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Solar Energy

The sun emits energy 24 hours per day, 365 days per year more than enough to supply the world's energy demand. However, the earth rotates and the earth's surface is exposed to solar energy for only about half of each day; and clouds and dust, sometimes reduce the amount of solar energy reaching the earth's surface.

Solar Radiation Varies with Location

The annual average daily solar radiation is highest where the atmosphere is very dry.

For example, in the western desert regions of USA, Arizona, Nevada, and California, the annual average daily direct solar radiation ranges from 8.5 to 9.0 kWh/m2 at some locations. However, along the US Pacific coastline, where moisture levels in the atmosphere are higher, it drops to less than 6.0 kWh/m2, even without changes in latitude.

Solar Energy

The sun emits energy 24 hours per day, 365 days per year more than enough to supply the world's energy demand. However, the earth rotates and the earth's surface is exposed to solar energy for only about half of each day; and clouds and dust, sometimes reduce the amount of solar energy reaching the earth's surface.

 Solar Radiation Varies with Location

The annual average daily solar radiation is highest where the atmosphere is very dry.

For example, in the western desert regions of USA, Arizona, Nevada, and California, the annual average daily direct solar radiation ranges from 8.5 to 9.0 kWh/m2 at some locations. However, along the US Pacific coastline, where moisture levels in the atmosphere are higher, it drops to less than 6.0 kWh/m2, even without changes in latitude.

Forms of Solar Energy

Solar energy can be converted to thermal and photopic energy.Solar thermal is heat energy, which can be used directly in heating water for residential or commercial use.

Heat may be stored in a thermal medium such as heating water, dry rocks or other materials for later use. Heat may be transferred in boilers and heat exchangers to produce steam or other vapours and converted to mechanical or electrical energy by means of steam engines or turbines and generators.

Solar photopic devices directly absorb photons of light that act as individual units of energy--without complete conversion to heat.

The absorber then either converts the photon energy to electricity as in a photovoltaic PV cell or stores it as chemical energy through a chemical reaction as in photosynthesis or the dissociation of water into hydrogen and oxygen

Solar Electrical Power.

Present day PV array installations require around 8 to 12 m2 per kW of peak power. A very large area is therefore required to produce dispatch able electricity using a PV system.

Enough PV cells to generate 1 MW, for example, would occupy between 8,000 and 12,000 m2Improvements in manufacturing, performance, and quality of PV modules are helping to reduce costs and open up more opportunities for Solar Electricity.

Common applications include battery charging for navigational aids, signals, telecommunications equipment, and other critical, low-power needs.

PV cells have became a popular power source for consumer electronic devices, including calculators, watches, radios, lanterns, and other small battery-charging applications.

Significant advances have been made in developing PV power systems for residential and commercial uses for both for stand-alone, remote power as well as for grid-connected applications.

Applications of PV systems to power rural health clinics, refrigeration, water pumping, telecommunications, for off-grid households has increased dramatically, and remains a major portion of the present world market for PV products.

Solar Thermal Energy

Solar thermal energy is used in many localized uses and for dispatchable uses commonly referred to as concentrating solar power (CSP) technology.

CSP technology utilizes mirrors to concentrate radiation so that it can be captured in the form of heat. That heat is then converted to electricity by using conventional technology.

Commercial CSP parabolic trough plants have been constructed in desert areas of USA. And in several European Union countries, including Germany, Spain, and Italy, as well as in Israel and South Africa.

CSP technology encompasses four technological approaches--trough, power tower, dish/engine and tracking mirrors

The trough and power tower approaches are suitable for producing grid electricity, as is a tracking mirror system

The dish/engine system also may be configured to produce grid electricity, and the modular character of dish/engine systems makes this approach suitable for small-scale distributed applications as well.

Trough Systems.

A trough system consists of a large field of single-axis tracking parabolic concentrators, arranged in parallel rows that focus sunlight on receivers running along the focal lines of the concentrators. The solar field is modular and the rows of concentrators are aligned on a north-south horizontal axis. The concentrators, track the sun from east to west during the day in order to keep the sunlight focused on the linear receiver, are made up of parabolic reflectors (mirrors), metal support structures, receiver tubes, and tracking systems that include drives, sensors, and controls.

A heat transfer fluid is pumped through the linear receiver where it becomes heated. The heat transfer fluid then circulates through a series of heat exchangers where the fluid is used to generate high-pressure superheated steam. The superheated steam is fed to a conventional reheat steam turbine/generator to produce electricity. The spent steam is condensed in a standard condenser and recycled.

A cooling tower or once-through system removes excess heat from the condenser. The cooled heat transfer fluid is recirculated through the linear receiver. Plant output may range from 1.0 to 100 MW of electricity.

Current solar trough technology produces about 100 kWh/yr per square meter of collector surface

Power Tower Systems.

In a power tower system (also called a central receiver), a field of large two-axis, flat, tracking mirrors reflects the solar energy onto a receiver that is mounted on top of a centrally located tower

The solar energy is absorbed by a working fluid (typically molten salt or water) is then used to generate steam, which powers a turbine.

Even when the sun is not shining, some designs can effectively store thermal energy for hours (either in the working fluid for molten salt systems or in such materials as rock or sand for a water/steam system) if desired, to allow electricity production during periods of peak need.

