Rapid Shutdown Device vs. Traditional Safety Switch Which is Better

When installing residential solar panels, many friends struggle with this question: "If we already have traditional protective switches, do we still need to install a Rapid Shutdown Device (RSD)?" Some even think, "The two have similar functions—just choose the cheaper one." Today, I’ll compare the two in plain language, explaining from the perspectives of safety, compliance, and practicality to help you understand which one to choose.

First, clarify this: They are not a "substitute relationship" but "each performs its own duties"First, we need to correct a misunderstanding: Traditional protective switches (such as circuit breakers and residual current devices) and RSDs target completely different risks and cannot replace each other.

Traditional protective switches are like the "main gate of a home," mainly preventing overloads, short circuits, and electric leakage—for example, if an air conditioner’s power is too high (causing excessive current) or someone accidentally touches a live wire, they will trip to cut off power. However, they have a fatal flaw: They cannot control the "DC-side voltage" of the solar system.

RSDs, on the other hand, are specialized "DC bodyguards" designed for solar systems, targeting the high-voltage DC risks between modules and inverters. Even without direct sunlight, as long as the modules are exposed to light, they will generate 600V high voltage. Traditional switches cannot detect this "high voltage without current changes," but RSDs can reduce the voltage to below 30V within 30 seconds—this is the key to solar safety.

Core Comparison: 3 Dimensions Showing Why RSDs Are More Suitable for Solar Systems?

1. Safety Protection: RSDs Guard Against "DC Risks That Traditional Switches Cannot Handle"

The obvious shortcoming of traditional protective switches is that they only recognize "abnormal current" but not "high DC voltage."

What’s more important is the maintenance scenario: Tripping a traditional switch shuts down the entire household’s solar system. If maintenance is performed in summer, the air conditioner cannot be used; RSDs, however, can accurately cut off power to "faulty strings/modules" while other parts continue generating electricity.

2. Compliance: Installing Solar in 2025—No RSD Means Failed Inspection

Now, solar safety is strictly enforced nationwide, and traditional switches can no longer meet new regulations:

• China’s GB/T 38947 standard clearly stipulates that all new solar systems built after 2021 must be equipped with RSDs;
• Australia’s AS/NZS 5033 and the US NEC 690.12 have the same requirements.

Even if traditional switches comply with "household circuit standards," they lack special certifications for the solar industry. Installing only traditional switches means "non-compliance," and you may face fines during subsequent grid inspections—this is a significant risk.

3. Power Generation Loss: RSDs Enable "Precise Power Cutoff," While Traditional Switches Use "One-Size-Fits-All"

The top concern for residential solar systems is "power generation." Traditional switches trip to cut off power entirely—even if only one module has a problem, all generation modules must be shut down.

To summarize their roles:

• Traditional protective switches: Responsible for household AC circuits (e.g., air conditioners, sockets), preventing overloads and electric leakage;
• RSDs: Responsible for the solar DC side (modules to inverter), protecting against high voltage and arcs, and ensuring compliance.

Don’t think "RSDs are unnecessary"—when installing solar in 2025, safety and compliance are the bottom line. Traditional switches can ensure the safety of household circuits, but the high-voltage DC risks of solar systems depend on RSDs for protection. Spending a little money to guarantee safety, compliance, and reduced power generation loss is a cost-effective choice! If you’re still struggling with which RSD to match with your solar system, feel free to share your inverter brand and power capacity, and I’ll help you make a precise recommendation～