Electric Generator's Basic Principles!
Going shopping for an electric generator can be a daunting task for many people. Everyone
Seems to have their own ideas as to what is the best type of electric generator to buy. There are an enormous amount of makes and models now available, all vying for your money with
attractive colors, housings and price tags. Considering that for a large number of people the
electric generator is going to provide emergency or stand-by power, it is important to walk away from the deal with confidence and peace of mind that the correct decision has been made.
These are key factors that you must consider, which will help simplify the selection process.
1. How much electric power do you require? This of course is where you start from. There is no point in going out and purchasing an electric generator and hope that it is going to produce enough power for all your needs. Although you would be surprised at how many people do exactly that. First you need to determine which electrical devices you need to run and then add up the number of watts hat are required to run them - this will be shown either on manufacturer's labels or accompanying manuals. You also need to determine if they have a starting wattage requirement, such as a refrigerator. If they do, then use this reading instead. Once you have added all these together this will be the minimum wattage your electric generator will need to produce. It is always a good idea to add an extra 20 - 25% to give you some extra leeway
2. Diesel, gasoline, LP or natural gas? There are an enormous amount of gasoline electric generators on the market now which offer great warranties and are perfectly suited for small business, recreation, and emergency use. One thing that should be remembered with them is that they are not usually designed to work for long periods of time under load. If this is what you require of your electric generator then diesel would be a far better option. It is worth considering a diesel electric generator if you are looking for a prime power source. These are more fuel efficient and dependable.
3. Brand name? Recognized brand names which have a good reputation are best. You will have easy access to service centers, support and parts. Yamaha, Honda and Briggs and Stratton are well named brands who produce many different models of electric generator.
4. Emergency shutdown? There are some features that are very desirable on an electric generator which can mean the difference between a seized engine to one that has automatically shut itself down. Low oil shutdown is one of the most important ones and it is activated when the oil level drops below a safe operating level.
Times have changed and more and more people are finding that the electric generator brings them security, convenience and much peace of mind.
Courtesy- indieselgenerators.com
Sunday, September 16, 2007
SOLAR ELECTRICITY
HAVE YOU EVER THOUGHT ABOUT SOLAR ELECTRICITY, THAT IS, ELECTRICITY FROM THE SUN?
IN AFRICA THESE IS NOT PREDOMINANT DESPITE THE AVAILABLE AND ABUNDANT SOLAR RESOURCES, BUT SOLAR ELECTRICITY IS A VIABLE ALTERNATIVE TO CONVENTIONAL POWER SUPPLY.
HOW DO WE GET SOLAR ELECTRICITY?-
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.
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 12volts, 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.
Let’s consider some fallacies about the solar cells
1. PV is too costly and will never compete with "the big boys" of power generation. Besides, you can never get the energy out that it takes to produce the system.
The cost of producing PV modules, in constant dollars, has fallen from as much as $50 per peak watt in 1980 to as little as $3 per peak watt today. This causes PV electricity costs to drop 15¢-25¢ per kilowatt hour (kWh), which is competitive in many applications
2. Solar electricity cannot serve any significant fraction of world electricity needs.
PV technology can meet electricity demand on any scale. The solar energy resource in a 100-mile-square area of Nevada could supply the United States with all its electricity (about 800 gigawatts) using modestly efficient (10%) commercial PV modules.
3. Solar electricity can do everything — right now!
No way. Solar electricity will eventually become a major player in the world's energy portfolio. The industry just doesn't have the capacity to meet all demands right now. But assuming that the proper investments are made now and are sustained, the industry will become significant in the next few decades.
4. Photovoltaic is a polluting industry.
The PV industry is neither "squeaky clean" nor a major environmental, safety, or health problem. When it comes to emissions, PV's electricity-generating portion of the fuel cycle is the clear winner versus fossil fuel sources.
Watch out for more details in subsequent posts, but if you need more details, please contact me. I would be showcasing some inverters in the maeket shortly and the price ranges. I will also be comming up with some special packages on inverters and others very soon.
IN AFRICA THESE IS NOT PREDOMINANT DESPITE THE AVAILABLE AND ABUNDANT SOLAR RESOURCES, BUT SOLAR ELECTRICITY IS A VIABLE ALTERNATIVE TO CONVENTIONAL POWER SUPPLY.
HOW DO WE GET SOLAR ELECTRICITY?-
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.
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 12volts, 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.
Let’s consider some fallacies about the solar cells
1. PV is too costly and will never compete with "the big boys" of power generation. Besides, you can never get the energy out that it takes to produce the system.
The cost of producing PV modules, in constant dollars, has fallen from as much as $50 per peak watt in 1980 to as little as $3 per peak watt today. This causes PV electricity costs to drop 15¢-25¢ per kilowatt hour (kWh), which is competitive in many applications
2. Solar electricity cannot serve any significant fraction of world electricity needs.
PV technology can meet electricity demand on any scale. The solar energy resource in a 100-mile-square area of Nevada could supply the United States with all its electricity (about 800 gigawatts) using modestly efficient (10%) commercial PV modules.
