GOOGLE Inc.'s Innovative approach to generate revenues backfired wen it started allowing ads on its famous networking website ORKUT ! An example is the lawsuit filed by Thiago Tavares Nunes de Oliveira, a 28-year-old Brazilian law professor against GOOGLE Brazil led to a completly new law being made in d cyber world.......
chk out d link for more info
http://online.wsj.com/public/article/SB119273558149563775-6_LyeLHpy85P7ZUe7ryt_g_bfMI_20081018.html
Tuesday, March 18, 2008
Tuesday, January 22, 2008
GEOTHERMICITY VIA SEISIMICITY
WHY DO WE NEED GEOTHERMAL ENERGY?
Over the years we have realised the importance of renewable sources of energy and with global warming becoming a universal problem geothermal will occupy a very important role in providing energy.But this geothermal power plants will not only be a source of energy but also help u in predicting EARTHQUAKE.It can be used for predicting earthquakes. At present with the oil prices as high as 100$ per barrel i think we need to seriously look at geothermal energy as the source of energy in future.In a country like India where oil and gas reserves are very low and our oil and gas needs are met by gulf countries and the central asian nations geothermal energy may just be the answer we are looking for.
According to a recent study India has a potenial of 10,600MW from geothermicity and most of the earthquakes occuring in India are at a shallow depth of about 10-12 kms. Thus,this very facts states that geothermal power plants are very much viable in India from technical point of view.
ADVANTAGES OF GEOTHERMICITY
The innovative approach requires finding these seisimic hotspots where the geothermal gradient is high .Drilling of wells in such places should be done keeping in mind the line of rock fractures in order to maximise the energy output.Temperature of underground rocks is calculated using sophisticated geothermometers like silica thermometer.Reducing the strees in the rocks has dual benefits .Firstly ,the high energy content can vapourise steam and run turbines .Secondly ,te stress build up in the rocks is lowered thereby reducing the chance of a high intensity earthquakes.The water sent through the fault lines lubricates them thereby cutting out regression.
CONTRIBUTED BY-
GAURAV JHA
MIT,1st year,
Electronic & Communication
Friday, January 18, 2008
HOW TO MAKE A SOLAR POWER GENERATOR FOR LESS THAN 300$
One of the recent innovative ideas have lead to a more efficient and cheaper way of making a solar power generator.The time has come when we start utlilising the abundant solar energy in a efficient way and cutting down on non-renewable sources of energy.To begin with here we have a very suitable and efficient way of utilising solar energy by using a solar power generator
2. Buy yourself a battery. Get any size deep cycle 12 volt lead/acid or gel battery. You need the deep cycle battery for continuous use. The kind in your car is a cranking battery--just for starting an engine. Look for bargains, it should cost about $50-60.
3. Get a battery box to put it in for $10. (This is good for covering up the exposed terminals in case there are children about If you going to install the system in a pump shed, cabin, or boat, skip this.)
3. Buy a 12 volt DC meter. Radio Shack has them for about $25.
4. Buy a DC input. Triple inlet model is recommended in which one can find at a car parts store in the cigarette lighter parts section for about $10. This is enough to power DC appliances, and there are many commercially available, like fans, one-pint water boilers, lights, hair dryers, baby bottle warmers, and vacuum cleaners. Many cassette players, answering machines, and other electrical appliances are DC already and with the right cable will run straight off the box.
5. But if you want to run AC appliances, you will have to invest in an inverter. This will convert the stored DC power in the battery into AC power for most of your household appliances. A 115 volt 140 watt inverter made by Power-to-Go at Pep Boys for $50. More powerful inverters are available by mail. Count up the number of watts you'll be using (e.g., a small color television(=60 watts) with a VCR(=22 watts), you'll need 82 watts).
6. Use a drill to attach the meter and DC input to the top of the box.
7. Use insulated wire to attach the meter to the wingnut terminals on the battery. Connect the negative (-) pole first. Only handle one wire at a time. Connect the DC inlet to the battery in the same way. Connect the solar panel to the battery in the same way.
8. Close the lid . Put the solar panel in the sun. It takes 5-8 hours to charge a dead battery; 1-3 hours to top off a weak one. It will run radios, fans, and small wattage lights all night, or give you about 5 hours of continuous use at 115 volt AC, or about an hour boiling water. This system may be added on to with larger panels, inverters, and batteries.
Options: A pop-up circuit breaker may be added between the positive treminal and the volt meter. Some of you will want an ampmeter as well. The panels recommend have built-in bypass diodes, but charge controllers are recommended for people who have panels without diodes. Another option is a voltage regulator, which is not necessary for a system this small, but a larger system would require one .
