Solar Water Heating

One of the easiest installs to perform to get an immediate cost savings is solar water heating. It also happens to be one of the simplest things to change out when migrating to a green home.

Most people think of solar power in terms of large, dark blue panels supplying electricity to a home or business. While this is a very popular application there are other ways to harness the energy of the sun. Solar heating is one, and its roots actually go back much further back than the use of photovoltaic arrays. The use of direct sunlight for heating water dates back thousands of years to ancient Greece where crude mirrors and lenses were used to harness the sun’s energy for heating water.

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Solar Power History

Human use of the sun’s energy may seem like a recent phenomenon but solar energy has been in use in various forms for thousands of years. The sun is necessary to the growth of the plants that we eat and there are also more technological uses of the sun’s energy that go back millennia.

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The Tools You Need to Go Solar

To implement solar heating and power for your home requires a number of relatively expensive items; which over the long run can be cost effective. Changing to effective solar systems requires the right technology and some planning. First, you need to estimate how much electricity you require to run your home. If all you want to do is supplement your power needs; that is fine just calculate the percentage you want to offset.

The cost should be offset against what you would pay for electricity from the power company over the lifetime of the system..

A glance at your electricity bill will make the task easier as most utility bills will show a chart of month by month usage throughout the year. You can average the total, or use the peak demand. If you plan to go ‘off grid’ i.e. stop using power from the utility company completely, then you need to focus on the peak. Those numbers will allow you to estimate how many and what size PV modules you need. PV is short for photovoltaic, the method almost all solar cells use to convert sunlight into electricity. Matching the area of your south-facing rooftop section to the number and size of modules needed is a matter of simple arithmetic.

Each module will generate a certain amount of power at a given cost, when connected the right way the modules add up, so finding the total output (and cost) is equally easy. For a modest-sized home, the cost of panels is about $10,000-$16,000 at current prices. But bear in mind when you are planning the expense that there are tax rebates and other programs that will help you offset the amount invested.

..uncontrollable factors reduce the amount of sunlight available this means that almost anyone going ‘off grid’ will want a battery storage system.

Modules alone will not do it, they have to connect to something. The connectors, clamps, wires and other components add to the total. These vary considerably and you will also need to add something for installation costs as most homeowners don’t have the skill to build the system themselves.

The sun doesn’t shine all day every day it is dark at night and rain and heavy cloud cover will reduce the amount of insulation, as it’s called. Other uncontrollable factors reduce the amount of sunlight available this means that almost anyone going ‘off grid’ will want a battery storage system. Those not taking the complete plunge can draw power from the local utility company during those times.

If your system generates more than you need at any given time, some utility companies will enter into an agreement to buy any excess you put into their system. This is usually done technically by running your meter backwards when you’re supplying the utility company – normally it runs forward as you draw power from their system.

The company will insist on inspecting your system before finalizing any agreement and most municipalities will require that you have your system inspected and approved even if you go entirely off grid. They need to ensure that it’s implemented to a standard that is safe for local lineman. During power outages they have to assume there is no power running through the lines – your system has to be installed in a way that guarantees that.

Between panels, batteries, installation costs and other expenses most modest-sized solar panel systems will cost around $32,000-$50,000 – some less, some more. The cost should be offset against what you would pay for electricity from the power company over the lifetime of the system, usually about 20 years without substantial replacements.

Costs are falling and efficiency is improving as time goes on while the price of electricity continues to rise. In the near future it may well be worth your while to have a solar powered electrical system for your home.

Solar Technology and Cost – An Overview

Solar power technology has been around in some form or another for thousands of years and even many so called modern solar devices and designs are now decades old. Yet, they have not fulfilled the promise that many hope due to their high cost and lower efficiency.

There are approximately 1,000 watts per square meter of sunlight power falling on the surface of the Earth (at the equator) but only a small portion can get converted into usable electricity. Part of the problem is the result of internal losses of all the photons that hit a solar panel, only some will knock loose an electron – and not all of these will travel down the module and into the device before being recaptured.

The latter effect is due to something called carrier lifetime. The longer the electrons wander around loose, the more likely they are to flow out of the module and down the wires to an outlet. Most modules can only achieve around 10-15% efficiency, although several companies have raised the efficiency of their devices to as much as 20% by extending that carrier lifetime.