3. Solar electricity can do everything — right now!
No way. Solar electricity will eventually become a major player in the world's energy portfolio. The industry just doesn't have the capacity to meet all demands right now. But assuming that the proper investments are made now and are sustained, the industry will become significant in the next few decades.
4. Photovoltaic is a polluting industry.
The PV industry is neither "squeaky clean" nor a major environmental, safety, or health problem. When it comes to emissions, PV's electricity-generating portion of the fuel cycle is the clear winner versus fossil fuel sources.
Watch out for more details in subsequent posts, but if you need more details, please contact me. I would be showcasing some inverters in the maeket shortly and the price ranges. I will also be comming up with some special packages on inverters and others very soon.
YOUR INVERTER'S BATTERY
We can not really talk about the inverter without talking about the battery which powers it (though in some application we shall be seeing later, this may not be necessary). Here are tips you need to know about the battery
HOW LONG CAN MY BATTERY POWER THE INVERTER?
As how long as you want your load to run? The load to be supported by the inverter can be determined. After this is known, specific calculations can be made to determine the proper battery bank size.
WHAT TYPES OF BATTERIES ARE APPROPRIATE FOR MY INVERTERS?
There are two principal types of batteries: starting and deep-discharge. Batteries can be either sealed or non-sealed (vented).
Deep discharge types
The battery types recommended for use in an inverter system are: Flooded Lead Acid
(FLA), Sealed Gel Cells (GEL), Sealed Absorbed Glass Mat (AGM); and alkaline types
such as Nickel-iron (NiFe) and Nickel-Cadmium (NiCad).
Starting Automotive (starting) batteries
Are designed to provide high starting current for short periods of time and are not appropriate for inverter applications.
Deep-cycle Flooded Lead Acid (FLA)
Description- A flooded lead acid battery is designed to be deep-discharged before being recharged, making it suitable for inverter applications. Flooded batteries require periodic maintenance consisting mainly of adding distilled water to the cells.
Sealed Batteries (Gel and AGM)
Description- Gel Cell and Absorbed Glass Mat (AGM) batteries are sealed and do not require the addition of distilled water. Since these batteries are valve regulated, over-charging can
cause irreversible damage.
NiCad and NiFe Batteries
These types of batteries can be used but may not be the best for your inverter for the
following reasons:
• Alkaline batteries, such as NiCad and NiFe types, have a nominal cell voltage of 1.2
volts per cell, whereas most inverters and battery chargers are optimized for use with lead acid
batteries having a nominal 2.0 volts per cell (that is, 12 cells for a 24-volt system and
24 cells for a 48-volt system).
• Alkaline batteries require a higher charge voltage to fully recharge, and drop to a
lower voltage during discharge compared to a similarly sized lead-acid type battery.
Battery Capacity Ratings
Amp-hour capacity-
Every deep cycle battery has a capacity which is measured in amp hours. Amp hours are a measure of current flow over time. An amp-hour figure is derived simply by multiplying
current (amperes) by the amount of time the current flows (hours) andare frequently referred to by the abbreviations A-h
As how long as you want your load to run? The load to be supported by the inverter can be determined. After this is known, specific calculations can be made to determine the proper battery bank size.
WHAT TYPES OF BATTERIES ARE APPROPRIATE FOR MY INVERTERS?
There are two principal types of batteries: starting and deep-discharge. Batteries can be either sealed or non-sealed (vented).
Deep discharge types
The battery types recommended for use in an inverter system are: Flooded Lead Acid
(FLA), Sealed Gel Cells (GEL), Sealed Absorbed Glass Mat (AGM); and alkaline types
such as Nickel-iron (NiFe) and Nickel-Cadmium (NiCad).
Starting Automotive (starting) batteries
Are designed to provide high starting current for short periods of time and are not appropriate for inverter applications.
Deep-cycle Flooded Lead Acid (FLA)
Description- A flooded lead acid battery is designed to be deep-discharged before being recharged, making it suitable for inverter applications. Flooded batteries require periodic maintenance consisting mainly of adding distilled water to the cells.
Sealed Batteries (Gel and AGM)
Description- Gel Cell and Absorbed Glass Mat (AGM) batteries are sealed and do not require the addition of distilled water. Since these batteries are valve regulated, over-charging can
cause irreversible damage.
NiCad and NiFe Batteries
These types of batteries can be used but may not be the best for your inverter for the
following reasons:
• Alkaline batteries, such as NiCad and NiFe types, have a nominal cell voltage of 1.2
volts per cell, whereas most inverters and battery chargers are optimized for use with lead acid
batteries having a nominal 2.0 volts per cell (that is, 12 cells for a 24-volt system and
24 cells for a 48-volt system).
