glossy spots (indicating un-recovered areas), and the adhesive (if present) should be visible as a small bead at each end of the sleeve. Finally, record the batch number and manufacturer of the tubing used at each junction\u2014this traceability is essential for warranty claims and failure analysis.<\/p>\n

Frequently Asked Questions<\/h2>\n

Q: What shrink ratio should I use for sealing MC4 solar connectors?<\/strong><\/p>\n

A: A minimum 3:1 shrink ratio is recommended for MC4 connector sealing to accommodate the diameter transition from the cable (5\u20137 mm OD) to the connector coupling (13\u201318 mm OD). For connectors with larger body diameters or for field splices incorporating crimp ferrules, a 4:1 ratio provides additional recovery range.<\/p>\n

Q: Can standard polyolefin heat shrink tubing be used outdoors in solar installations?<\/strong><\/p>\n

A: No. Standard polyolefin tubing without UV stabilizers will chalk, embrittle, and crack within 2\u20133 years of direct solar exposure. Solar applications require UV-stabilized grades with carbon black loading (2\u20133%) or HALS additives, verified to survive accelerated weathering per ASTM G154 for a minimum of 7,000 hours.<\/p>\n

Q: Is adhesive-lined tubing really necessary for solar DC splices, or is single-wall sufficient?<\/strong><\/p>\n

A: Adhesive-lined dual-wall tubing is strongly recommended\u2014and in many jurisdictions required by code\u2014for outdoor DC cable splices. Single-wall tubing does not create a moisture seal and will fail water immersion testing within hours. For 25-year service life, the adhesive liner is essential to prevent moisture ingress and corrosion at the splice.<\/p>\n

Q: What temperature rating should solar-grade heat shrink tubing have?<\/strong><\/p>\n

A: Solar applications typically require a continuous operating temperature rating of 125\u00b0C or higher (per the tubing’s Relative Thermal Index). This provides adequate margin above the 85\u201395\u00b0C temperatures that module junction boxes can reach under full sun at high ambient, and ensures the tubing retains its mechanical and dielectric properties over decades of thermal cycling.<\/p>\n

Q: Does heat shrink tubing need to be UL recognized for solar applications?<\/strong><\/p>\n

A: For module-level applications subject to IEC 61730 or UL 61730 certification, yes\u2014tubing should carry a UL Yellow Card with an appropriate UL 94 flame rating (V-0 or V-1), a temperature index of 90\u00b0C or higher, and UV resistance per UL 746C. For field-installed accessories in Europe, compliance with EN 50618 aging requirements should be documented.<\/p>\n

Q: Can I use colored heat shrink tubing for string polarity identification in solar arrays?<\/strong><\/p>\n

A: Yes, UV-stabilized colored compounds using HALS additives are available in red, blue, green, and yellow for polarity marking. These typically achieve 15\u201320 years of outdoor service life\u2014slightly shorter than carbon-black grades\u2014and should be inspected periodically in long-life installations. For utility-scale ground-mount plants, black carbon-black tubing is the default due to its superior 25+ year UV resistance.<\/p>\n

Summary<\/h2>\n

The 25-year design life of a solar PV installation places extraordinary demands on every component in the DC wiring chain, and heat shrink tubing\u2014often treated as an afterthought\u2014is in fact the primary defense against the moisture, UV, thermal cycling, and mechanical stress that cause premature junction failures. By specifying UV-stabilized, adhesive-lined, appropriately shrink-ratioed tubing at every field-splice and connector coupling, solar designers and installers can eliminate the most common failure modes that erode system performance over time. The incremental cost of upgrading from generic single-wall tubing to solar-grade dual-wall adhesive-lined tubing is negligible\u2014typically less than one-tenth of one percent of total system cost\u2014yet it protects the string-level connections that determine whether a plant delivers its nameplate energy harvest for two decades or for two seasons. For projects where uptime is revenue and reliability is reputation, heat shrink tubing is not a commodity to be value-engineered; it is an engineered component to be specified with the same rigor as the modules and inverters it connects.<\/p>\n

\u3067 Willele<\/strong>, we manufacture solar-grade heat shrink tubing in our vertically integrated facility, with UV-stabilized polyolefin compounds, adhesive-lined dual-wall constructions, and shrink ratios from 2:1 to 4:1 to suit every solar junction geometry. Every batch is tested for UV resistance, dielectric strength, and adhesive seal performance, with full material certifications available to support IEC 61730 and UL 61730 compliance. Whether you need standard black MC4 sealing sleeves or custom-cut adhesive-lined tubing for a 1500 VDC utility-scale project, our engineering team<\/a> can specify the right material and dimensions for your application. Contact us with your specifications and drawings, and we will respond within 24 hours.<\/strong><\/p>","protected":false},"excerpt":{"rendered":"

On a 50-megawatt solar farm in the Mojave Desert, the midday sun pushes module surface temperatures past 85\u00b0C, while DC string currents run at 1500 volts through hundreds of parallel-connected connectors. Every junction box, every MC4 coupler, every field-spliced cable termination represents a potential point of failure that, if left unprotected, can arc, corrode, or combust\u2014taking an entire string offline and slashing the plant’s revenue-generating capacity for the remainder of its 25-year design life. The difference between a junction that survives three decades and one that fails in year five often comes down to a few cents’ worth of polymer: specifically, the heat shrink tubing applied over the connector interface […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2625","post","type-post","status-publish","format-standard","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/posts\/2625","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/comments?post=2625"}],"version-history":[{"count":1,"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/posts\/2625\/revisions"}],"predecessor-version":[{"id":2627,"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/posts\/2625\/revisions\/2627"}],"wp:attachment":[{"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/media?parent=2625"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/categories?post=2625"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/willele.net\/ja\/wp-json\/wp\/v2\/tags?post=2625"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}