Saturday, March 13, 2010

How to Convert Solar Energy Into Electricity

Most of the energy on earth comes from the sun. It warms, lights and provides us with nutrients. Clean wind and wave power is nothing but indirect solar energy. Our food supply is based on plants that have captured solar energy through photosynthesis. We, too, can convert this solar energy into an energy that is accessible for our needs.
1
Understand solar energy. Solar energy is heat and light, which has the qualities of waves and individual particles called photons across a vast range of the electromagnetic spectrum. The sun is a nuclear furnace, converting hydrogen to helium through nuclear fusion. The sun releases the energy of 100 billion H-bombs every second. It's a very efficient process, converting mass directly to energy through Albert Einstein's famous equation: E= MC2 where E is energy, M is Mass and C is the speed of light times itself. At 186,000 miles per second light is the fastest speed in the universe. A tiny bit of mass can make a vast amount of energy.
Step
2
Realize how energy is converted. Energy is transformed from one form to another by a device known as a transducer. A microphone converts the sound waves to electricity. To convert solar radiation to electricity we need to start with a solar panel.
Step
3
Look into solar panels. Solar photo voltaic cells (PVC) are essentially semi-conductors, which have electrical transmission properties existing between conductors like metal or salt water and insulators like rubber. Solar panels are constructed with sheets of doped silicon, the primary element in beach sand, with impurities added like phosphorus that allow electrons to flow. When the kinetic solar energy of moving photons hits a PVC, a flow of electrons starts that can be drawn off by a pair of wires, creating direct current (DC) like a battery.
Step
4
Check with your local utility for rebates and with your state government and the federal government for tax breaks. Once you get a clear understanding as to what help is available, do the math. In many states a solar system will pay for itself in a dozen years. In all cases, if you finance a solar installation with a home equity loan, the interest is tax-deductible.
Step
5
Install solar panels in an area, preferably a roof, where they will get the most unobstructed exposure to the sun for most of the year. The best way to do this is to get a reliable solar contractor by referral. In some cases, calling your local utility is a good place to start.
Step
6
Get and install an inverter. Unlike battery power, your house current is alternating, which reverses directing sixty times a second. Before using solar energy to power your appliances, it has to be converted by a device known as an inverter. With most utilities today an inverter will also allow you to feed power back to the electric grid so on a bright sunny day, while you are at work, your electric meter will run backwards.

How many solar cells would I need in order to provide all of the electricity that my house needs?


f you have read the HSW article entitled How Solar Yard Lights Work, then you can get a feeling for how much power a solar cell can produce. The solar panel shown in that article contains 4 cells, and each of them can produce 0.45 volts and 100 milliamps, or 45 milliwatts. Each cell measures 2 inches by 0.5 inches. In other words, with these solar cells you can generate 45 milliwatts in one square inch (6.45 square cm). For the sake of discussion, let's assume that a panel can generate 70 milliwatts per square inch.
To calculate how many square inches of solar panel you need for a house, you need to know:

How much power the house consumes on average.
Where the house is located (so you can calculate mean solar days, average rainfall, etc.). This question is impossible to answer unless you have a specific location in mind. We'll assume that on an average day the solar panels generate their maximum power for 5 hours.
The first question is actually pretty interesting, so let's work on it.
A "typical home" in America can use either electricity or gas to provide heat -- heat for the house, the hot water, the clothes dryer and the stove/oven. If you were to power a house with solar electricity, you would certainly use gas appliances because solar electricity is so expensive. This means that what you would be powering with solar electricity are things like the refrigerator, the lights, the compute r, the TV, stereo equipment, motors in things like furnace fans and the washer, etc. Let's say that all of those things average out to 600 watts on average. Over the course of 24 hours, you need 600 watts * 24 hours = 14,400 watt-hours per day.
From our calculations and assumptions abo ve, we know that a solar panel can generate 70 milliwatts per square inch * 5 hours = 350 milliwatt hours per day. Therefore you need about 41,000 square inches of solar panel for the house. That's a solar panel that measures about 285 square feet (about 26 square meters). That would cost around $16,000 right now. Then, because the sun only shines part of the time, you would need to purchase a battery bank, an inverter, etc., and that often doubles the cost of the installation.

