Inverter air conditioners

Inverter air conditioners

Introduction

To understand DC Inverter ACs, we first need to understand how they work. Air conditioners use a refrigerant (a gas which exists in low pressure but turns liquid as the pressure increases), which is compressed and liquefied by the compressor. It is then cooled down in the condenser and later allowed to expand (become a gas) in the evaporator, albeit in a controlled manner. Those who have studied physics, would know that this expansion causes a cooling effect which, in turn, causing the condenser to become warm.

The same principle is used in refrigerators; they move the heat from the inside to the outside. When an AC is in cooling mode, the heat from the room is removed and pushed towards the outdoor unit of the split AC. If the AC has the ability to heat, it can reverse the process, the energy is absorbed from the outside while heating the room. In most cases, the reverse process, i.e. heating mode, consumes less power than the cooling mode because the compression energy is added to the overall heating cycle.

The remaining two important components of an AC are its motored fans. The outdoor fan chucks the air out of the condenser to the outside. However, the indoor unit makes use of the blower and louvers/fins to dissipate the cool air (or hot air if the AC is in heating mode) to the room.

Until a few years ago every single air conditioner unit was those of stable speed when we switched on our unit with a remote or wired remote our unit began to run and it worked at its full power, at its 100% of capacity, when it reached to the adjustable temperature or when we stopped it manually, the unit “stopped” completely and it didn’t keep throwing cold or heat (heat pump),the air conditioner stable speed units only have 2 speeds (0% and 100%) and when you start them they pass from being completely stopped to be at their full capacity because they give their maximum capacity right after switching on them. That’s the reason we could feel in the intensity of current of our house or office creating in many occasions a lowering in the light intensity of our room, dining hall, etc. It was noticed like the bulb didn’t give off much light just when you switched on the air conditioner (voltage descent) due to the big energy consumption the unit needs to pass from 0% to 100%, later the situation was settled and there weren’t more intensity descents (until the next starting), that’s why after starting the unit directly to 100% of its nominal capacity and maintain itself through all time the unit was running, we noticed that feeling of an intense cold so many people miss, the inverter air conditioner units don’t work this way, because these begin running slowly and then they accelerate to its full capacity reaching a 140% of its nominal capacity, but after reaching the desired temperature the unit scales down the power used and operates at much lower power  levels .

Non-Inverter Air Conditioners

Non inverter or fixed speed air conditioners operate on a fixed amount of power at a fixed speed. This means the compressor has to stop and start again to maintain the desired room temperature..In this type of arrangement the compressor is either off or on. When it is on, it works at full capacity consuming full electricity. When the thermostat reaches the required temperature setting, the compressor stops and the fan continues to function. When the thermostat senses that the temperature in the room has fluctuated, the compressor starts again.

Inverter Air Conditioners

This technology was developed in Japan and is now being used globally for air conditioners and refrigerators alike. In inverter air conditioning systems, the speed of the compressor varies to ensure energy efficient operations and precise cooling or heating as required.

A DC inverter converts AC current to DC current. It then uses a modulation technique (called Pulse Width Modulation) in another inverter to produce AC current based on the desired frequency and voltage. The variable frequency AC drives the brushless motor or induction motor. The speed of the motor is proportional to frequency of the new AC voltage. Thanks to this, the compressor can now run at multiple speeds.

The inverter technology acts like an accelerator in a car. When the compressor requires more power, it gives it more power. When it needs less power, it provides less power. In this kind of setting, the compressor is always turned on, but draws less power or more depending on the temperature of the incoming air and the setting adjusted in the thermostat. The speed and power of the compressor is also adjusted accordingly.

Major difference between the two

An air conditioner with DC inverter technology has the ability to control its cooling (or heat) transfer rate by changing the output from its compressor. The rate can be modified depending on the requirements of the room. To put it more simply, the AC uses electricity depending on the environment’s requirements.

The compressor in a common AC runs at full 100 percent all the time. When it is not needed it shuts off. So a common AC uses start/stop cycles to control the temperature.

