Wednesday, July 27, 2011

Benefits of Solar Photovoltaic Panels

Solar photovoltaic are made of silicon. That is a great benefit to us since silicon is relatively a common element in nature. 15% of the Earth’s mass which is approximately 5.98×1021 metric tons is made out of silicon. There is no need to worry about running out of this naturally common element on Earth.

Silicon Cost for Solar Photovoltaic Panels:

The use of silicon in photovoltaic started in 1954, however; it was not worth it to be produced commercially at that time. The cost of the electricity they produced was relatively very high compared to coal; silicon cost was $250 per 1 Watt compared to $3 per watt for coal. Improvements were slow over the years. Benefit from solar photovoltaic panels was not put to use during that period except for satellite uses.

However, with the technological advancements these days and increased silicon demand for the electronic industry, the price of silicon dropped down considerably and an installed cost of a solar photovoltaic panel could be lower than $4 per watt.

With cost price of solar photovoltaic panels dropping down, solar panel cells became affordable and that benefited most people who were unable to afford it in the past. The price of solar panels is expected to drop down further in the next 2-5 years as the world is turning to alternative renewable solar energy sources and green sustainable energy.

Lifetime Expectancy of solar Photovoltaic Panel:

The solar photovoltaic panels are durable and built to last. It is beneficial to us since the expected lifetime of a solar photovoltaic panel is 20 + years. Usually a performance warranty of 20 + years is provided by most manufacturers and a warranty of 10 + years for 80% power output performance. The solar photovoltaic panel has no moving parts or mechanical parts; therefore, maintenance is not required except for surface cleaning once in a long while.

Solar Photovoltaic Power Generation and Energy Saving:

Solar photovoltaic panels are designed to generate electricity during the day time. If you were to install a solar photovoltaic system, on sunny days you should be able to use the solar energy from sunlight during the day and have sufficient energy stored in your battery for night time. But that depends on the type of system installed.

On average, energy saved due to using solar photovoltaic panels in North America or Europe could save somewhere between 25 – 150% per household per day. The access power is fed to the utility grid-lines in North America and some European countries. This is a great encouragement for the use of alternative solar energy.

Furthermore, many countries don’t require planning permission if an owner decides to install solar photovoltaic panels to power his electrical equipments. There are a few exceptions, however; nowadays many countries are encouraging household owners to make the switch and benefit from the easy long term payment plans governments offer.

Solar photovoltaic panel power and other alternative green energy sources are offered with extremely low interest rates just to push the green energy issue forward.

Solar Photovoltaic and Carbon Footprint:

Solar photovoltaic panels are considered part of the green energy resources that is naturally available and replenishable. On average, a single household owner can reduce his carbon footprint by approximately 1.4 metric tons per year if a solar photovoltaic panel system is installed on his property.

Considering the reduced amount of carbon footprint, this makes the solar photovoltaic system an environmentally friendly solution that does not destroy our environment and protects our Eco system.

Solar Photovoltaic Panel Payback Period:

Free energy from the sun provides us with unlimited amount of solar energy that is renewable. On average, the payback period for solar photovoltaic system is usually 7-10 years. Then it is profit to its owner. The output power produced is identical and even better than power utility from the grid.

Better output power from solar photovoltaic panels is due to the use of pure sine wave inverters and shorter transmission lines. This protects connected electrical equipments from voltage fluctuation, disturbances, and power surges and enhances the lifetime of our appliances.

On-Grid, Off-Grid Solar Photovoltaic Panels:

The solar photovoltaic panel system can be installed independent of the utility grid or can be integrated to feed the grid. When affordable, many household owners prefer to be independent from the utility grid and only use the utility power in case of shortages or during emergencies.

In either case electrical appliances are protected due to a better power output. In either case the power has to pass through the pure sine wave inverter provided that the grid connection is set that way.

The benefit for those who are living off the utility grid is that they will always have electric power in case of blackout or brownouts compared to their counter parts. In case of a blackout or brownout the user will never notice the difference. The switching time can only be measured by delicate devices.

A good online pure sine wave inverter drawing power from solar photovoltaic panels should have a switching time less than 4 microseconds. This would insure that PC computers are not affected by power fluctuating.

