anyone used a 600V charge controller yet?

I'm looking into doing a DC coupled battery backup for an existing grid-tied system using the new Morningstar TS-MPPT-60-600V 600V charge controller.
The even more pricey version of it has a built in HVdc disconnect, but to use it to tap into an existing GT's dc side, I really need a transfer switch. And to make it harder, I really want it to be automatic which needs a magical HVdc relay good for 500V (no can find). This seems expensive to only use this controller to keep the battery backed system going during outages - but the alternative AC coupled system (SMA Sunny Island) is even more expensive plus (since it is a 120Vac output) you have to get the "smartformer" at >$1500 and now your grid intertie is 120Vac at double the amps and limited to 6000W. Anyway.... Has anyone messed with this application before?

Comments

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: anyone used a 600V charge controller yet?

    Well, you should be able to find a relay which is rated for 600V DC (and even interrupting) as long as you are willing to follow the accompanying instructions (such as wiring all three poles of a three pole relay in series to give you a single HV pole.
    Now the problem with that is that you will probably not be able to do that using three form C contacts to give you one form C HV pole.
    But since you do not have the really bad consequences of connecting two power sources together that you have with an interlock failure in an AC ATS, you can make do with two separate relays, one NO and one NC.
    SMA SB 3000, old BP panels.
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: anyone used a 600V charge controller yet?
    solarix wrote: »
    but the alternative AC coupled system (SMA Sunny Island) is even more expensive plus (since it is a 120Vac output) you have to get the "smartformer" at >$1500 and now your grid intertie is 120Vac at double the amps and limited to 6000W.

    What about using a Xantrex XW, AC coupled with the existing GTI? It won't be able to do a smooth absorb or float, but that shouldn't matter if the batteries will only be used during the occasional grid outage.
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: anyone used a 600V charge controller yet?

    I think what I'll do is dedicate 12 panels to a 250V midnite charger (2 strings of 6) for feeding the batt bank as the load is pretty consistent 24/7 and should use 3kW of array by itself. Can then downsize the other 21 panels to feed a 5kW Sunnyboy and avoid all the problems (and expense) of tying the two systems together. Of course, if the battery based system runs short of power, it can pull from the AC mains.
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