When using a DC Inverter in an air conditioner, it uses a processor to check the surrounding temperature and adjusts the speed (power input) of the compressor based on it. It can provide different levels of cooling or heating. So the DC Inverter AC regulates its output capacity to uniformly control the temperature of the room.

Both the inverter and non-inverter systems offer similar functions but differ in terms of compressor motor type running in the system. The compressor is responsible for compressing the refrigerant into liquid after which it shuts off and allows it to expand. As this process takes place, the refrigerant begins to cool thus producing the desired effect of cooling. Inverter air conditioner units are designed in such a way that they save up to 30-50% of electricity units consumed as compared to a regular air conditioner.

The magnitude of cooling or heating required by an air conditioning unit varies depending upon the outdoor temperature and the amount of heat in the room. When the cooling or heating effect needs to be amplified, the compressor will operate at a higher speed and will upsurge the amount of refrigerant flow.

On the contrary, during moderate outside temperatures for example, when the cooling and heating capacity needs to be reduced, the compressor will run at a low speed and will decrease the amount of refrigerant flow. When the inverter air conditioner is switched on, the compressor operates at a high speed in order to cool or heat the area rapidly. As room temperature approaches the desired temperature, the compressor slows down, maintaining a constant temperature. Any spontaneous fluctuation in the room temperature will be detected and promptly adjusted to bring the room temperature back to the set temperature.

There are many benefits of the inverter ac First of all, it requires less electricity in comparison to traditional air conditioning unit. And the other benefit is that it comes with a compressed circuit board that is able to handle various cooling loads. You will not get this feature in the non-inverter air conditioners. Moreover, the traditional type of air conditioner or non-inverter type of air conditioner offers less cooling than the inverter ac. Inverter ac is not prone to voltage fluctuations like the traditional one. It is durable and requires less maintenance than the non-inverter type of air conditioners.

                         
The inverter type ac is energy efficient. This is one of the key features of this air conditioner. It consumes around thirty percent less electricity in comparison to the traditional and non-inverter type air conditioners. In this developed system, you do not need to keep the system on and off to get the required temperature. It comes with an automatic system that makes necessary adjustments to maintain temperature

Operating principles

The Inverter technology   is the latest evolution of technology concerning the electro motors of the compressors. An Inverter is used to control the speed of the compressor motor, so as to continuously regulate the temperature. The DC Inverter units have a variable-frequency drive that comprises an adjustable electrical inverter to control the speed of the electromotor, which means the compressor and the cooling / heating output. The drive converts the incoming AC current to DC and then through a modulation in an electrical inverter produces current of desired frequency. A microcontroller can sample each ambient air temperature and adjust accordingly the speed of the compressor.. The biggest difference between inverter and non-inverter AC is the fact that the motor of the inverter compressor has a variable speed. The speed of the non-inverter compressor is fixed. This means that it operates either at full or minimum speed. A censor in the inverter adjusts the power according to the temperature in the room, lowering the electrical consumption and saving energy.

Efficiency and Operating cost

The inverter air conditioning units have increased efficiency in comparison to traditional air conditioners. A conventional AC starts multiple times and always runs at peak capacity. This means that every time it starts it needs extra electricity to jump start its stationary motors and compressor, i.e. torque current. Without being too technical, you can think of it this way, it needs more power when it starts and it starts too many times. It also runs at full capacity each time requiring a lot of current.

In comparison, a DC Inverter AC never turns off its compressor or motors. It reduces the electricity it needs and constantly keeps cooling (or heating) the room. When it does start the first time, a DC Inverter AC starts off slowly so it doesn’t require a massive torque current. Inverter ACs can start at low voltages as well thanks to the inversion mechanism. By running in a low power consumption state, DC Inverter ACs save a lot of electricity.

DC Inverter ACs isn’t as effective when running at full capacity, however, when they are running at partial capacity, which is how ACs are normally used, they can save a lot of energy.

The inverter AC has lower operating cost and with less breakdowns .The inverter AC units is more expensive in upfront cost than the constant speed air conditioners, but this is balanced by lower energy bills. The payback time is approximately two years depending on the usage.

 Due to the sophisticated operational method of the inverter, its compressor does not work at its full capacity all the time. When the speed is lower, the needed energy is lower too and you pay less money for electricity.

