Passive Solar Design How-to

A “passive” solar house provides cooling and heating to keep the home comfortable without the use of mechanical equipment. This style of construction results in homes that respond to the environment.

For passive heating and cooling, the plan of the house, careful site selection and planning, construction materials, building features and other aspects of the home are designed to collect, store and distribute the sun’s heat in winter; and to block the sun’s rays in summer. Passive solar houses can be built in any architectural style and in any part of the country.

The following techniques use passive solar strategies to provide heat

Direct Gain is radiant heat resulting from sunlight admitted directly to the living spaces through south-facing windows, which warms the interior surfaces (walls, furniture, floors, etc.). For direct gain, the south-facing window area must be sized for the climate, the type of window used and the amount of thermal mass in the home.

Passive Solar Design

Graphics courtesy of North Carolina Solar Center

Indirect Gain In a design that employs indirect gain, an attached sunspace or Trombe wall collects heat from the sun before transferring it to other spaces within the home. The air heated in a sunspace circulates naturally or with the aid of fans to other rooms.

Thermal Mass is any material in the home that absorbs and stores heat. Concrete, brick, tile and other masonry materials are the most common choices for thermal mass in a passive solar home, these materials absorb and release heat slowly and are easily and inexpensively integrated into the house design. They are most effective when dark colored and located in direct sunlight. The addition of thermal mass allows saved solar energy to heat the house at night or on cloudy days. The combination increases the performance and energy-saving characteristics of the home, generally for only a modest cost increase.

The following techniques use passive solar strategies to provide cooling

Passive solar cooling can reduce or even eliminate the need for air conditioning in homes. At its simplest, passive cooling includes overhangs for south-facing windows, few windows on the west, shade trees, thermal mass and cross ventilation. Some of the same strategies that help to heat a home in the winter also cool it in the summer. For example, with a well-designed overhang, the south-facing windows that admit the low-angled rays of the winter sun are shaded from the high-angled summer sun. Thermal mass, which stores heat in the winter to release in the evening, works in reverse in the summer. The mass cools down in the evening and retains that coolness the next day, moderating the effects of high daytime temperatures.

Graphic courtesy of North Carolina Solar Center.

Passive solar design works by utilizing overhangs to shade a house during the heat of the summer and allow sunlight to penetrate the interior of the house during the winter.

Passive solar design utilizes energy efficiency

Energy efficiency minimizes the need for heating, cooling and electricity, solar or otherwise. Designers of solar homes use insulation levels that are higher than those found in typical construction and energy efficiency appliances and lighting.

Windows are up to twice as resistant to heat loss as those used in conventional construction. Air infiltration is also reduced by carefully sealing and caulking around window and door openings and under sill plates.

Adapted from “Consumer Guide to Solar Energy,” K. Sheinkopf and S. Sklar, Bonus Books, Inc. and “Buildings for a Sustainable America Case Studies,” Burke Miller Thayer, American Solar Energy Society.

The Future of Solar Energy

With the current concentration on global warming, the existence of which is denied by only a few naysayers, developments in solar power are moving at a pace to fill the need for efficient green solutions to our seemingly insatiable desire for energy.

The failure of solar power to be more widely adopted to date seems primarily to be due to cost concerns, where the payback periods are now quoted to be 7+ years, and thus beyond the normal financial horizon for many potential participants, whose average occupancy of any particular house is expected to be 7 years. When a lower cost can be achieved, the benefits of mass production will cause a snowball effect in purchasing systems, and that time would seem to be drawing closer.

Durham University in the UK, ever photovoltaic solar research project, with more than $12M to be spent in the next four years, starting in April. The principal investigator, Professor Ken Durose, has committed to “make a major contribution to achieving competitive photovoltaic solar energy”. Nine industrial partners and eight institutions will be involved in the project, which is aimed at reducing the thickness, and thus cost, of solar cells.

