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About Solar

The sun's energy is captured and turned into usable electricity for everyday consumption in a solar cell – the heart of a solar electric system.

The word Photovoltaic (PV) is composed of two terms: Photo - Photon which means "light" and Voltaic from "Volt" which is the unit used to measure electric potential at a given point.
The most common semi conductor material used in photovoltaic cells is silicon, an element most commonly found in sand. There is no limitation to its availability as a raw material; silicon is the second most abundant material in the earth’s mass.

The performance of a solar cell is measured in terms of its efficiency at turning sunlight into electricity. A typical commercial solar cell has an efficiency of 15% about one-sixth of the sunlight striking the cell generates electricity.
The amount of solar power reaching the Earth’s surface varies significantly. This is due to the Earth’s tilt, rotation, atmosphere, and various climatic conditions. The estimate of peak solar energy hitting the Earth’s surface is known as Peak Sun and has been given the value of 1000 W/m2. According to Natural Resources Canada, Toronto International Airport receives 3.67 Peak Sun Hours (kwh/m2/day) of solar irradiation on a horizontal surface. For surfaces tilted to latitude, this number increases to about 4.07 Peak Sun Hours per day. The higher the number of peak sun hours an area receives, the more electricity a PV system in that area will produce.

Click on here to see Photovoltaic potential and solar resource maps of Canada

PV Systems

The figure shows how electricity generated by solar cells in roof-mounted PV modules is transformed by an inverter into AC power suitable for export to the grid network. The householder/generator then has two choices: either to sell all the output to the local power utility (if a feed-in tariff) or to use the solar electricity to meet demand in the house itself, and then sell any surplus to the utility. It is financially advantageous in Ontario to sell all the generated energy back to the grid.
Elements of a grid-connected PV system are: PV modules - converting sunlight into electric power, an inverter to convert direct current into alternating current, sub-construction consisting out of the mounting system, cabling and components used for electrical protection, and a meter to record the quantity of electric power fed into the grid.
Off-grid (stand-alone) systems use charge controllers instead of inverters and have a storage battery for supplying the electric energy when there is no sunlight e.g. during night hours.

Inverters

When sunlight strikes a photovoltaic cell, direct current [DC] is generated. By putting an electric load across the cell, this current can be utilized. An inverter is an electrical device which converts direct current [DC] to alternating current [AC]. Solar cells produce direct current. Most of the electrical devices we commonly use however, expect a standard AC power supply. An inverter takes the DC from the solar cells and creates a useable form of AC. An inverter is moreover necessary to connect a PV system to the grid.

Balance of the system

The remaining electrical and mechanical components of a PV system are known as the balance of system components (BOS). Mechanical components include fasteners, brackets, enclosures, racks, and other structural supports. Electrical components include conductors, cables, conduits, junction boxes, enclosures, connectors, and terminations needed to make circuit connections between modules, disconnects, inverters, meters, and other electrical systems and equipment.

System Output

The electricity production of a PV system depends on external (environmental conditions) and internal (technology, layout of the system) parameters.

The efficiency of the PV module depends on:

Weather and temperature

Weather naturally affects the performance of solar modules but not entirely as you might expect. The amount of sunlight, of course, is most important in determining the output a solar electric system will produce at a given location, but temperature is also important.

As the electrical output of a PV module is dependent on the intensity of the light to which it is exposed, it is certain that a PV module exposed to the sun at midday by clear sky, will produce maximum of its output electricity. You can thus indeed say that PV modules will tend to generate more electricity on bright days than when skies are overcast. Nevertheless, photovoltaic systems do not need to be in direct sunlight to work, so even on overcast days a PV module will be generating some electricity.

Contrary to most people's intuition, solar electric panels actually generate more power at lower temperatures with other factors being equal. This is because solar cells are electronic devices and generate electricity from light, not heat. Like most electronic devices, solar cells operate more efficiently at cooler temperatures. In temperate climates, solar panels will generate less energy in the winter than in the summer but this is due to the shorter days, lower sun angles and greater cloud cover, not the cooler temperatures.

Environmental benefit

The environmental benefits of solar power are indisputable. Electricity generated from the sun produces no harmful emissions or pollutants. By installing solar panels, you can directly contribute to the repair and preservation of the environment by producing your own clean power.

Feed in Tariff

Feed in Tariffs put a legal obligation on utility companies to buy electricity from renewable energy producers at a premium rate, usually over a guaranteed period, making the installation of renewable energy systems a worthwhile and secure investment for the producer. The extra cost is shared among all energy users, thereby reducing it to a barely noticeable level. FITs have been empirically proven to generate the fastest, lowest-cost deployment of renewable energy, and with this as a priority for climate protection and security of energy supply, not to mention job creation and competitiveness, FITs are the best vehicle for delivering these benefits.

The FIT system means that the pay-back time for PV is no longer several decades but several years instead. In countries such as Germany and Spain the demand for renewable energy systems has risen dramatically and the installation costs are coming down fast. This financing model has now been taken up widely around the world, including Ontario.

Lifetime of the PV System

The estimated lifetime of a PV module is 30 years. Furthermore, the modules' performance is very high providing over 80% of the initial power after 25 years which makes photovoltaic a very reliable technology in the long term. Most PV systems installed more than 25 years ago, still produce energy today!

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