Source-Phil Heiphle
UTILITIES OF SOLAR POWER GENERATORUsing parts easily available from your local stores, you can make a small solar power generator for $250 to $300. Great for power failures and life outside the power grid. Power your computer, modem, vcr, tv, cameras, lights, or DC appliances anywhere you go. Use in cabins, boats, tents, archaeological digs, or while travelling throughout the third world. Have one in the office store room in case of power failures in your highrise. People can use it in their bedrooms to power cd player, turntable, lights, modem, laptop, and (ahem) a back massager by running a line out of the window to an 8" x 24" panel on the roof.
SIMPLE STEPS TO BUILD ONE OF THE CHEAPEST AND EFFICIENT WAY1. Buy yourself a small solar panel. For about $100 you should be able to get one rated at 12 volts or better (look for 16 volts) at an RV or marine supplies store.
TO GENERATE SOLAR POWER
2. Buy yourself a battery. Get any size deep cycle 12 volt lead/acid or gel battery. You need the deep cycle battery for continuous use. The kind in your car is a cranking battery--just for starting an engine. Look for bargains, it should cost about $50-60.
3. Get a battery box to put it in for $10. (This is good for covering up the exposed terminals in case there are children about If you going to install the system in a pump shed, cabin, or boat, skip this.)
3. Buy a 12 volt DC meter. Radio Shack has them for about $25.
4. Buy a DC input. Triple inlet model is recommended in which one can find at a car parts store in the cigarette lighter parts section for about $10. This is enough to power DC appliances, and there are many commercially available, like fans, one-pint water boilers, lights, hair dryers, baby bottle warmers, and vacuum cleaners. Many cassette players, answering machines, and other electrical appliances are DC already and with the right cable will run straight off the box.
5. But if you want to run AC appliances, you will have to invest in an inverter. This will convert the stored DC power in the battery into AC power for most of your household appliances. A 115 volt 140 watt inverter made by Power-to-Go at Pep Boys for $50. More powerful inverters are available by mail. Count up the number of watts you'll be using (e.g., a small color television(=60 watts) with a VCR(=22 watts), you'll need 82 watts).
6. Use a drill to attach the meter and DC input to the top of the box.
7. Use insulated wire to attach the meter to the wingnut terminals on the battery. Connect the negative (-) pole first. Only handle one wire at a time. Connect the DC inlet to the battery in the same way. Connect the solar panel to the battery in the same way.
8. Close the lid . Put the solar panel in the sun. It takes 5-8 hours to charge a dead battery; 1-3 hours to top off a weak one. It will run radios, fans, and small wattage lights all night, or give you about 5 hours of continuous use at 115 volt AC, or about an hour boiling water. This system may be added on to with larger panels, inverters, and batteries.
Options: A pop-up circuit breaker may be added between the positive treminal and the volt meter. Some of you will want an ampmeter as well. The panels recommend have built-in bypass diodes, but charge controllers are recommended for people who have panels without diodes. Another option is a voltage regulator, which is not necessary for a system this small, but a larger system would require one .
Source-Phil Heiphle
SOLAR ENERGY-The energy of future
Solar power works well for most items except large electric appliances that use an electric heat element such as a water heater, clothes dryer and electric stove - for example - or total electric home heating systems. It is not cost effective to use solar power for these items. Conversion to natural gas, propane or other alternatives is usually recommended. Solar power can be used to operate a gas clothes dryer (Maytag, etc) because the electrical requirement is limited to the drum-motor and/or ignito-lighter, but not a HEAT element for drying the clothes, for example.
electricity using solar power, which provides common 120 volt AC power for daily use are: Solar panels, charge controller, battery and inverter. Solar panels charge the battery, and the charge regulator insures proper charging of the battery. The battery provides DC voltage to the inverter, and the inverter converts the DC voltage to normal AC voltage. If 240 volts AC is needed, then either a transformer is added or two identical inverters are series-stacked to produce the 240 volts.
BASIC OF SOLAR POWER
Using solar power to produce electricity is not the same as using solar to produce heat. Solar thermal principles are applied to produce hot fluids or air. Photovoltaic principles are used to produce electricity. A solar panel (PV panel) is made of the natural element, silicon, which becomes charged electrically when subjected to sun light.
Solar panels are directed at solar south in the northern hemisphere and solar north in the southern hemisphere (these are slightly different than magnetic compass north-south directions) at an angle dictated by the geographic location and latitude of where they are to be installed. Typically, the angle of the solar array is set within a range of between site-latitude-plus 15 degrees and site-latitude-minus 15 degrees, depending on whether a slight winter or summer bias is desirable in the system. Many solar arrays are placed at an angle equal to the site latitude with no bias for seasonal periods.
This electrical charge is consolidated in the PV panel and directed to the output terminals to produce low voltage (Direct Current) - usually 6 to 24 volts. The most common output is intended for nominal 12 volts, with an effective output usually up to 17 volts. A 12 volt nominal output is the reference voltage, but the operating voltage can be 17 volts or higher much like your car alternator charges your 12 volt battery at well over 12 volts. So there's a difference between the reference voltage and the actual operating voltage.