Portable Solar Photovoltaic Panels:

The solar photovoltaic power system is portable for those who are living in portable cabins or renting properties. The solar photovoltaic system is usually installed on the roof top of a portable cabin. The owner can take his cabin anywhere he goes and power would always be available.

Those who are renting can dismantle the solar photovoltaic system to the newly rented dwelling if circumstances necessitate such a move. Portable solar photovoltaic system owners have a peace of mind from the benefits the solar photovoltaic system provides. They never have to worry about electric power shortage.

Related links coming soon:

Solar Photovoltaic Panels:
  1. Solar Photovoltaic Panel Construction
  2. Benefits of Solar Photovoltaic Panels
  3. Applications of Solar Photovoltaic Panels
  4. Profits from Solar Photovoltaic Panels

Solar Photovoltaic Panel Construction

Solar Photovoltaic panels are made out of sand that is converted to silicon. Sand converted to silicon is cut into layers known as solar cell wafers. Chemical impurity elements such as boron and phosphor ions are added to these silicon wafers. These impurity elements enhance the electrical production properties of the silicon wafer when exposed to sunlight or rays.

Each added element has a property of being positively or negatively charged, the wafers are known as p-type silicon and n-type silicon respectively. One negatively charged wafer layer is placed on top of a positively charged wafer layer. The area between the two is known as the wafer junction as seen in the diagram below.

Silicon - Solar Photovoltaic Solar Panel Diagram

Silicon Wafer - Solar Photovoltaic Component Diagram

How do Solar Panels Generate Electric Power:

Solar panels generate electric power (current & voltage) when they are exposed to sunlight rays. When light rays strike the top silicon wafer, electric current is produced between the two silicon wafers and a negatively charged voltage is created on top of the layer. Usually, small mesh copper contacts are placed on top of the upper silicon layer as seen in the diagram above.

The copper mesh allows sunlight to penetrate to the silicon layer below it. The copper mesh draws the negative electric charge produced from the upper silicon layer and a negative voltage is created.

The bottom silicon layer is joined to a solid copper sheet at the bottom. Since a negative electric charge is created on the upper wafer layer, the bottom wafer layer becomes positively charged. The positively charged layer is connected at the bottom to the metal copper sheet.

The copper sheet is connected to the other lead of the electric circuit. The current produced between the top and bottom layers flows in the electric wires to power electric devices that uses direct current similar to battery powered electrical devices or stored in batteries. Later inverters are used to convert power stored in batteries to utility electric power for various uses.

Temperature Effect on Solar Photovoltaic Panels:

One thing to note about solar photovoltaic panels is that they are sensitive to varying temperatures. Temperature effect solar panel output power. And increase in temperature above 25 degrees Celsius would require compensation during site design. This would insure that the output power is able to charge the batteries or feed the designated load. Usually, solar system design engineers have many criteria to consider during initial site evaluation besides temperature.

Temperature has an effect on the output power of a solar photovoltaic panel. The panel is naturally dark. When exposed to sunlight rays, its temperature will increase. At temperatures below 25 degrees, there is little effect on output power; actually it is to the benefit of the output power. A positive gain of about 5% would be expected at zero degrees Celsius.

However, at temperatures higher than 25 degrees C, the power output would drop down. This effect can be as much as 20-30% if not higher (dependent on location and other factors). Usually the manufacturer’s data sheets should display a graph as to how temperature change influences the output power of the solar photovoltaic panel system.

Related links coming soon:

Solar Photovoltaic Panels:
  1. Solar Photovoltaic Panel Construction
  2. Benefits of Solar Photovoltaic Panels
  3. Applications of Solar Photovoltaic Panels
  4. Profits from Solar Photovoltaic Panels

Monday, July 25, 2011

Solar Photovoltaic Panels

Solar photovoltaic panels are also known as solar PVs; they produce electric power from solar radiation and rays from sunlight. Solar panels convert light energy to electric power by the photovoltaic effect. 

Photovoltaic solar panels capture energy from sunlight and energy captured by these solar panels is commonly known as solar power, sunlight energy harvesting is an example of solar energy that is renewable.

Each solar Photovoltaic panel consists of an array of single photovoltaic cells called solar cells, they are grouped together to make one solar panel. Each photovoltaic solar cell produces a constant voltage or direct current (similar to battery voltage).

The energy output of each solar cell is too small on its own, so solar cells are grouped together in a panel in order to produce large power outputs that we can benefit from and use.