Much as this may seem to be a promising advance, an alternative approach is being adopted by commercial interests, in the form of a company called G24i which is also in the UK, in Wales. They have developed what are called fourth generation solar cells, which are a thin-film product, the latest buzzword in the solar marketplace.

Their invention is a dye-sensitized solar cell (DSSC), which is, simply, printing a thin layer of titanium oxide on to a thin-film of metal foil, and then performing some molecular manipulations to achieve the desired reaction to light. The product is manufactured on a roll-to-roll process, similar to that used in the textile industry. They commenced production last year, and are planning to expand this year to a production capacity of 200 Megawatts.

The process by which DSSC works has been compared to that of photosynthesis in plants, and it is more sensitive than conventional silicon cells, producing electricity from a wider range of the light spectrum and lower levels of lighting. It is very flexible and one-fiftieth of the weight of conventional glass silicon cells, and can even be produced in designer colors! The initial market is for devices that could not be made with the older technology, supplying power for portable electronics, particularly for mobile phones in the developing world.

With a growth in the traditional solar cell market of 35% per annum, and a continuing global shortage of silicon projected up to 2010, G24i would seem to be very well placed to take away business from the conventional suppliers. Their technology is available at much lower cost, and expansion would seem to be limited only by their ability to grow in a controlled manner.

On what seems to be a more esoteric front, it’s reported that scientists are considering the possibility of a space engineering project that would dwarf any other that has been attempted to date. While the sheer size of the project would require governments to take the first steps at an international level, researchers from the USA, Europe and Japan are proposing building giant solar arrays in orbit and beaming the energy to Earth.

Lieutenant Colonel Paul Damphousse of the Pentagon has spoken of the need for “hundreds of sorties every week” in order to move the tons of material that would be required. A recent study by the Pentagon concluded that such a project was nearly technologically possible right now, and that robots could be used to facilitate the construction in space. More realistically, perhaps, Leopold Summerer of the European Space Agency has projected that the generation of power in space may be about 20 years away, but the concept is being actively pursued.

Finally, what may prove to be the most promising current development in solar energy has just been announced by Global Warming Solutions, Inc. of Houston. Successful tests have been conducted on hybrid solar modules, which produce both heat and electricity from one unit. The combined efficiency of the modules is reported to reach 85%, significantly better than the 40%+, then a record, achieved a year ago by Spectrolab using concentrator solar cells to produce electricity only.

The technologies used include some originally developed for industrial lasers, stated Dr. Alexander Kornaraki, the COO. “The quantum pump separates the heat and the electrical photons of the incident solar light”, giving the most efficient spectra to the photovoltaic process. The modules produce up to 28 Watts of electricity and 93 Watts of heat per square foot. The projected payback period is no more than five years.

Global Warming Systems have several pilot systems, and one with 108 square feet of panels provides 100% of the energy, both electrical and heating, to a single family home. Even more promising, these panels are efficient even as far north as Alaska, which is a new achievement for the industry.

Learn more about Solar Power and how you can use it to produce electric power, to heat, or even cool your home!

Solar Power Kits For Your Home

Solar power is one way to power your home where bringing a traditional power supply into the residence may be costly. Without the use of a generator, this unique source of energy can avoid the noise, pollution and even regular maintenance issues that you would have with another source of electricity at your home or cottage. By using solar power kits for your home, you are recognizing the need for environmentally friendly alternatives that can be practically maintenance free for you.

For those who may experience power outages on a sporadic basis such as in the countryside or during catastrophic environmental events such as earthquakes, solar power is a resource that you cannot put a price tag on. When you rely on many electrical appliances for your everyday living, it is necessary to have a source of backup power in order to maintain that standard of living should an outside force interfere with your electricity.

There are a number of reasons that a homeowner may want to purchase and install a solar power kit for their own use. From lowering their personal power costs, to helping the environment or even just as a backup plan in case of a power outage, these energy kits are designed to meet a number of needs for the consumer. No matter what your reason is for purchasing a solar power kit for your home, you will need to be sure that it is one fashioned to suit your needs.

