12-volt household lighting has gotten a lot better.

If you’re rigging a solar-powered electrical system for an off-grid home, it has become entirely practical to use lighting that bypasses the need for an inverter. In fact it’s so seamless as to almost be a problem; I have 12-volt DC and 120-volt AC LED bulbs that all fit the same socket, and some of the Chinese ones aren’t even labeled. So I have to carefully label the spares I have in storage.

This 12-volt residential LED business is relatively new. I went with all AC lighting when I first wired the cabin because the only DC lighting I was familiar with was automotive. And even then, as late as 2009, I had to go with CFLs because anything LED was out of my league.

Since then non-dimmable LEDs have come way down in price. The one big promise we were made 10-15 years ago was incredible longevity, and so far that has not been my experience. Your typical screw-in LED ‘bulb’…

…doesn’t have any better overall longevity than an old-fashioned incandescent. So you do have to stock spares. But LEDs are a helluva lot easier to live with than CFLs and lately the prices are bearable.

CFLs use roughly half the power of comparable incandescents, and LEDs use about half the power of comparable CFLs, which makes LEDs the only way to go for a small solar power outfit. And if you really want to get stingy with your power output, dimmable LEDs are your friend.

The real price difference these days is between dimmable and non-dimmable, so you have to choose your application. If you’ll never want to dim that light, spending the money there doesn’t make sense. All the lighting in the bedroom addition is 12 volt LED but this is the only dimmable one, a gift from Big Brother 3 years ago for the new bedside…

…and you can clearly see the obsessively professional manner in which I installed the dimming rheostat. This light has seen three winters and two summers so far, still works great, and more and more the rheostat is irrelevant because I virtually always keep it cranked low – just bright enough to light up that corner without blinding me first thing in the morning.

To my shock I frequently don’t even bother turning it off during the day and normally that would be a sin against the power system. Yesterday morning I noted the early-morning battery readout with no load at all. It was getting light but there wasn’t any push yet from the solar panels…

…and then I turned the light on…

…and it – eventually – had the following startling effect on battery voltage…

Actually at first there was no effect at all. In terms of power usage, when turned way down the thing is practically free.

In fact using it is so painfree that, as I said, it has lulled me into bad habits since I often don’t bother turning it off during the day, and even though it’s cranked way down that’s probably bad for its longevity. It’s a really nice little lamp and I don’t know what it would cost to replace.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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9 Responses to 12-volt household lighting has gotten a lot better.

  1. TK421a says:

    I’ve had nothing but good luck (fingers crossed, looking for wood to knock on, etc.) with my LED bulbs. When the cost of LED lights dropped a couple of years ago, I spent the bucks and replaced every light inside and outside the house. So far over the last three years none have failed. I wonder why your LEDs aren’s a long lasting as advertised?

    As for how little energy they use, I can attest to that. Our power bill (yes I’m on the grid) cames down a fair bit. I figure the ROI on the LEDs is such that the bulbs have already paid for themselves.

  2. Rick T says:

    We went CFL then LED a while ago for most lighting but the kitchen *was* a 300W halogen fixture.

    When it died I replaced it with a 3 bulb unit, 3x100W LED bulbs is under 50W total draw. My house base load is now under 500W continuous. No AC needed but the whole house fan can pull a bunch of power if we run it.

  3. Robert says:

    Our 120vac LEDs go “poof” far too often or quickly (one year’s use) get so dim as to be quite an irritant. Yes, they’re “rated for enclosed fixtures”; no dimmers- either on or off. No, we don’t slam the doors. Yes, the line voltage looks good. It’s a Habitat for Humanity house so dog knows about the wiring.

  4. RCPete says:

    I don’t know 12V LED lights, but we had bad luck with some early LED bulbs from Home Depot. They failed within a couple of years. The power supply in them tended to run hot, and that’s potentially a sketchy design.

    The FEIT bulbs (9.5W and 9.5W) that we got from Costco have behaved well.

    On the other hand, my computer desk light uses a Cree with a vented plastic shell. It doesn’t have a fancy heat sink, and it’s lasted several years now. All the overhead lights are the FEITs in 7.5W (40W “equivalent”), and those are 6-7 years old now. Those are for enclosed fixtures.

  5. Zendo Deb says:

    The best way to generate power is to not use it in the first place.

    That said when I had DC lighting, I hated florescent bulbs. They were the thing for the head, the galley, etc. I think reading light was either xenon or halogen. Bright and hot, but it gave a decent light for reading. And I did have a couple of AC lights, because when you’re tied up at the dock, why not?

    A couple of people had good luck with the LED rope lights – they were new at the time, so I don’t know how they lasted or if they’ve gotten better. But just for general illumination, so you didn’t trip over stuff walking around. I never thought they looked right, But they they usually just strung them up anywhere. Shelves, overhead handrails, wherever.

  6. Norman says:

    Make and model of the bedside light?

  7. Malatrope says:

    I really like the look and light of the “filament LED” bulbs designed to look like old Edison bulbs. They don’t use a separate power supply that gets hot, and they seem to use less energy.

    This link is just an example of what I mean, not a recommendation for this brand:

    They make 12VDC versions also, and the 40W equivalent only uses 4 watts.

  8. Joel says:

    Norman: don’t know.

  9. Ratus says:

    “… I often don’t bother turning it off during the day, and even though it’s cranked way down that’s probably bad for its longevity.”

    It’s probably not doing any damage at all.

    LEDs are more efficient and last longer when running at a fraction of their rated output.

    It’s heat and running at or over their rated voltage/current that reduces their lifespan.

To the stake with the heretic!