The intensity of the Sun's radiation changes with the hour of the day, time of the year and weather conditions. To be able to make calculations in planning a system, the total amount of solar radiation energy is expressed in hours of full sunlight per m², or Peak Sun Hours. This term, Peak Sun Hours, represents the average amount of sun available per day throughout the year.
It is presumed that at "peak sun", 1000 W/m² of power reaches the surface of the earth. One hour of full sun provides 1000 Wh per m² = 1 kWh/m² - representing the solar energy received in one hour on a cloudless summer day on a one-square meter surface directed towards the sun. To put this in some other perspective, the United States Department of Energy indicates the amount of solar energy that hits the surface of the earth every +/- hour is greater than the total amount of energy that the entire human population requires in a year. Another perspective is that roughly 100 square miles of solar panels placed in the southwestern U.S. could power the country.
The daily average of Peak Sun Hours, based on either full year statistics, or average worst month of the year statistics, for example, is used for calculation purposes in the design of the system. To see the average Peak Sun Hours for your area in the United States, you can click the following link which will open a new window - just close it [X] when you're done to return here; U.S.-Solar Insolation Choose the area closest to your location for a good indication of your average Peak Sun Hours.
For a view of global solar insolation values (peak sun-hours) use this link: Global Peak Sun-hour Maps , then, you can use [back] or [previous] on your browser to return right here if you want to.
So it can be concluded that the power of a system varies, depending on the intended geographical location. Folks in the northeastern U.S. will need more solar panels in their system to produce the same overall power as those living in Arizona. We can advise you on this if you have any doubts about your area.
Solar panels are directed at solar south in the northern hemisphere and solar north in the southern hemisphere (these are slightly different than magnetic compass north-south directions) at an angle dictated by the geographic location and latitude of where they are to be installed. Typically, the angle of the solar array is set within a range of between site-latitude-plus 15 degrees and site-latitude-minus 15 degrees, depending on whether a slight winter or summer bias is desirable in the system. Many solar arrays are placed at an angle equal to the site latitude with no bias for seasonal periods.
This electrical charge is consolidated in the PV panel and directed to the output terminals to produce low voltage (Direct Current) - usually 6 to 24 volts. The most common output is intended for nominal 12 volts, with an effective output usually up to 17 volts. A 12 volt nominal output is the reference voltage, but the operating voltage can be 17 volts or higher much like your car alternator charges your 12 volt battery at well over 12 volts. So there's a difference between the reference voltage and the actual operating voltage.
The intensity of the Sun's radiation changes with the hour of the day, time of the year and weather conditions. To be able to make calculations in planning a system, the total amount of solar radiation energy is expressed in hours of full sunlight per m², or Peak Sun Hours. This term, Peak Sun Hours, represents the average amount of sun available per day throughout the year.
It is presumed that at "peak sun", 1000 W/m² of power reaches the surface of the earth. One hour of full sun provides 1000 Wh per m² = 1 kWh/m² - representing the solar energy received in one hour on a cloudless summer day on a one-square meter surface directed towards the sun. To put this in some other perspective, the United States Department of Energy indicates the amount of solar energy that hits the surface of the earth every +/- hour is greater than the total amount of energy that the entire human population requires in a year. Another perspective is that roughly 100 square miles of solar panels placed in the southwestern U.S. could power the country.
The daily average of Peak Sun Hours, based on either full year statistics, or average worst month of the year statistics, for example, is used for calculation purposes in the design of the system. To see the average Peak Sun Hours for your area in the United States, you can click the following link which will open a new window - just close it [X] when you're done to return here; U.S.-Solar Insolation Choose the area closest to your location for a good indication of your average Peak Sun Hours.
For a view of global solar insolation values (peak sun-hours) use this link: Global Peak Sun-hour Maps , then, you can use [back] or [previous] on your browser to return right here if you want to.
So it can be concluded that the power of a system varies, depending on the intended geographical location. Folks in the northeastern U.S. will need more solar panels in their system to produce the same overall power as those living in Arizona. We can advise you on this if you have any doubts about your area.
The four primary components for producingCOMPONENTS USED TO PROVIDE SOLAR
POWER
electricity using solar power, which provides common 120 volt AC power for daily use are: Solar panels, charge controller, battery and inverter. Solar panels charge the battery, and the charge regulator insures proper charging of the battery. The battery provides DC voltage to the inverter, and the inverter converts the DC voltage to normal AC voltage. If 240 volts AC is needed, then either a transformer is added or two identical inverters are series-stacked to produce the 240 volts.