• Alkaline batteries require a higher charge voltage to fully recharge, and drop to a
lower voltage during discharge compared to a similarly sized lead-acid type battery.
Battery Capacity Ratings
Amp-hour capacity-
Every deep cycle battery has a capacity which is measured in amp hours. Amp hours are a measure of current flow over time. An amp-hour figure is derived simply by multiplying
current (amperes) by the amount of time the current flows (hours) andare frequently referred to by the abbreviations A-h
Discharge rate
Deep cycle batteries have their amp-hour rating expressed as "at the x-hour rate". This is
an average rate of current flow that would take x number of hours to discharge the
batteries. Common amp-hour figures are at the 6-hour rate, the 20-hour rate and the 100-
hour rate. A battery is classified as having fewer amp-hours if is being discharged at a
faster rate, such as the 6-hour rate. There is an inevitable amount of heat associated with
the flow of current through a battery. The higher the amount of current, the greater the
amount of heat generated. The heat is energy which is no longer available to the battery to
power loads. Hence, at a higher discharge rate, the batteries effectively have fewer amp
hours available. Generally the 20-hour rate is the most common one.
CCA rating-Starting batteries are rated in CCA (Cold Cranking Amps), or other types of "cranking
amps". This expresses battery capacity in terms of its ability to provide large amounts of
current instantaneously to start an engine. It has no time factor, such as hours, taken into
account. This is one reason that starting batteries are not appropriate for inverter systems.
However, batteries such as marine starting batteries, are rated in both CCA and amp
hours. This type is appropriate.
Running time and size
The battery bank’s size determines the length of time the inverter can supply AC output
power. The larger the bank, the longer the inverter can run and the longer the recharge
time.
Depth of discharge. In general, the battery bank should be designed so the batteries do not discharge more than 50% of their capacity on a regular basis. Discharging up to 80% is acceptable on a limited basis, such as a prolonged utility outage. Totally discharging a battery can reduce its effective life or permanently damage it.
Deep cycle batteries have their amp-hour rating expressed as "at the x-hour rate". This is
an average rate of current flow that would take x number of hours to discharge the
batteries. Common amp-hour figures are at the 6-hour rate, the 20-hour rate and the 100-
hour rate. A battery is classified as having fewer amp-hours if is being discharged at a
faster rate, such as the 6-hour rate. There is an inevitable amount of heat associated with
the flow of current through a battery. The higher the amount of current, the greater the
amount of heat generated. The heat is energy which is no longer available to the battery to
power loads. Hence, at a higher discharge rate, the batteries effectively have fewer amp
hours available. Generally the 20-hour rate is the most common one.
CCA rating-Starting batteries are rated in CCA (Cold Cranking Amps), or other types of "cranking
amps". This expresses battery capacity in terms of its ability to provide large amounts of
current instantaneously to start an engine. It has no time factor, such as hours, taken into
account. This is one reason that starting batteries are not appropriate for inverter systems.
However, batteries such as marine starting batteries, are rated in both CCA and amp
hours. This type is appropriate.
Running time and size
The battery bank’s size determines the length of time the inverter can supply AC output
power. The larger the bank, the longer the inverter can run and the longer the recharge
time.
Depth of discharge. In general, the battery bank should be designed so the batteries do not discharge more than 50% of their capacity on a regular basis. Discharging up to 80% is acceptable on a limited basis, such as a prolonged utility outage. Totally discharging a battery can reduce its effective life or permanently damage it.
Battery Configurations
The battery bank must be wired to match the inverter’s DC input voltage specifications. In
addition, the batteries can be wired to provide additional run time. The various wiring
configurations are:
The battery bank must be wired to match the inverter’s DC input voltage specifications. In
addition, the batteries can be wired to provide additional run time. The various wiring
configurations are:
1. Series Wiring batteries in series increases the total bank output voltage. This voltage MUST
match the DC requirements of the inverter or inverter and/or battery damage may occur.
2. Parallel Wiring the batteries in parallel increases the total run time the batteries can operate the AC loads. The more batteries connected in parallel the longer the loads can be powered from
the inverter.
3. Series-Parallel Series-parallel configurations increase both the battery voltage (to match the inverter’s DC requirements) and run-time for operating the AC loads. This voltage must match the DC requirements of the inverter.
match the DC requirements of the inverter or inverter and/or battery damage may occur.
2. Parallel Wiring the batteries in parallel increases the total run time the batteries can operate the AC loads. The more batteries connected in parallel the longer the loads can be powered from
the inverter.
3. Series-Parallel Series-parallel configurations increase both the battery voltage (to match the inverter’s DC requirements) and run-time for operating the AC loads. This voltage must match the DC requirements of the inverter.
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