Home Solar Power

Private solar installations are really taking off nationwide. In just two years, (about the same length of time it takes to get a pair of 250 MW solar power plants approved in California, for example), homeowners and businesses have added that much power to the Californian grid, just from individual rooftops throughout the state. Read More….

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A solar inverter (photovoltaic inverter)  is a type of electrical inverter that is made to change the direct current (DC) electricity from your solar panels or wind turbines into alternating current (AC) for use with home appliances. Some inverters are designed to be connected to the power utility company’s grid.

Three Basic Types Of Solar Inverters

Stand-alone inverters: Used in independent solar energy systems or any energy system that is completely off the grid. The inverter is designed to draw  DC energy from batteries charged by solar panels or wind turbines, and change it to AC power.

Most stand-alone inverters also incorporate integral battery chargers and charge controllers to replenish the batteries. The charge controller regulates the input from the solar panels, regulates the battery output, and handles charging the batteries. Normally these do not interface in any way with the utility grid.

Grid Tie Inverters: Many solar inverters are designed to be connected to a utility grid and they contain special circuitry to precisely match the voltage and frequency of the power supplied by the utilities grid.

The inverter takes the electricity generated by your renewable energy system and sends it to the power distribution panel, from there the power may be used by  appliances within your home, or if not needed it will redirected to the utility grid.

This redirected energy is used by the other utility customers, and you receive some form of compensation for putting excess power into the grid. When there is no energy generated, utility power is pulled from the grid to provide power to your home.

Grid-tie inverters are designed to shut down automatically for safety reasons as required by law, upon the loss of the utilities power supply to protect the utility workers who are repairing the system.

Battery Backup Inverters: These are special inverters which are designed to draw energy from your battery bank, manage the battery charge via an on board charger and charge controller. The DC power is converted to AC power for your appliances and they export excess energy to the utility grid.

Unlike a standard grid tie inverter, these inverters are capable of supplying energy to your home during a utility outage, and are also required to disconnect from the grid during power outages.

No matter what type of system you use, an inverter is an integral part of it.

Here is a video, keep in mind that a small home system will be less complicated.

Thin film solar cells are a rapidly advancing alternative and solar energy technology. A new development comes from  Konarka, maker of a unique solar plastic called Power Plastic.

Its patented photovoltaic material, called Power Plastic, is more efficient than even the best thin-film systems devised by the likes of  First Solar and Solyndra. It is lightweight, portable, and perhaps most importantly, flexible — making it suitable for a host of interesting applications ranging from rooftops to apparel. Read More..

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A “grid-tie” solar energy system is designed to sell power back to the utility company and can be used with or without batteries.

Batteries Or No Batteries

If you are using batteries the power generated by your solar panels will be used to charge your batteries and any left over electricity generated by your  solar power system is directed onto the power grid. It adds to the overall total of kilowatt hours that can then be used by someone else.

With a battery less system if the grid supplied power goes out due to a storm or other malfunction, the user has no power for lights, furnace, refrigerators, etc, which could be powered by batteries for a limited amount of days.

There is a difference in cost between a battery less grid tie system and one with battery back-up. A battery-less system requires an inverter and a solar array or other renewable power source.

In addition to these two components, a battery grid-tie system requires several batteries, a charge controller for efficient battery recharging, breaker panels, circuit breakers, and enclosures to house the components.  A grid-tie system with battery back-up adds 10%-20% more cost over a stand-alone grid-tie system.

If you are not using batteries, any and all left over electricity generated by your residential solar power system and not used in your home, is directed onto the power grid, where it adds to the overall total of kilowatt hours available, and can then be used by everyone.

These systems will offset your utility usage, with the correct size system it will earn you a credit during the day that you would consume at night. These systems are easy to install and since some do not have batteries for back-up, the lack of batteries in these systems means no battery maintenance or replacements to worry about.

Grid-Tie systems are part of your overall solar system, the number and type of solar panels will determine how much energy you can produce, as will your geographic location. The DC power generated by your panels goes into an inverter.

Inverters

Inverters work by taking the DC power from the source, such as an array of solar panels or wind generators and converts it to AC power so it can be used by your appliances and fed into the grid.

The inverter must also synchronize its frequency with that of the grid (e.g. 60 Hz) using a local oscillator and limit the voltage to no higher than the grid voltage.

Grid-tie disconnects allow you to stop the flow of electricity between your solar power system and your electrical system. This provides for the safe maintenance of electrical and utility systems.  Grid-tie disconnects are also designed to quickly disconnect from the grid if the utility grid goes down.

This is an NEC requirement that ensures that in the event of a blackout, the grid tie inverter will shut down to prevent the energy it produces from harming any line workers who are sent to fix the power grid.

