By  Steven Stiles

Solar thermal space cooling is, one might say, a little known offshoot of the solar energy movement. Most of the present hoopla goes toward photovoltaics, solar thermal electric, or even solar thermal heating. So where does solar space cooling come in? Solar cooling systems are relatively expensive to purchase and install; they are also rather complex.

Known as Thermally Activated Cooling Systems (TACS), there are two types of solar space cooling systems: solar absorption and solar desiccant systems. Because of their high cost and complexity, cooling systems exist primarily in large scale, commercial arenas. Even on such a large scale, solar cooling systems are used to provide just 30% to 60% of a building’s cooling load, according to the Department of Energy. What needs remain are usually provided by systems driven by natural gas.

Solar Absorption Systems

• Absorption systems use heat from the sun to separate a refrigerant fluid (e.g., water vapor) from an absorbent one (e.g., lithium bromide salt). That evaporated refrigerant is then condensed in a chiller to produce cold water. This chilled water is then pumped into coils over which indoor air is blown and cooled.
• There are single-effect and double-effect absorption systems. Double-effect systems use the heat twice in the series and are twice as efficient but require nearly twice as much heat.

Solar Desiccant Systems

• Desiccant systems use solar thermal energy to regenerate desiccants which dry out the air, thus producing a cooling effect of its own. Desiccants are typically solids and sit on a wheel (think of a steamboat’s paddlewheel) that rotates into the stream of air flowing into the home. The desiccants remove the humidity, and subsequently cool that air. As the desiccants then rotate out of the incoming air, thermal energy from the solar collectors re-dries them and the process is repeated.

Solar space cooling is still a very new technology and not yet competitive with its conventional counterparts. For now, its best bet is in conjunction with other systems such as solar hot water or solar space heating systems. At this point of combined effort, the solar system comes close to competitive. Beside high initial costs, solar space cooling systems need a high ration of sunlight and heat to work. This limits the areas where it can be used efficiently, but also makes it useful where it is needed most. These needs will likely drive solar cooling innovations, especially in areas such as Africa, Australia, and the Southwestern United States.

Renewable & Alternative Energy Resources: http://www.alternativeenergybase.com
Steven Stiles is a technology writer for CalFinder’s Residential Solar Power website; an excellent resource for information on residential solar energy systems and for finding certified solar contractors nation wide.

by Sam Deane

As the prices of oil and gas continues to go up and up, the installation of solar panels is giving many families solace and stability. The sun offers an almost infinite source of energy. No wonder so many people are rushing to install solar panels. Indeed, their popularity is increasing so rapidly that manufacturers of solar panels are having difficulty keeping up with demand.

Two Types Of Solar Panels

Predominantly, solar panels come in two types. There are solar energy panels in the form of ’solar thermal collectors’. These focus solar energy into a liquid medium, usually water, heating the liquid that is then utilized as and where it is required. The other of the two types of solar panels is known as the photovoltaic module. These solar panels convert the sun’s energy into electricity, which can then be distributed immediately or stored within a battery to be used later.

Solar panels have been commonplace for decades. Think of calculators and watches. Many swimming pools have been heated using solar panels for years. These days, the electricity to homes and offices often comes from the cleaner alternative energy source of bigger, better, more efficient solar panels.

The influence of solar panels has spread so wide that even the National Grid take some of their power from solar energy panels.
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by Joseph H. Ben

Although solar technology has been around for years, it has only been recently adopted on a large consumer scale. If you are interested in buying solar panels, you are probably asking yourself ‘How do I know how much energy my panels will yield’?

There are several factors determining the amount of electricity a solar panel unit will generate, some are fixed and some vary, depending on location and time. Fortunately, all factors are predictable, making buying and using solar technologies a safe investment.
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by Charles Koty, A.I.A.
Source: Sustainable Living Articles

The popular word today is GREEN, meaning protecting our environment, enhancing our ecology, conserving our energy and, also, fighting global warming, pollution and waste.

Utilizing the solar system, instead of fuel, for space heating is part of GREEN. And that’s where solar homes come in.

The Traditional Way: Active Solar Homes
Early on, architects learned to harness the sun to heat our homes and minimize our dependence on imported oil. South-facing solar panels on the roof, with circulating water, can produce free domestic hot water. This system is still popular and is cost-effective.

Multiple such panels, with anti-freeze liquid instead of water, and with elaborate pumps and insulated storage tanks have been used for space heating. This system is called “active solar,” due to the hardware involved in the system, and it is not cost-effective.

Another upcoming system, born out of the space age, is “photovoltaic.” Photovoltaic roof panels use sun power to run the house’s entire electrical system. This option is clean, efficient and almost care-free, but very costly to install. However, it does have future potentials as costs come down.

The Practical Way: Passive Solar Homes

“Passive solar” is an old concept with a new shine. Energy-saving passive solar does away with costly panels and mechanical devices and taps directly into the sun’s energy and house orientation to heat the home. The advancement of technology and available materials has further enhanced the system.

