Best Solid State Latching Relay Solutions for Reliable Control
Solid state latching relays provide fast switching, high isolation, and low wear compared to mechanical relays. This guide highlights five top SSR options suited for hobby projects and small to mid-scale automation, emphasizing input control compatibility, output ratings, and thermal handling. Each pick includes key specs, typical use cases, and practical considerations to help you choose a durable, maintenance-free switching element for microcontroller and PLC projects.
Product Comparison at a Glance
| Product | Brand | Input/Output Range | Current Rating |
|---|---|---|---|
| Wired DC-DC Isolated SSR Module | OONO | DC 3–32V input; DC 5–30V output | 10 A (on-state) |
| DPST 1NO 1NC 8A Power Relay Module | OONO | 12V control; AC/DC output | 8 A |
| SSR-40AA AC to AC Relay | CGELE | 70–250VAC input; 24–480VAC output | 40 A |
| 8 Channel 5V SSR Module | AITRIP | 5V input; high/high-level trigger | 8 × 2 A (per channel) |
| SSR-25DA DC to AC Relay | CGELE | 3–32V DC input; 24–480V AC output | 25 A |
Wired DC-DC Isolated Solid State Relay Module
This isolated SSR module from OONO is designed for microcontrollers and embedded systems. It features photocoupler isolation between input control and the controlled power, with a surge rating up to 5000 V. The input accepts 3–32 V DC for turn-on and 0–0.8 V DC for turn-off, with an LED indicating relay action. Output supports 5–30 V DC, and the device can handle up to 10 A continuous on-state current, with peak currents up to 160 A for short transients. The module’s low on-state resistance (about 0.008 ohm) minimizes heat under typical loads. This model is appropriate for Raspberry Pi, Arduino, ESP32, PLCs, and other MCU platforms seeking solid isolation and reliable switching. Consider heat sinking if operating near the higher end of the current range or in tight enclosures.
DPST 1NO 1NC 8A Power Relay Module
The OONO DPST relay module combines a compact plastic housing with straightforward connections for mounting in projects requiring one normally open and one normally closed contact. It accepts a 12 V control signal (AC or DC) with a modest current draw (about 33 mA). The module switches up to 8 A at 250 VAC or 30 V DC per contact, making it suitable for small loads, fans, lighting, or actuators. A LED indicator confirms relay operation. This device offers practical packaging for quick prototyping and educational labs, but for high-cycle or high-current applications, a more robust SSR with higher ratings may be preferred.
Gele SSR-40AA AC to AC Relay
The CGELE SSR-40AA is a high-capacity solid state relay module designed for AC-to-AC switching. It supports input on 70–250 VAC and output in the 24–480 VAC range with a rated current of 40 A. The device ships with thermal grease for improved heat dissipation and a compact metal-plastic housing. Typical use cases include heating elements, motor control, and industrial automation where robust SSR performance is required. While it handles substantial current, proper heat management is essential to maintain reliability and longevity in continuous duty.
AITRIP 8-Channel 5V SSR Module
The AITRIP 8-channel SSR module provides convenient modular control for multiple devices with a single board. Each relay is individually indicator-enabled, and the board measures roughly 155 × 55 × 24 mm, making it suitable for compact enclosures and prototypes. The board is designed for 5 V logic and is compatible with Arduino Uno, MEGA boards, and similar microcontrollers. It serves well for multi-channel automation tasks, such as LED strip control, small pumps, or fans, where separate opto-isolated channels reduce noise coupling and interference between devices.
CGELE SSR-25DA DC to AC Relay
The CGELE SSR-25DA handles DC-to-AC switching with a 3–32 V DC input range and 24–480 VAC output. It is rated for 25 A and supports standard 50/60 Hz operation. The package includes thermal grease to enhance heat dissipation. The compact design, combined with solid isolation and low on-state resistance, makes this SSR suitable for driving AC loads such as heaters, lighting, or other actuators in automation projects. As with SSRs in this class, ensure adequate cooling in higher duty cycles and consider derating for ambient temperature.
Buying Guide
When selecting a solid state latching relay, consider these key factors to ensure reliable operation and longevity:
- Load type and voltage: Confirm both input control voltage range and output load voltage/current. For DC inputs and AC loads, choose compatible SSRs or opto-isolated modules.
- Control signal compatibility: Many SSRs accept 3–32 V DC or 5 V logic. Plan for the driving hardware (microcontroller, motor driver, PLC) and ensure proper isolation.
- Isolation and safety: Photocouplers and optical isolation reduce ground loops and noise coupling. Higher isolation voltage provides robustness in industrial environments.
- Heat management: Higher current or continuous operation requires effective cooling. Look for devices with thermal grease, heatsinking options, or lower on-state resistance.
- Response time and switching frequency: SSRs switch rapidly and with low wear, ideal for automation. Confirm whether latching behavior suits your use case—latching SSRs hold state without continuous drive, improving efficiency in some topologies.
- Mechanical vs. solid-state: SSRs have no moving parts, reducing wear. For high inrush loads, verify surge ratings and non-repetitive peak currents to avoid premature failure.
- Packaging and mounting: Consider enclosure space, mounting method, and wiring convenience. Compact modules are great for prototyping, while rugged housings suit industrial settings.
- Compatibility with control firmware: Some modules ship pre-assembled or with LED indicators and simple wiring diagrams, which can save setup time on Arduino, Raspberry Pi, or ESP32 projects.
In choosing between the options above, weigh the balance between current rating, input voltage compatibility, and thermal management. For small hobby projects, an 8–10 A module with a 3–32 V input range is often sufficient. For hobbyist automation across multiple channels, multi-channel modules provide practical scalability. For higher-power needs, a 40 A or 25–40 A device with proper cooling can handle larger loads without compromising reliability.