Solar PV (photovoltaic)

Solar “photovoltaic” (PV) technologies convert solar energy (or radiation or light) directly into electricity. The PV technology produces electricity directly from the interaction of sunlight (photon) with certain semiconductor materials such as silicon in the PV module. The building block of PV technology is the solar cell. Many cells may be wired together to produce a PV module and many modules are linked together to form a PV array.

 

The PV modules sold commercially range in power output from 250 to 450 watts and produce a direct current (DC) like the battery. The PV systems are extremely reliable and durable (for example, commercial PV modules usually have a 15-year product warranty with an 85% 30-year performance guarantee.) They require a very little maintenance and generate no noise and pollutants, as well as the degree of independence they provide.

 

A solar PV system usually consists of one or more module strings connected to an inverter that changes the PV's DC electricity to alternating current (AC) electricity to power electrical devices and to be compatible with the electric grid. Batteries are often included in the system to operate as stand-alone (off-grid) or to provide backup power in case of utility power outages. There are three types of solar PV systems depending on the desired applications; off-grid (autonomous), hybrid and grid-connected.

 

There have been some myths about the PV technology such as

  • “There is not enough sunlight in Canada”

  • “Solar electric technology is not efficient in a cold climate”

  • “Photovoltaic is not a proven technology”

  • “PV systems are too expensive”

 

However, these myths are proven not to be true. For example, many locations in Canada that have a dry continental climate have higher number of daylight hours as some European countries. Note that annual PV potential, i.e., annual electricity (kWh) produced at a given PV system (kWp) is as follows; Edmonton (1245kWh/kWp), Toronto (1161 kWh/kWp), Montreal (1185 kWh/kWp), Quebec (1134 kWh/kWp), Paris (938 kWh/kWp), Berlin (848 kWh/kWp), London (728 kWh/kWp), etc. Contrary to what many people think, PV systems convert sunlight into electricity more efficiently at lower temperatures. However, the winter months provide less hours of sunlight as in summer especially in higher latitude locations.

 

Since improved manufacturing has substantially reduced the cost since the 2000s, PV electricity can cost below 10 USD cents or less per kilowatt-hour (kWh) for utility-scale PV systems to achieve a "grid-parity". Most of PV electricity’s cost comes from the expense of initially purchasing the system. This up-front investment is like paying for years of electricity bills all at once. One may also want to consider the “economies of scale” associated with the system, which means that a larger system costs less per kilowatt-hour generated, even though it costs more overall.

However, it is important to realize that PV power systems are capital intensive from the buyer’s perspective, especially for residential buyers and are still expensive when compared with the low price of utility power in Canada (for example, about $ CAD 0.09~0.10/kWh for residential consumers in Quebec in 2019).

 

PV systems produce the most electricity from spring through fall when the sun is shining. Energy production will vary, of course, depending on geography and climate. Actual energy production will vary depending on specific geographic location, the system’s angle and orientation, the potential shading and the quality of the system’s components and installation. That is why the optimal design consideration including most of parameters is very important.

 

References:

 

- Levelized Cost of Energy and Levelized Cost of Storage 2018, www.lazard.com

- https://www.nrel.gov/news/press/2017/nrel-report-utility-scale-solar-pv-system-cost-fell-last-year.html

- Photovoltaic systems; a buyer’s guide, Natural Resources Canada

- Buying a photovoltaic solar electric system; a consumer guide, California Energy Commission

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