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The cost of electricity generated by a PV system is in principle a function of the investment cost and the financing cost divided by the total electricity production over the lifetime of the system. The investment cost is largely dependent on the cost of the PV module which, to a large degree, depends on the cost of solar grade silicon. The cost of PV modules is constantly falling due to intense competition and technology improvements throughout the value chain. In most markets the cost of electricity is increasing. When solar cells can produce electricity at the same price as, or less than, the electrical energy you can buy off the grid, without including subsidies or feed-in tariffs, the market is at “grid parity”. From then on, it is expected that it will be cheaper to buy a solar system than to buy electricity from the grid. Grid parity will be reached first in areas with abundant sun and high electricity prices, like Italy and California.
In remote areas with a low density of potential customers and long distances to existing grids or power plants, off-grid solutions are often the only practical and economical solution for electricity supply. These solutions might either be systems for a single house or micro-grids supplying a village from one or several connected PV systems. These systems need storage capacity such as batteries and/or some other power generating technology.
The advantages of on-grid are that there's no need for a battery, you can sell surplus power, and you can get electricity from the grid during nighttime.
Yes, it can. The annual production is dependent on a range of parameters such as the size of the PV-array, orientation and sloping of the roof, irradiation (latitude, local weather conditions), efficiency (module type, temperature). In ideal conditions, with high quality solar modules installed, a rooftop installation can cover the typical electricity for a residential house.
When a cell is shaded it produces less current. Because the cells are connected in series, the total energy production of the module is reduced to a level determined by the most shaded cell. Solar modules should therefore never be mounted in a way that leaves them partially shaded much of the day (chimneys, antennae, etc…).
Installing a solar PV system enables you to generate your own clean, green electricity directly from the sun. This not only reduces electricity bills but also CO2 emissions and greenhouse gases. The financial advantages of installing a PV system are enhanced in many markets by local incentives, e.g.:
Investments subsidies/tax credits (The authorities refund part of the cost of installing the system)
Feed-in tariffs (feed-in tariffs works by guaranteeing a long-term premium payment for electricity generated from renewable sources and fed into the grid)
Net metering (the electricity utility buys PV electricity from the producer under a multiyear contract at a guaranteed rate)
Solar photovoltaic systems are built by assembling solar modules. The manufacturing of the modules starts with silicon, the second most abundant element in the planet's crust, usually in crystalline form. Purified silicon is then cast and cut into wafers a fraction of a millimeter thin. The wafers are then turned into solar cells. Finally, the cells are assembled into solar modules. The modules are made from PV cells that are linked together in series to generate power output. A number of PV modules can be linked together in an array to produce the desired electrical output.
Depending on the type of application, the rest of the system ("balance of system" or "BOS") consists of different components such as the mounting structure (racks/trackers), DC switches, inverters, and meters.
The industry's standard power output guarantee from leading manufacturers is 25 years, however the estimated lifetime for high quality modules is estimated to be much longer.
Power output is determined by the size of the system and solar irradiation in the area. REC systems are usually installed in areas with many stable sun hours per day. For example, an installation for residential use in Germany generally requires 5 kW to provide stable output for an average household for one year. (For more information see
Solar Math in our About Solar section)
Since the electricity generated depends on light intensity and not irradiation or direct sunlight, it will work in cloudy conditions. However the greater the intensity of the light, the greater the flow of electricity. Hence you generate more on sunnier days. REC modules are optimized to produce power on cloudy days as well.
PV systems will normally be installed in areas with high irradiation. Although generally installed on a roof, they can be installed on any surface such as a facade, sunshade, garage or on the ground, usually by constructing a tracker system. They should not be placed in shaded locations (e.g., places that are in the shadow of other buildings or large trees) since this will decrease electricity output.