Selling Power Back To Your Utility Company

Ideally you want the utility company to buy back any excess electricity that you produce at the same retail rate that you buy electricity from them at. This is called net metering and is the simplest way to setup a grid-tie solar system.

In such a system you only have one utility kWh meter and it is allowed to spin in either direction depending on if you are buying or selling energy. If your solar power array produced enough electricity, your utility meter would begin to run backwards, and you earn credits on your electric bill.

In a non net metered system, the utility company will require that you install a second kWh meter to record any excess energy that you sell back to them and they will only pay you the wholesale rate.

To find out if your state offers “net metering” or any other incentives for installing a renewable energy system, Click Here.

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Basic Information

Solar cells (photovoltaic cells) are joined together in a series and put into a container to make a solar panel. Multiple Solar panels working together are a solar array.

A single photovoltaic cell, called a solar cell when used to harness the suns energy, does not create a lot of electricity. A single cell produces a voltage of approximately 0.5 volts, so cells are joined together in a series.

The more solar cells in a solar panel and the higher the quality of the
solar cells, the more total electrical output the solar panel can produce.
The conversion of sunlight to usable electrical energy is known as the Photovoltaic Effect.

The panel has a non reflective glass top made of tempered glass which is much stronger than normal plate glass, and they are completely sealed to protect them from humidity and the elements. One square meter of solar panels can produce up to 150 watts of maintenance-free power for 20-25 years

The 3 Basic Types Of Solar Panels

Monocrystalline cell : The most efficient and expensive solar panels are made with monocrystalline cells. Pure silicon is used to grow a single crystal in the shape of a long silicon rod. The rods are then cut into thin wafers of .2 to .4 mm thick, and are processed to make individual photovoltaic cells.

Polycrystalline or Multi-crystalline cell : Polycrystalline cells are a little less expensive and slightly less efficient than monocrystalline cells. The silicon is not grown in single crystals, but in a block of many crystals. This gives them a shattered glass appearance, they are then sliced into wafers and processed.

Amorphous cell : These are not really crystals, but a thin layer of silicon deposited on a base material to create the solar panel. Amorphous solar panels are much cheaper, but their energy efficiency is also much less so more square footage is required to produce the same amount of power as the mono or Polycrystalline type of solar panel. They can be made into long sheets of roofing material to cover large areas of a south facing roof surface.

Volts x Amperes = Watts

To get the general idea of volts and amperes, imagine two vehicles on the same road traveling at the same rate of speed, call that speed the ‘voltage’. One of the vehicles is a car the other a truck, the truck carries twice as much as the car so call that double capacity the ‘amperes’.

They are both traveling at the same rate (same voltage) but the truck is carrying more (amperes). A panel that produces 2 amperes sends twice as many electrons (electricity) as a one-ampere panel. For solar panels what you want to know is the watts (their power).

Simple multiplication will give you the answer. Connecting in series raises the voltage. Connecting in parallel raises the amps.

A 12-volt panel producing 2 amps of current has 24 watts of power (2 times 12).

If you take two of these (12volt) 24 watt panels and connect them in series it will add to their voltage, with no change in amperage, the result is 24 volts at 2 amps, 24 times 2 = 48 watts.

The same two panels connected in parallel results in the voltage staying the same but the amps are doubled, 12 volts at 4 amps, 12 times 4= 48 watts.

Knowing your voltage, amps, and watts helps you plan your entire system.

Mounting The Panels

Face the panels true south (not magnetic south). Try to position your solar array directly under the noontime sun, so sunlight hits them at a 90%  angle for maximum efficiency. Trace the path of the sun in the sky to determine if an object is casting a shadow, remove it if possible, and trim any branches that may be blocking sunlight to your solar unit.

Fixed mounts: Unmovable, you can decide to leave it at the best angle for the winter to help even out seasonal performance. It is advisable to have at least a 15° tilt to avoid rain accumulating on your panels. A greater angle will also help keep them free of snow.

Adjustable mounts: You can adjust your panels position manually to get the best tilt angle for each season. Take your latitude and add 15° for the winter, and subtract 15° for the summer to compensate for the suns position. At the spring and autumn equinoxes, the best angle is equal to your latitude.

Tracking mounts: Tracking solar panel mounts follow the path of the sun during the day to maximize the solar radiation that the solar panels receive, they are the most efficient type.

However they are very expensive and can break down or freeze up in the winter. An option is to just add two more fixed panels to make up for the 20 to 30 percent gain and save yourself a lot of money.

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How Solar Cells Work

Solar cells are all photovoltaic cells. Photovoltaic, as the word implies convert light into electricity (photo = light, voltaic = electricity). The term solar cell is reserved for devices that convert the suns energy into electrical energy, also called solar power, while the term photovoltaic cell is used when the light source is unspecified.

