Does anyone run 60vdc systems or is it considered too dangerous?

azrc
azrc Solar Expert Posts: 43 ✭
in Solar Beginners Corner #1
I've read the thread at http://forum.solar-electric.com/showthread.php?t=7688&highlight=60vdc . I also have experience working on 50kw+ hv plasma power supplies so I'm somewhat comfortable (famous last words) working with this.

Both the outback mppt and 48v inverters support 60v operation, but haven't really seen anyone do this. Is it just not worth the risk and better to stay at 48v? Is lower even better?

Thanks
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    But if you had a "60 volt" system, there would be times during charging / EQ etc, that the voltage could exceed 75 volts. Haven't checked the Outback specs, but is the mentioned 60 volts the Max that the Outbacks can handle, or can they handle a 60 volt system where voltages may regularly exceed 75?
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  • Frxddy
    Frxddy Solar Expert Posts: 113 ✭✭✭✭
    #3
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    I have a home made electric motorcycle that is 60 volts. It's simple: Treat it as if it were 220 volts. It can and will kill you if you let it.

    50 is the secret number. Be it AC or DC, anything over 50 volts is considered "High voltage".
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #4
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    According to Outback, they can charge a 60 volt nominal battery bank:
    12, 24, 36, 48, or 60 VDC (Single model - selectable via field programming at start-up)

    Depending on which regulations/safety codes you look at, "high voltage" ranges between 30 and 60 volts (or even a bit more)... You want to be very careful with these DC voltages--treat them like 120-240 VAC. Wearing gloves when wiring up battery banks, etc., would not be a bad idea.

    Electricians use rated rubber gloves with a second set of leather outer gloves for working on live wiring (outer gloves protect the soft rubber glove from damage).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    There's not much advantage to running 60 VDC over 48 VDC. When you select from 12, 24, or 48 you're doubling Voltage and halving Amperage. The jump to 60 is only a 25% difference. And you may have difficulty finding circuit protection/disconnects rated for the higher Voltage.

    Not worth the effort in my opinion.
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  • azrc
    azrc Solar Expert Posts: 43 ✭
    #6
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    I was skimming this ECMA paper (http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-287.pdf) and it seemed to indicate that anything under 60v was safe...but haven't read it too closely yet.

    My thought on going to 60v as opposed to 48 is that it would be easier on the batteries. Anyway, I am not there yet and don't have any loads that would come close to maxing out an OB3648. I'm just running with some old 12v marine batteries for now, but thinking what I can do for the longer term when I buy some T105s.

    Thanks
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    "Safe" is a relative term: 12 or even 6 Volt high Amperage batteries can weld your wrenches across their posts and kick up some significant, fire-inducing sparks while they're at it (hydrogen & oxygen gassing from the cells is highly inflammable). 15 Volts is "arc point", above which a DC arc becomes sustainable (can arc all day long until something ignites).

    Safe? Nothing is ever 100% safe. :roll:
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  • azrc
    azrc Solar Expert Posts: 43 ✭
    #8
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    I fell out of bed once. OK, twice. :)

    Just wondering if there was anything 'weird' to watch out for.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #9
    Re: Does anyone run 60vdc systems or is it considered too dangerous?
    azrc wrote: »
    I fell out of bed once. OK, twice. :)

    hey, me too.:D ok, it might've been more times as that could be my source of my brain damage.:roll::p:p
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #10
    Re: Does anyone run 60vdc systems or is it considered too dangerous?
    azrc wrote: »
    My thought on going to 60v as opposed to 48 is that it would be easier on the batteries. (T105s.)

    Thanks
    From the point of view of the # of batteries in a string, the 60 volt system would be easier on the batteries than a 48 volt system, because the load would be shared by ten T-105's, while the 48 volt system would have to share the load among "only" eight T-105''s. On the other hand, if you doubled up and ran two strings on 48 volts, you'd be sharing the load among 16 batteries, which would be even easier on them.
    Also, looking to the future, 48 volt systems are "common", therefore items designed to operate on 48 volts will be far more common and therefore more readily available and at better prices, than would 60 volt items.
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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #11
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    Say you ran a battery bank at this higher voltage.. what inverter are you going to use? Just my $.02
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #12
    Re: Does anyone run 60vdc systems or is it considered too dangerous?
    TheBackRoads wrote: »
    Say you ran a battery bank at this higher voltage.. what inverter are you going to use? Just my $.02

    He says the Outback 48 volt inverter supports 60 volts. I haven't seen the specs myself so can't comment. Must look it up.
    Just checked a couple of them and sure enough, operating voltage range of the 48 volt unit I checked, ranged from a low of 42 volts, all the way up to 68 volts. Quite the operating range I'd say.
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  • halfcrazy
    halfcrazy Solar Expert Posts: 720 ✭✭✭
    #13
    Re: Does anyone run 60vdc systems or is it considered too dangerous?

    that is the operating window so it will not work above 68vdc so you could not do a nominal 60 vdc battery
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #14
    Re: Does anyone run 60vdc systems or is it considered too dangerous?
    halfcrazy wrote: »
    that is the operating window so it will not work above 68vdc so you could not do a nominal 60 vdc battery

    YES! forgot that a 60 volt system could at times hit at least 75 volts. That rules out the Outback!
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