Solar thermal devices, on the other hand, use sunlight-heated salt water panels to generate steam that can be turned into electricity. The efficiency is often as high as 30% but such devices are high risk and expensive – the high temperature and pressure of the water means that if it escapes it can do considerable damage. Efficiency considerations aside costs remain relatively high and most types of solar panel remain fairly expensive. A 30-watt module costs around $250, while a 195-watt panel will run to almost $1000. To install a solar panel power system for even a modest home will cost somewhere around $10,000-$16,000 for the panels add to these batteries and other components and the cost rises from around twenty to thirty thousand dollars.

Fortunately manufacturers have begun to respond to the rising costs of gas and oil. As the market matures for solar technology, research dollars have been directed at finding new ways of increasing efficiency and lowering costs. Even with the relatively high price of large application panels and accounting for inflation, the cost of this technology is still much lower than it used to be.

The cost of PV (photovoltaic) cells has fallen by about 15% per year for the past 10 years. The fact that these cells can last 20 years, householders can have clean power while recouping the initial investment. Improvements continue to be made and a major European chip maker, ST Microelectronics, now has prototype solar cells that are expected to be considerably cheaper than today’s panels.

Organic compound solar panels are now found in applications such as computer keyboards and monitors. These flexible plastics mean that a computer can be folded or rolled like a magazine – although these are still expensive, the costs are coming down as the technology matures. A French-Italian company estimates that it will soon be able to produce an organic cell soon that will produce electricity at around 20 cents per watt, compared with around $4-$8 per watt for ordinary solar power.

Solar powered water heating also has variable costs. In the 1920s some municipalities used large storage tanks for storing and solar heating water that was then supplied to homes. However, when the price of electricity and oil came down these were no longer cost-effective. However these methods may well become competitive again if current research pays off. If the price of oil and electricity from gas and coal fired plants continues along the upward trend of the last ten years just a small improvement could make new applications more economically viable.

Solar Panel Applications

The large, dark-blue panel atop a rooftop supplying solar-powered electricity is now a familiar image. Thousands of magazine stories have been written over the past 30 years accompanied by photos depicting them; even though relatively few homes have them. Such systems are often regarded as ‘the wave of the future’ always just out of reach, due to their relative rarity. The sticking points with these applications are always their cost and efficiency – even though there are dozens of cost-effective solar-panel applications available today.

Lawn lights are a popular example of these applications and come in the form of stakes about a foot long with lights mounted on the stake with solar panels on top of those. They don’t generate much power, but then not much is needed for them to do the job. They can be placed anywhere as they require no wires and can last for years without any maintenance since they use no batteries and the bulbs are ultra-long lasting.

Calculators that are purely solar powered have been in use for decades now and that same technology has recently been expanded to encompass laptops. While these don’t currently generate enough power to run a standard hard drive or monitor, solar power has been combined with new inventions to make that unnecessary as they use something called organic cells.

A standard solar cell uses layered wafers of silicon doped with phosphorus – other elements and more complex molecules however, are also subject to the photoelectric effect. Many organic molecules will shoot off electrons when struck with light; they’re not currently as efficient, but they make up for it by being flexible and super cheap – what is more; they can be incorporated into certain inexpensive plastic alloys. This makes it possible to make an affordable keyboard or monitor that can be folded or rolled-up. With this technology, it’s possible to roll up a computer like a newspaper and tuck it in your pocket; when you want to use it, it is unrolled and powered by the available light.

There are still more applications that can be powered by a solar system. One common use of solar power is electrical fencing – whether you need to power a dog retainer system or a cattle barrier, low voltage systems are often used to keep animals in check. A small stun doesn’t harm and is often enough to keep them from wandering outside the perimeter. Many animals can jump over standard fencing, but electrifying the system discourages these attempts.

Powered boats, like cars, have batteries that start the engine and power small electrical devices when the motor is off, running lights, speedometer and more; however, those batteries need to be recharged after use. In normal circumstances the running motor recharges the battery, replacing the power needed to start it.

Clearly, the fact that battery chargers exist means that the method doesn’t always work. However, when you’re out on the water, and in many cases even when you’re near the shore, it is nigh on impossible to use a standard charger. Electrical outlets aren’t always available in docks and never on the water; this means that a solar-powered charger can come in handy just when you need it most. That same charger can recharge the battery in your RV just as easily as your boat. But beyond that emergency use, a solar-powered system can be useful for an RV in lots of ways.

Many times an RV is stationary, with its motor off. Some have generators to power the RV at those times but generators are noisy and consume gasoline or diesel that produces smelly fumes. Not exactly what you want when you’re outdoors enjoying the fresh air, however, a solar power system can supply at least part of the energy needed. It can run a radio; power a DVD and/or TV, or a small refrigerator.

