It used to be tougher to find, but the Solar business has made them more available now. Siemens, Sq. D, Cutler Hammer and GE all have "solar" disconnect switches, as in UL 98 style knife switches, available now. I know Siemens has a version that can be put in a panel with a flange mounted handle.
But if you are looking for a rotary through-door disconnect rated for 600VDC, and I assume UL listing is necessary, your choices are more limited. That process is tough because UL testing for DC switching is brutal, much more so than IEC requirements. ABB was actually the first one to get a rotary thru-door version through UL. The Socomec one that Besoeker mentions is hard to find here in the US under their own name, but many other well known North Am. companies brand label it, including Schneider, Bussman, Littlefuse and I think Eaton. Siemens was talking about doing it via Socomec too right before I left.
PS: I mentioned Eaton and Bussman as if they were still separate, LOL, my mistake. And looking at it, although the Socomec switch is still in the Bussman area, it does not show the 600VDC rating. So either Socomec lost it with UL, or they signed some sort of exclusivity deal with someone else on that version. Being a French company, I would bet Schneider.
