Check out this link to a comparison between different types of light bulbs. You can change the kwh cost at the bottom and a few other variables. Might be nice for your own use or to show some of your clients. http://www.productdose.com/LightBulb_Comparison.xls
I know that LED's are very reliable when they connected up to a suitable circuit which controls the nominal current through the LED and limits it to say 10 mA, they will last for 15 years and more. ( 131400 hrs )
We use them as PT indicators on CT metering as an add on and meters from 1990 still in service have the LED's going as bright as when they were put in.
In bulk LED lamps I'm not to sure yet as for the reliability. I have seen traffic lights with LED's fail or loose segments of 5 LED's or so fail within the cluster of lamps over the last 2 years.
It comes all back to design and how cheap it can be made. (China)??
Eventually they will become the standard for house lighting, perhaps 10 years away.
See what happens.
Also have a look under the topic "The end of the bulb" where we discuss pro's and cons re LED lamps.
Edited for typo's RF.
[This message has been edited by RODALCO (edited 05-06-2006).]
The product of rotation, excitation and flux produces electricty.
First off the price for incandescent lamps is way off. Looking at Home Depot's website (where many consumers would shop for light bulbs) a 4-pack of Phillips DuraMax (long life) lamps is $1.44 or 36¢ per (not $1.35 as in the spreadsheet).
Second $2.98 for compact fluorescent is really low too. Again from HD, more like $5 per Philips lamp.
Third, there's no mention of lumens. CF's (and any fluorescent) have a decreased light output over time.
Finally some of the calculations are based on a 60k hours. Well, at 5 hours per day 60k hours is 32 years. If I have the math right replacing the 30 lamps with LED would cost me $1650. At my current electric rate (8.5¢ per kWh) it would take me 6+ years just to break even for the outlay on the lamps. And I think the 30 lamps and 5 hours per day is way off too.
I wondered about the "30 lamps" thing too. I had my kids and grandkids here this weekend and they are terrible about turning off lights. At the worst case monent when I finally had enouigh and started turning them off I only had about 16 going. We usually have about 3 or 4 on and some of them are dimmed. If I had to point to the biggest energy saver in my house it would be the motion detectors. Lights come on when you walk around but they go out when you leave.
I wondered about the "30 lamps" thing too. I had my kids and grandkids here this weekend and they are terrible about turning off lights. At the worst case monent when I finally had enough and started turning them off I only had about 16 going. We usually have about 3 or 4 on and some of them are dimmed. If I had to point to the biggest energy saver in my house it would be the motion detectors. Lights come on when you walk around but they go out when you leave.
One of my hobbies is lighting for bicycles. I've spend quite a bit of time exploring different solutions for these lights.
LEDs have tremendous potential. They are _not_ the best solution at the present time for bulk 'area lighting'. For this application, there are other light sources that are cheaper and more energy efficient. However LEDs with performance in the 100 lumen per watt range have been reported; when these devices reach actual production, they will be more efficient than any white gas discharge source, including florescent lighting. (Low pressure sodium will probably still have an edge for quite a while, if you like orange lights.)
LEDs are _great_ for low power light sources. The reason is 'economies of scale'. Most high temperature lights sources have a bunch of parasitic losses that become proportionately larger as the size gets smaller. 1W incandescent lamps are much less efficient than 20W incandescent lamps. 10W HID lamps are no more efficient than good incandescent lamps, even though 35W HID lamps are _much_ more efficient than incandescent. Compact florescent lamps reach good efficiency down as low as 7W, but produce output from a very large source; good for area lighting but not for a focused light. A 1W CF lamp is probably not in the cards.
LEDs on the other hand are efficient right down to a couple of milliwatts. LEDs also tolerate dimming far better than other light sources; most light sources get less efficient when dimmed below full power; LEDs get more efficient. This is why LED flashlights do so well as the batteries discharge; they get dimmer, but remain white and efficient, and so seem to be lasting 'forever'.
LEDs are normally monochromatic light sources; white LEDs actually require a bunch of tricks that can only reduce efficiency. Because most light sources are not monochromatic; if you need a single color you need to add a filter. Take a 20 lumen/watt white incandescent lamp, and add a red filter to it, and you are down to only a few lumen per watt. Compare this to a red LED at 40-60 lumen per watt, and you see why LEDs have replaced so many traffic signals. LEDs are currently the _best_ light source if you want a colored source.
LEDs are also great for night-lights; using much less power than an incandescent lamp, operating at lower temperature, and not burning out.