Related links coming soon:

Solar Photovoltaic Panels:
  1. Solar Photovoltaic Panel Construction
  2. Benefits of Solar Photovoltaic Panels
  3. Applications of Solar Photovoltaic Panels
  4. Profits from Solar Photovoltaic Panels

Solar Panels

There is a misunderstanding when it comes to solar panels. There are many people who think solar panels can only produce electric power. There are others who think solar panels are only used to heat water.

Few people really know what is the real difference between the two types of solar panels, how they are constructed, what benefits they provide, and how to put and use this technology that uses a free source of energy from the sun to monetize and save their earnings.

In general, there are two types of solar panels. Solar panels that produces electric power, known as photovoltaic cells or photoelectric cells. And solar panels that heats water, commonly known as thermal solar panels.

Each one of these panels has different applications and uses, however; they both have something in common, they are constructed as panels and they make use of solar energy from the sun’s solar radiation to operate.

Below you will find links to detailed information on solar photovoltaic panels and thermal solar panels with diagrams, images and pictures to simplify complicated information on solar panels.
  1. Solar Photovoltaic Panels
    1. Solar Photovoltaic Panel Construction
    2. Benefits of Solar Photovoltaic Panels
    3. Applications of Solar Photovoltaic Panels
    4. Profits from Solar Photovoltaic Panels
  1. Thermal Solar Panels
    1. Thermal Solar Panel Construction
    2. Benefits of Thermal Solar Panels
    3. Applications of Thermal Solar Panels
    4. Profits from Thermal Solar Panels

Sunday, July 17, 2011

How is Wind Formed

Many people don't know "how is wind formed" on Earth. For those who are eager to learn, an explanation is given below.
Wind is formed by the indirect effect of the sun on the Earth’s surface. There is a reasonable explanation why is it so. As the sun shines, the Sun heats the Earth's surface; the air near ground level gets hot and rises up. Cold air at higher altitudes replaces it. At nighttime the process is reversed. This is  in principal how is wind formed on Earth.

Vertical Wind Formation:

This process of hot air rising and colder air sinking, causes high and low air pressure areas and results in wind formation. The more the pressure changes in an area, the faster the wind speed will be. If two areas are close to each other, pressure difference will cause higher wind speed to be produced compared to areas that are far apart from each other. This is how the wind is formed on Earth and this phenomena is known as vertical wind formation.

How Wind is Formed During the Day and at Nighttime:

Wind is formed on Earth from the air motion. Air over land gets heated faster than air over water. When warm air over land rises, cold air over water replaces it. Land loses heat faster than water, during nighttime, the air above water cools faster than air above land. The same process happens again during nighttime but in reverse. This is how wind is formed on Earth during the nighttime. It is the reverse process of vertical wind formation of daytime.
Interestingly enough, most wind moves horizontally and not vertically, that is; wind moves along the Earth’s surface above the ground. This doesn’t contradict with what was stated earlier about hot air rising up and cold air sinking down as this process only causes two areas of different pressures that is responsible for wind and its motion. Usually, wind moving up and down happens during thunderstorm downdrafts. Vertical winds have low speed. Gravity has a lot of effect. It is the driving force that controls the vertical movement of air.
Then what makes wind travel horizontally rather than vertically?

There is another force that has significant affect on wind patterns. It is the earth’s rotation. Wind is deflected from being in a straight line just like all other flying things including birds and planes. Wind is usually deflected mostly near the Earth’s poles and least near the equator. The amount of air deflection is directly related to both the wind speed and its latitude. Therefore, slow winds are deflected only by a small amount, while stronger winds are much more deflected. This is how is wind formed horizontally.

Other Forces that Affect Wind Behavior:

There are other forces that affect the behavior of wind. Friction for instant influence to a large extent winds near ground level. Friction reduces wind speed near ground level and acts in the direction opposite to the wind direction. Therefore, it affects the flow of wind near ground. That is why most horizontal axis wind turbines are installed at high level above ground level and far away from urban cities.
The rotational force of the Earth has an effect on air speed. Air friction reduces air speed and the atmosphere adjusts by turning the wind from high pressure areas towards low pressure areas. Together the Earth’s rotational force, friction and the horizontal pressure gradient force, leads to a balanced system in the atmosphere with spiral wind motion instead of straight motion from high pressure areas to low pressure areas.
With winds directed from high pressure areas to low pressure areas and air that rises from low-pressure area, water reaches its condensation point in clouds. as a result storms and rain are formed in the atmosphere.
Formation of Jet Stream Wind on Earth:

Also, a change in temperature has direct affect on pressure. With large change in temperature wind gets generated. An area in the atmosphere is created with higher winds, it is known as jet stream areas. These jet streams travel across continents due to the differences between warm and cold air areas in the atmosphere. These atmospheric winds are responsible for moving storms from West to East. Jet streams have a great benefit in driving wind turbines that generates power at selected locations.