 The inverter AC is able to cool or heat your room faster than the non-inverter. This is due to the fact that in the beginning of the process, the inverter uses more power than the non-inverter and diminishes the power when it gets close to the desired temperature. The inverter air conditioner units may vary its capacity according to their needs; this makes the consumption to get adapted and lowers the electrical consumption significantly.

The stable speed units were very old in comparison to that, for they don’t have such electronics and they couldn’t modify its way of running and they worked in the same conditions though the weather was a 24ºC normal day or an extreme hot day with 38ºC, some stable speed units had pressure relief valves and condensing controls or different fan speed in the condenser, but this is nothing in comparison with all the things an inverter unit can do, regulating the gas flow with the electronic expansion valve, reducing or increasing the compressor speed, such as the condenser fan motor does. 

Cooling capacity of 1 ton is equal to 3.517 kW of power. For 1 ton AC inverter, power consumption of ac = cooling capacity/EER = 1.5*3.517/2.7=1.954 kW. AC consists of two units, Indoor unit which is called the evaporator and the Outdoor Unit which called the Compressor.

If you have a 1-DC Inverter AC, it will save you around 40-50 percent in electricity bills under normal usage. 3-DC and 4-DC Inverter ACs can achieve over 60 percent in savings. You probably won’t get 75 percent in savings under normal usage and extreme heat in Pakistan. However, if your AC has the heating-mode, it will cause more cost savings compared to the cooling mode.

Normal conditions mean that the user does not set temperatures to extremes. If the temperature is set to extremely low (for cooling) or extremely high (for heating) then you cannot expect such huge savings. However, even at extremes, DC Inverter ACs beat the conventional ACs.

Noise level and other benefits

The variable speed function makes the inverter AC unit’s quieter, extends life of their parts and the sharp fluctuations in the load are eliminated.  As the compressor motor of the inverter air conditioner does not turn on and off all the time, but keeps working at low power, the operation is more quite. The technology of the inverters not only makes cooling and heating more efficient, but it also makes the AC’s life longer As the compressor motor of the inverter air conditioner does not turn on and off all the time, but keeps working at low power, the operation is more quite.
The inverter air conditioner units get more comfort and faster than the stable speed ones.the inverter units reach to an assigned temperature faster than the stable speed units, apart from that, being capable of regulating their refrigerating capacity these maintain the room in a much more precise way than the stable speed ones because they go reducing their capacity slowly while reaching the desired temperature, maintaining that temperature “never stopping”. And that is put in inverted commas because I have heard that a lot. The inverter units never stop, my machine never stops”.

 Speed in cooling and warming.

The inverter units start slowly, it’s like a long-distance race, starting this way there’s neither a change in the intensity of current nor we feel a change in the intensity of bulbs, but they began to increase its capacity until they reach a 140% capacity in some cases.  In comparison to steady speed air conditioner units which either go or don’t go, the inverter air conditioner units have a wide range of operations, that’s the reason why catalogues used to show three different capacities: the nominal capacity, which is the “real” capacity or “basic” of that air conditioner and it’s the one we have to use to do the numbers more accurately (there are so many people who are wrong when taking as a reference the maximum capacity), the minimum capacity and the maximum capacity.

  The inverter air conditioner units  do stop  but only a few times In comparison to a stable capacity unit which switches itself on when the temperature goes a degree over our assigned temperature (cold mode) and it stops when it exceeds -1ºC, the inverter units work in a different way, these go reducing its capacity slowly when they reach their objective, and that’s the reason why seldom they exceed or reduce the temperature more than what it’s needed because it will keep itself a few degrees over or below our assigned temperature. It doesn’t mean it doesn’t stop, it does, but in general reducing its capacity and therefore its consumption is enough to keep the desired temperature.

Much more capacity

The inverter air conditioners are way much more efficient than those which aren’t inverter and they achieve an energy coefficient wider. Thanks to its electronics and the obvious progressions over these years, an actual inverter unit can reach a 5, 15 energy coefficient, that in comparison with a 2,76 of a non-inverter unit but same model, it is something to be aware of, it is almost the double of capacity and for that it means the half of consumption when doing the same work and air-conditioning the same room. Just for this reason choosing between an inverter and non-inverter one should be an easy choice to anybody.