Your solar panels should contain Photovoltaic cells that are necessary to provide your electrical requirements. These panels of Photovoltaic cells can be mounted either on the roof of your home or on poles as a ground mount. Once these cells transform the sunlight into energy they need to store it in a bank of deep cycle batteries for later usage. These Photovoltaic cells produce energy at a DC current and is typically at 12 volts or 24 volts of energy.

With the solar power kit that you have chosen, there should be an inverter that will convert the DC energy current into 110 AC in order to be useful as an energy source for your home. Depending on how you set up your unit, your home can be powered by solar energy alone or have the option of drawing from the storage of battery banks for use when it is needed in times of power-outages or when you feel it is necessary.

There are a variety of places to obtain solar power kits for your home depending on where you are located and what type of system you are looking for. Your personal electrical needs will depict the exact style and type of kit you will need to purchase in order to either power your home entirely or as a backup source. You can browse the Internet for many manufacturers of solar power kits that are easy to install yourself.

About the Author: Milos J Leonard is a solar power expert that can help you find the perfect solar power kit Find the best solar power kit discounts on the web and help save our earth by powering your home with natural energy.

History To Solar Power Energy

“I have no doubt that we will be successful in harnessing the sun’s energy… If sunbeams were weapons of war, we would have had solar energy centuries ago.” These are words of Sir George Porter (December 1920 – August 2002), Nobel Laureate in Chemistry, which today is a reality. The energy which is derived from the sun and responsible for practically all life on earth is today harnessed for generating heat, light, power and electricity for meeting global needs for alternate energy resources. Yet the concept and use of solar energy is not new. Early Greeks, Native Americans and Chinese have used it to their benefit by orienting their home and hearth toward the sun for centuries. The term solar power has today become synonymous with solar energy which is obtained by converting sunlight to electricity.

While the application span of solar energy now encompasses the domestic (including cooking and heating), commercial, industrial, farming, aviation and surface transport sectors, there are several technologies which are in place to generate this type of natural energy. In fact, solar energy has now found its place in every day use items like cars and calculators.

Back in historical times, solar energy may not have been known by any name, but its use has always been the backbone of agriculture ever since man learned to till the land and grow food or crops. We have seen the importance of this energy in medieval Europe where farmers deployed elaborate agricultural strategies to get the maximum out of sunlight for the wellbeing of their yield. Even today, sunlight optimization is the primary agenda for anyone who is involved in farming or gardening, starting from planning their planting schedule, strategizing row orientation, altering plant heights between rows, etc.

Man has always built his home to take the most out of available sunlight. Critical use of solar energy is evident in today’s urban building designs where not only the building orientation but window placements and proportions and building materials are chosen to harness the most of this invaluable energy form. The importance of solar energy was realized by first century Roman architect Vitruvius who commented that home designs must be made according to the diversity of the climate of that particular region. Solar energy when deployed to supplement day lighting techniques, homes can save enormous amount of resources by making maximum use of sunlight during all the time that it lasts. The importance of solar lighting or natural light was appreciated way back in 6th century Rome and later corroborated by the British in 1832. In fact, it was only in the 20th century that artificial methods became the primary source of interior lighting. The energy and oil crises during 1973 and 1979, made people re-focus on natural lighting, but soon the interest died due to cheap available sources of energy.

One of the areas where solar energy is most widely used today is in the field of solar thermal applications, where the applied technology uses heat from the sun to heat water and space; for ventilation; for processed heat required for industrial applications, cooking, for water distillation plants, etc.

For more information, on the history and benefits of solar energy visit www.solar-reviews.com

http://www.solar-reviews.com is an indepth site focussing on the benefits of solar energy in the 21st century

Solar Cell Electricity – How It Works

We have all seen solar cell electricity generators by now, blue or black panels dotted around, silently generating pollution free electricity. But how do they do it?

