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How a wind turbine works

Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, a turbine uses wind to make electricity.

The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity The electricity is sent through transmission and distribution lines to a substation, then on to homes, business and schools.

High-tech turbines equal low environmental impact. That’s why wind power is gaining public approval and generating increased awareness.

It is also becoming economically competitive with more conventional power sources – a fact that’s greatly improving its prospects as a viable energy source.

### Components of Wind Energy Systems

The basic components of a typical wind energy system are shown below:

Components of a wind energy system.

These basic components include:

• A rotor, consisting of blades with aerodynamic surfaces. When the wind blows over the blades, the rotor turns, causing the generator or alternator in the turbine to rotate and produce electricity.
• A gearbox, which matches the rotor speed to that of the generator/alternator. The smallest turbines (under 10 kW) usually do not require a gearbox.
• An enclosure, or nacelle, which protects the gearbox, generator and other components of the turbine from the elements.
• A tailvane or yaw system, which aligns the turbine with the wind.

If you plan on building a horizontal axis wind turbine, you will need a tower on which to mount the turbine (vertical axis turbines are usually built on the ground).

Several types of towers are available:

• Guyed lattice towers, where the tower is permanently supported by guy wires. These towers tend to be the least expensive, but take up a lot of space on a yard. A radio broadcast tower is a good example of a guyed lattice tower.
• Guyed tilt-up towers, which can be raised and lowered for easy maintenance and repair.
• Self-supporting towers, which do not have guy wires. These towers tend to be the heaviest and most expensive, but because they do not require guy wires, they do not take up as much space on a yard.

An important factor in how much power your wind turbine will produce is the height of its tower. The power available in the wind is proportional to the cube of its speed. This means that if wind speed doubles, the power available to the wind generator increases by a factor of 8 (2 x 2 x 2 = 8). Since wind speed increases with height, increases to the tower height can mean enormous increases in the amount of electricity generated by a wind turbine.

Relationship between wind speed and wind power.

Wind speeds increase with height.

Wind turbine schematic. (Modified image from Natural Resources Canada)

### Picking the Best Location for a Wind Turbine

Where you choose to build your wind turbine is important. Remember that if nearby houses, tree lines and silos obstruct the full force of the wind from your wind turbine, you will not be able to generate as much power.

Also keep the following in mind:

• Wind speeds are always higher at the top of a hill, on a shoreline, and in places clear of trees and other structures.
• Remember that trees grow over the years; wind turbine towers do not.
• Inform neighbours of your plans to avoid conflict later on.
• Be courteous. Keep the turbine as far away from neighbours as possible. 250-300 m away is typical.
• Check with the local government for any other bylaws and regulations about zoning.

Wind speeds tend to be higher on the top of a ridge or hill, and for that reason it is a good idea to locate wind turbines at hilly locations Just remember to keep your turbine away from high turbulence. Neighbours must also be taken into consideration when picking a spot to build your turbine. The farther your wind turbine site is from neighbouring houses, the better.

Do not expect your wind turbine to generate the same amount of power all the time. The wind speed at a single location may vary considerably, and this can have a significant impact on the power production from a wind turbine. Even if the wind speed varies by only 10%, the power production from a wind turbine can vary by up to 25%!

Example of wind speed distribution by hour of the day.
Values shown are monthly averages of measurements made by anemometers.
(Source: US Department of Energy)

### Types of Wind Turbines

There are two basic types of wind turbines: horizontal axis wind turbines and vertical axis wind turbines. Horizontal axis turbines (more common) need to be aimed directly at the wind. Because of this, they come with a tailvane that will continuously point them in the direction of the wind. Vertical axis turbines work whatever direction the wind is blowing, but require a lot more ground space to support their guy wires than horizontal axis wind turbines.

Two basic wind turbines, horizontal axis and vertical axis.
(Source: Ontario Ministry of Energy)

### Choosing an appropriate wind turbine size

To determine the appropriate size of wind turbine to use, review your monthly electricity consumption in kilowatt-hours (kWh). To do this look at your electricity bills for the last year, add the kilowatt-hours you consumed, and divide by 12. Then compare this total to estimates of the power production for different wind turbines, a figure available from a wind turbine dealer.

To get a preliminary estimate of the performance of a particular wind turbine, use the formula below:

AEO = 1.64 D2 V3

Where:

AEO = Annual energy output, kWh/year
D = rotor diameter, meters
V = Annual average wind speed, m/s

By making your home or farm more energy efficient and reducing the size of your peak demand electrical loads, you can reduce the size of wind turbine you'll need, thereby decreasing the purchase cost.

Off-Grid and Grid-Tie Wind Systems:

Small wind systems are used for individual homes and businesses that are off-grid and grid-tie. A small off-grid wind system consists of a wind turbine, which generates electrical power, a controller, a battery bank that stores the power, an inverter and a tower. In many locations hybrid systems that include solar panels and a generator are used to ensure a “round-the-clock” electricity supply.

A grid-tie wind system consists of a wind turbine, a grid-tie inverter and a tower. Depending on the amount of power being used by the household, electricity is either fed to or accepted from the utility. They can be set up with or without emergency back-up power (will have a controller if using a battery back-up).

Batteryless grid-tie systems may see increased performance (sometimes dramatically) from the wind turbine compared to battery-based systems. This is because the inverter´s electronics can match the wind´s load more exactly, running the turbine at optimum speed, and extracting the maximum energy. A grid-tie wind power system can have almost exactly the same components as the off-grid system except that the inverter is a special inverter that connects directly into the public utility grid. These inverters tend to be much more expensive due to their complexity.

### How loud might a wind turbine be?

At a distance of 250 m, a typical wind turbine produces a sound pressure level of about 45 dB(A) (decibels). As the picture shows, this sound level is below the background noise level produced in a home or office. Most small wind turbines, in fact, make less noise than a residential air conditioner.

#### Small wind turbines:

The blades rotate at an average range of 175-500 revolutions per minute with some as high as 1150 rpm. Large turbines turbine blades rotate in the range of at 50-15 rpm at constant speed, although an increasing number of machines operate at a variable speed.

Comparison of decibel levels from a hypothetical wind turbine
(from 250 m away) with other sources of noise. (Source: American Wind Energy Association)

Glossary of Basic Terms in the Industry:

# Grid tie inverter

A grid-tie inverter, or a (GTI) is an electrical device that allows solar & wind power users to complement their grid power with solar or wind power. It works by regulating the amount of voltage and current that is received from the direct current solar panels (or other D.C. energy source) and converting this into alternating current. The main difference between an Inverter (electrical) and a grid-tie inverter is that the latter also ensures that the power supplied will be in phase with the grid power. This allows individuals with surplus power (wind, solar, etc) to sell the power back to the utility. This is sometimes called "spinning the meter backwards" as that is what literally happens.