Wider working range

Another inverter air conditioner characteristic which makes it better than a not inverter one is its working range, for example in heat mode. When the outside temperature reaches between 5 and 0ºC, a not inverter unit starts to fall its capacity heavily, even becoming ineffective and useless if the temperature descends even more, This is due to working in heat mode, the condenser will be cooling and it reaches to a point when it produces frost and it finally freezes itself, making impossible the heat or cold exchange with the outside. This is a solution with the called “defrost”, which almost every inverter unit has. With this defrost mode, what the unit does during a few minutes is to send the heat that should be going to the outside in order to warm our house, it sends it to the external unit to defrost it, loosing with this process the heat that should be impelling in the internal unit. After that, the unit will work normally until the next defrost, which will be more usual and shortened in time if there is more cold and humidity in the outside.

The inverter units don’t have such problems, or, if they have it is much less pronounced due to its electronics regulate the gas flow for this not to happen thanks to measurements, being able to work to -15ºC and loosing much less capacity than not inverter air conditioner units. There also exists special inverter units which works to -25ºC, giving a full capacity when they reach -15ºC

What Are the Different Types of DC Inverter ACs

Some manufacturers claim they have 3-DC Inverter ACs, All DC Inverter ACs, 4-D Inverter ACs, etc, while others simply claim to have Inverter ACs. They also claim to have varying savings percentages from 60 percent to 75 percent. The reason behind that is, some manufacturers employ older technologies and only upgrade their compressors to DC inverters. Others also convert the indoor and outdoor fan motors hence, completely upgrading all motors to DC inverters.

Those, which claim to save about 50 or 60 percent in electricity bills and simply state DC Inverter (or only Inverter) ACs, are using the inverter tech for the compressor only. 3-DC Inverter or 4-D Inverter systems, sometimes referred to as All DC Inverter, upgrade other motors or major electrical components as well. This means more savings as more electrical components get the ability to vary their speeds. In short, a number besides the “D” or “DC” mean the number of components using the inverter technology.

Conclusions

The inverter unit gives more comfort, capacity, saving, and other benefits and it has more working possibilities given the weather. On the contrary, the benefit of a not inverter unit will be that it costs less (upfront cost) and it also will cost less if it need to be repaired, because they are easier and cheaper to fix.  Not only do these ACs help save money, their use is good for the environment. The DC inverter technology is being used in other products as well

Light Emitting Diodes (LED)

Light Emitting Diodes (LED)

Introduction

Light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n junction diode that emits light when activated. When a suitable current is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons.   This effect is called electroluminescence, and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor. LEDs are typically small (less than 1 mm²) and integrated optical components may be used to shape the radiation pattern. Unlike a laser, the color of light emitted from an LED is neither coherent nor monochromatic, but the spectrum is narrow with respect to human vision, and for most purposes the light from a simple diode element can be regarded as functionally monochromatic

  LEDs are like tiny light bulbs. However, LEDs require a lot less power to light up by comparison. They’re also more energy efficient, so they don’t tend to get hot like conventional light bulbs do   this makes them ideal for mobile devices and other low-power applications The LED is a light source which uses semiconductors and electroluminescence to create light.  LED   uses a small semiconductor crystal with reflectors and other parts to make the light brighter and focused into a single point. Basically, LEDs are just tiny light bulbs that fit easily into an electrical circuit. But unlike ordinary incandescent bulbs, they don't have a filament that will burn out, and they don't get especially hot. They are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor. The lifespan of an LED surpasses the short life of an incandescent bulb by thousands of hours. Tiny LEDs are already replacing the tubes that light up LCD HDTVs to make dramatically thinner televisions.

History

LEDs appeared as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are still frequently used as transmitting elements in remote-control circuits, such as those in remote controls for a wide variety of consumer electronics. The first visible-light LEDs were of low intensity and limited to red. Modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness.