Semiconductors-Silicon

Solar cells are made of special materials called semiconductors such as silicon, which is currently the most commonly used. Pure silicon is a actually a poor conductor of electricity because its electrons are  not free to move about. The electrons are all locked in its crystalline structure, unlike good conductors like copper where electrons can move more freely.

N-type And P-type

Impurities are added to the silicon, other atoms mixed in with the silicon atoms to make it a much better conductor than in it’s pure form, changing the way electrons flow in it.

The process of adding impurities on purpose is called doping, and when doped with phosphorous, the resulting silicon is called N-type (“n” for negative).

When silicon is doped with boron, it becomes P-type silicon (“p” for positive). A positive and negative field is necessary for an electric current.

The P-N Junction

A solar cell has three layers necessary for energy conversion, a top junction layer, made of an N-type semiconductor. A middle layer which is the core of the device, this is the absorber layer (the P-N junction). And a bottom layer made of a P-type  semiconductor.

The Basic Construction Of Solar Cells

The top layer has some type of electrical conductors attached and needs a careful balance of electrical contact surface area and light collection surface area. Some solar cells overcome this problem with transparent conductors, but this is very expensive and few employ such a technique.

The top is covered with a non reflective covering (giving them the blue colour), the bottom of the cell also has a conductive surface, which has no size limitations.

The Process

When light strikes the cell the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely between the positive and negative field. At the junction the electrons can only move in one direction creating a negative charge at the top and a positive charge at the bottom.

Similar to a battery with a positive and negative terminal, with the placement of metal contacts on the top and bottom of the photovoltaic cell we can draw that current off to use externally for whatever application is needed.  When you connect a series of solar cells together you have a module, better known as a solar panel. That’s the basic process of solar cells simplified.

Free Power From The Sun

Solar cells perform the electrical conversion free, without moving parts, noise, pollution, maintenance, or radiation. On a bright, sunny day, the sun shines approximately 1,000 watts of energy per square meter of the planet’s surface.

Adding solar panels to an existing home can be expensive, but there are alternatives. There are many solar power kits available at a lower cost
or you can just make your own. Recently many people have turned to building their own solar panels, solar cells have become inexpensive, and an ambitious diy enthusiast can make their own solar panels at a surprisingly low cost.

Home Solar Power

Using home solar power systems will help the problem of decreasing oil supplies. This country is facing a serious two headed energy crisis.

First off is the use of fossil fuels. The problem with this is the ever increasing prices, and the dependence on having to get these resources from overseas suppliers that can shut off the supply at any time.

Will Oil Run Dry?

Contrary to popular belief there are tremendous petroleum resources still available in this country, like oil shale and oil sands for instance. That being said, the process of extracting usable oil products from these resources is extremely complicated and very expensive.

So while oil is probably not going to suddenly run dry, decreasing supplies of relatively cheap oil only means increasing prices of the harder to get resources.

For families already struggling to get by this is not a good prospect, and for those that think this is in the future, you only need to look back a short time to when oil prices took a huge jump. And this is just the beginning, ever higher rising prices are inevitable.

Pollution And Oil

The second problem and the one that is considered the worse of the two is pollution. Bad air quality and the threat of global warming is real and it is not going to go away as long as the burning of fossil fuels continue to add to the problem.

This country has been dependent on this form of energy for the last 150 years. Initially people were not aware of the consequences, but we now are beginning to realize what they are.

Unfortunately this form of power is deeply entrenched and will be around for a long time. Additionally the government has been slow to react and make any changes, even with the knowledge of increasing pollution. That means it is has been left up to the individual person to act.

The Abundance Of Solar Energy

The sun’s energy or solar energy is the most abundant form of energy available on earth, it is time to take advantage of it. What most people do not realize is that switching to solar power has now became affordable to everyone. There are three options:

• Build Your Own. Solar cells have became quite inexpensive lately, using these and materials that are readily available at your own local home store you can make your own home solar power system. These home solar systems are not only cheap to build, they are very reliable, low on maintenance, and are a great investment for your homes power supply. With a good manual they are surprisingly easy to build.

• Purchase A Kit. Everything you need delivered to your home. Like homemade project, only much easier to put together, as all the measuring and cutting has been done for you. They are also very reliable, low on maintenance, and easy to assemble, but do cost substantially more than a do it yourself project.

• Professional Installation. Sit back and let a reputable company do all the work. More and more home solar power companies are converting homes to solar energy. The cost associated with this plan is quite high, but if you can afford the cost it is a great option.

With decreasing oil supplies and increasing pollution, the time has come to not only help the environment but to reduce, or even end your monthly power bills. Convert to home solar power today.