Inverter for grid connected PV

On the AC side, these inverters must supply electricity in sinusoidal form, synchronized to the grid frequency, limit feed in voltage to no higher than the grid voltage including disconnecting from the grid if the grid voltage is turned off.

On the DC side, the power output of a module varies as a function of the voltage in a way that power generation can be optimized by varying the system voltage to find the 'maximum power point'. Most inverters therefore incorporate 'maximum power point tracking'.

The inverters are designed to connect to one or more strings.

For safety reasons a circuit breaker is provided both on the AC and DC side to enable maintenance. The AC output usually goes through across an electricity meter into the public grid.

The meter must be able to run in both directions.

In some countries, for installations over 30kWp a frequency and a voltage monitor with disconnection of all phases is required.

## Typical Operation

Inverters work by taking the 12 or 24 volt DC voltage from the source, such as solar panels or micro hydroelectric generators and 'chopping' by turning it on and off at grid supply frequency (e.g. 60 Hz) using a local oscillator and a power transistor. This chopped DC signal is then filtered to make it into a sine wave (removing the upper 3,5,7 harmonics that make up the square wave and then applying it to a transformer to up the voltage to 120 or 240 to supply the needs of load.

A grid tie inverter does the same but has two key differences. Firstly the frequency has to be matched in phase to the grid. This means the local oscillator has to be in sync with the grid. Secondly the voltage of the inverter output needs to be variable to allow it to be slightly higher than the grid voltage to enabling current to flow out to the grid. This is done by sensing current flow and raising the voltage on the output (or duty cycle of the transformer input) until the current flow results in the resulting output power matching the input power from the DC supply.

## Effects on Grid Power Quality

In order for grid tie inverters to comply with utility electrical standards, the output power needs to be clean, undistorted and in phase with the AC grid. Typical modern GTI's have a fixed unity power factor, which means its output voltage and current are perfectly lined up, and its phase angle is within 1 degree of the AC power grid. The inverter has an on board computer which will sense the current AC grid waveform, and output a voltage to correspond with the grid.

# Inverter (electrical)

An inverter is an electrical or electro-mechanical device that converts direct current (DC) to alternating current (AC). Inverters are used in a wide range of applications, from small switching power supplies in computers, to large electric utility applications that transport bulk power. The inverter is so named because early mechanical AC to DC converters were made to work in reverse, and thus were "inverted", to convert DC to AC. The inverter performs the opposite function of a rectifier.

## Applications

The following are examples of inverter applications.

### DC power source utilization

Inverter designed to provide 115 VAC from the 12 VDC source provided in an automobile

An inverter converts the DC electricity from sources such as batteries, solar panels, or fuel cells to AC electricity. The electricity can then be used to operate AC equipment such as those that are plugged in to most house hold electrical outlets.

### Uninterruptible power supplies

An uninterruptible power supply is a device which supplies the stored electrical power to the load in case of raw power cut-off or blackout. One type of UPS uses batteries to store power and an inverter to supply AC power from the batteries when main power is not available. When main power is restored, a rectifier is used to supply DC power to recharge the batteries.

### Induction heating

Inverters convert low frequency main AC power to a higher frequency for use in induction heating. To do this, AC power is first rectified to provide DC power. The inverter then changes the DC power to high frequency AC power.

### High-voltage direct current (HVDC) power transmission

With HVDC power transmission, AC power is rectified and high voltage DC power is transmitted to another location. At the receiving location, an inverter in a static inverter plant converts the power back to AC.

### Variable-frequency drives

Main article: variable-frequency drive

A variable-frequency drive controls the operating speed of an AC motor by controlling the frequency and voltage of the power supplied to the motor. An inverter provides the controlled power. In most cases, the variable-frequency drive includes a rectifier so that DC power for the inverter can be provided from main AC power. Since an inverter is the key component, variable-frequency drives are sometimes called inverter drives or just inverters.

### Electric vehicle drives

Adjustable speed motor control inverters are currently used to power the traction motor in some electric locomotives and diesel-electric locomotives as well as some battery electric vehicles and hybrid electric highway vehicles such as the Toyota Prius. Various improvements in inverter technology are being developed specifically for electric vehicle applications. In vehicles with regenerative braking, the inverter also takes power from the motor (now acting as a generator) and stores it in the batteries.

### Basic designs

In one simple inverter circuit, DC power is connected to a transformer through the centre tap of the primary winding. A switch is rapidly switched back and forth to allow current to flow back to the DC source following two alternate paths through one end of the primary winding and then the other. The alternation of the direction of current in the primary winding of the transformer produces alternating current (AC) in the secondary circuit.

The electromechanical version of the switching device includes two stationary contacts and a spring supported moving contact. The spring holds the movable contact against one of the stationary contacts and an electromagnet pulls the movable contact to the opposite stationary contact. The current in the electromagnet is interrupted by the action of the switch so that the switch continually switches rapidly back and forth. This type of electromechanical inverter switch, called a vibrator or buzzer, was once used in vacuum tube automobile radios. A similar mechanism has been used in door bells, buzzers and tattoo guns.

As they have become available, transistors and various other types of semiconductor switches have been incorporated into inverter circuit designs.

Square waveform with fundamental sine wave component, 3rd harmonic and 5th harmonic

### Output waveforms

The switch in the simple inverter described above produces a square voltage waveform as opposed to the sinusoidal waveform that is the usual waveform of an AC power supply. Using Fourier analysis, periodic waveforms are represented as the sum of an infinite series of sine waves. The sine wave that has the same frequency as the original waveform is called the fundamental component. The other sine waves, called harmonics, that are included in the series have frequencies that are integral multiples of the fundamental frequency.

The quality of the inverter output waveform can be expressed by using the Fourier analysis data to calculate the total harmonic distortion (THD). The total harmonic distortion is the square root of the sum of the squares of the harmonic voltages divided by the fundamental voltage:

$\mbox{THD} = {\sqrt{V_2^2 + V_3^2 + V_4^2 + \cdots + V_n^2} \over V_1}$

The quality of output waveform that is needed from an inverter depends on the characteristics of the connected load. Some loads need a nearly perfect sine wave voltage supply in order to work properly. Other loads may work quite well with a square wave voltage.

H-bridge inverter circuit with transistor switches and antiparallel diodes

There are many different power circuit topologies and control strategies used in inverter designs. Different design approaches address various issues that may be more or less important depending on the way that the inverter is intended to be used.