Working

The LED consists of a chip of semiconducting material doped with impurities to create a p-n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge-carriers—electrons and holes—flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level and releases energy in the form of a photon.

The wavelength of the light emitted, and thus its color, depends on the band gap energy of the materials forming the p-n junction. In silicon or germanium diodes, the electrons and holes usually recombine by a non-radiative transition, which produces no optical emission, because these are indirect band gap materials. The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible, or near-ultraviolet light.

LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have enabled making devices with ever-shorter wavelengths, emitting light in a variety of colors.

LEDs are usually built on an n-type substrate, with an electrode attached to the p-type layer deposited on its surface. P-type substrates, while less common, occur as well. Many commercial LEDs, especially GaN/InGaN, also use sapphire substrate.

If you connect an LED directly to a current source it will try to dissipate as much power as it’s allowed to draw, and, like the tragic heroes of olde, it will destroy itself. That’s why it’s important to limit the amount of current flowing across the LED.. Resistors limit the flow of electrons in the circuit and protect the LED from trying to draw too much current. 

LEDs create light by electroluminescence in a semiconductor material. Electroluminescence is the phenomenon of a material emitting light when electric current or an electric field is passed through it - this happens when electrons are sent through the material and fill electron holes. An electron hole exists where an atom lacks electrons (negatively charged) and therefore has a positive charge. Semiconductor materials like germanium or silicon can be "doped" to create and control the number of electron holes. Doping is the adding of other elements to the semiconductor material to change its properties. By doping a semiconductor you can make two separate types of semiconductors in the same crystal. The boundary between the two types is called a p-n junction. The junction only allows current to pass through it one way, this is why they are used as diodes. LEDs are made using p-n junctions. As electrons pass through one crystal to the other they fill electron holes. They emit photons (light).

Applications

Early LEDs were often used as indicator lamps for electronic devices, replacing small incandescent bulbs. They were soon packaged into numeric readouts in the form of seven-segment displays and were commonly seen in digital clocks. Recent developments have produced LEDs suitable for environmental and task lighting. LEDs have led to new displays and sensors, while their high switching rates are useful in advanced communications technology. . Light-emitting diodes are used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, lighted wallpaper and medical devices. They form numbers on digital clocks, transmit information from remote controls, light up watches and tell you when your appliances are turned on. Collected together, they can form images on a jumbo television screen or illuminate a traffic light.Oter uses incuude :Indicator lights ; LCD panel backlighting Specialized white LEDs are used in flat-panel computer displays ;Fiber optic data transmission Ease of modulation allows wide communications bandwidth with minimal noise, resulting in high speed and accuracy ; Remote control Most home-entertainment "remotes" use IREDs to transmit data to the main unit; Optoisolator Stages in an electronic system can be connected together without unwanted interaction.

,LEDs serve as the foundation of networked lighting systems that also provide information to other systems connected to an internal building management network. For example, the heating, ventilation, and air conditioning systems could be alerted that certain parts of the building are empty, and could adjust the temperature or shut off the air conditioning entirely.

Energy savings

LEDs use about 85% less electricity than incandescent bulbs and as much as 50% less than fluorescents. The amount saved with fluorescents will vary depending on whether you’re using a fluorescent tube or a compact fluorescent bulb (CFL). The efficiency of a light bulb is measured in lumens per watt and currently LED technology is providing higher lumens per watt than fluorescent, but is not practical for every application a fluorescent source is being used.

One of the main problems with incandescent bulbs is they emit a great deal of energy as heat (that’s why you can burn yourself if you touch a lit incandescent bulb), and this heat signifies that some energy is being wasted instead of converted to light. On the other hand, if you touch an LED light it is typically cool to the touch and will likely not notice any heat at all. This is because more electricity is being converted to light — about 85% more.

A few of the major advantages of LEDs over CFLs are they don’t produce any UV rays, last 5 times longer, save 20% in energy costs and are lead and mercury free.

By design LEDs can last as much as 50 times longer than other bulbs and have lifetimes ranging from 30,000 to 100,000 hours or more at constant operation. Depending on how many hours a day your facility is lit, this can equal a lifespan of anywhere from 6 to 30 years. In comparison, incandescent bulbs only last an average of 1000 to 5000 hours, CFLs last 8,000 to 10,000 hours, and fluorescent tubes have lifetimes of 20,000 to 50,000 hours.

