Can I use this relay for DC
According to one review on DX:


  by Docteh on 11/26/2012 Involvement:Expert (understands the inner workings) - Ownership:1 week to 1 month
  
  Pros:
  Works perfectly. There is a red LED on the DC side of the Solid State Relay. This one also comes with a plastic cover. The cover has holes that allow a screwdriver to go in and be used without the cover.
  
  Cons:
  Appears to use more power on the DC side than a similar more pricier SSR like the Crydom ones. Another downside is that AC SSRs such as this only turn off at the zero crossing point, which means you have to use this with AC voltage on the output side.


Most likely (as no datasheet or part list to confirm), it uses a Triac or similar for the actual load control switching, which means that no current can be flowing for it to turn off. On AC, this is simple as the AC signal crosses the Zero point between Positive and Negative. On DC, the DC signal needs to be off for that to happen. It's a catch 22.

So no, you need a DC switching SSR. This one will not work well for you.