Photovoltaic

Modern solar cells with practical efficiency were invented in the early 1950s, and have been used to power satellites since 1959. In the mid-1970s, they became popular applications such as remote telecommunications, navigational aids and other rugged, remote industrial uses including microwave, TV, radio and cellular repeater stations. They have been powering urban applications such as roadside emergency telephones and traffic signs since the mid-1980s. With prices dropping steadily, solar technology is now becoming affordable for homes and businesses alike.

Energy created through a solar electric system produces no pollutants. Our smallest system typically cuts greenhouse gas emissions as effectively as 50 trees.

Yes. Solar cells are mostly silicon, the main component of sand. There is no exhaust and no toxic materials to leak out of the system. The electricity coming through the inverter is just like the electricity coming from wall sockets — so, you should use the same care you would with utility power. All solar components are approved for utility interconnection and are installed according to standard construction practices.

Solar panel failure is most often caused by water damage to the panel, sealant, or connections. To prevent damage or failure, the panel should be mounted carefully. Horizontal orientation encourages water collection in the frame, so it’s best to mount the panels vertically. Allow for a sufficient air gap beneath the panel. Keep the panel dry and clean to ensure efficient, maximum output.

Although the production of solar panels incorporates a high-tech manufacturing process, it’s really very easy to use a photovoltaic system. Solar panels have no moving parts to wear out, they can be used alone or in combination with other energy sources, and they are silent, reliable and long lasting.

Solar panels benefit from a non-abrasive cleansing agent. When you review battery levels, check to see if battery connections and fuse holders are clean and dry. If necessary, use a silicon sealant to seal any gaps that may appear around the frame.

Yes. Solar panels will directly power equipment such as fans and pumps as long as the load is accounted for correctly. Equipment load that is greater than the output of the solar panel will weaken equipment efficiency — overcast or cloudy days reduce output. Equipment that requires a more stable voltage should pair solar power with a battery backup.

Solar panels work with light — not heat. With shorter daylight hours in winter, solar panels produce proportionately less power. If the modules become covered with snow they stop producing power. But, snow generally melts quickly when the sun strikes the modules. If you brush the snow off, they resume operation immediately.

A cloudy day provides sufficient diffused light to produce electricity. You’ll get the best electrical production with bright and sunny weather conditions. Under a light overcast, the modules might produce about half as much as under full sun, ranging down to as little as five to ten percent under a dark overcast day. In remote, off-grid applications, a PV system is connected to a battery storage system as a backup power source.

In grid-connected applications, the PV system works in parallel with the utility power grid. So, if electrical needs exceed the solar power output, the local utility makes up for the shortfall. Conversely, when the PV system generates more energy than the building requires, the excess power is exported to the utility grid, actually reversing the electrical meter!

No. Solar cells only convert sunlight into an electric current that must be used immediately or stored in batteries for later use.

PV conversion efficiency is the ratio of the electric power produced by a PV device to the power of the sunlight shining on the device. Cell efficiency defines how much energy in sunlight is actually converted into electricity. Shapeless silicon modules have lower efficiency than other PV materials. Cell efficiency degrades progressively with use.

A blocking diode prevents the solar panel from discharging the battery in the absence of sunlight and is connected to the cable. For example, a car battery will not act as an impedance load on a solar panel because of reverse blocking diodes that prevent nighttime battery discharge.

A PV array is an interconnected system of PV modules that function as a single, electricity-producing unit. The modules are assembled as a discrete structure, with a common support or mounting. In smaller systems, an array can consist of a single module. A complete set of components for converting sunlight into electricity includes a module, a support structure, wiring, an inverter, a meter, plus other equipment.

Solar modules — or panels — are a series of solar cells wired together into strings and enclosed in self-contained glass units for harsh-weather protection. Solar cells are mounted into groups called modules that produce about 0.5 volts of current to power lights and appliances. On the sunward side, a highly transparent solar glass pane protects cells. The underside acts like an insulating film or a second pane of glass. A connection socket picks up the generated direct current. Modules are connected together via cables, which link them to the inverter.

A photovoltaic cell, or "solar cell," is the smallest semiconductor element that converts sunlight into electricity. Each cell is made of silicon or another semi-conductor material, like a computer chip. The silicon is treated so that it generates a flow of electricity when light shines on it.

A stack of thin layers of semiconductor material exhibits the photoelectric effect, such as silicon or cadmium telluride. The layers contain small amounts of intentional impurities, such as the element germanium. These impurities give the semiconductor the ability to produce a current when exposed to light. Cells convert about five to fifteen percent of the solar energy they receive into electricity.

Solar cells are solid-state devices in which photons collide with atoms. This process transforms the resulting energy into electrons. These electrons flow into wires connected to the cell, thus providing electric current to appliances, lighting systems or other electrical loads. A typical PV cell is a thin 3"x3” unit, producing only a small amount of electricity.

PV takes advantage of the characteristics of impure silicon crystals. Pure silicon is not electrically active, because its atoms are locked into a solid crystal structure. There are no spare electrons, and no open spots for electrons. Silicon impurities create crystal with either a slight tendency to lose electrons or a slight tendency to attract them. When the two kinds of silicon are placed close together and exposed to sunlight, photons (particles of light) knock electrons loose on the unattractive side. An electrical current is created as electrons travel across the junction to the attractive side.