Part of the reason LEDs last so long is because they are durable (no glass components) and do not have a filament (like incandescent bulbs) that can break our burn out. Their illumination comes exclusively from the movement of electrons in a semiconductor material.

Lighting accounts for about 20 percent of the total energy usage worldwide, approximately 1,944 terawatt hours. Because lighting is relatively simple to upgrade, the trend in recent years is to switch to LEDs. Doing so greatly improves energy efficiency; mitigating global warming’s impact and reducing energy dependence on other countries.

Globally, LEDs make up less than 10 percent of lighting systems, according to the U.S. Department of Energy Solid-State Lighting R&D Plan, published in June 2016. But the DOE forecasts LEDs to become the predominant source of illumination—for indoor and outdoor spaces—over the next decade. The DOE’s “Energy Savings Forecast of Solid-State Lighting in General Illumination Applications,” released in September, predicts that by 2035, LED lamps and luminaires will be used in 86 percent of all lighting products in the United States, compared with 6 percent in 2015. That translates into an annual savings of 1,495 terawatt hours over traditional lighting systems, nearly the total annual energy consumed by 45 million U.S. homes today. This adds up to nearly $52 billion in energy costs savings.

Because LEDs are semiconductor devices, integrating additional electronics in the bulbs, such as occupancy and daylight sensors connected to a network interface, provides the bulbs with new functions. This design enables, for example, the automatic dimming of lights when there’s sufficient natural light in the room, and it senses the presence of people in a room and adjusts overhead lighting accordingly. These capabilities not only provide the optimal amount of lighting throughout a building but also save energy and money.

LEDs also help lower electricity costs in exterior lighting systems. Those used in parking lots, garages, and walkways can be configured to automatically dim or turn lights off when sensors detect an unoccupied area, and much faster than today’s systems. This type of automation is an especially attractive cost-saving option for cities. About half of a city’s monthly electricity budget is devoted to keeping the streetlights on.

Other Benefits  

LEDs also are changing the way architects and interior designers use lighting. Because the bulbs are smaller and weigh less than traditional ones, LED products allow for greater flexibility and creativity in lighting venues such as concert halls, museums, and retail stores, where aesthetics are especially important, while reducing energy usage.

LEDs in malls can motivate people to linger in a store longer and therefore boost sales. The ability to adjust from warmer to cooler shades of white, referred to as color tuning—along with precise light distribution—allows the retailer to create an inviting space that could appeal to the shopper’s sense of comfort, safety, and familiarity. In the home, LED lights could automatically mimic a bright, sunny day even if it is gloomy out. Such lighting systems will allow us to adjust our environments in ways that older technologies never could.

High Upfront Cost

Although LED prices have dropped dramatically, and continue to do so as technology advances, they typically cost more than other lighting systems. However, their high level of efficiency means you can recoup your upfront costs in a relatively short period of time. Besides requiring less electricity, LED’s long lifespan also saves you money on maintenance and replacement bulbs,  .

 Advantages:

The U.S. Department of Energy sees LEDs as the lighting source with the greatest potential for the future. They predict that, with widespread adoption of LEDs, by 2025 the country will:

·         Lower electricity demands for lighting by 62%.

·         Reduce carbon emissions by 258 million metric tons.

·         Diminish amount of materials in landfills.

·         Prevent construction of 133 new power plants.

·         Save $280 billion.

Although LEDs aren’t practical for every application (yet), they are certainly the lighting choice of the future and offer huge benefits, including energy savings, for your facility and the country as a whole.

LEDs have many advantages over incandescent light sources, including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. They are also significantly more energy efficient and, arguably, have fewer environmental concerns linked to their disposal.

Benefits of LEDs and IREDs, compared with incandescent and fluorescent illuminating devices, include: Low power requirement,  Most types can be operated with battery power supplies; High efficiency Most of the power supplied to an LED or IRED is converted into radiation in the desired form, with minimal heat production; Long life When properly installed, an LED or IRED can function for decades.