SOLAR PANELS
The output of a solar panel is usually stated in watts, and the wattage is determined by multiplying the rated voltage by the rated amperage. The formula for wattage is VOLTS times AMPS equals WATTS. So for example, a 12 volt 60 watt solar panel measuring about 20 X 44 inches has a rated voltage of 17.1 and a rated 3.5 amperage.
V x A = W 17.1 volts times 3.5 amps equals 60 watts
If an average of 6 hours of peak sun per day is available in an area, then the above solar panel can produce an average 360 watt hours of power per day; 60w times 6 hrs. = 360 watt-hours. Since the intensity of sunlight contacting the solar panel varies throughout the day, we use the term "peak sun hours" as a method to smooth out the variations into a daily average. Early morning and late-in-the-day sunlight produces less power than the mid-day sun. Naturally, cloudy days will produce less power than bright sunny days as well. When planning a system your geographical area is rated in average peak sun hours per day based on yearly sun data. Average peak sun hours for various geographical areas is listed in the above section.
Solar panels can be wired in series or in parallel to increase voltage or amperage respectively, and they can be wired both in series and in parallel to increase both volts and amps. Series wiring refers to connecting the positive terminal of one panel to the negative terminal of another. The resulting outer positive and negative terminals will produce voltage the sum of the two panels, but the amperage stays the same as one panel. So two 12 volt/3.5 amp panels wired in series produces 24 volts at 3.5 amps. Four of these wired in series would produce 48 volts at 3.5 amps. Parallel wiring refers to connecting positive terminals to positive terminals and negative to negative. The result is that voltage stays the same, but amperage becomes the sum of the number of panels. So two 12 volt/3.5 amp panels wired in parallel would produce 12 volts at 7 amps. Four panels would produce 12 volts at 14 amps.Series/parallel wiring refers to doing both of the above - increasing volts and amps to achieve the desired voltage as in 24 or 48 volt systems. The following diagram reflects this. In addition, the four panels below can then be wired in parallel to another four and so on to make a larger array.
CHARGE CONTROLLER:A charge controller monitors the battery's state-of-charge to insure that when the battery needs charge-current it gets it, and also insures the battery isn't over-charged. Connecting a solar panel to a battery without a regulator seriously risks damaging the battery and potentially causing a safety concern.
Charge controllers (or often called charge regulator) are rated based on the amount of amperage they can process from a solar array. If a controller is rated at 20 amps it means that you can connect up to 20 amps of solar panel output current to this one controller. The most advanced charge controllers utilize a charging principal referred to as Pulse-Width-Modulation (PWM) - which insures the most efficient battery charging and extends the life of the battery. Even more advanced controllers also include Maximum Power Point Tracking (MPPT) which maximizes the amount of current going into the battery from the solar array by lowering the panel's output voltage, which increases the charging amps to the battery - because if a panel can produce 60 watts with 17.2 volts and 3.5 amps, then if the voltage is lowered to say 14 volts then the amperage increases to 4.28 (14v X 4.28 amps = 60 watts) resulting in a 19% increase in charging amps for this example.
Many charge controllers also offer Low Voltage Disconnect (LVD) and Battery Temperature Compensation (BTC) as an optional feature. The LVD feature permits connecting loads to the LVD terminals which are then voltage sensitive. If the battery voltage drops too far the loads are disconnected - preventing potential damage to both the battery and the loads. BTC adjusts the charge rate based on the temperature of the battery since batteries are sensitive to temperature variations above and below about 75 F degrees.
BATTERY:The Deep Cycle batteries used are designed to be discharged and then re-charged hundreds or thousands of times. These batteries are rated in Amp Hours (ah) - usually at 20 hours and 100 hours. Simply stated, amp hours refers to the amount of current - in amps - which can be supplied by the battery over the period of hours. For example, a 350ah battery could supply 17.5 continuous amps over 20 hours or 35 continuous amps for 10 hours. To quickly express the total watts potentially available in a 6 volt 360ah battery; 360ah times the nominal 6 volts equals 2160 watts or 2.16kWh (kilowatt-hours). Like solar panels, batteries are wired in series and/or parallel to increase voltage to the desired level and increase amp hours.
The battery should have sufficient amp hour capacity to supply needed power during the longest expected period "no sun" or extremely cloudy conditions. A lead-acid battery should be sized at least 20% larger than this amount. If there is a source of back-up power, such as a standby generator along with a battery charger, the battery bank does not have to be sized for worst case weather conditions.
The size of the battery bank required will depend on the storage capacity required, the maximum discharge rate, the maximum charge rate, and the minimum temperature at which the batteries will be used. During planning, all of these factors are looked at, and the one requiring the largest capacity will dictate the battery size.
One of the biggest mistakes made by those just starting out is not understanding the relationship between amps and amp-hour requirements of 120 volt AC items versus the effects on their DC low voltage batteries. For example, say you have a 24 volt nominal system and an inverter powering a load of 3 amps, 120VAC, which has a duty cycle of 4 hours per day. You would have a 12 amp hour load (3A X 4 hrs=12 ah). However, in order to determine the true drain on your batteries you have to divide your nominal battery voltage (24v) into the voltage of the load (120v), which is 5, and then multiply this times your 120vac amp hours (5 x 12 ah). So in this case the calculation would be 60 amp hours drained from your batteries - not the 12 ah. Another simple way is to take the total watt-hours of your 120VAC device and divide by nominal system voltage. Using the above example; 3 amps x 120 volts x 4 hours = 1440 watt-hours divided by 24 DC volts = 60 amp hours.
Lead-acid batteries are the most common in PV systems because their initial cost is lower and because they are readily available nearly everywhere in the world. There are many different sizes and designs of lead-acid batteries, but the most important designation is that they are deep cycle batteries. Lead-acid batteries are available in both wet-cell (requires maintenance) and sealed no-maintenance versions. AGM and Gel-cell deep-cycle batteries are also popular because they are maintenance free and they last a lot longer.
USING AN INVERTER:An inverter is a device which changes DC power stored in a battery to standard 120/240 VAC electricity (also referred to as 110/220). Most solar power systems generate DC current which is stored in batteries. Nearly all lighting, appliances, motors, etc., are designed to use ac power, so it takes an inverter to make the switch from battery-stored DC to standard power (120 VAC, 60 Hz).
In an inverter, direct current (DC) is switched back and forth to produce alternating current (AC). Then it is transformed, filtered, stepped, etc. to get it to an acceptable output waveform. The more processing, the cleaner and quieter the output, but the lower the efficiency of the conversion. The goal becomes to produce a waveform that is acceptable to all loads without sacrificing too much power into the conversion process.
Inverters come in two basic output designs - sine wave and modified sine wave. Most 120VAC devices can use the modified sine wave, but there are some notable exceptions. Devices such as laser printers which use triacs and/or silicon controlled rectifiers are damaged when provided mod-sine wave power. Motors and power supplies usually run warmer and less efficiently on mod-sine wave power. Some things, like fans, amplifiers, and cheap fluorescent lights, give off an audible buzz on modified sine wave power. However, modified sine wave inverters make the conversion from DC to AC very efficiently. They are relatively inexpensive, and many of the electrical devices we use every day work fine on them.
Sine wave inverters can virtually operate anything. Your utility company provides sine wave power, so a sine wave inverter is equal to or even better than utility supplied power. A sine wave inverter can "clean up" utility or generator supplied power because of its internal processing.
Inverters are made with various internal features and many permit external equipment interface. Common internal features are internal battery chargers which can rapidly charge batteries when an AC source such as a generator or utility power is connected to the inverter's INPUT terminals. Auto-transfer switching is also a common internal feature which enables switching from either one AC source to another and/or from utility power to inverter power for designated loads. Battery temperature compensation, internal relays to control loads, automatic remote generator starting/stopping and many other programmable features are available.
Most inverters produce 120VAC, but can be equipped with a step-up transformer to produce 120/240VAC. Some inverters can be series or parallel "stacked-interfaced" to produce 120/240VAC or to increase the available amperage.
EFFICIENCY LOSSES:In all systems there are losses due to such things as voltage losses as the electricity is carried across the wires, batteries and inverters not being 100 percent efficient, and other factors. These efficiency losses vary from component to component, and from system to system and can be as high as 25 percent. That's why it's a good idea to speak to someone who has extensive design experience - like us! - to properly configure the right equipment for you.
V x A = W 17.1 volts times 3.5 amps equals 60 watts
If an average of 6 hours of peak sun per day is available in an area, then the above solar panel can produce an average 360 watt hours of power per day; 60w times 6 hrs. = 360 watt-hours. Since the intensity of sunlight contacting the solar panel varies throughout the day, we use the term "peak sun hours" as a method to smooth out the variations into a daily average. Early morning and late-in-the-day sunlight produces less power than the mid-day sun. Naturally, cloudy days will produce less power than bright sunny days as well. When planning a system your geographical area is rated in average peak sun hours per day based on yearly sun data. Average peak sun hours for various geographical areas is listed in the above section.
Solar panels can be wired in series or in parallel to increase voltage or amperage respectively, and they can be wired both in series and in parallel to increase both volts and amps. Series wiring refers to connecting the positive terminal of one panel to the negative terminal of another. The resulting outer positive and negative terminals will produce voltage the sum of the two panels, but the amperage stays the same as one panel. So two 12 volt/3.5 amp panels wired in series produces 24 volts at 3.5 amps. Four of these wired in series would produce 48 volts at 3.5 amps. Parallel wiring refers to connecting positive terminals to positive terminals and negative to negative. The result is that voltage stays the same, but amperage becomes the sum of the number of panels. So two 12 volt/3.5 amp panels wired in parallel would produce 12 volts at 7 amps. Four panels would produce 12 volts at 14 amps.Series/parallel wiring refers to doing both of the above - increasing volts and amps to achieve the desired voltage as in 24 or 48 volt systems. The following diagram reflects this. In addition, the four panels below can then be wired in parallel to another four and so on to make a larger array.