The issue of waveform quality can be addressed in many ways. Capacitors and inductors can be used to filter the waveform. If the design includes a transformer, filtering can be applied to the primary or the secondary side of the transformer or to both sides. Low-pass filters are applied to allow the fundamental component of the waveform to pass to the output while limiting the passage of the harmonic components. If the inverter is designed to provide power at a fixed frequency, a resonant filter can be used. For an adjustable frequency inverter, the filter must be tuned to a frequency that is above the maximum fundamental frequency.

Since most loads contain inductance, feedback rectifiers or antiparallel diodes are often connected across each semiconductor switch to provide a path for the peak inductive load current when the switch is turned off. The antiparallel diodes are somewhat similar to the freewheeling diodes used in AC/DC converter circuits.

Fourier analysis reveals that a waveform, like a square wave, that is antisymmetrical about the 180 degree point contains only odd harmonics, the 3rd, 5th, 7th etc. Waveforms that have steps of certain widths and heights eliminate or “cancel” additional harmonics. For example, by inserting a zero-voltage step between the positive and negative sections of the square-wave, all of the harmonics that are divisible by three can be eliminated. That leaves only the 5th, 7th, 11th, 13th etc. The required width of the steps is one third of the period for each of the positive and negative voltage steps and one sixth of the period for each of the zero-voltage steps.

Changing the square wave as described above is an example of pulse-width modulation (PWM). Modulating, or regulating the width of a square-wave pulse is often used as a method of regulating or adjusting an inverter's output voltage. When voltage control is not required, a fixed pulse width can be selected to reduce or eliminate selected harmonics. Harmonic elimination techniques are generally applied to the lowest harmonics because filtering is more effective at high frequencies than at low frequencies. Multiple pulse-width or carrier based PWM control schemes produce waveforms that are composed of many narrow pulses. The frequency represented by the number of narrow pulses per second is called the switching frequency or carrier frequency. These control schemes are often used in variable-frequency motor control inverters because they allow a wide range of output voltage and frequency adjustment while also improving the quality of the waveform.

Multilevel inverters provide another approach to harmonic cancellation. Multilevel inverters provide an output waveform that exhibits multiple steps at several voltage levels. For example, it is possible to produce a more sinusoidal wave by having split-rail direct current inputs at two voltages, or positive and negative inputs with a central ground. By connecting the inverter output terminals in sequence between the positive rail and ground, the positive rail and the negative rail, the ground rail and the negative rail, then both to the ground rail, a stepped waveform is generated at the inverter output. This is an example of a three level inverter: the two voltages and ground.

### Three phase inverters

3-phase inverter with wye connected load

Three-phase inverters are used for variable-frequency drive applications and for high power applications such as HVDC power transmission. A basic three-phase inverter consists of three single-phase inverter switches each connected to one of the three load terminals. For the most basic control scheme, the operation of the three switches is coordinated so that one switch operates at each 60 degree point of the fundamental output waveform. This creates a line-to-line output waveform that has six steps. The six-step waveform has a zero-voltage step between the positive and negative sections of the square-wave such that the harmonics that are multiples of three are eliminated as described above. When carrier-based PWM techniques are applied to six-step waveforms, the basic overall shape, or envelope, of the waveform is retained so that the 3rd harmonic and its multiples are cancelled.

3-phase inverter switching circuit showing 6-step switching sequence and waveform of voltage between terminals A and C

To construct inverters with higher power ratings, two six-step three-phase inverters can be connected in parallel for a higher current rating or in series for a higher voltage rating. In either case, the output waveforms are phase shifted to obtain a 12-step waveform. If additional inverters are combined, an 18-step inverter is obtained with three inverters etc. Although inverters are usually combined for the purpose of achieving increased voltage or current ratings, the quality of the waveform is improved as well.

## History

Early inverters

From the late nineteenth century through the middle of the twentieth century, DC-to-AC power conversion was accomplished using rotary converters or motor-generator sets (M-G sets). In the early twentieth century, vacuum tubes and gas filled tubes began to be used as switches in inverter circuits. The most widely used type of tube was the thyratron.

The origins of electromechanical inverters explain the source of the term inverter. Early AC-to-DC converters used an induction or synchronous AC motor direct-connected to a generator (dynamo) so that the generator's commutator reversed its connections at exactly the right moments to produce DC. A later development is the synchronous converter, in which the motor and generator windings are combined into one armature, with slip rings at one end and a commutator at the other and only one field frame. The result with either is AC-in, DC-out. With an M-G set, the DC can be considered to be separately generated from the AC; with a synchronous converter, in a certain sense it can be considered to be "mechanically rectifed AC". Given the right auxiliary and control equipment, an M-G set or rotary converter can be "run backwards", converting DC to AC. Hence an inverter is an inverted converter.

### Controlled rectifier inverters

Since early transistors were not available with sufficient voltage and current ratings for most inverter applications, it was the 1957 introduction of the thyristor or silicon-controlled rectifie (SCR) that initiated the transition to solid state inverter circuits.

12-pulse line-commutated inverter circuit

The commutation requirements of SCRs are a key consideration in SCR circuit designs. SCRs do not turn off or commutate automatically when the gate control signal is shut off. They only turn off when the forward current is reduced to zero through some external process. For SCRs connected to an AC power source, commutation occurs naturally every time the polarity of the source voltage reverses. SCRs connected to a DC power source usually require a means of forced commutation that forces the current to zero when commutation is required. The least complicated SCR circuits employ natural commutation rather than forced commutation. With the addition of forced commutation circuits, SCRs have been used in the types of inverter circuits described above.

In applications where inverters transfer power from a DC power source to an AC power source, it is possible to use AC-to-DC controlled rectifier circuits operating in the inversion mode. In the inversion mode, a controlled rectifier circuit operates as a line commutated inverter. This type of operation can be used in HVDC power transmission systems and in regenerative braking operation of motor control systems.

Another type of SCR inverter circuit is the current source input (CSI) inverter. A CSI inverter is the dual of a six-step voltage source inverter. With a current source inverter, the DC power supply is configured as a current source rather than a voltage source. The inverter SCRs are switched in a six-step sequence to direct the current to a three-phase AC load as a stepped current waveform. CSI inverter commutation methods include load commutation and parallel capacitor commutation. With both methods, the input current regulation assists the commutation. With load commutation, the load is a synchronous motor operated at a leading power factor.

As they have become available in higher voltage and current ratings, semiconductors such as transistors that can be turned off by means of control signals have become the preferred switching components for use in inverter circuits.

