The MidNite Solar Surge Protector Device (MNSPD) is a Type 2 device, designed for indoor and outdoor applications. Engineered for both AC and DC electric systems, it provides protection to service panels, load centers or where the SPD is directly connected to the electronic device requiring protection. Maximum protection will only be achieved if the SPD is properly installed.
The MidNite Solar SPD is offered in three different voltages to maximize the required protection level. Protection is achieved by reducing the clamping voltage to a safe voltage that your system can sustain without damaging any electronics in the system.
The MidNite SPD is a welcome replacement for less sophisticated arrestors that have been the mainstay of the industry for many years. Other din rail SPD's are physically small and typically can only provide 1/8th the protection of the MidNite product. When exposed to transients above their capability, permanent damage occurs. Din rail SPD's are always mounted inside of a box such as a PV combiner. When the din rail SPD fails from a near lightning strike, it just quits working. This means that it also quits protecting. Since it is locked away inside of a box, you have no way of knowing it has failed until your next lightning storm! The MidNite SPD is mounted on the outside and has blue LED's viewable from a distance that show your system is still protected. They are also built to last, in the case that the MNSPD does eventually wear out, they can easily be repaired.
The MidNite Solar SPD voltage rating should be chosen according to the nominal voltage of the system. Do not install an SPD with Maximum Continuous Operating Voltage (MCOV) below the nominal voltage of the system; this will deteriorate the SPD and making it unavailable when you most need it. The 115V SPD provides protection for battery circuits, the 300V SPD provides protection for the Classic & other charge controllers as well as off-grid PV combiners for up to 300 volts DC. The 300VAC model specifically targets 120/240VAC circuits. The 600V SPD is available as a special order item for Grid-Tie PV combiners and inverter input circuits.
The 300V SPD is also available in an AC version. The difference between the AC and DC SPD is the way the LEDs are powered. The protection side of things are identical.
Here is a short video about the Midnite Solar SPD: