Why is LED bad?
Why is LED bad?
Outdoor LEDs are unsuitable for many reasons that they probably don't want you to know about. But to understand why,
let's look at a list of requirements that a good streetlight should fulfill:

1. Aesthetics
2. Reliability
3. Optics
4. Economics
5. Energy consumption

Let's start with aesthetics:
Many LED streetlights resemble things that aren't streetlights, such as tennis rackets, flyswatters, and waffle irons.
It's hard to say if this is a bad thing or not, but it can be odd to look at a light pole and see a weid-shaped item that shines right in your eyes. NEW: See what they actually look like at the gallery.

How about reliability?
Many LED streetlights tout high reliability and long lives, but they're not telling you the whole story.
With most the traditional (non-LED) fixtures, you can simply change out a bulb and it's ready for the next few years of illumination.
But with LED, many of them aren't as simple as this. A dead fixture often means the whole thing being replaced,
as replacing the ballast can take a while compared to replacing a light bulb.
Here's more about the ballast:
To run a streetlight, you need a ballast, also called a driver. HID (high intensity discharge) fixtures almost always use a magnetic ballast, with the exception of a few rare models that use an electronic one. Fundementally, the magnetic ones are just some wire wrapped around a metal core, and then coated with varnish or an equivalent insulator. As you might expect, this setup is very reliable, since it is very simplistic. In fact, it's common for a streetlight ballast to last 20 years, and many of them are still around today.
But with LED, it's another story.
To run a LED streetlight, electronic ballasts are used. As you may know, "electronic" usually means the item in question uses various electronic components. Here's where the trouble begins:
Streetlight luminaires are used outdoors. Protecting the circuit board in this electronic ballast from corrosion is a tricky task. One option is to use epoxy resin plastic, but that might not be such a good idea. When the epoxy hardens, it becomes very hard to work with. Dissolving it requires powerful solvents, and doing this may destroy the electronics you were trying to get to. Recycling may also be a problem. Epoxy resin takes a lot of effort to remove, and e-waste recycling has to be quick and efficient to be economical.
Now let's check out the other option, a bare circuit board.
The biggest problem with using a bare circuit board (not coated in epoxy resin) is corrosion. Because streetlights are used outside, moisture can get in and do its dirty work on the components that lay inside. Defending against this pertinent problem is hard, and not doing it perfectly can increase early failures and thus increase maintenance costs. If it is done well, the problem of corrosion will be stopped, but this will add to the total fixture cost. Perhaps a conformal coating could be used.
But wait, there's more!
Transistors are certaintly used in the LED driver's design. They can only handle chip-junction temperatures of 100-150 Celsius, and without a heat sink (using a heat sink increases costs!) this limit is reached easily. One way to solve this problem is to use more than one transistor, but this also adds to the total fixture price.
Want to see how high costs make the payoff time too long? Check out LED Economics.

Now let's check out the optics:
LED streetlights commonly suffer from a lack of good optics. Compared to HID fixtures,
outdoor LEDs skimp on the optics to save costs and make them look more efficient. Want to see this for yourself? Get an LED barn light, then inspect it. You may be surprised at the optics, in a bad way!
There are only a couple models of LED streetlights that have good optical systems, and even these sometimes can't beat a standard streetlight.
Also, bad optics means that glare can be higher, and for drivers, this is an important problem!
NEW: Check out a comparison of 3 different streetlights at Optics.
Let's finish with energy consumption:
While LED lighting may save energy, this sometimes means lower light levels.
The efficacy/efficiency of traditional streetlights is often said to be lower than it actually is.
If we have a 250 watt HPS bulb with 28000 lumens, and the optics has an efficiency of 75%, we still have 21000 lumens of pleasant light.
Then if the total fixture wattage is 300 watts (because of the ballast) we have a 70 lumens per watt efficiency. This might look like it has a bad efficiency,
but it makes up for this as you're getting excellent light control, this means the light is going where it should.

In short, here are some reasons why LED streetlights are such a big problem:

1. Most of the old streetlights work perfectly fine! Try to imagine throwing out your refrigerator just because something is marketed to be "new" and "more efficient", but the new one can't be repaired and doesn't last as long.

2. LED has higher glare and often lower light levels compared to the older lighting. Do you want dimmer streets that hurt your eyes? Because that's what a lot of LED streetlights offer.

3. The high blue content causes impaired sleep and potential eye damage. It's a lot like constantly staring at a smartphone, which isn't a very healthy thing to do. NEW: More info on blue light. 4. LED lights often look uglier compared to what they are replacing. Some of them look like something you might find on an alien planet!
Because of this, the aesthetics of them sometimes ruins the looks of an area.

5. With the regular streetlights, you can change out the lamp. But with the LEDs, it's usually trickier to change out its components.

6. They cause light pollution that can't be easily filtered out, leaving astronomers unhappy.
The other lighting technologies have spectrums that are easier to work with.

7. White LED is more harmful to sea turtles than HPS (High Pressure Sodium) or LPS (Low Pressure Sodium),
and this is because it has a lot of blue light.

8. Many of them are made cheaply, making it harder to find a good-quality fixture.

9. LED streetlights often have bad optics, and only light up a small area, not the whole road. This also creates substantially higher amounts of light trespass. The traditional streetlights almost always have better optics, allowing for better control of the light.

10. The spectrum of white LED isn't very good, creating low-quality light. This is due to the blue chips creating a large spike of blue light.

11. White LEDs are fundamentally the same as almost all smartphone screens, and they say to not stare at phone screens for too long.
LED streetlights are pretty bright, and this could mean that you have a higher risk of getting your vision damaged. All of this adds up to LED lights creating poorly-lit streets with stark light, and this isn't just for roadways, it also applies to your yardlights.

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