 In a molten salt system, the molten salt is pumped at 290ºC from a "cold" tank and cycled through the receiver, where it is heated to about 565ºC and returned to a "hot" tank. The hot salt can then be used during the next 3 to 13 hours to generate electricity when needed.

SOLAR ENERGY SUMMARY

Solar energy can be converted to other more usable energy forms through a variety of technologies that are divided into two categories: thermal and photonic.

Grid electricity can be produced using either thermal technological approaches, called CSP systems, or photonic technological approaches, called PV systems.

CSP technology utilizes mirrors to focus the solar radiation so that it can be captured in the form of heat. That heat is then converted to electricity by using conventional technologies.

PV technology converts sunlight (direct and scattered) directly into electricity when a PV cell absorbs and transfers the energy of the light to electrons in the atoms of the cell. PV cells may be arranged into flat-plate PV systems or CPV systems.

Like CSP technology, CPV systems focus sunlight. However, rather than focusing sunlight to capture its heat energy as CSP technology does, CPV systems utilize mirrors

 Typical Life Expectancy for A Solar Battery 

4000 cycles to 10% discharge

3000 cycles to 50%

1500 cycles to 80%

From the above information provided by a Tasmanian Solar Installer, you can determine life expectancy of your Solar Battery: A solar system discharged on average 10% per day could be expected to have a battery life of around 4000 days or 10.9 years.

If you were a little harder on your battery and discharged it to 80% down every day before recharging it fully you could expect a battery life of around 4.1 years.

Given that the worst thing you can do to a battery is to leave it standing around "flat" and a daily discharge of 80% is enormous and in reality not likely. Your battery life is realistically about 8 - 15 years. Quite commonly, good quality deep cycle batteries are still in service after 20 or more years so the above figures are conservative.

Worlds Smallest Desktop Computer

The World's Smallest Desktop does the same job and consumes more than 4 times less electrical power than a conventional (280W) computer claim the manufacturers, E-nano.

That means that a single 80W Solar Panel can now run 2 or 3 Energy Saving Lights in your Off grid Office or Home as well as a new small form 'E-nano' energy saving desktop PC connected to the broadband internet and more.

Alternatively, in a big city office with 100 desktops you could save over $15,000 per year in computer electricity costs. This is assuming each computer uses 800 WH less per day, averages 40 hours work per week and electricity costs 15 Cents per KWH.

Have you ever thought that your big old desktop computer box may be too large, noisy and hot for your needs?

.The super efficient E-nano desktop runs at about 20 - 25 watts for average computing and at about 40 watts under heavy load.

It can be tucked away under your desk or be part of the kitchen or any room in the house to extend broadband Internet anywhere you can think of.

Energy Saving Refrigeration

According to Mr. Electricity you can make a fridge that uses 90% less electricity than a normal fridge. Tom Chalko in Australia has figured out a way to make a super-efficient refrigerator that uses a mere 0.1 kWh a day. The trick is to just use a chest freezer as a fridge, after installing a new thermometer to turn the freezer off when the temperature drops too low.

Chest freezers are more efficient than fridges because they have more insulation and because the cold air doesn't spill out when you open the door, because cold air falls down, not up.

There are a couple of obvious downsides. First is that it might not be as easy for you to access your food in a chest freezer. Another is that the new fridge will take up more floor space. Finally, you'll need a separate freezer. But if things don't put you off, then you can save quite a bit of energy.

Questions and Answers

Q. Name four energy sources used by humans to source electricity besides fossil and nuclear fuels.      

 A. Water, air, fire and earth.

       Water Energy sources is hydroelectric energy, wave energy and tidal energy.

       The Air Energy source is wind.

       The Fire Energy source is the Sun or Solar Energy, which can produce electricity using

        Photovoltaic cells or thermal energy to turn water to steam and turn turbine generators.

        Earth energy is in the form of crops, wood, biomass and organic materials. Geothermal Energy

        Comes from underground stored heat.

Q.   What is Energy Security?

A.   Energy security is access to reliable energy supplies, which is fundamental to every country's economy.

Q    What does a watt, ohm, amp and volt have to do with solar energy and where do they come from.

A.  Solar energy can be converted into electricity and watts, ohm's, amps and volts are electrical units. A Watt is a unit of power named after James Watt a Scottish Engineer who invented fundamental improvements to the steam engine, which led to the Industrial Revolution. An Ohm is a unit of electrical resistance named after the German physicist Georg Ohm Ohm's Law of electricity is Watts = Volts x Amps. An Amp is the unit of electric current named after the French Physicist Andre- Marie Ampere, one of the main discoverer's of electromagnetism. A Volt is a unit of electromotive force named in honor of Physicist Alexandro Volta who invented the voltaic pile or the first chemical battery.

Q.    How can we utilize solar energy in agriculture?

A.     Solar Energy can be used to produce light, heat, water and electricity on the farm. Agricultural uses could be drying crops, heating buildings, powering a water pump or making your farmhouse more efficient. Renovate buildings and sheds to use natural light and skylights. Warm livestock buildings with heat boxes and fans. Consider solar water heaters for hot water for pen cleaning and cleaning farm equipment. Greenhouses and electric fences may be possible. Financing solar energy equipment as part of a mortgage and depreciating it, as a business expense may be something you could take a look at.

 
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