If you want to have a small room air conditioner in your bedroom, double everything.

Because solar electricity is so expensive, you would normally go to great lengths to reduce your electricity consumption. Instead of a desktop computer and a monitor you would use a laptop computer. You would use fluorescent lights instead of incandescent. You would use a small B&W TV instead of a large color set. You would get a small, extremely efficient refrigerator . By doing these things you might be able to reduce your average power consumption to 100 watts. This would cut the size of your solar panel and its cost by a factor of 6, and this might bring it into the realm of possibility.

The thing to remember, however, is that 100 watts per hour purchased from the power grid would only cost about 24 cents a day right now, or $91 a year. That's why you don't see many solar houses unless they are in very remote locations. When it only costs about $100 a year to purchase power from the grid, it is hard to justify spending thousands of dollars on a solar system.

How I built an electricity producing Solar Panel

Several years ago I bought some remote property in Arizona. I am an astronomer and wanted a place to practice my hobby far away from the sky-wrecking light pollution found near cities of any real size. I found a great piece of property. The problem is, it's so remote that there is no electric service available. That's not really a problem. No electricity equals no light pollution. However, it would be nice to have at least a little electricity, since so much of life in the 21st century is dependant on it.

I built a wind turbine to provide some power on the remote property. It works great, when the wind blows. However, I wanted more power, and more dependable power. The wind seems to blow all the time on my property, except when I really need it too. I do get well over 300 sunny days a year on the property though, so solar power seems like the obvious choice to supplement the wind turbine. Solar panels are very expensive though. So I decided to try my hand at building my own. I used common tools and inexpensive and easy to acquire materials to produce a solar panel that rivals commercial panels in power production, but completely blows them away in price. Read on for step by step instructions on how I did it.

SOLAR ELECTRICITY EXPLAINED


Solar electricity is created by using Photovoltaic (PV) technologyby converting solar energy into solar electricity from sunlight. Photovoltaic systems use sunlight to power ordinary electrical equipment, for example, household appliances, computers and lighting. The photovoltaic (PV) process converts free solar energy - the most abundant energy source on the planet - directly into solar power. Note that this is not the familiar "passive" or Solar electricity thermal technology used for space heating and hot water production.

A PV cell consists of two or more thin layers of semi-conducting material, most commonly silicon. When the silicon is exposed to light, electrical charges are generated and this can be conducted away by metal contacts as direct current (DC). The electrical output from a single cell is small, so multiple cells are connected together and encapsulated (usually behind glass) to form a module (sometimes referred to as a "panel"). The PV module is the principle building block of a PV system and any number of modules can be connected together to give the desired electrical output.

PV equipment has no moving parts and as a result requires minimal maintenance. It generates solar electricity without producing emissions of greenhouse or any other gases, and its operation is virtually silent.

What is PV power used for?

PV systems supply solar electricity to many applications in the UK, ranging from systems supplying power to city buildings (which are also connected to the normal local solar power network) to systems supplying power to garden lights or to remote telecom relay stations.

The main area of interest in the UK today is grid connect PV systems. These systems are connected to the local solar electricity network. This means that during the day, the solar electricity generated by the PV system can either be used immediately (which is normal for systems installed on offices and other commercial buildings), or can be sold to one of the electricity supply companies (which is more common for domestic systems where the occupier may be out during the day). In the evening, when the electrical system is unable to provide the electricity required, power can be bought back from the network. In effect, the grid is acting as a Solar electricity energy storage system, which means the PV system does not need to include battery storage.

Grid connect PV systems are often integrated into buildings. PV technology is ideally suited to use on buildings, providing pollution and noise-free solar power without using extra space. The use of photovoltaics on buildings has grown substantially in the UK over the last few years, with many impressive examples already in operation.

PV systems can be incorporated into buildings in various ways. Sloping rooftops are an ideal site, where modules can simply be mounted using frames. Photovoltaic systems can also be incorporated into the actual building fabric, for example PV roof tiles are now available which can be fitted as would standard tiles. In addition, PV can also be incorporated as building facades, canopies and sky lights amongst many other applications.