The key to understanding how they do it lies in the chemistry of the elements used. Each panel is an array of individual cells. Each cell generates a small voltage and together they produce a useable current.

Each cell uses what is called a p-n junction to convert sunlight to electricity. This does not mean much to most of us so a clear explanation is required.

Silicon is the main component of each cell. Silicon is special because it is what is called a semiconductor. This means that under certain conditions it will conduct electricity whereas at other times it will not. For our purposes, we will assume it is conducting, ie allowing electrons to move through it.

The silicon in solar cells is doped which means has specific impurities added. Silicon is either doped with another element that has a shortage of electrons (called p-doped for positive or has an excess electrons (called n-doped for negative).

A solar cell consists of a wedge of p-silicon and a wedge of n-silicon. In between these wedges is a one-way gateway, a barrier that allows electrons to go from the n- to the p- wedge, but not back the other way.

That creates what is called a p-n junction.

Now we have a flow of electrons that move naturally from the n- silicon to the p-silicon. This is natural; it’s just the charges balanging out. But…

HOW DOES THIS GENERATE ELECTRICITY?

The p-silicon layer of the solar cell does not have a strong grip on the electrons that move into it from the n-silicon layer. When sunlight falls on the p-layer, the electrons break free of the layer and begin to move. As the electrons cannot go back through the one way barrier, the only way they can move is through the circuit the cell is connected to. That is why the solar cell will generate a current if it is attached to a circuit.

If a solar cell is NOT attached to a circuit, there is no opportunity for electron flow and all it will do in the sunlight is heat up.

Roger.

For more details on the operation of solar cells, the chemistry involved, types of cells and much more, visit http://www.green-planet-solar-energy.com. This site gives clear explanations of the major concepts behind the operation of solar cells.

Exploring the Use of Solar Power For Homes

The concept of using solar power for homes has come a long way in a relatively short period of time. Although solar power has been used for ages, systems designed to replace or augment electrical use are only now just catching on in a very big way. In general there are three main system types for home use. Each can have a major and positive impact on how well a home functions.

The systems that provide solar power for homes all operate off the same principles. These systems are designed to use solar panels or modules in an array design to absorb energy from the sun’s rays. This energy is transformed within the panels to create direct current electricity. The electricity created by the panels is then sent to an inverter for transformation into alternating current. This AC power is then stored in a battery for future use. The three basic systems that drive solar power for homes vary in design and function. They include:

• Full, off-grid systems – As energy costs climb, more homeowners are exploring this option. It is feasible for solar power for homes to take a property completely off the electrical grid. How efficient this type of system will actually be will depend on its location, the amount of sunlight received, the design and the efficiency of the individual components. To make solar power for homes more reliable, many builders are exploring energy saving measures that can coincide with their use. This can include strategic positioning of a home to provide the best insulation, landscaping for shade and other similar moves that would cut demand for power within an off-grid home.

• Augmentation systems – Most solar power for homes comes in this form. This type of system is meant to power a specific system within a home – not the entire home. Solar systems, for example, might be self-contained devices that operate outside lights, or water heaters. Some systems are designed to completely power heating and cooling systems. This type of system can take a lot of the pressure of powering a home off the electrical system and put money back in a homeowner’s wallet.

• Backup systems – Solar power for homes can also extend to backup systems, such as sun-powered generators. This type of system works much like an augmentation system in that it might not be designed to keep a home completely functional when backup is needed. Backup systems are ideal, for example, for running heating, cooling or refrigeration systems during a blackout.

Solar power for homes has improved greatly over the last few decades. More and more homeowners are realizing that the sun’s power can helps make their homes more energy efficient and environmentally friendly. In the process, these systems can also save homeowners money in electric costs.