### Rectifier and inverter pulse numbers

Rectifier circuits are often classified by the number of current pulses that flow to the DC side of the rectifier per cycle of AC input voltage. A single-phase half-wave rectifier is a one-pulse circuit and a single-phase full-wave rectifier is a two-pulse circuit. A three-phase half-wave rectifier is a three-pulse circuit and a three-phase full-wave rectifier is a six-pulse circuit.

With three-phase rectifiers, two or more rectifiers are sometimes connected in series or parallel to obtain higher voltage or current ratings. The rectifier inputs are supplied from special transformers that provide phase shifted outputs. This has the effect of phase multiplication. Six phases are obtained from two transformers, twelve phases from three transformers and so on. The associated rectifier circuits are 12-pulse rectifiers, 18-pulse rectifiers and so on.

When controlled rectifier circuits are operated in the inversion mode, they would be classified by pulse number also. Rectifier circuits that have a higher pulse number have reduced harmonic content in the AC input current and reduced ripple in the DC output voltage. In the inversion mode, circuits that have a higher pulse number have lower harmonic content in the AC output voltage waveform.

 Choosing the right off-grid inverter

 Getting ready to move back to the land and say "Adios" to the local power company? It's an empowering feeling, but it's also a process that takes a ton of planning. As your mind swims in a veritable sea of options for the off-grid solar and wind system you'll be installing for your home, cabin or workshop, you will probably discover that choosing the right power inverter-the magical component that transforms low-voltage DC to high-voltage AC-is the hardest decision you'll have to make. Solar modules are pretty much all the same, and the batteries and charge controller you select will likely be determined as much by your budget as your preferences. But inverters are different; there are several ways to go-from rock-bottom basic to highly sophisticated-and ultimately you may discover that the one you need is not the one you want to pay for.

How do off-grid inverters differ? Primarily in the waveform they produce, and in the range of abilities beyond simple power transformation.

### Sine wave or modified sine wave?

The alternating current (AC) produced by your local power company is a pulsing waveform, undulating between a positive peak and a negative trough. In normal house current, the peaks and troughs top (and bottom) out at 170 volts before gliding obliquely through the zero-voltage point. Mathematically, it works out to an effective 120 volts, pulsing at a standardized frequency of 60 cycles per second (Hertz). Except for a few DC appliances and lights, this is the type of electricity used by every common electrical device on the U.S. market.

A pure sine wave is the natural waveform produced when you spin fixed magnets around stationary coils of wire, and this is exactly how power companies do it. Power inverters, however, are solid-state devices. Nothing spins around anything. Instead, electrical engineers use a clever device called an H-bridge to approximate a pulsing current. An H-bridge uses a series of gates, or switches, to ferry direct current (from the battery bank) first one way, then the opposite way, through a coil of wire. The overall effect is a crude, square-ish waveform that rises and falls in discrete, choppy steps. But by using a series of H-bridges, the current can be made to approximate a waveform that is close enough to a true sine wave for most purposes.

The more steps you add to the process, the pricier the inverter becomes. That's why we're given a choice: you can either have a bargain-basement modified sine-wave inverter, or a much more expensive sine-wave model. What difference does it make? It depends on what sort of things you intend to operate with it. If you're only going to use it for lights, power tools, coffee makers, microwaves etc., then you'll probably do fine with a modified sine-wave inverter, though most loads will draw more power than with a sine-wave model.

The real trouble begins when you try to operate things such as dimmer switches, variable-speed drills, sewing machines, battery chargers, or anything else where the current varies. All of these devices use solid-state switches called Silicon Controlled Rectifiers (SCRs) to control how much current is allowed through the circuit. To do this, an SCR needs a point of reference to continually reset its "clock," and the handiest one to use is the point where the slope of the sine wave passes through the zero-voltage point.

A modified sine wave, however, does not pass through the zero-voltage point at a gentle angle. It instead drops abruptly from 150 to zero volts, and then lingers at zero for a moment before dropping abruptly again to the negative side of the waveform. With no distinct zero-voltage point, the SCR cannot effectively reset its clock. The SCR becomes confused and the tool or appliance will either not work at all, or will behave erratically.

In addition, you may discover that fluorescent lights and stereo equipment produce an annoying buzz with a modified sine-wave inverter, and certain computers and peripherals that utilize SCRs may not work properly (though, admittedly, every computer and printer I ever tried with a modified sine-wave inverter worked fine). Nor will electric clocks keep proper time, but that's really a blessing in disguise, since plug-in clocks are so wasteful you'll be doing yourself a favor by switching to battery-powered clocks.

### Battery charging, and other goodies

Once you determine which waveform is adequate or preferable, you'll need to decide what else you want the inverter to do. The main dividing line here runs between inverters that can charge the batteries with a gas-powered generator, and those that can't. I should point out here that, generally (though not always), inverters capable of charging batteries are made for home use, while the less expensive, non-charging inverters are designed more for boats, trucks and recreational vehicles. The former have hard-wired AC outputs, while the latter simply have female sockets. Examples of these types of inverters are those made by Aims and Invertech, though there are many others. The point is, if your system requires an electrical inspection, I'd advise you to have a friendly chat with the electrical inspector before you buy, just to make sure the inverter you have your eye on is up to snuff.

The multi-stage battery chargers built into most high-end inverters are powerful and sophisticated, and can add a lot to the price (and, yes, the weight) of the unit. When charging, the inverter will first use the generator's input to run whatever loads may be drawing power at the time, then use the remaining wattage to charge the batteries. For this reason, after a run of cloudy weather it's common for those of us living off-grid to charge our batteries with a generator, while running a clothes washer or dishwasher, or some other large load.

Will you need battery charging? There's really nothing chiseled in stone here, but usually folks who use inverters to power fulltime residences will want the battery-charging option, while those with solar and wind systems in weekend cabins or small workshops that only see occasional use can generally get by fine without it. The theory is that you probably won't waste enough energy in a day or two to deplete a battery bank that has a week or better to recharge from the normal solar and wind sources.

Other features that often come standard with battery-charging models, such as Xantrex's DR Series, include a search function that will allow the inverter to rest in a low-energy state unless a load is running. Most sine-wave models, such as the Xantrex SW Series and most OutBack inverters, include multiple AC inputs for grid and generator power, and computer interface options which will allow you to program and monitor the inverter from your computer.