Does the information provided above answers "How the Wind is Formed on Earth?" If not, post your question in the comment section below.

Monday, July 11, 2011

Wind Turbine Swept Area

The wind turbine swept area is the area through which the wind strikes the wind turbine blades and causes the blades to spin. The wind spinning the blades causes the rotor to turn and generates power that can be used.

Wind Turbine Swept Area
Swept Area –This refers to the area swept by the blades of the wind turbine when the wind turbine rotates. It is also called the 'capture area' as seen in the diagram to the left.

Wind Turbine Radius – it is the distance measured from the center of the turbine blade (hub) to the end of one of the blades. Most if not all wind turbine manufacturers print the blade’s length on the nameplate of the rotor and/or on the manufacturer’s data sheet. The blade’s radius (or diameter which is twice the radius) is simply the diameter the blade’s cover circle wise.

For a three bladed wind turbine with radius (r) and diameter (2r), the wind turbine swept area would be the area of the circle (A) = Pi r2 as seen in the diagram. The equation for area swept by the wind turbine is employed as part of the power equation that is used to calculate the power output of a wind turbine.

The wind turbine power output is directly related to the swept area of its blades. Increasing the radius of the wind turbine or the longer the blades would result in an increase of the power that can be extracted from the wind. With larger blades, a lot of wind force will be applied on the wind turbine blades. These blades need to be built to be strong in order to withstand higher levels of centrifugal and varying gravitational loads.

Swept Area and Output Power Relationship:

So what is the relationship between the wind turbine swept area and the power output? Looking at the equation for output power you can see that the capture area of the wind turbine blades is utilized to calculate how much power can be extracted from the wind turbine.

Power Output (Watts) = ½ ρ CP A V3 = ½ ρ CP (pi r2) V3
Air density is: (ρ)
Betz limit (Cp): 35% (for a good design)
Swept area is: (A) = Pi r2
and Wind speed is: (V)

See examples on Output Power Calculations

Have you found what you where looking for about "wind turbine swept area"? If not, post your needs in the comment section below and you will see a response within a couple of days.

Sunday, July 10, 2011

Wind Turbine Power Output

Everybody talks about wind turbine power output, however; few people know what wind turbine output power really means or "how to calculate wind turbine power output". Formula for calculating output power of wind turbine is a simple equation given towards the end, but general explanation about wind turbine power output will be explained first.


Wind Turbine Power Output Overview

The output power of a wind turbine has to be one of the most misunderstood and over quoted aspects of a wind turbine. In order to shed some light on this subject you have to know that wind turbines convert kinetic energy (rotational energy) to mechanical energy and the mechanical energy will be transformed to electrical energy.

In other words, when the alternator (also known as generator) spins and rotate, power will be produced. This is usually typical for all power generating equipments whether it is used for renewable energy or conventional energy such as the alternator that charges your car’s battery (Note: Car's alternator shouldn't be used as a wind turbine alternator without modifications).

However, this does not mean that the alternator can run at any speed and produce the same output power; there is a limitation to how much each and every generator can produce.

Power Output Production and Speed:

When the alternator starts spinning, very little power will be produced. With increased speed, the output power increases and a point will be reached where the power output will be the rated power of the alternator. However, the wind turbine generator can spin faster than its rated power and can produce much more output power.

Eventually, a shutdown value will be reached at higher speed which is usually assigned by the wind turbine alternator manufacturer and will force the generator to stop delivering output power by applying the internal breaking system in order to slowdown the wind turbine and prevent damage to the alternator.

How to Calculate Wind Turbine Power Output?