The evolution of LEDs as a source of white light has progressed dramatically in the last two decades, especially in terms of efficacy, or how well a light source produces visible light, measured in output lumens/input watts. The increase in efficacy has been achieved primarily through advances in LED chip technology, and is helping to drive LED adoption. LED products are also more affordable than incandescent bulbs over their life cycle, because their power requirements are lower and the bulbs themselves can last more than 10 years, compared with today’s incandescent bulbs they are replacing, which often last up to a year or so. Advntgaes of LEDs include:

-Energy efficient source of light for short distances and small areas. The typical LED requires only 30-60 milliwatts to operate
-Durable and shockproof unlike glass bulb lamp types
-Directional nature is useful for some applications like reducing stray light pollution on streetlights

Disadvantages:

-May be unreliable in outside applications with great variations in summer/winter temperatures, more work is being done now to solve this problem
-Semiconductors are sensitive to being damaged by heat, so large heat sinks must be employed to keep powerful arrays cool, sometimes a fan is required. This adds to cost and a fan greatly reduces the energy efficient advantage of LEDs, it is also prone to failure which leads to unit failure
-Circuit board solder and thin copper connections crack when flexed and cause sections of arrays to go out
-Rare earth metals used in LEDs are subject to price control monopolies by certain nations
-Reduced lumen output over time

Efficiency

Typical indicator LEDs are designed to operate with no more than 30–60 milliwatts (mW) of electrical power. Around 1999, Philips Lumileds introduced power LEDs capable of continuous use at one watt. These LEDs used much larger semiconductor die sizes to handle the large power inputs. Also, the semiconductor dies were mounted onto metal slugs to allow for greater heat dissipation from the LED die.

One of the key advantages of LED-based lighting sources is high luminous efficacy. White LEDs quickly matched and overtook the efficacy of standard incandescent lighting systems. In 2002, Lumileds made five-watt LEDs available with luminous efficacy of 18–22 lumens per watt (lm/W). For comparison, a conventional incandescent light bulb of 60–100 watts emits around 15 lm/W, and standard fluorescent lights emit up to 100 lm/W.

As of 2012, Philips had achieved the following efficacies for each color. The efficiency values show the physics – light power out per electrical power in. The lumen-per-watt efficacy value includes characteristics of the human eye and is derived using the luminosity function.

	Color	Wavelength range (nm)	Typical efficiency coefficient	Typical efficacy (lm/W)
	Red	620 < λ < 645	0.39	72
	Red-orange	610 < λ < 620	0.29	98
	Green	520 < λ < 550	0.15	93
	Cyan	490 < λ < 520	0.26	75
	Blue	460 < λ < 490	0.35	37

Red and Infrared LEDs are made with gallium arsenide
Bright Blue is made with GaN -gallium nitride
White LEDs are made with yttrium aluminum garnet

There are also orange, green, blue, violet, purple, ultraviolet LED

In September 2003, a new type of blue LED was demonstrated by Cree. This produced a commercially packaged white light giving 65 lm/W at 20 mA, becoming the brightest white LED commercially available at the time, and more than four times as efficient as standard incandescent. In 2006, they demonstrated a prototype with a record white LED luminous efficacy of 131 lm/W at 20 mA. Nichia Corporation has developed a white LED with luminous efficacy of 150 lm/W at a forward current of 20 mA. Cree's XLamp XM-L LEDs, commercially available in 2011, produce 100 lm/W at their full power of 10W, and up to 160 lm/W at around 2 W input power. In 2012, Cree announced a white LED giving 254 lm/W, and 303 lm/W in March 2014. Practical general lighting needs high-power LEDs, of one watt or more. Typical operating currents for such devices begin at 350 mA.

These efficiencies are for the light-emitting diode only, held at low temperature in a lab. Since LEDs installed in real fixtures operate at higher temperature and with driver losses, real-world efficiencies are much lower. United States Department of Energy (DOE) testing of commercial LED lamps designed to replace incandescent lamps or CFLs showed that average efficacy was still about 46 lm/W in 2009 (tested performance ranged from 17 lm/W to 79 lm/W).