Is it any wonder why the average home owner has not invested in solar power? With all the hurricanes and power outages, fuel costs rising and the US dollar falling…

Thanks for reading,

Denis W Darling

http://www.sustained-development.com/solar

The Pros And Cons Of Solar Energy

So you like the idea of solar energy, but you’re not sure that you know enough about the negative aspects? It’s true that many sellers of the technology would like to gloss over the less palatable aspects, but our comprehensive list below will keep you well informed. We think that the positive aspects of solar power and energy use greatly outweigh the negatives, and to help you decide for yourself here are the pros and cons of solar energy.

The negatives include:

* The worst thing about solar energy is that it is typically expensive to install. This means that the effective cost of the power is high compared with just buying it from your local utility company.
* Solar panels can take up a lot of space.
* You may find that your roof is not at a good orientation or angle to the sun, which would make the installation on your roof less effective or not possible.
* You can’t make solar power at night, so you have to have a way to store it.
* Your power output will also be affected by bad weather.

On the other hand, here are the positives:

* The greatest thing about solar energy is that it is virtually free to use.
* Solar energy causes no pollution when you generate it.
* You can get financial incentives from the government to help you pay for your system.
* Companies are starting to produce rental plans that allow you to avoid the large capital costs.
* There was a law passed a couple of years ago that allows you to “sell” your excess power back to the utility, reducing or eliminating your bills, and covering your need for power at night.
* You don’t need to order any fuel to be delivered to your house, and you can’t run out.
* Solar power does not suffer from inflation and increasing prices.
* Typically there are no or few moving parts to a solar installation, cutting down on maintenance.
* Solar power can be generated anywhere, even if there is no local electrical supplier, so you can have power in remote areas.
* Using solar power reduces the amount of fossil fuel burnt, and decreases greenhouse gas creation.

Some of the “cons” above about solar energy can be solved. For example, you can get government grants (depending on your location), or even rent your system to avoid the capital cost.

Undoubtedly, solar energy technology is here to stay and it’s future looks even more promising!

Learn more about using Solar Panels to power your home.

Solar Energy Today – Not Just For Heating

The sun is great at heating things up – just ask the driver of a car in the Arizona summer, when a parked vehicle can top 150° F inside. And solar energy can be and frequently is used to provide heating. Often solar power is used to provide heat to a house or for hot water by installing solar collectors which trap the heat and circulate it with water. This is also used to heat swimming pools and so extend the period of the year that they can be used.

But there are a number of less obvious ways that the power of the sun is used nowadays, and you may have seen some of them. A range of uses come from photovoltaic technology, that is, generating electricity from the sun to light a house. You can buy outside path lights that don’t need connection to an electricity supply, and these have photovoltaic cells built into the top with a battery inside. When it gets dark, the lights come on, using the solar energy stored in the battery, to provide lighting in the garden during the evening. Exactly the same idea is used for road signs in remote areas – you can identify these by the solar cells which are attached. A further use, which many people own, is a calculator with built-in solar cells, usually supplementing the battery power.

A major focus of research and design in solar energy today is the development of solar cells that can supplement or replace the power to your house. These are substantial in size, perhaps a couple of hundred square feet in area, often fixed to the roof, and they will provide enough electrical energy for an efficiently run house to function normally. This type of use received a big boost in the USA in 2005, when a law was passed requiring electricity suppliers to implement net metering, where excess electricity generated on site and fed into the network offsets the cost of electricity delivered. Effectively, this can replace the previous requirement for batteries for energy storage, as the power grid becomes the storage, and it significantly reduces the cost and inconvenience. This law is still being worked on in some states, while others have embraced it more enthusiastically, and it’s set to change the way we look at solar energy in the future.

Finally, while you may be fairly familiar with the uses of solar energy today described above, one you may not have heard of is using solar energy for cooling or air conditioning. Without going too deeply into the technicalities, this is mainly used for commercial purposes, and it functions in a similar way to a gas refrigerator, such as you can find in an RV. The cycle is called absorption cooling, and it uses the sun’s heat to produce the cooling effect. Solar energy today is a very flexible energy source!

Learn more about Solar Power and how you can use it to produce electric power, heating or cooling.