Definition
The junction box is the weatherproof enclosure on the back of a PV module containing bypass diodes, terminal connections, and MC4 output connectors. Critical reliability component; failure modes include water ingress and bypass diode burnout.
Key Takeaways
- Junction box houses bypass diodes and MC4 connectors.
- Rated IP67/68 for outdoor weather.
- Failure modes: water ingress, diode burnout, corrosion.
- Quality directly affects 25-year module reliability.
- Tier 1 manufacturers use sealed potted designs.
Frequently Asked Questions
2 commonly searched questions about Junction Box.
What's in a junction box?
Bypass diodes (typically 3), cell terminal connections, MC4 connector outputs. Encapsulated in potting material for moisture protection. Rated IP67/68.
Common failure modes?
Water ingress (potting compound degradation), bypass diode burnout (lightning, hot spot), terminal corrosion. Causes 1–3% module-level failure rate over 25 years.
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