CHARGE CONTROLLER:A charge controller monitors the battery's state-of-charge to insure that when the battery needs charge-current it gets it, and also insures the battery isn't over-charged. Connecting a solar panel to a battery without a regulator seriously risks damaging the battery and potentially causing a safety concern.
Charge controllers (or often called charge regulator) are rated based on the amount of amperage they can process from a solar array. If a controller is rated at 20 amps it means that you can connect up to 20 amps of solar panel output current to this one controller. The most advanced charge controllers utilize a charging principal referred to as Pulse-Width-Modulation (PWM) - which insures the most efficient battery charging and extends the life of the battery. Even more advanced controllers also include Maximum Power Point Tracking (MPPT) which maximizes the amount of current going into the battery from the solar array by lowering the panel's output voltage, which increases the charging amps to the battery - because if a panel can produce 60 watts with 17.2 volts and 3.5 amps, then if the voltage is lowered to say 14 volts then the amperage increases to 4.28 (14v X 4.28 amps = 60 watts) resulting in a 19% increase in charging amps for this example.
Many charge controllers also offer Low Voltage Disconnect (LVD) and Battery Temperature Compensation (BTC) as an optional feature. The LVD feature permits connecting loads to the LVD terminals which are then voltage sensitive. If the battery voltage drops too far the loads are disconnected - preventing potential damage to both the battery and the loads. BTC adjusts the charge rate based on the temperature of the battery since batteries are sensitive to temperature variations above and below about 75 F degrees.
BATTERY:The Deep Cycle batteries used are designed to be discharged and then re-charged hundreds or thousands of times. These batteries are rated in Amp Hours (ah) - usually at 20 hours and 100 hours. Simply stated, amp hours refers to the amount of current - in amps - which can be supplied by the battery over the period of hours. For example, a 350ah battery could supply 17.5 continuous amps over 20 hours or 35 continuous amps for 10 hours. To quickly express the total watts potentially available in a 6 volt 360ah battery; 360ah times the nominal 6 volts equals 2160 watts or 2.16kWh (kilowatt-hours). Like solar panels, batteries are wired in series and/or parallel to increase voltage to the desired level and increase amp hours.
The battery should have sufficient amp hour capacity to supply needed power during the longest expected period "no sun" or extremely cloudy conditions. A lead-acid battery should be sized at least 20% larger than this amount. If there is a source of back-up power, such as a standby generator along with a battery charger, the battery bank does not have to be sized for worst case weather conditions.
The size of the battery bank required will depend on the storage capacity required, the maximum discharge rate, the maximum charge rate, and the minimum temperature at which the batteries will be used. During planning, all of these factors are looked at, and the one requiring the largest capacity will dictate the battery size.
One of the biggest mistakes made by those just starting out is not understanding the relationship between amps and amp-hour requirements of 120 volt AC items versus the effects on their DC low voltage batteries. For example, say you have a 24 volt nominal system and an inverter powering a load of 3 amps, 120VAC, which has a duty cycle of 4 hours per day. You would have a 12 amp hour load (3A X 4 hrs=12 ah). However, in order to determine the true drain on your batteries you have to divide your nominal battery voltage (24v) into the voltage of the load (120v), which is 5, and then multiply this times your 120vac amp hours (5 x 12 ah). So in this case the calculation would be 60 amp hours drained from your batteries - not the 12 ah. Another simple way is to take the total watt-hours of your 120VAC device and divide by nominal system voltage. Using the above example; 3 amps x 120 volts x 4 hours = 1440 watt-hours divided by 24 DC volts = 60 amp hours.
Lead-acid batteries are the most common in PV systems because their initial cost is lower and because they are readily available nearly everywhere in the world. There are many different sizes and designs of lead-acid batteries, but the most important designation is that they are deep cycle batteries. Lead-acid batteries are available in both wet-cell (requires maintenance) and sealed no-maintenance versions. AGM and Gel-cell deep-cycle batteries are also popular because they are maintenance free and they last a lot longer.
USING AN INVERTER:An inverter is a device which changes DC power stored in a battery to standard 120/240 VAC electricity (also referred to as 110/220). Most solar power systems generate DC current which is stored in batteries. Nearly all lighting, appliances, motors, etc., are designed to use ac power, so it takes an inverter to make the switch from battery-stored DC to standard power (120 VAC, 60 Hz).
