Combiner Box Checklist: 17 Things to Check
07/08/2021

We do a lot of solar PV and renewable energy asset inspections here at HelioVolta and SolarGrade! Every time we visit a site, we use the SolarGrade platform to guide our workflow and document our findings.

Here are 17 things we look for every time we approach a combiner box:

1️⃣ Missing/Improper Label
Improper labeling can be a risk to personnel and should conform to applicable code, AHJ requirements and site drawings.

2️⃣ Pest Ingress
Pest intrusion may result in unintended current paths or component damage and can result in an electric fault.

3️⃣ Damaged Enclosure
Damage to the enclosure may result in a mechanical impact on contained components and can also compromise the protection rating of the enclosure.

4️⃣ Damaged Handle
This damage may result in limited component operation and may pose a system reliability risk.

5️⃣ Water Ingress
This may result in component protection failure. Without proper component protection electrical failures and thermal events may occur.

6️⃣ Corrosion
Corrosion will degrade the long term durability of the component and may compromise the enclosure rating.

7️⃣ Weep Holes
Weep holes help drain moisture in the enclosure, reducing corrosion and electrical failure risk.

8️⃣ Debris
Debris may result in unintended circuit paths or leakage current and can result in an electric fault.

9️⃣ Missing Duct Seal
Duct seal is used for wire management in enclosures and helps avoid dust, moisture and pest ingress.

1️⃣0️⃣ Gasket Missing/Loose
Improperly installed or missing gaskets may result in moisture ingress.

1️⃣1️⃣ Missing Torque Marks
Torque marks are necessary to assess if fasteners/connections have been properly torqued. Under-torqued fasteners may come to loose which may result in mechanical damage or bad connections. Over-torqued fasteners may result in improperly seated hardware.

1️⃣2️⃣ Improper Wire Terminations
Improper termination may result in electric arcing, higher resistance connection, overcurrent instances and overheating.

1️⃣3️⃣ Grounding
Non-current carrying conductors must be grounded for site safety and component protection.

1️⃣4️⃣ Sharp Edges
Over time, with thermal expansion and contraction, wire insulation may abrade against sharp edges and result in an electrical short which may lead to a fault or thermal event.

1️⃣5️⃣ Wire Management
Improper support, routing and protection of wires can lead to UV degradation, exposure to sharp edges, insulation damage, contact with moving parts, and improper wire bend radius.

1️⃣6️⃣ Improper Enclosure Installation
With improper installation (refer to manufacturer specs), component protection may not be satisfied. For example, installing horizontally rather that vertically (if specified), leading to insufficient enclosure moisture egress.

1️⃣7️⃣ Hotspot
Hotspots indicate a higher resistance connection which may result in component breakdown and electrical failure. We use a thermal camera to find hotspots.

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