Well what you are going to find if you know what you are doing is going to be disappointing. Cree has the most efficient LED on the market period, there are none better at any price point. They claim 160 L/w when operated at 2 watts. Problem is that is a lab rating inside a refrigerator more or less keeping lamp temperature at a cool 10 Centigrade. LED intensity drops dramatically as the base heats up to as much as 75% which is not included in the specs. It is also with the 15 degree bean angle and if you get off the ocus point the light intensity drops dramatically. They make great flashlights but poor room lighting.
The other little dirty secret is the manufactures tell you l/w efficiency of the LED only, which is all they can tell you because they do not make the fixtures and drivers. So any power consumed by the drivers or ballast is not specified or included.
When all added up LEDs ar not much more efficient than incandescent bulbs., and not as good as quality CFL lamps. They dot even come close to the king of indoor lighting the T5HO High Bay Lighting. Go into any modern indoor sports arena, warehouse, or office and you will find only T5HO High Bay lighting. There are a ton of T5 lighting systems for your home and office. With ballast and line losses you are looking at 105 L/Watt in a full spherical illumination, not a focused beam of LED.
FWIW th eFederal Government will not allow LED lighting in any public building. They are too inefficient. All lighting in government buildings will be either T5, T8, or CFL. That ought to tell you something.
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DC LED efficiency
Alert readers will note the "DC" here, as I'm well aware of the CFL/LED efficiency discussions and what they mean.
Let me put things in this light: I am fully aware that AC LEDs are inefficient, if and only if for the reason they are taking AC and converting it to DC. Throw in the inefficiencies created when DC is turned into 120 VAC, and yeah, I see the losses accumulate.
What I'm looking for are suggestions/leads on DC LEDs that may function in a residential setting. Looking at spot lighting, kitchen lighting. I don't mind 12vdc systems, as I can run two of those in series if/when we do the new house and the 24vdc system that seems to be the one we're aiming at.
To contribute, I've ordered a 10-30 vdc LED light out of Singapore: cost me $15. I'll do some tests and report back, perhaps with pictures (with a camera set on manual to lock down aperture/exposure and thus provide a real sense of illumination, compared to a CFL and the handy-dandy kerosene lamp, just for giggles and grins.
The current plan is to look at a split lighting system: CFL for when you just gotta have light, and LED for localized lighting. As an aside, we've just put a pair of battery-powered, portable LED sticks (four LEDs, powered by three AAA batteries) over our stove. This is a darker, yet perfectly functional replacement for the incandescent (three xenon bulbs) fixture over the sink.
This is part of our ongoing test of solar (our living room is partly off-grid, at the moment) this winter. Currently, about the only major thing we're running off the batteries is a lamp (50 watt, three-stage CFL) and a few other things as we gain comfort in the energy draw and recharging rates, and so on.
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