The 300V MidNite Solar Surge Protector Device (MNSPD) is a Type 1 device per UL1449 rev3. It is designed for both AC and DC systems and provides protection to service panels, load centers or where the SPD is directly connected to the electronic device requiring protection.
The DC SPD will work well on all DC circuits up to 300 volts as well as any 120/240 VAC circuits. The difference between the AC and DC SPD is the way the LED's are powered. The protection side of things is identical.