Sunlight is composed of particles of energy called photons. When sunlight strikes PV material, photons will either pass through, be reflected, or be absorbed. If the photon is absorbed, its energy will be transferred to an electron in an atom of the PV material. With new energy, the electron is able to escape from its normal position in orbit around that atom. In this way, the electron can become part of, and augment, the current in an electrical circuit. This photovoltaic effect is the basic physical process through which sunlight is converted into electricity.

Light-emitting diodes (LEDs) are made of similar materials and take advantage of the same physical principles, but in reverse. Powering LEDs with a PV panel works compatibly — photons in, electrons out; electrons in, photons out.

The time it takes to recoup the cost of a solar system is surprisingly shorter than most people expect. Some projects — depending on size and current incentives — are paid back within two years. Each situation is different, but on average it is between three and five years.

Your solar potential depends on a few factors such as geographic location. Obviously, sunnier areas will have a higher solar potential, or insulation, which is the measurement of how much sunlight falls in one square meter per day. You can easily search the Internet to find the insulation rating for your property. A typical value for a sunny area is 5 Kilowatt-hours per square meter per day. Next, consider roof space, which can determine the size of your potential solar system. Solar panels are typically mounted on the roof, though ground stands are also available. The more space you have to mount solar panels, the more potential energy you can create.

To go completely off-grid, you must be in a sunny climate and install a large enough solar system to power all of your energy needs. The batteries you depend on can be heavy, may require maintenance and eventually need replacing. When batteries are fully charged and the sun is still blazing away in the sky, any excess energy is simply wasted (neither consumed nor stored in your batteries).

As an alternative to a battery-dependent, off-grid system, your solar system can also tie into the local power company’s grid. This means excess electricity (that which you aren’t directly using) is fed back into your utility company’s storage system — often at a credit to you — instead of stored locally in batteries. Then, when the sun goes down or is behind a cloud and its energy isn’t available to you, your system will revert to grid-based electricity.

The advantages of going on-grid are you don’t have to include batteries in your system, which can save in costs. Additionally, you can save even more money by selling your surplus energy back to your utility company. The downside of going on-grid is that you are still technically dependent on the grid, and to avoid voltage hazards, when the grid goes down (power is out in your area) so do you. Going on-grid is more beneficial for a building which may not have as much annual sunlight, or whose solar system cannot produce all of its energy needs. In either case — on- or off-grid — solar panel installation can save you money in the long run.

When it comes to converting to solar energy use, the most popular place to install solar panels is on the roof, but they can actually be installed anywhere where they will receive direct sunlight. As an alternative to roof installation, some solar panels can be placed on adjustable stands that sit on the ground.

There are two issues to consider when deciding where to install your solar panels — obstructions and angle towards the sun. The first is easy — don’t install your panels anywhere trees, poles or other physical obstructions block sunlight. There’s nothing you can do about clouds!

As for angle towards the sun, if you are located in the northern hemisphere you will want your panels to be tilted facing south. The opposite applies if you are located in the southern hemisphere.

How much of a tilt should you have? Typically, the farther away from the equator, the more tilt is required. The goal is to make sure panels face the direct line of the sun at noon. One simple guideline is to tilt panels according to your building’s latitude line. So if you are at the 25-degree latitude, then your tilt angle should be 25 degrees. This angle should be increased during winter by as much as 55 degrees, since the sun is shining in the opposite hemisphere (due to the tilt in the earth’s axis) and it takes more of an angle to optimally catch rays.

Once you know your average power consumption and the amount of sunlight you receive each day, you are ready to calculate the number of panels you’ll need.

It is easy.
First, divide the total watts you use each day by the hours of sun you receive. That is the number of watts you need to generate in one hour.

Solar panels are rated in watts. For instance, a 200-watt solar panel will produce 200 watts of power each hour of peak sunlight. Therefore, if you need to produce 500 watts of power each hour then you’ll need five, 100W solar panels. Note that panel ratings vary, meaning you could choose five, 100W panels; 10, 50W panels; or just one, 500W panel.

While some people can get all their power from solar panels, most use solar panels to supply a percentage of their electrical needs. You can always start small and add on later.

Think about your energy goals, the amount of money you hope to save each month, and how much you can afford to pay up-front for a system. C-TEC Solar certified installers can help you design your solar system and help you with purchasing, rebates and installation.

Daily power consumption is determined by how much power, in watts, you use on a daily basis. You will need your electric bill to obtain this information. Many utility companies break out this information on your monthly statement. If not, there are online tools that can help.

Yes. A cloudy day provides sufficient diffused light to produce electricity. You’ll get the optimal electrical production with bright and sunny weather conditions. Under a light overcast, solar panels might produce about half as much as under full sun, ranging down to as little as five to ten percent under a dark overcast day.

Typically, the farther away from the equator, the more tilt is required. The goal is to make sure panels face the direct line of the sun at noon. One simple guideline is to angle panels according to your building’s latitude line. So if you are at the 25-degree latitude, then your tilt angle should be 25 degrees. This angle should be increased during winter by as much as 55 degrees, since the sun is shining in the opposite hemisphere (due to the tilt in the earth’s axis) and it takes more of an angle to optimally catch rays.

Some solar panels incorporate bypass diodes, which are integrated into the panel.

PV panels are reliable, long lasting and designed for outside use. Life expectancy is typically greater than 25 years.

Solar panels turn daylight and sunlight into electricity. The cells absorb the light and produce electric voltage, solar cells do not store any electricity so all power produced is fed through a regulator to the battery and stored there.