In an inverter, direct current (DC) is switched back and forth to produce alternating current (AC). Then it is transformed, filtered, stepped, etc. to get it to an acceptable output waveform. The more processing, the cleaner and quieter the output, but the lower the efficiency of the conversion. The goal becomes to produce a waveform that is acceptable to all loads without sacrificing too much power into the conversion process.
Inverters come in two basic output designs - sine wave and modified sine wave. Most 120VAC devices can use the modified sine wave, but there are some notable exceptions. Devices such as laser printers which use triacs and/or silicon controlled rectifiers are damaged when provided mod-sine wave power. Motors and power supplies usually run warmer and less efficiently on mod-sine wave power. Some things, like fans, amplifiers, and cheap fluorescent lights, give off an audible buzz on modified sine wave power. However, modified sine wave inverters make the conversion from DC to AC very efficiently. They are relatively inexpensive, and many of the electrical devices we use every day work fine on them.
Sine wave inverters can virtually operate anything. Your utility company provides sine wave power, so a sine wave inverter is equal to or even better than utility supplied power. A sine wave inverter can "clean up" utility or generator supplied power because of its internal processing.
Inverters are made with various internal features and many permit external equipment interface. Common internal features are internal battery chargers which can rapidly charge batteries when an AC source such as a generator or utility power is connected to the inverter's INPUT terminals. Auto-transfer switching is also a common internal feature which enables switching from either one AC source to another and/or from utility power to inverter power for designated loads. Battery temperature compensation, internal relays to control loads, automatic remote generator starting/stopping and many other programmable features are available.
Most inverters produce 120VAC, but can be equipped with a step-up transformer to produce 120/240VAC. Some inverters can be series or parallel "stacked-interfaced" to produce 120/240VAC or to increase the available amperage.
EFFICIENCY LOSSES:In all systems there are losses due to such things as voltage losses as the electricity is carried across the wires, batteries and inverters not being 100 percent efficient, and other factors. These efficiency losses vary from component to component, and from system to system and can be as high as 25 percent. That's why it's a good idea to speak to someone who has extensive design experience - like us! - to properly configure the right equipment for you.
MODERN WATER PUMPS
Water pumping is a wonderful use for alternative power technology. Even if your ranch house is powered by conventional power from the grid, what about getting water to your cattle on the back 40? Windmills have been used for over 100 years for this purpose, but other alternative power methods are effective too. Really, ANYTHING is better than pumping water by hand, but gas powered generators are the worst of the bunch.
First, a word about your well pump. The standard well pump your well drilling company will install is usually a 220 volt AC model. If they tell you, "don't worry, your solar system will run this just fine if you add a 220 volt transformer," DON'T believe them! This has been a big problem with a certain well pump company in our area. Standard 220 well pumps are very inefficient, and the required 220 transformer wastes lots of power. A huge Trace 2500 watt inverter can only sometimes power one of these behemoths--even if the pump IS able to start, all your lights may dim every time the well pump kicks on, resulting in premature inverter failure. It is recommend to avoid this sort of system if at all possible. The only solution if you have this sort of well pump is to run a generator to fill your cistern, or replace the pump with a variety suited to remote power. And if you have a remote power system, why be dependent on a gas powered generator for all your water? It will eventually leave you stranded without water, and usually at midnight when its 20 below zero outside. Spend an extra 1000 bucks on a 12 volt deep well pump or a super efficient 120 volt AC model. You can pump with your regular remote power system, your generator will last longer, and if it won't start when its 20 below zero, you still have water.
The single 75 watt solar panel shown here can pumps water to any house from a shallow spring. It moves the water at 75 gallons per hour in full sun. The total lift to the house from the spring is 35 feet, the total horizontal distance is 480 feet. The pump is an inexpensive Shurflo pressure pump, controlled by a Photocomm controller and Linear Current Booster (LCB). There are float switches at the spring and at the cistern underneath the house. No batteries are used, but a installed jumper cable lugs at the pump so that one can hook up a truck battery to the pump for times of no sun (like if we have a cistern of 150 gallons). This system has run oon tril basis for over a year without any maintenance.
In any remote water pumping situation, use of batteries is avoided if AT ALL possible! Your water storage tank should be your battery--that is, your system should pump water fast enough and your cistern should be big enough that you can last through as many days of no sun or wind as necessary. Batteries are a waste of money and resources in a remote water pumping system, unless one is planning some sort of specialized application.
Home water pressure pumps--For pressurizing your tap water, the best choice is a 12 volt DC pressure pump. These are inexpensive, efficient and reliable, and the pressure settings for turning on and off are built-in. They cost from $40 to $200. 120 volt AC versions are very inefficient, using far more power than necessary. It uses one solar panel to pump spring water 480 feet horizontally and 45 feet vertically to our cistern under the house.