Electricity generation isn’t the only possible application either water heating is a popular home-oriented application for solar power.

Small parabolic dishes are used to focus the sun’s energy into a small area; energy which is then transmitted to a water storage system. Not all such systems are meant solely for inside the house; the hot water supplied can be used to bathe the dogs outside or provide an alternative to washing the car with cold water.

Any kind of washing chore is usually easier with warm water and water from the hose gets soon cools. A solar heating system can provide a reservoir of warm water to wash the exterior of the windows, supply a sink in the garage and other uses around the house and garage.

Today’s solar systems are more efficient and cost effective than ever. They provide householders with freedom from dependence on the utility companies for all their electrical and hot water needs – and this alone makes them a good deal.

Solar Electricity Generation By Water

Using solar cell arrays to produce electricity is a now-familiar application. Most applications that use PV (photovoltaic) modules are still small scale, other than certain experimental stations trying to generate power at the level of utility companies. Nowadays, everything from lawn lights to full power supply systems for homes are available. However, there is actually another method for generating electricity that has been in use for some time; that of heating water.

Steam generation plants have been in use for decades; as a general rule the water is heated by burning coal, oil or natural gas. The heated water is then turned to steam, which drives a turbine and that circular motion can be used to generate electricity.

Michael Faraday, the great 19th century British scientist and inventor, discovered that if a coil of wire is turned near a magnet, electricity is produced and this has become the basis for countless applications that use a generator to provide power. The same basic principle is at work in turbines, only in this case the turning is provided by steam power. The turbine doesn’t ‘care’ what heats the water that turns the blades that produce electricity; and using solar heated water is significantly less polluting than other methods, even taking the component manufacturing effects into account.

Some day solar power may well provide a significant percentage of the total energy needs..

One such method is that used in ordinary solar water heating systems, which typically use collector panels on top of a roof – the water is heated by the greenhouse effect and then passes down a series of channels and pipes into a storage tank.

But there is a difficulty.

At any one time the total sunlight received in a given area is fixed; this will vary depending on cloud cover, dust in the air and other factors. However, it can’t be adjusted upwards because we cannot control the sun’s output – by adjusting how that energy is used, we can control the amount of usable energy and how it is applied.

More efficient collector systems make that possible and one of these is the parabolic mirror method.

A mirror shaped roughly like a section of a sphere can focus the sun rays to approximately a point or line. The quality and shape of the mirror determines exactly how focused and to what geometry this will be. A circular parabola, like a satellite dish, focuses to a point. A cylindrical parabola focuses to a line and that shape concentrates the energy received into a smaller area – this makes it possible to use the same energy to raise the water temperature much higher than by other methods.

Through the use of parabolic troughs and other shapes, solar heating collectors can raise the water temperature to as much as 428F (220C). Water boils at 212F (100C) and that extremely high temperature water creates steam under very high pressure in a contained vessel. The steam is then used to power a turbine to produce electricity.

Since the temperature and pressure are high, the conversion efficiency of the device is correspondingly high – following the basic principles of the physics of heat. That makes it possible to create solar electricity generation devices that are as high as 40% efficient. PV (photovoltaic) panels range from roughly 10-15% efficiency.

Of course, such systems may not be suitable for the average homeowner yet; but businesses are beginning to experiment with them as the cost of coal, oil and natural gas rises and the price of solar systems comes down. Some day solar power may well provide a significant percentage of the total energy needs of the average person, who could receive electricity from large solar turbine-based plants.

Revamping an Old Idea

Solar power has been around for millions of years – even the earliest humans benefited from the sun, since it makes plants grow and animals thrive. Early man soon learned to direct the sun to provide warmth and it wasn’t long before someone figured out how to use it to start a fire.

Battery chargers, electric fences and many more applications have solar energy as their primary power source.

Many thousands of years later clever individuals learned to harness it even more exactly.
Hero of Alexandria devised a working steam engine around the turn of the first millennium and some models used solar energy to heat the water. In 1767, Swiss scientist Horace de Saussure devised the first known modern solar collector. He used glass boxes that later evolved into solar ovens. In 1839 Edmond Becquerel discovered the photovoltaic effect i.e. that sunlight could generate a current in certain electrolytes. But it was in 1954 that the modern solar power industry really started to take off when scientists at Bell Labs developed the first efficient PV (photovoltaic) cell.

