LED lighting for net metering system

labradoodleladyJuly 12, 2007

Because of my net metering system, I'd like to keep my night time electrical usage as low as possible. That would seem to mean using LEDs for the exterior lights and the can lighting in the kitchen, and I'm willing to pay the additional cost (OK, so I'm crazy). :)

I've been reading and researching, but would like feedback on two sources I've found for LED floods supposedly producing between 350 and 600 lumens.

I'd like some input on how low a lumen level I can get by with on the exterior deck and front porch. The deck ceilings are 10 foot high, and I was planning on putting in shower enclosed fixtures (although I've been reading about heat build up in LED fixtures and now wonder if that's a good idea?). Do I need more than 300 lumens for that type of application?

I've found two sources that claim LED floods in the 400 - 600 lumen range for warm (or what they call neutral) white. An online site (http://www.wiedamark.com/index.asp?PageAction=VIEWCATS&Category=92

is showing three different sets of bulbs that range up as high as 400 lumens for floods.

Then there's an ebay seller who claims to be selling 600 plus lumen bulbs - http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=010&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=200122747669&rd=1&rd=1

The kitchen recessed lights are worth it to me to pay the extra cost for LEDs since they're wired directly into the PV system -- i.e., when the power goes out these lights will continue to function.

I'm not an electrical expert in any way -- but I'd really appreciate some input on this issue.



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I suggest you read the threads here and in the lighting forum about LEDs. Look here, here, and here.

For some reason, LEDs have really caught the imagination and attention of the public. There's a perception that they're extraordinarily efficient. While they certainly are quite an improvement in some applications, for home lighting use, they're (so far) not worth anything like what they cost. (I was about to write "they're a bust," but that's a little unfair.)

Where LEDs shine (sorry ;-) is as indicators, for pure colored light, and where rather small amounts of light (in the tens of lumens) are required. But they're not really all that efficient for producing the amounts of light people need for home or office use. You might be surprised that LED cans have to struggle to attain California Title 24 standards (see the threads linked above).

Be very careful with the LED vendors making offers on Ebay. There is a lot of "enhancement" in their claims. For example, note that this seller is offering a lamp which he claims produces 600 lumens as a replacement for a 100 watt incandescent lamp. That's a bit optimistic. A 100 watt incandescent lamp produces almost 3 times that amount of luminous flux (1700 lumens).

Even if it does meet its specifications, about which I'm dubious, its efficacy is 60 lumens per Watt. That's no better than a compact fluorescent that costs one-tenth as much (or less).

A linear fluorescent fixture can yield 80-100 lumens/Watt for about one-fourth to one-third the price - and when the lamp fails, you replace only the lamps at a cost of around $3 per lamp, not the entire unit.

Someday LED fixtures will no doubt be competitive for home lighting, but I don't expect them to be available and price-competitive for at least 7-10 years. I would be surprised and pleased if the field advances more rapidly than I predict.

    Bookmark   July 12, 2007 at 7:54PM
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Hi David,
I had already read those posts, but they don't address my specific concerns. I'm not concerned about LED bulbs being cost effective -- I'm concerned about whether I can buy ones that produce enough light for outdoor decks and kitchen cans.

I have my reasons for not wanting to use fluorescent lights. I live on a small island in the Pacific that does not have any means for disposing of the CF bulbs in a manner that prevents the mercury from escaping into the landfill, and from there into the soil and eventually the ocean. Our local power company is handing them out right and left, but everyone is just throwing them into the trash, and our landfill is next to the beach.

Second, my daughter has severe brain damage, and her body does not detoxify itself the way a healthy persons' would. She already has toxic levels of mercury stored in her kidneys, and I really don't want to introduce any additional possible sources of mercury into my household. I'm not trying to get into any argument about how much mercury is too much or not enough to worry about, I'm just stating that this is my position.

And third, the kitchen lights are wired directly into the pv system, so when the power goes out, I still have kitchen lighting. Obviously I want to pull as little power as possible from my backup batteries in those situations, while minimizing the amount of power I have to buy back from the power company in the evenings.

So, if I don't want to use CF bulbs, and I want to keep my power usage as low as possible in the evenings when the lights are on, LEDs are, I'm hoping, the best bet. I wouldn't be putting 100 watt incandescent bulbs in my kitchen recessed fixtures anyway, so if the bulbs don't produce the equivilent, I'm not concerned. The enlux bulbs sold by weidamark claim 400 lumens, and that was why part of my question was is this enough for an outdoor deck, or a kitchen?

I know I don't know how to read spec sheets on bulbs, all I can do is try to compare on the basis of lumens. And I still have concerns because I read somewhere about how the warm white degrades over time into a cooler white, and don't know how to read a spec sheet to figure that one out.

Does this help?

    Bookmark   July 12, 2007 at 8:32PM
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I don't know anything about degradation of warm white LEDs. However, I can speculate on it. AFAIK all commercially available white LEDs are really blue LEDs with a phosphor coating (this is what reduces the efficiency). I suppose that if the phosphor output declines over time, the blue light would become more prominent.

