IP Protection Ratings and the Importance of Inverter Sealing?

In inverter technical specifications, we often encounter the term “protection rating,” with common examples including IP20, IP65, and IP66. So, what is an IP protection rating?
         The IP protection rating (Ingress Protection Rating) is a standard established by the International Electrotechnical Commission (IEC) to define the level of protection provided by the enclosure of electrical equipment against foreign objects (such as dust, tools, fingers, etc.) and water. This rating consists of two digits, where the first digit represents the degree of protection against the ingress of solid foreign objects, and the second digit indicates the level of protection against the ingress of liquids. The higher the number, the stronger the protection.

The first number (solid protection)

0 - No protection
1 - Protects against the ingress of solid objects larger than 50 mm in diameter
2 - Protects against the ingress of solid objects larger than 12.5 mm in diameter
3 - Protects against the ingress of solid objects larger than 2.5 mm in diameter
4 - Protects against the ingress of solid objects larger than 1 mm in diameter
5 - Dust-resistant (limited ingress that does not affect normal operation)
6 - Completely dust-tight

The second number (liquid resistance)
0 - No protection
1 - Protection against vertically falling water droplets (e.g., condensation)
2 - Protection against vertically falling water droplets that do not affect the equipment when the enclosure is tilted up to 15 degrees
3 - Protection against water spray (at a 60-degree angle to the vertical)
4 - Protection against splashing water
5 - Protection against low-pressure water jets (from all directions)
6 - Protection against powerful water jets (from all directions)
7 - Protection against brief immersion in water (immersion depth of 1 meter for 30 minutes)
8 - Protection against continuous immersion in water (under conditions specified by the manufacturer)

Our two types of inverters feature differentiated protection ratings designed for different installation scenarios:
① Hybrid Inverter (IP66)
This model is designed for both indoor and outdoor use.
When installed on outdoor walls, balconies, rooftops, and similar locations, exposure to wind, sun, and rain is common. The IP66 rating ensures the equipment continues to operate reliably even in environments with heavy rain, high humidity, and high dust levels.
② Off-Grid Inverter (IP20)
This model is primarily intended for indoor installation scenarios, such as residential electrical rooms, equipment rooms, and energy storage cabinets. Since these environments are relatively clean and free from the risk of water spray, IP20 is sufficient to meet protection requirements.

All equipment undergoes rigorous airtightness testing before leaving the factory; however, during maintenance, foreign objects such as insects and dust have been found inside some inverters, which can lead to equipment malfunctions or even damage. Therefore, proper on-site sealing is equally critical—especially in outdoor or humid environments—as effective sealing prevents moisture and dust from entering and protects internal components from corrosion.