The wind turbine power output can be calculated using one formula that relates the wind turbine blade diameter (swept area) to the wind speed. You don’t have to concern yourself with how this equation was derived which will be explained somewhere else, however; you can use it to calculate the wind turbine power outlet of three bladed wind turbine.
Formula for Calculating Wind Turbine Power Output

Example: Calculating Wind Turbine Power Output:

Assume you have the below data and you want to calculate the output power of your wind turbine.

Wind speed (V): 3 m/s
Air density (ρ): 1.23 Kg/m3
Betz limit (Cp): 35% (for a good design)
Swept area (A): 5.73 m2

If you plug these values in the power equation, your calculated wind turbine power output would be:

Power Output= ½ (1.23) (.35) (5.73) (3x3x3) = 33.2 Watts

The power output is really too low for you to use, the 3 m/s is usually around the cut-in wind speed, however; if the wind speed was 7 m/s then the wind turbine power output would increase dramatically and can be calculated with the same equation and would produce:

Power Output = ½ (1.23) (.35) (5.73) (7x7x7) = 421.6 Watts

So your turbine can extract about 423.05 watts when the wind speed is 7 m/s which would lead to about 12.8 times more power. However, what would you get if the wind speed was 12 m/s?
Plugging the values in the previous equation while changing only the wind speed value, the wind turbine power output equation yields:

Power Output = ½ (1.23) (.35) (5.73) (12x12x12) = 2,123.8 Watts

What is unique about wind turbine power output is that doubling the wind speed will give 8 times power output while tripling the wind speed will give 27 times the power output and so on. Why is that? It is basically because the wind speed (velocity) is cubed in the power formula. 

Below the graph represents the wind turbine power output curve at different wind speed. The values plotted where taken from the above power equation formula.


Data for Calculating Wind Turbine Power Output:


Wind Turbine Power Output Data
Wind Speed (m/s) 1 2345678910111213
Power Output (Watts) 1.29.833.278.7153.6265.5421.6629.3896.01,229.11,635.92,123.82,700.3
Data Plot: Wind Turbine Power Output Curve
Have you found what you where looking for about "wind turbine power output"? If not, post your needs in the comment section below and you will see a response within a couple of days.

Wednesday, July 6, 2011

Wind Turbine Rated Power

Wind Turbine Rated Power – Wind turbine are basically rated in terms of how much power they can produce at a particular wind speed. Most manufacturers if not all will rate their wind turbines at a particular wind speed.

If you take a look at a wind turbine power curve below you would notice that the Y-axis has values starting from zero Kilowatt to some maximum Kilowatt value. These Power rated value are usually the turbine output  power that corresponds to different wind speed values on the X-axis.
Wind Turbine Power Curve

However, this is not the wind turbine rated power. Usually the manufacturer will rate the output power at around 50%-75% of the maximum power output of the alternator and would consider that point to be the wind turbine rated power. Having said that, it means that the wind turbine can produce more power than its rated power. But, why is that?

There is a reasonable explanation why manufacturers rate their turbines lower than the maximum output power. The wind speed is never constant at the same particular value; rather it is fluctuating all the time. Sometimes wind speed with small fluctuation can’t be noticed and some other times large fluctuation can be noticed.

For small fluctuating wind speed, the power output from the wind turbine would stay around the average wind speed of that location, however; for large fluctuating wind speeds, the power output can reach the maximum peak value and even exceed that point.

It is interesting to know that when the wind speed exceeds the maximum peak value its output power starts to drop down and can bring the output power to the wind turbine rated power value or even below. However, if the wind speed becomes excessive, the wind turbine has to protect itself by applying the internal breaking system to slow down the turbine blades and prevent damage to its equipments.


To simplify things, look at the wind turbine power curve in the graph below. You will notice that the wind turbine rated power is around 6.5 kilowatts at 8.5 meters per second (the red lines). While the maximum output power (peak power) is 10 Kilowatt accruing at around 10.5 meters per second (dotted pink line).

However, if wind speed increases without being turbulent (above 17 m/s), the output power will start to drop down as the wind speed increases till it reaches a pre-assigned value (6 Kilowatts) by the manufacturer. At that point the wind turbine will apply its internal breaking system to slow down the wind turbine from over speeding (to the right of blue dotted line).
Wind Turbine Rated Power Graph

Note that the wind turbine breaking system of the wind turbine are applied in case of over speeding in order to keep the output power near the wind turbine rated power but on the upper limit of the power curve.