### ELECTRIC POWER AROUND THE WORLD

The table below summarizes information on the electrical systems in use in most countries of the world.
The voltages listed here are the “nominal” figures reported to be in use at most residential or commercial sites in the country or area named. Most electrical power systems are prone to slight variations in voltage due to demand or other factors. Many former 220 V countries have converted or are in the process of converting to the EU standard of 230 V. Generally, this difference is inconsequential, as most appliances are built to tolerate current a certain percentage above or below the rated voltage. However, severe variations in current can damage electrical equipment.
The electric power frequency is shown in the number of hertz (cycles per second). Even if voltages are similar, a 60-hertz clock or tape recorder may not function properly on 50 hertz current. All systems described here use alternating current (AC). The plug types listed indicate all types known to be in use in that country. Not all areas of a country may use all types of plugs listed for that country, since there may be regional differences based on the power system in a certain area.

What is islanding?

The first safety issue that comes to everyone's mind for small customer-sited systems is a condition called islanding. Islanding is where a portion of the utility system that contains both loads and a generation source is isolated from the remainder of the utility system but remains energised. When this happens with a distributed power system, it is referred to as supported islanding. The safety concern is that if the utility power goes down (perhaps in the event of a major storm), a distributed generation system could continue to unintentionally supply power to a local area.

While a utility can be sure that all of its own generation sources are either shut down or isolated from the area that needs work, an island created by a residential system can be out of their control. There are a number of potentially undesirable results of islanding. The principal concern is that a utility line worker will come into contact with a line that is unexpectedly energised. Although line workers are trained to test all lines before working on them, and to either treat lines as live or ground them on both sides of the section on which they are working, this does not remove all safety concerns because there is a risk when these practices are not universally followed.

Fortunately, static inverter technology developed for grid-interactive systems is now specifically designed so that there is practically no chance of an undesired supported island stemming from an interconnected residential or small commercial systems. This feature is referred to as anti-islanding. Grid-tied inverters monitor the utility line and cease to deliver power to the grid as quickly as necessary in the event that abnormalities occur on the utility system. Such performance requirement is generally described in both the inverter and the interconnection standards.

What is manual disconnect?

An external manual lockable disconnect switch ("manual disconnect") in the interconnection context is a switch external to a building that can disconnect the generation source from the utility line. The requirement for a manual disconnect, stems from utility safe working practices that require disconnecting all sources of power before proceeding with certain types of line repair.

Whether a manual disconnect for small systems, such as photovoltaic (PV) systems, using certified inverters should be required has been the source of considerable debate. In strict safety terms, a manual disconnect is not necessary for most modern systems because of the inverter¡¯s built-in automatic disconnect features as discussed in the previous section. Both the Canadian Electrical Code (CE Code) and the National Electrical Code (NEC) in the United States, refers to the need for an additional switch that is (1) external to the building, (2) lockable by utility personnel, and (3) offers a visible-break isolation from the grid.

As such, a manual disconnect is an additional means of preventing an islanding situation. And, the key from the utility perspective is that the switch is accessible to utility personnel in the event of a power disruption when utility line workers are working on proximate distribution system lines. In addition, in many situations, utility line workers can provide redundant protection against islanding by removing a customer's meter from the meter socket. Still, many utilities require a separate, external manual disconnect.

While the cost of installing such a switch is not large relative to the overall cost of a micropower system, a PV system for example, when compared to expected energy savings from the system, such a switch is relatively expensive. Also, for systems located on the top of tall buildings, such a switch becomes very
expensive.

In the USA, some state-level net metering and interconnection rules require that the utility pay for the installation of a manual disconnect. In New Mexico, use of the meter is an optional alternative to a separate switch while in many other states a manual disconnect is not required, at least for small systems; that is the case of California, New Jersey, Washington, and Nevada. Also, some utilities, such as those owned by the New England Electric System, have established their own interconnection guidelines that do not require an external manual disconnect for small systems.

What is a wind farm?

Wind farms are clusters of turbines that generate electricity. Wind is a free and renewable resource that produces clean energy - no emissions, no waste products. Wind farms are located in areas with reliably favorable wind speeds.

#### What causes wind?

The wind that turns the turbine blades is a form of solar energy. The sun warms the earth's atmosphere unevenly, causing the air to move and swirl, creating wind.

For centuries, wind movement has been converted into mechanical power for low-tech jobs like watering cattle. Now, we can use it to efficiently turn high-tech turbines for electrical generation.

#### Why use wind power?

For centuries, wind has been harnessed to power ships, grind grain, run sawmills and pump water.

Today, high-tech wind turbines are becoming an increasingly familiar part of the landscape around the world, cropping up in cornfields, on wind-swept deserts and along breezy mountain passes.

As the need for clean, safe, reliable energy grows, wind is taking on a new role. Wind power is a free, non-polluting, renewable resource. No matter how much is used, there will still be a plentiful supply in the future. That's why wind is the world's fastest growing energy source!

#### What are the benefits of wind power?

Thanks to two decades of innovative technical developments, modern wind turbines are highly reliable and cost effective. They run quietly with little or no direct impact on the environment.

In many parts of our country, wind-powered electric generating projects are becoming a preferred way to develop safe, new sources of energy for a variety of reasons:

• Most people understand that using wind power can help preserve our environment - and they want to be a part of the solution.
• The communities in which wind projects are located receive substantial economic and community development benefits.
• Individual landowners receive economic benefits from wind projects located on their property.

Wind projects create little or no interference with existing farming or ranching operations - livestock graze among the turbines as though they weren't there.

How much does a wind system cost?

Small wind turbines can range in size from 90 - 10,000 watts (10 KW), and range in price from $800 -$37,000. With these turbines you need towers, which vary in size and price as much as the turbines. Some turbines can connect directly to the utility (Grid-tie) and some are designed to charge batteries. If you go with a battery system you will need batteries and an inverter to convert the DC power from the batteries to AC power for use in your home.

Basically, asking how much a wind system costs is like asking how much a car costs - it depends on many factors and can vary widely.

What is the payback period for a system?

The only way to put this question into perspective is to ask another question:

What's the payback period on your car?

Your car will dramatically reduce in value the minute you drive out of the dealership, will not last as long as one of these power systems, and will often cost more. I guarantee that all of our systems are better value than your car.

How much is our environment worth?

Every one of our systems will reduce your impact on the environment. Since we cannot live without the environment, it is absolutely priceless. This means that all of our systems are priceless and beyond value or payback periods.

*However...typically a small complete system depending on the size and cost of the system,  will take about 3-8 years to pay for itself. Larger systems will take longer...approximately 6 - 15 years.

Solar Power:

Thousands of homeowners are using solar power to heat their homes and their water, as well as provide natural lighting.