So what’s in a passive solar home? A typical one has the major rooms facing south, or nearly-south. The house is constructed with thick insulation in walls and ceilings to keep the house warm in winter and cool in summer. Window and door glazing is double-paned for better insulation (in colder climates, triple-glazing is recommended). A wood-burning stove is selected over a fireplace to optimize heat efficiency.

Most windows and glass doors are on the south side for solar gain. Roof overhangs shade the house from high summer sun. Strategically placed clerestory windows create air circulation by convection for summer cooling.
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The solar panels most familiar to most people are made up of arrays of commercial solar cells or wafers formed of a thin layer of a material such as cadmium telluride or amorphous silicon sprayed or electroplated onto a base such as glass or ceramics. This is the technology most commercial solar kits use. These kinds of solar cells are relatively expensive and not terribly efficient, but that may be changing: Israeli scientists at the University of Tel Aviv claim to have discovered a new method of creating solar cells that will result in costs of less than 1/100th what they have been. According to an article in the EE Times Europe,

The reactive element in the researchers’ patent pending device is genetically engineered proteins using photosynthesis for production of electrical energy.

The scientists applied genetic engineering and nanotechnology for the construction of a hybrid nano — bio, solid state device. According to the researchers, although using photosynthesis for photovoltaic application is not new, their specific technique is the first to enable the production of useful photosynthesis-based photovoltaic cells.

. . .

The researchers suggest existing silicon based photovoltaic cells offer low average energy conversion efficiency of 12-14 percent, while their system is capable of efficiencies of about 25 percent. They based their photovoltaic device on genetically engineered dry proteins photosystem I (PS I), encapsulated in solid state substrate bottom metal and a top transparent electrode.

Another method of lowering the cost and increasing the output of solar cells is to use a fresnel lens as a solar concentrator. Here is a video showing a cheap and efficient homemade fresnel lens concentrator:
Solar Breakthrough

A good video from Easy Home Solar Power

Here is a more detailed explanation of how to build solar cells, using the oxidized-copper and salt water method. From the website Solar4Scholars:

Solar4Scholars: Make Your Own Solar Cell

You will need:

• A small (2′ x 1′) sheet of copper flashing (available at your local hardware store)
• An electric stove (a propane torch may also be used)
• A large clear plastic bottle
• Table salt
• Tap water
• Sandpaper (or steel wool)
• Sheet metal shears (also called “tin snips”)
• Two alligator clip leads
• A micro-ammeter (available from Radio Shack or other electronics store)

Instructions: How to build a solar cell

1. Cut the piece of copper sheeting, so that it fits the stove burner. Clean it first, so that there is no corrosion or other materials. Use the sandpaper.
2. Heat the copper sheeting until it is red hot. This will create two kinds of copper oxide: cuprous oxide is the one you are interested in. It will be red or tinges of orange or pink. This will be found underneath the black cupric oxide (which is no use to us). These copper oxides will begin to form after only a few minutes, but let the copper ‘fry’ for up to half an hour, forming a fairly thick coat of cupric oxide.
3. Turn off the stove and let the copper flashing cool slowly. The copper will shrink as it cools, and some or most of the black cupric oxide will actually pop off. Remove the copper from the stove element, once it has cooled (after about 20 minutes).
4. Lightly clean or rub the copper flashing with the sandpaper, under running tap water if you wish. Remove the cupric oxide but be sure to not remove much of the cuprous oxide.
5. Cut another piece of copper about the same size as the first. Bend both pieces of copper and set them inside the jar or bottle, making sure they are not touching. Connect the two plates to the ammeter. Connect the plate with cuprous oxide to the negative terminal and the clean plate to the positive terminal. You now have a solar cell, with a charge being read on the micro-ammeter.

You’ve probably heard that solar panels cost a lot of money. Bought ready-made and installed by professionals, that can be true. But there is another option– build and install them yourself!

There are a couple of ways to build your own solar panels.  First, you can buy solar panel kits.  These are designed so that they can be built by anyone who is moderately handy.  Or you can build your own solar panels from scratch.  These require better skills– and probably a good guide or handbook to help.

Kits provide the photovoltaic cells, wiring, assembly hardware and the mounting devices.  If you’ve ever put together an electronic project this shouldn’t be beyond your powers.

Cheaper, but more difficult and time-consuming is to build your solar cells from scratch and link them together into larger panels.  For this you need raw copper sheeting, (available at most hardware stores), and a heat source.  The copper is heated for about a half hour– long enough to oxidize the surface of the copper sheet.

After the copper panel has cooled,  it is combined with a non-oxidized copper panel of the same size, placed in a salt water solution and encased in a shatterproof glass panel.  With the wiring and mounting components, this produces a low-voltage panel.  You will need a number of them in an array in order to produce enough electricity to run household appliances.

Building your solar panels from scratch is fairly cheap, but is quite a bit of work. A good solution might be to buy a solar kit in order to get familiar with the components. When you are comfortable that you know how it all works and how the components fit together, try building your solar panel from scratch.  Don’t forget to check your local building codes first– or to find out if your new installation qualifies for any tax incentives.