question about light ballast

I have a solar system which consists of a small array, 2(two) 6 volt batteries, a Sunlight® controller, and 2(two) PL13w (fluorescent) light fixtures, designed to light a flag.

One of the fixtures has had a ballast fail.

My question is why does this lamp require a ballast(inverter?). I have seen other 12vdc fixtures with 35watt fluorescent lamps that don't require the additional ballast(inverter?), so why does this one?

How does one go about finding out if a fluorescent lamp will run on dc voltage?

Does anyone have a link to a ballast (inverter?) supplier that you will post?

How about some links to flagpole light fixture suppliers?

I don't want to have to scrap the whole system in order to light this flag, so those units that mount right on the pole with their own array will not work for me.

Any ideas?

Thanks in advance.

Rick Miell


  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: question about light ballast

    ALL fluorescent lamps REQUIRE a ballast of some type to work. Sometimes they are well hidden in the fixture, sometimes they are a stinky melted transformer on the outer shell of the fixture.
    I would think a LED light would be a good replacement, for the same or less power (7W LED = 40W incandacent)
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    gen: ,

  • BB.BB. Super Moderators, Administrators Posts: 32,924 admin
    Re: question about light ballast

    Our host has replacement 12 volt Ballasts. Looks like a replacement will be in the $20-$25 range.

    Here is a chart for Thinlite ballast supported lamps/configurations.

    Iota has a ballast selector that lists a direct replacement for a PL-13 two wire lamp (among many others).

    Iota: Ballast selection tool for all DC ballasts

    A ballast provides a high starting voltage (and for some, a current for the lamp heaters to vaporize the elemental mercury)--then once the arc is started, feeds a fixed current to the arc. 12 volts is typically too low of voltage to strike an arc in a florescent tube--so there will be an inverter involved to get the 100+ volts need to start the arc. Typically, 120 VAC fixtures do not need the step-up in voltage to start their lamps.

    If you need help picking/wiring one--please feel free to ask. We should be able to figure it out together.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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