Solar Electric System Basics

A stand-alone solar electric system consists of 4 basic parts. Photovoltaic (solar electric) panels, charge controller, batteries and inverter. The photovoltaic panels make DC electricity, which is fed to the charge controller. The controller feeds the current to the batteries at a regulated rate. The batteries store electricity for when it is needed and then sends it to an inverter, which converts DC to AC current. This output can be wired into your standard circuit breaker box. In addition to the basic components, there are various switches and fuses to make the system safe and to protect the electronic components from the high currents possible from batteries. The National Electric Code puts requirements on wiring these systems.

Photovoltaics

Photo is Greek for Light and Voltaic is after Allesandro Volta pioneer in the study of electricity. Thus photovoltaic means *light to electricity*. The photovoltaics (PV) convert sunlight directly to direct current (DC) electricity by use of a semiconductor. The most common type is made from the chemical element silicon. Silicon is one of the most common substances on Earth. For example, sand and glass are made of silicon dioxide. Our entire electronic age is built upon silicon. Almost all integrated circuits (chips) are made of silicon. What is a semiconductor? The essential miracle of a semiconductor p-n junction is that an electric field is maintained purely by virtue of the material. In other words, no external voltage need be applied. For a solar cell, this means that when light hits the cell, electrons are bumped from atoms and drawn to one side of the junction by the internal electric field. Current flows. You get electricity.

Silicon PV comes in several varieties. Shell PV panels are made with single-crystal silicon. The cells are cut from a single crystal of silicon. Single crystals give the highest efficiency of conversion of light to electricity, 15 to 17%. Solarex panels are made of polycrystalline silicon. These are close in efficiency but polycrystalline cells are easier to make because small crystals take less time to grow than big ones. Astropower PV panels are made of microcrystalline silicon, which again is easier to make. A very different type of cell is made of amorphous silicon, that is completely non-crystalline. Efficiencies of these cells is about 6%, much lower than crystalline. However, amorphous silicon is a thin film material which can be made in ultra thin ( micrometers) on thin backing. It can be made into flexible products such as the Unisolar PV shingles and PV Laminates.

There is one other type of PV which is common in the aerospace industry, gallium arsenide. These cells can be 30% efficient (some even higher) and are resistant to radiation damage (in the environment of low orbit). They are still very expensive and used only on spacecraft.

Because the solar cell is a solid state device, it can last for decades. The only part of a panel which can degrade is the material which encapsulates the relatively fragile cells. Some of these encapsulants will brown if subjected to multiplied sunlight (such as by a focusing mirror), or after many decades of regular exposure. The panels are not fragile. They are subjected to hail tests (1 inch hail at 50 miles per hour) at the factory. All indications are that solar panels installed today, will still be working perfectly in 30 years. Most panels have a 25 year warranty from the manufacturer.

Charge controller

The charge controller is a solid state electronic device which measures the charge state of the batteries and turns the current from the PV on if the batteries need charging or off if they don’t. This protects the batteries from over-charging which can shorten their life.

Batteries

Stand-alone solar electric systems use lead acid batteries to store power for cloudy weather or for nighttime. Lead acid batteries can be made to withstand deep-cycling, that is discharging them to near-empty. They do not have any *memory* like NiCds do. They can even be re-invigorated if they are abused, for example, sulfation can be reversed, more water can be added, etc. If charged properly, good lead acid batteries will last for years. The larger deep cycle batteries last 10 to 15 years.

Inverters

An inverter is another electronic device which takes the direct current from the batteries and changes it to alternating current (AC). Most households run on AC because AC wiring is cheaper and somewhat safer than DC wiring. Inverters are made to convert from 12,24, 48, 225, or 400 volts DC to 120 or 240 AC. The AC output of inverters is either a modified sine wave or true sine wave. Get a true-sine-wave inverter for whole-house systems and net metering systems.

Wiring

Since solar electric systems are basically DC, they have wiring requirements different form AC systems.

To highlight some of these:

• Large wires between the panels and controller are required to avoid voltage loss if the panels are far from the controller. For example, a 24 volt system of panels 150 feet from the controller will require wire 0.6 inches in diameter, costing $1.1/foot. • A large switch with fuses is required between the inverter and batteries to protect the inverter. Batteries are capable of putting out thousands of amps. How to Choose a Solar Power System Check with your utility company before installing. There is a range of federal and local incentives. Your utility company will know the ins and outs. Most solar panels are guaranteed for 25 years with inverters warranted for 10. They are extremely reliable with no moving parts, so for 15 years, you can expect to have no electric bill. Your power company is required to buy back any excess electricity that you generate at full retail rate. To do that your system has to convert the generated DC to alternating current, AC, the sort of power we use in our homes. The box that does this is called an inverter, which is essential to hook you up to the power grid. On a bright sunny day when your family is away, your meter will actually run backwards as you get paid for the power that your system is generating. Hire a reputable contractor. Your utility can provide a list. Bring in your electric bills over the past year and discuss any changes in your consumption that you foresee. Get an estimate and begin rebate and incentive paperwork. When choosing your equipment, make sure that it qualifies for incentives. On the federal level, you can get tax credits for solar hot water – unless it is used to heat a swimming pool. You want a system that is big enough to cover your projected electric needs for the life of the system. Some homes simply won’t get enough light or have enough roof area to do that. In those cases, you should consider much more efficient panels to use. Get an estimate and arrange financing. Most systems can be installed in a single day. If you finance your system with a home equity loan, the interest is tax deductible. Sizing A PV Array: 1. Determine what your KWh electric consumption is. Then match PV production to your electric consumption. For example, if you consume 600 kilowatt-hours per month (KWh/month) and want to produce 100% of your electricity with a PV system with no battery backup. Do this equation to calculate; 600 KWh/month x 12 months equals 7,200 KWh/year or approximately 20 KWh/day. Most of the U.S. has 3.5 to 5 Sun Hours of solar input. This means that a 1 kilowatt AC PV system in a 4.5 Sun Hour region will produce 4.5 kilowatt-hours per day. 20 kWh/day divided by 4.5 sun hours equals 4.4 KW AC. Go to "PVWATTS" at: http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/ and enter your location, 4.4 KW, your roof tilt and orientation. See your monthly and annual estimated PV production for a 4.4 KW system or any other size system. 2. Match your PV array size to your roof space. You need full sun on your solar array all day (from at least 9am to 4pm). Trees, chimneys, vents and other buildings can block the sun or make array installation difficult. Square footage examples; 225 sq. ft. array (Qty of 32 - 70 Watt modules) / 140 sq. ft. array (Qty of 20 - 75 Watt modules). 3. Match your PV system cost to your budget. PV modules are about half of the total system cost. The other equipment you may need depending on your system configuration are mounting hardware, combiner boxes, disconnect switches, power center, charge controller, inverter, battery bank and wiring. *Find out what State / Provincial or Federal Government incentives are available in your area. Different mounts available Mounts for your solar photovoltaic system can come in all shapes and sizes; some are stand-alone, others are designed for special situations, such as pole mounts designed to track the sun in the sky for optimal output. We will cover the most common types of solar panel mounts, and you will discover what mount or solar panel rack is best for your photovoltaic system. Considerations that will be addressed include size, affordablility, utility, and convienience. ## Types of Solar Panel Mounts Solar Panel Mounts are available in three primary categories: flush mounts, roof/ground (or universal) mounts, and pole mounts. Each type of solar panel mount has its own merits and disadvantages, and if you are installing a solar panel mount you should weight in these factors when making your final descision. ### Flush Mounts Flush mounts are the cheapest and most simple solar panel mounting solution available, and are achieved by placing a metal end bracket on each side of the solar panel, elevating it several inches from the surface. Flush Mounts are typically used with small solar arrays on rooftops and RVs, because the structural design of a flush mount cannot support large solar panels. When installing a flush mount with your solar panel, be sure that you have ample clearance between the surface of the roof and the underside of your solar panel. This distance should be at a minimum of 2-4 inches, so that air can flow under the unit and keep it cool. This is vitally important for your flush mount system: if you do not allow clearance, your solar unit will rapidly overheat and the functional lifespan will be significantly reduced.  Although flush mounts are simple and cheap to install, they offer no flexibility in the orientation of your solar panel, and they can only support small photovoltaic units. To the left is a typical flush mount. ### Roof-Ground (Universal) Mounts Roof-Ground solar panel mounts are typically used with larger solar panel systems, or in areas away from the city electric grid. Roof-Ground mounts are called by that name because they can be installed both on the ground and on rooftops. Roof-Ground mounts are typically constructed by a grid-like system of supports, and are typically bulky and unsightly, and many cities and neighborhoods have shamefully passed ordinances against them for asthetic reasons. You would be wise to consult with your residential director before installing a roof-ground solar panel mount. There are many ways to install custom roof-ground mounts or increase the heights of your system by adding poles or concrete blocks to elevate your system above plants and vermin on the ground. Many Roof-ground mounts are adjustable, and if you change the tilt of your solar panel at the prescribed 1/4 year interval, your system will produce a little more power than a standard unit. Roof-ground systems are more expensive than flush mounts, and they may be difficult to install on rooftops due to heavy wind resistance or city ordinances, but they may be your only solution if you have a paticularly large solar panel system. ### Pole Mounts  Pole mounts are divided into 3 subcategories: top of pole mounts, side of pole mounts, and poll tracking mounts. These poll mounts are differentiated by how they are positioned on the pole. Pictured is a typical top-of-pole mount. Top of Pole Mounts are comprised of a metal rack and rail unit that is bolted to a large sleeve that rests on top of the pole. In order to install a top of pole mount, you will need to use an existing pole at least 3-8 inches wide with a concrete base, or construct one yourself. The mount simply slips over the top of the pole, and you can bolt (or weld) your solar panel unit into place. Large Top of pole mounts can encounter a substantial measure of wind resistance and can be very heavy, so you may need a small crane or several able-bodied men at hand in order to install a large top-of-pole system. Side of Pole Mounts are typically fastened and bolted to the side of telephone or utility poles. Side of pole solar panel mounts typically involve small solar panels, for larger units, it is reccomended that you use a top of pole solar panel mount. Tracking pole mounts are top of pole mounts with a special function - tracking pole mounts track the motion of the sun in the sky throughout the course of the day. This maximizes the operating efficiency of the solar panel unit. Daylighting "Daylighting" is one of the easiest and most cost-effective ways to use solar energy at home. This technique involves building a house to take advantage of the sun's rays. The architect and builder work together to "site" the house on the lot to bring in natural sunlight throughout the day. Windows are strategically positioned to provide adequate light without overheating the area, and the interior design is planned to diffuse the light throughout the room. #### Solar Water Heating Another "passive" method of using solar energy at home is a thermal solar water heater. These systems use the familiar flat glass or plastic panels seen on roofs and in backyards. Sunlight passes through the panels and is collected by a dark absorber plate. The plate warms liquid passing through pipes - either the household water supply or an antifreeze solution that is used in a heat exchanger in the water storage tank. Solar water heaters are popular in areas that do not have natural gas service - replacing an electric water heater with a solar model can reduce water heating costs by 50 to 80 percent every year. And over the 20-year lifespan of the equipment, more than 50 tons of carbon dioxide emissions will be displaced. If you're interested in a solar water heating system, be sure to check your local building codes - many communities require a conventional water heater as a back up. Solar Glossary Of Basic Terms: AC (Alternating Current): An electrical current whose direction alternates. AC is the form in which electricity is used in our households and businesses. It can be thought of as “standard” electrical power. DC (Direct Current): An electrical current whose direction stays constant. The photovoltaic cells on solar panels capture energy from sunlight in the form of DC. Batteries also hold and put out DC. In order to power your home, this current must be converted to AC by an inverter. Electrical Current: The flow of charged electrons through a circuit. Depending upon its behavior, an electrical current can be alternating or direct (AC or DC). Electric Panel: An electrical distribution board that houses electrical circuit breakers. It is the main point at which electricity is distributed throughout a building. It is otherwise known as a breaker box. The circuit breakers can be turned on or off, thus permitting or restricting the flow of electrical current to electrical outlets. ETL Listed: The assembly is built in an ETL-approved panel shop, where it is built and tested to North American standards, and the "ETL Listed" sticker on the panel means it is legal to be connected, without the sticker it is not legal. ETL shops are government inspected, certified and reviewed every year. Fossil Fuel: Fuels that are derived from natural resources, usually in the form of coal, oil, or natural gas. There is a limited supply of these resources, and they are only located in certain parts of the world, causing them to be subject to political and international maneuvering, and making energy prices unstable. Greenhouse Gases: Gases that allegedly contribute to warming the planet. The most common of these gases is carbon dioxide, which is released in large quantities such as when Alberta burns coal for most of its electrial generation. Since sunlight is directly converted into electricity or heat it has no emissions and is considered “Green .” Grid Tied System: Solar or wind electric system connected to feed back and forth with the electric utility grid. Ground Mounted Systems: Solar system that is supported by pilings or a structure that is built specifically to support it. They are ideal for buildings with shady or undersized roofs. Inverter: A device that converts DC power captured by the photovoltaic cells on solar panels or in your batteries into AC power that any home appliance or light can use. KW (kilowatt): A measurement of power based on the Watt, the standard unit used to measure power. A kilowatt is one thousand watts. A typical household requires a solar power system that produces between 4-5 KW. KWh (kilowatt hours): A measurement of energy consumption. One kilowatt hour equals one “unit” of electricity. One kilowatt hour is defined as the amount of energy consumed by a 1000-Watt appliance running continuously for 1 hour. This is the measurement your utility company uses to calculate your electric bill. Net Metering: An agreement between a solar system owner and the local electric utility that allows the system owner to buy and sell energy. When the solar system produces excess energy, it is sold back to the electric utility at the same rate your contract says. When the system is not producing energy, the system owner can use the inputs to the grid to buy back electricity. Off-grid System: see Stand-Alone System. Photovoltaic Cells: More comonly called Solar cells, the small elements of semiconducting material that capture sunlight and convert it into power. A group of photovoltaic cells make up a solar panel or a photovoltaic module. Pool Price: The price of wholesale power paid and sold by the utilities, then distibuted to us, the pool price varies widely and quickly. The price climbs as demand goes up, as during the "electricity rush hour". Roof Mounted Systems: A solar system in which solar panels are mounted directly on the roof of a building or adjacent structure. Solar Array: A group of solar panels collectively makes up a solar array. A solar array is the entire system of solar panels that capture sunlight and convert it into power Solar Energy: Energy emitted from the sun. Solar Panels: A grouping of solar cells arranged into a panel that can be installed onto a flat surface. The panel captures sunlight and converts it into usable power. Smart Meter: A meter that varies the price you pay for electricity based on the "Pool price" of power at that moment. Stand-Alone System: A solar energy system that is not connected to the utility grid. Also called an Off-Grid system. In order to provide continuous power, these systems must be connected to storage units (batteries) that can store excess power produced during daylight hours for use when it's dark. TES: The acronym for Thermal Energy Storage, it serves as a place to put heat energy until it is able to be best utilized. Although it can take some exotic forms consisting of anything from caustic salts to stone beds, as a medium, most often and as we use it, it is simply a large quantity of water in a highly Insulated tank. Water has some excellent traits, it holds a lot of heat, is totally safe and it is easily transported to where the heat is required. Tilt Angle: The angle at which a solar array is tilted towards the sun. Depending on the geographic location of a building, a solar array might be installed flat or tilted. Utility Grid: The infrastructure that delivers electric power to homes and businesses. Utility Meter: A device that measures the flow of electricity or gas between a site that uses electricity/gas and the utility company. Vampire: The actual electrical name given to the transformer cubes used on many computer devices, cordless phone bases and many other devices. They have 2 fangs and suck electricity 24-7, hence the name. Photovoltaics: An emerging type of residential solar power is called photovoltaics. This technology uses semiconductor material to convert sunlight directly into electricity - if you have a solar calculator or watch, you're already using photovoltaics. More than 10,000 homes in the United States are entirely powered by solar energy. The advantages of a photovoltaic (PV) system are numerous: it's non-polluting, there are no moving parts, it operates silently and requires little maintenance. Photovoltaic power can also be stored in deep-cycle batteries for evening or back-up use. Photovoltaics can be used to produce large amounts of electricity. PV power plants, located primarily in California, use massive lenses and reflectors to concentrate the sun's energy on a fluid-filled pipe. The heated fluid is used to drive a conventional electric generator. As with wind turbines, solar energy is used to supplement existing fossil fuel power plants. Lighting: Incandescent versus LED lighting: Cost Comparison Take the example of a$0.99 standard 100 Watt incandescent light bulb that is operational 24 hours per day, 7 days per week. This fixture will use 870 kW/h over a year, at $0.7 per kW hour, it will cost you a little over$61.00 for the year, with a gross cost including purchase of $62.00 Compare this to a 13 Watt LED bulb, which costs$45 to purchase. This fixture replaces the old 100 Watt fixture, and provides the same light intensity. It will consume 112 kW/h per year and cost you $7.84 in electricity costs for the year, with a gross cost of$52.84 for the year.

