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SMA•Sunny Boy

Analysis by Marcus & Team

SMA Sunny Boy: Salt Air Corrosion Repair

Troubleshoot salt air corrosion on SMA Sunny Boy inverters in coastal residential solar systems. Preventative maintenance and safety guidelines included.

Frequently Asked Questions

•What are the recommended cleaning solutions for removing salt air corrosion from solar inverters?

Use a non-corrosive electronics cleaner specifically designed for removing salt deposits and corrosion. Avoid using abrasive cleaners or solvents that can damage the inverter's protective coatings.

•How often should I inspect my solar inverter for salt air corrosion in a coastal environment?

Inspect your solar inverter for salt air corrosion at least annually. In areas with heavy salt spray, consider inspecting it more frequently (e.g., every six months).

•What type of sealant should I use to protect electrical connections from salt air corrosion?

Use a marine-grade corrosion-resistant sealant specifically designed for electrical connections. Ensure that the sealant is compatible with the materials used in the inverter and wiring.

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Marcus leads the technical research department at Storage Faults. Together with a team of systems analysts, he specializes in translating complex solar storage error codes into actionable diagnostic steps for the US market.

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Possible Causes:

Direct exposure to salt spray or high humidity environments near the coast.
Inadequate sealing of the inverter housing and electrical enclosures, allowing moisture ingress.
Use of non-marine-grade connectors and wiring that are not resistant to corrosion.
Galvanic corrosion between dissimilar metals (e.g., aluminum inverter housing and steel mounting hardware).
Improper grounding practices that exacerbate corrosion.
Failure to regularly clean and inspect the inverter and its components.

Technical Recommendation:

Use a thermal camera to identify hotspots caused by corroded connections. A high-resistance connection will generate excessive heat, which can be detected by the thermal camera. Compare the temperature of similar connections to identify potential problems before they lead to complete failure. Also check the SMA system logs for error history related to grounding or insulation failures.

Critical Safety Precautions:

Solar PV systems operate at high DC voltages (up to 600V or higher). Contact with these voltages can cause serious injury or death. Always disconnect the AC and DC power to the inverter before performing any maintenance or repairs. Wear appropriate personal protective equipment (PPE), including insulated gloves and safety glasses. Only qualified electricians should perform work on solar PV systems. Follow all applicable NEC and local electrical codes. Engage rapid shutdown procedure if applicable.

How It Works:

Salt air, containing chlorides, is highly corrosive. It accelerates the oxidation of metals used in the Sunny Boy inverter and its associated components (aluminum, copper, steel). This corrosion increases resistance at electrical connections, leading to voltage drops, heat generation (I²R losses), and eventual component failure. In hybrid inverters, corrosion can affect both the DC side (PV strings, battery connections) and the AC side (grid connection). The inverter's MPPT algorithm may become unstable due to fluctuating PV string parameters. Anti-islanding protection can be compromised if AC voltage and frequency sensing circuits are affected.

Symptoms:

Reduced inverter performance, erratic voltage/current readings from PV strings, visible green or white deposits on electrical connections and components (particularly DC disconnects, wiring terminals, and inverter housing), increased inverter temperature, frequent error messages related to grounding or insulation faults, shortened component lifespan.

Solution:

1

*Safety First:** Disconnect the AC power to the inverter by turning off the breaker at the main service panel. Then, engage the DC disconnect switch located near the inverter. Verify complete power isolation using a calibrated multimeter. Follow NEC 690.15 for disconnecting means.
2

*Visual inspection:** Carefully inspect the inverter housing, wiring connections, and internal components for signs of corrosion. Pay close attention to the DC disconnect, PV string terminals, and grounding connections.
3

*Cleaning:** Use a soft brush and a non-corrosive cleaning solution (specifically designed for electronics) to remove salt deposits and corrosion from affected areas. Avoid using abrasive cleaners that can damage the inverter's protective coatings.
4

*Component Replacement:** Replace any severely corroded components, such as connectors, wiring, or circuit boards. Use marine-grade components whenever possible.
5

*Sealing and Protection:** Apply a corrosion-resistant sealant to all electrical connections and around the inverter housing to prevent moisture ingress. Consider using a conformal coating on sensitive circuit boards.
6

*Grounding Verification:** Ensure that the inverter and all associated components are properly grounded according to NEC Article
7

Check the grounding electrode conductor for continuity and corrosion.
8

*Functional Testing:** After completing the repairs, reconnect the AC and DC power to the inverter. Monitor its performance using the SMA Sunny Portal or Sunny Explorer software. Verify that the inverter is operating within its specified voltage, current, and power limits.

Preventative Care:

Regularly inspect the inverter and its components for signs of corrosion (at least annually)
Clean the inverter housing and electrical connections with a non-corrosive cleaning solution
Apply a corrosion-resistant sealant to all exposed connections
Ensure proper ventilation around the inverter to prevent moisture buildup
Consider using a protective enclosure to shield the inverter from direct exposure to salt spray
Check the DC disconnect functionality every six months