Over the years a succession of impressive devices continued to improve in efficiency at lower manufacturing costs. At some point, the curves will cross and solar power will become a viable technology for even more uses than it sees today. To a degree this is already happening and some solar powered homes have been a reality for decades. Whether using PV (photovoltaic) modules to generate electricity or collector systems to heat water or supply warmth, these applications are now installed in thousands of homes.

While the cost is relative to power generated by large utility companies it remains expensive for some applications while for others it is actually cheaper. Millions of phones and lights along highways use small solar panels to power them and homeowners around the country use solar-powered lawn lamps to illuminate their yards without wires or batteries. Battery chargers, electric fences and many more applications have solar energy as their primary power source.

In developing countries solar devices are commonly used for water treatment although this may be as simple as pouring a gallon of water into a jug that sits in the sun for a few hours. In some cases it may consist of a solar still that kills disease-causing pathogens, and purifies at the same time. Chlorine is boiled off and minerals remain behind as the evaporate flows up and is distilled into containers.

Such methods are relatively cheap and require only simple technology, making them a much more viable method for those who can’t yet afford the high cost of more sophisticated applications.

Solar power has many valuable uses whether that is producing non-polluting electricity, enhancing health, or providing a convenient alternative to recreational vehicle users. With costs coming down and the price of oil, coal and other energy producing materials continuing to rise, those applications will become more prevalent – and that is beneficial for us all.

Rent Your Solar Electricity

The problem for any homeowner considering solar generated power is the high upfront cost. Powering the average home using the sun’s energy requires fairly large solar panels. Panel systems usually cover most of the south facing roof of the house but the cost of the panels alone can easily amount to $10,000-$16,000. Once you add batteries, installation and other related costs you are looking at an initial investment of anywhere from $32,000 to about $50,000.

..today there are various loan, lease, rebate or grant systems that can offset part or all of the cost..

Many find that being independent of the local utility company justifies the cost. In rural areas, power outages are common; wind storms knock trees onto the lines and transformer blow outs are common. Most of these systems’ components are decades old and there is insufficient income or other incentives for the power company to upgrade. Having an ‘off-grid’ system at least provides a backup during times when the power is out.

Given that the pay back on home solar panel systems can be 20 years or more, some may still see the initial cost as too high compared with the inconvenience of the occasional blackout. However, today there are various loan, lease, rebate or grant systems that can offset part or all of the cost which means that start up costs cease to be a reason for not installing solar power.

Federal tax rebates or outright payments help to some extent and special legislation in most states allows utility companies to enter arrangements that can reduce the cost of solar power. Some contracts and systems allow for purchasing back any excess solar power. If your system generates more than your home needs, the difference goes into the utility grid and you receive a rebate on your bill.

Leasing..means the equipment can be returned after a set period of time. That opens up new options.

Many companies will subsidize part of the cost by offering homeowners who install a solar power system a discount. Not many companies will pay you to purchase less of their product or service but the crazy mixture of regulations in electricity generation gives the utility company a financial incentive to do just that.

There are a few companies just now who promise to lease equipment and that opens up the option of lowering the major share of the upfront cost of a solar system. Just as the total cost over time may be slightly higher when leasing a car; but lowering the initial investment from $50,000 to $1,000 puts a solar power system within reach of many more people.

Most people today own their home for less than seven years. That’s one of the major reasons mortgage companies can offer the flexible rates and terms that have become common in the past 15 years – this is another factor that affects the feasibility of installing a solar system.

Most people who only expect to own their home for five years or so; are going to be reluctant to sink $50,000 more into it. Installing a solar system certainly raises the value of a home but it rarely raises it enough to get a new buyer to cover the total cost. Leasing on the other hand, means the equipment can be returned after a set period of time. That opens up new options.

With changes in both solar technology and financial arrangements, solar power systems are becoming more attractive and investigating all the options may well put one within your reach.

Solar Power and Other Renewable Energy Forms

The claims of enthusiasts are sometimes overstated but it is still true that solar power and alternative energy forms are viable and valuable. Solar energy generates little pollution despite the effects of manufacturing in the making of the components. They are, in principle, inexhaustible sources of energy and do not require the supply of raw materials from unstable countries.

Solar energy, in the form of light emanating from the sun, is converted to usable power by a process that is now well understood. Sunlight strikes a PV (photovoltaic) module which responds by generating a current of electricity that flows into a home or business by the same components (wires, circuit breakers) as are used by the utility company.