So, which is the most expensive bulb at the end of the year? The LED bulb is a clear winner. Factor in that the LED bulb will outlast a conventional bulb by upwards of 10x, it continues to pay for itself long after the "cheap" bulb has burned out a few times. If you really want to see a huge impact, try the LED lights...they last up to 10x longer and have no mercury in them...therefore no disposal issues...unlike CFL bulbs.

DANGER! The (Compact Fluorescent Bulb) and (mercury) at home

IMPORTANT INFORMATION ABOUT ENERGY SAVER LIGHT BULBS!

Benefits Of LED Lighting:

Rising electricity cost, power shortage due to rise in demand, climatic changes due to pollution has compelled every human being to give a serious thought for pollution free, energy saving products.

LEDs have been in day to day life in the form of small decorative lights, spot lights, indicators & signaling systems and now LEDs are used for everyday functional lighting.

LEDs have the basic characteristics of a long lifespan, highly energy efficient, clean and eco-friendly (non emission of gases and harmful rays).

Our range of products for various applications are not only meant for saving energy but also keep the environment pollution free.

 Description LED CFL Incandescent Life in hours 50,000 10,000 1,500 Lumens/watt 162.5 54.17 11 Eco-Friendly yes No No UV Rays No Yes Yes Infrared Rays No Yes Yes Attract Bugs No Yes Yes Generates Thermal Heat No Yes Yes

Efficiency Tips

Lights used more often have the opportunity to save the most energy. Put the most efficient lights in main rooms, desk lights, the kitchen and the dining room. Don't forget about the outdoor lights - even better, install motion sensors or timers on outdoor lighting. Task specific lighting is a more efficient way of using lights. By illuminating a specific area rather than the whole room a much smaller light may be used.

Retrofitting existing fixtures:

Many kinds of LED bulbs are available with the E27 type base for easy replacement of your current Household CFL or incandescent lights. This means there is no need to change the light socket and it's just a simple straight replacement of your existing bulbs!

Off-Grid Applications

The ability to have bright, reliable light at any time is often the largest benefit of an alternative energy system. There is no longer any reason to have to tolerate candles or smelly, dangerous and expensive kerosene fixtures. Propane lighting may seem like a good option, but after a few days of their loud noises and glaring light, silent battery powered lights seem like a dream come true! In many renewable energy systems lighting is the first or second largest entry in the energy budget. LED lights can reduce the energy consumed even further saving you more money than CFL bulbs and lasting you a whole lot longer. They might be a bit more of an investment upfront, but are well worth it in the end.