Stand-alone photovoltaic systems have been used for many years in the UK to supply solar electricity to applications where grid solar power supplies are unavailable or difficult to connect to. Examples include monitoring stations, radio repeater stations, telephone kiosks and street lighting. There is also a substantial market for PV technology in the leisure industry, with battery chargers for boats and caravans, as well as for powering garden equipment such as solar electricity fountains. These systems normally use batteries to store the solar power, if larger amounts are required they can be combined with another source of power - a biomass generator, a wind turbine or diesel generator to form a hybrid power supply system.

PV technology is also widely used in the developing world. The technology is particularly suited here, where electricity grids are unreliable or non-existent, with remote locations often making PV power supply the most economic option. In addition, many developing countries have high solar radiation levels year round.

Electricity from: Solar Energy


he ultimate source of much of the world's energy is the sun, which provides the earth with light, heat and radiation. While many technologies derive fuel from one form of solar energy or another, there are also technologies that directly transform the sun's energy into electricity.


The sun bathes the earth in a steady, enormous flow of radiant energy that far exceeds what the world requires for electricity fuel.
Since generating electricity directly from sunlight does not deplete any of the earth's natural resources and supplies the earth with energy continuously, solar energy is a renewable source of electricity generation. Solar energy is our earth's primary source of renewable energy.

There are two different approaches to generate electricity from the sun: photovoltaic (PV) and solar-thermal technologies.

Initially developed for the space program over 30 years ago, PV, like a fuel cell, relies upon chemical reactions to generate electricity. PV cells are small, square shaped semiconductors manufactured in thin film layers from silicon and other conductive materials. When sunlight strikes the PV cell, chemical reactions release electrons, generating electric current. The small current from individual PV cells, which are installed in modules, can power individual homes and businesses or can be plugged into the bulk electricity grid.

Solar-thermal technologies are, more or less, a traditional electricity generating technology. They use the sun's heat to create steam to drive an electric generator. Parabolic trough systems, like those operating in southern California, use reflectors to concentrate sunlight to heat oil which in turn creates steam to drive a standard turbine.

Two other solar-thermal technologies are nearing commercial status. Parabolic dish systems concentrate sunlight to heat gaseous hydrogen or helium or liquid sodium to create pressurized gas or steam to drive a turbine to generate electricity. Central receiver systems feature mirrors that reflect sunlight on to a large tower filled with fluid that when heated creates steam to drive a turbine.

What are the environmental impacts?

PV systems operate without producing air, water or solid wastes.
When constructed as grid-connected central station systems, they require significant land, which can impact existing ecosystems. Nevertheless, most PV installations come in the form of distributed systems that use little or no land since the panels are installed on buildings.

Manufacturing PV cells involves the generation of some hazardous materials. Nonetheless, appropriate handling of these small quantities of hazardous material reduces risks of exposure to humans and to the environment.

Like PV, solar-thermal technologies generate zero air emissions, though some emissions are created during the manufacture of both technologies. Water use for solar thermal plants is similar to amounts needed for a comparably sized coal or nuclear plants.

The biggest concern with solar technologies may be land use...
...since five acres of land are often needed for each megawatt of capacity. PV can eliminate the land use impacts by integrating the generators into building construction, eliminating the need for dedicating land use to PV generation.

How Do You Produce Electricity From Solar Energy


The answer to the question of how do you produce electricity from solar energy is fairly easy to understand once you have a slight knowledge of the subject.
Before you are able to produce electricity through solar energy, there needs to be some form of solar cell or panel.The solar panels are made of a semi-conductive material, the most common material is silicon.The semi-conductive material contains electrons which are quite happy just sitting there.When photons (contained within the suns rays) hit the solar cells, the electrons absorb this solar energy, transforming them into conduction electrons.If the energy of these photons is great enough, then the electrons are able to become free, and carry an electric charge through a circuit to the destination.Any electrons that do not receive enough energy simply warm up, which heats your cell or panel, resulting in lowering the efficiency of the cellThe lowering in efficiency is down to two main factors and they are; that the cell is not working to its full potential (e.g. some electrons may be lost), the second factor is when the electrons release heat, the panel also becomes warm, interfering with other aspects of the solar cells.