Wind-generated electricity works by an entirely different principle; there are however, some similarities. Wind turns a propeller on a shaft surrounded by a magnet wrapped by a coil of wire, as the magnet turns near the wire or vice versa electrons in the wire experience a force. This force then moves them along inside the wire; and it is that movement which creates an electrical current. In principle both methods are simple, the sun and wind cost nothing; it is converting those energy sources into usable electricity which has costs as well as some interesting physical limitations and engineering challenges.

Creating the materials required to build a wind turbine or PV (photovoltaic) module, is not free of course. These have to be transported and installed, and, unfortunately, that costs money; nonetheless they are relatively cost-inefficient in terms of the amount of power produced when compared to coal, oil and natural gas.

The problem is that they don’t produce the same amount of power as other sources for the same cost even though improvements have been made. For example, roughly 1,000 watts per square meter of solar energy reaches the surface (at the equator) but latitude, weather and other factors often reduce the amount to between 125-375 W/m2. When you add that to the fact that the efficiency of a solar-powered PV (photovoltaic) module is generally 10-15% depending on how it’s made, and the available energy is relatively low.

Nevertheless given the ability to cover an area the size of a house roof with panels, even that relatively small amount can generate about 1.35 kWh/m2 a day. That’s enough to power an average home providing the homeowner is careful about how much power they use.

Wind systems also have their own unique problems. They regularly kill birds and rely on almost continual wind – otherwise they have to be connected to storage systems like solar powered systems. More to the point they don’t put out the amount of power demanded by most applications.

Despite their limitations, solar, wind and other alternative energy technologies can sensibly form part of a total power generation strategy. They are clean and this makes them highly desirable in a society which is continually striving to reduce pollution and improve the quality of their environment. These systems are not reliant on imported oil or the mining of coal and other materials which often cause environmental and political controversy.

With continued technological improvements to increase efficiency and lower costs, these alternative systems can contribute to meeting the demand for electricity supplies. However, it will be some time before they can reasonably be expected to replace a significant percentage of the supply from other sources – but there is always hope for the future.

How Solar Power Works

Solar power, particularly when it’s used to provide home electricity needs, may seem like a relatively recent invention. And it’s true that large, cost-effective panels that form the core of most systems have only been in use for about that past 30 years. The underlying method they employ however dates from 1839, when it was discovered by Becquerel who found that shining sunlight on an electrolytic cell would produce a current.

Other scientists built on Becquerel’s work. Albert Einstein is most well known for the Theory of Relativity however, he received his 1921 Nobel Prize for something quite different. According to the Nobel organization it was ‘for his services to Theoretical Physics and especially for his discovery of the law of the photoelectric effect’. His paper on the subject was written in 1905.

The photoelectric effect is similar to what solar power enthusiasts and workers know as the photovoltaic effect, the principle first found by Becquerel. When light, (in this case light from the sun) strikes certain materials it knocks loose electrons from their associated atoms it is these moving electrons which create a current that can flow through the material to provide electrical power.

Today’s materials are typically some type of doped silicon. ‘Doping’ is another way of saying that other elements are deliberately introduced into the material. Such impurities would be undesirable in other applications however, in solar power, they are essential. Pure silicon has its uses, but it’s not a good conductor of electricity adding phosphorus in the correct manner turns them into semiconductors.

Certain specialized applications use gallium-arsenide or other materials, instead of silicon but their relative rarity means the cost is much higher. Silicon, on the other hand, is a major component of ordinary sand and therefore plentiful.

The silicon-phosphorus compound is arranged in layers and then connected to a grid to enhance the flow of electricity; the compound also reduces the resistance losses. Then terminals are installed to allow for the electricity to flow into the home electrical system. The whole assembly is covered with protective glass to protect it and forms what is known as a PV (photovoltaic) cell. These cells are then arrayed into a module and these modules can then be connected together into a complete system.

The modules come in a variety of sizes that determine how much electricity they generate. All other things being equal, the larger the area, the more power they can produce – naturally, the larger panels tend to cost more.

Though the solar energy that reaches the surface (at the equator) is about 1,000 watts per square meter although not all of it is usable energy. A square meter is a square where the sides are a little larger than three feet – it’s about 10.7 square feet. Apart from losses due to latitude, atmosphere, dust and other natural factors, the modules themselves only convert with about 10-15% efficiency.

The growth of solar power as a practical energy production method is heavily dependent on increasing that efficiency and lowering production costs. That efficiency is bound to a certain degree by particular difficult-to-get-around physical constraints, so most of the research efforts center on lowering the manufacturing costs.

When and if that happens, solar power applications may well become even more evident in homes and businesses than they are today.

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