Assuming the LED lamps actually meet their specifications, perhaps this will give you some yardstick to compare. It's the lumen output of various typical incandescent bulbs. If you're familiar with them (and most people are), this should help. Good luck! (Scroll down to see the table; for some reason Gardenweb adds a bunch of space above it.) Wattage lumens

15 100

25 200

40 500

60 850

75 1200

100 1700

150 2800

200 3900

    Bookmark   July 13, 2007 at 1:13AM
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Our house is a stilt house with the deck at 12 ft high. You can walk around the house downstairs underneath the deck. The previous owner had lighting installed underneath the deck to shine down on the ground level. At 12 bulbs x 40 watts, we said sayonara,and changed them to night light bulbs. 4 watts each. (candelabra based- need socket adapter - no biggee.) Then I found some led night light bulbs at the local drugstore manufactured by feit. Less then 1 watt, bluish output, but you cannot read a book by these. You can walk around without bumping into the furniture. You can sit and see who you are talking to, but these are NOT task lights. They were $4/per two pack. We have issues with light pollution, and are trying to be aware of the light output outside of our home. This and the energy wasted were our two main motivators.
FYI, the amount of mercury in a typical CFL (E27 base) is equal to the size of the period at the end of this sentence. Most manufacturer's have great warranties -send them your old dead ones, get a free replacement, and let them do the disposal.

    Bookmark   July 15, 2007 at 3:56PM
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Exactly! That's one of the things that LEDs are good for - low output lighting. They're also usually quite good at directing most of the light in a specific direction.

When you're talking about a couple of Watts, an incandescent (especially at line voltage) is horrendously inefficient because of the low filament temperature. Even fluorescents lose some of their advantage at low power, because the ballast losses are fixed, and thus become larger by percentage at low outputs.

    Bookmark   July 15, 2007 at 7:25PM
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latefordinner, your idea about your underhouse lighting is what I'm hoping to do with my deck. I just need enough light to see where the dogs are.

I've ended up ordering some bulbs from the ebay seller, to see how bright they really are. I've actually spoken with him, he wanted to know exactly how I intended to use the bulbs to determine if they really were going to meet my needs. He says he's got bulbs bright enough for my kitchen, so I'll see.

By the way, the size of the amount of mercury contained in a CFL isn't the issue, it's the weight of that amount. The lowest, "green" certified CFLs still contain almost 4 mgs of mercury per bulb. The maximum allowed by the EPA to leach into a landfill is 0.2 mg per liter. So a single CFL contains nineteen times more mercury than is allowed to leach into a liter of landfill waste. Another way to look at it is if a CFL breaks with someone nearby who could accidentally inhale the mercury vapor (likely, since a lot of bulbs break because somebody dropped them), that person has a chance of inhaling up to 4 milligrams (equal to 4000 micrograms) of mercury (although likely less considering it would start dissipating immediately, of course). However, according to the EPA, the maximum non-toxic amount of mercury consumption per day is 1 microgram per kilo of body weight. Do the math -- even for a 200 pound adult the maximum that could be inhaled "safely" is 90 micrograms. In other words, one CFL bulb contains more than 44 times the maximum EPA allowed limit for human inhalation.

I'm also not comfortable sending these bulbs through the mail. Have you seen what can happen to glass in the hands of our postal departments?

I'm really keeping my fingers crossed for these LED bulbs.

    Bookmark   July 15, 2007 at 8:01PM
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Let us know how they work out. I'll be especially interested if you can measure their actual luminous flux and compare it to an incandescent lamp with equivalent beamspread.

I emphasize those last 3 words because recently I ran across an LED lighting manufacturer who argued that because his LEDs were directional, they were more efficient than fluorescents when you considered their focused output against the unfocused light of other devices. The manufacturer was using made-up, nonstandard units (something like "effective lumen output") that made his lights look like they had an efficacy of something like 280 lumens/Watt.

I guess they just forgot that incandescents and fluorescents can use reflectors to direct the light. ;-)

I already knew that some LED manufacturers were overstating their efficacy by citing "output Watts" instead of actual electrical consumption. This beamspread game seems like yet another way to fudge the numbers. (To their credit, though, the company admitted that the real efficacy of their LED lights was 20 lumens per Watt - about as good a a 300 Watt incandescent lamp.)

    Bookmark   July 16, 2007 at 6:09PM
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I have been interested in LED lighting for several years. They could work very efficiently as ceiling lights. It is true, the light output is focused, so the bulb does not shine in all directions. Many people spend big bucks for flood type lights, for room lighting. The one benefitt I see with LED's is the longer life. Imagine buying a house, and never changing a lightbult in the 2-story entry. Or never needing to replace bulbs on a ceiling fan fixture.

Cost is dependent on quanity sold. The more sold, the cheaper it will be. CF bulbs were very expensive only a few years ago. This summer, I saw a 3 pack at HD; the bulbs cost 99 1/2 cents each. Cosco had Feits for $1.12 each.

Since I changed to CF's in my house, I seldom have to change bad bulbs. I can imagine NEVER changing bulbs.

    Bookmark   September 30, 2007 at 1:55PM
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