Custom MC4 Jumpers and PV Home Runs for Solar Farms: How to Spec, Order and Label Them
Oct 07, 2026
On a solar farm, the cable between the string and the combiner is where schedule and warranty risk pile up. Field crimped MC4 connectors fail. Lengths cut on site waste copper. Unlabeled home runs turn commissioning into a hunt. Custom jumpers and home runs built to the string layout, crimped and pull tested before they ship, arrive ready to plug in. This guide covers what we build, how to spec it and how to send a cut list.
What we build to order
| Assembly | Build | Lengths | Typical use |
|---|---|---|---|
| 10 AWG MC4 jumper (4904-CUSTOM) | Male MC4 to female MC4, 10 AWG bare copper PV wire, 1500 V DC | 5 to 200 ft | String jumpers, row to row jumps, extension to combiner |
| 12 AWG MC4 jumper (4904-12-CUSTOM) | Male MC4 to female MC4, 12 AWG copper PV wire | 5 to 100 ft | Module to module jumps, short string runs |
| PV home run (4904-HR) | MC4 on the array end, stripped end for the combiner or inverter terminal | 25 to 250 ft | String home runs into combiners, disconnects and string inverters |
| MC4 to bare wire lead (4904-LEAD) | Male or female MC4 to stripped end, 10 AWG | 5 to 100 ft | Short leads into combiners, rapid shutdown and monitoring boxes |
| 8 AWG lugged lead (4908-CUSTOM) | Copper compression lugs both ends, heat shrink, 1/4, 5/16 or 3/8 in stud | 1 to 50 ft | Combiner outputs, DC bus jumpers, equipment bonding |
| 6 AWG lugged lead (4906-CUSTOM) | Copper compression lugs both ends, heat shrink, 1/4, 5/16 or 3/8 in stud | 1 to 50 ft | Inverter DC inputs, battery and BESS interconnects |
Every assembly is built on US-made UL 4703 PV wire and assembled in the USA, crimped with the correct die or connector tool, and pull tested before it ships. MC4 jumpers come with your choice of Conversions Tech MC4 or Stäubli MC4 (original MC4) connectors, so you can match Stäubli-fitted modules and combiners. Lengths outside the listed range, mixed ends (lug on one end, MC4 on the other), two hole lugs and fused MC4 ends are built on request. Crimping in house? Bulk 12 AWG, 10 AWG and 8 AWG PV wire ships on 500 and 1000 ft spools.
How to spec a jumper or home run
1. Connector type and gender
Match the connector to the module leads. MC4 style connectors from different makers are not automatically intermateable, and a mixed pair voids most listings. If the modules or combiner use Stäubli MC4, choose the Stäubli option on the jumper. Order the gender opposite to the lead you are mating: a male home run mates with a female string lead. Gender by polarity varies by module manufacturer, so check the module data sheet. Connector compatibility guide.
2. Conductor size
Size each circuit to NEC 690.8 for the module Isc, then check voltage drop. On 10 AWG copper the drop is about (2 × one way ft × amps × 1.24) ÷ 1,000. Example: a 250 ft home run at 14 A drops about 8.7 V, around 0.6 percent on a 1,400 V string. Use 12 AWG for short module jumps and 10 AWG for most home runs. Step up to lugged 8 or 6 AWG for combiner outputs and higher current DC runs. PV wire size guide.
3. Length
Measure along the cable path, not straight line: down the torque tube or cable hanger, across the row gap, and up into the combiner. Add a service loop at each end, typically 2 to 3 ft, and allow for tracker travel so the cable never pulls tight at full tilt.
4. Polarity and labeling
Red for positive, black for negative. On a commercial or utility array, ask for labels with the string or circuit ID on both ends so commissioning and O&M crews can identify every circuit at the combiner without tracing it by hand.
5. Voltage
Specify 1500 V DC for utility scale strings. Every connector in the string circuit must carry the same rating.
Sending a cut list
A cut list lets us build, label and kit the whole block in one order. Send a spreadsheet with one row per assembly type:
| Circuit ID | Assembly | Conductor | End A | End B | Length | Color | Qty |
|---|---|---|---|---|---|---|---|
| B1-INV2-S01+ | Home run | 10 AWG | Female MC4 | Stripped | 185 ft | Red | 1 |
| B1-INV2-S01− | Home run | 10 AWG | Male MC4 | Stripped | 185 ft | Black | 1 |
| ROW-JUMP | Jumper | 10 AWG | Male MC4 | Female MC4 | 12 ft | Black | 240 |
| CMB-OUT | Lugged lead | 6 AWG | 3/8 in lug | 3/8 in lug | 4 ft | Red | 36 |
Add a column for connector brand (Conversions Tech MC4 or Stäubli MC4) if the project calls for one. We return a priced quote by line. Assemblies ship labeled and grouped by block, inverter or combiner so crews can stage them straight to the row.
Why factory built beats field crimped
- Consistent crimps. Every connector and lug is crimped with the specified tool and die, then pull tested.
- No waste. Cut to the foot from the cut list instead of cutting on site from reels.
- Faster install. Crews plug in labeled assemblies instead of stripping and crimping in the field.
- Assembled in the USA. Built on US-made PV wire and assembled domestically, for projects that track where the assembly was made.
More on this: Factory built vs field crimped MC4 jumpers · Solar farm electrical hardware guide.
Order or quote
Standard lengths can be ordered online from each product page. For project quantities, email the cut list to CS@conversionstech.com or call (307) 206-0534. Approved trade accounts get project pricing and net terms.