Wind--The traditional windmill is still useful technology. The pump is directly coupled to the wind generator. The only problem comes if there is no wind for a few days at a time, and with maintenance. The leather seals on this sort of pump wear out and require replacement. The Bowjon windmill system uses pressurized air to pump water, and requires very little maintenance. It can also be used to generate power. Other systems have been built using an electric wind generator, linear current booster, and pump, as described in the Solar section above.
Water--Yes, water can be used to pump water. The device involved is called a "water ram." It uses your local stream's water pressure to move a fraction of the total stream flow uphill--as much as 30 times the total fall. Water rams can be purchased, or built at home with PVC pipe and valves. Look for more information on this here in the future.
Gasoline-- A waste of resources. Avoid it if possible.
Hand Pumps--Better than not having water, if you have no resources available. Or if you can get your kids to do it. Different hand pumps are available commercially (my grandma had one), or pumps can be constructed than run on foot power instead of hand.
Linear Current Booster (LCB)--This device trades voltage for extra current to start a pump. Electric pumps take more power to start up than they take to run, and the LCB takes care of this problem. It will allow your pump to start and run even on cloudy days.
First, a word about your well pump. The standard well pump your well drilling company will install is usually a 220 volt AC model. If they tell you, "don't worry, your solar system will run this just fine if you add a 220 volt transformer," DON'T believe them! This has been a big problem with a certain well pump company in our area. Standard 220 well pumps are very inefficient, and the required 220 transformer wastes lots of power. A huge Trace 2500 watt inverter can only sometimes power one of these behemoths--even if the pump IS able to start, all your lights may dim every time the well pump kicks on, resulting in premature inverter failure. It is recommend to avoid this sort of system if at all possible. The only solution if you have this sort of well pump is to run a generator to fill your cistern, or replace the pump with a variety suited to remote power. And if you have a remote power system, why be dependent on a gas powered generator for all your water? It will eventually leave you stranded without water, and usually at midnight when its 20 below zero outside. Spend an extra 1000 bucks on a 12 volt deep well pump or a super efficient 120 volt AC model. You can pump with your regular remote power system, your generator will last longer, and if it won't start when its 20 below zero, you still have water.
The single 75 watt solar panel shown here can pumps water to any house from a shallow spring. It moves the water at 75 gallons per hour in full sun. The total lift to the house from the spring is 35 feet, the total horizontal distance is 480 feet. The pump is an inexpensive Shurflo pressure pump, controlled by a Photocomm controller and Linear Current Booster (LCB). There are float switches at the spring and at the cistern underneath the house. No batteries are used, but a installed jumper cable lugs at the pump so that one can hook up a truck battery to the pump for times of no sun (like if we have a cistern of 150 gallons). This system has run oon tril basis for over a year without any maintenance.
In any remote water pumping situation, use of batteries is avoided if AT ALL possible! Your water storage tank should be your battery--that is, your system should pump water fast enough and your cistern should be big enough that you can last through as many days of no sun or wind as necessary. Batteries are a waste of money and resources in a remote water pumping system, unless one is planning some sort of specialized application.
Home water pressure pumps--For pressurizing your tap water, the best choice is a 12 volt DC pressure pump. These are inexpensive, efficient and reliable, and the pressure settings for turning on and off are built-in. They cost from $40 to $200. 120 volt AC versions are very inefficient, using far more power than necessary. It uses one solar panel to pump spring water 480 feet horizontally and 45 feet vertically to our cistern under the house.
Solar--Solar technology is very well suited to pumping water, even more so than the traditional windmill. A typical system includes one or more solar panels, an efficient 12 volt DC pump, a controller (with float switches), and a "linear current booster" (more about this later). As long as it's daytime and the float switches show that the water source is not empty and the cistern in the house is not overflowing, the pump will run. The linear current booster allows the pump to run even if it's cloudy out.Power for Water Pumping
Wind--The traditional windmill is still useful technology. The pump is directly coupled to the wind generator. The only problem comes if there is no wind for a few days at a time, and with maintenance. The leather seals on this sort of pump wear out and require replacement. The Bowjon windmill system uses pressurized air to pump water, and requires very little maintenance. It can also be used to generate power. Other systems have been built using an electric wind generator, linear current booster, and pump, as described in the Solar section above.
Water--Yes, water can be used to pump water. The device involved is called a "water ram." It uses your local stream's water pressure to move a fraction of the total stream flow uphill--as much as 30 times the total fall. Water rams can be purchased, or built at home with PVC pipe and valves. Look for more information on this here in the future.
Gasoline-- A waste of resources. Avoid it if possible.
Hand Pumps--Better than not having water, if you have no resources available. Or if you can get your kids to do it. Different hand pumps are available commercially (my grandma had one), or pumps can be constructed than run on foot power instead of hand.
Linear Current Booster (LCB)--This device trades voltage for extra current to start a pump. Electric pumps take more power to start up than they take to run, and the LCB takes care of this problem. It will allow your pump to start and run even on cloudy days.
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