Glossary

This page gives an understanding of some of the terms that are widely used in the solar community. 

Solar Photovoltaics: (also shortened to solar PV or PV) the direct conversion of sunlight into electricity using the photovoltaic process.

The energy conversion portion of a solar PV system has three components:

Solar Photovoltaic Cell: made of a semiconductor material that converts the solar radiation incident on the cell into electricity.

Solar Photovoltaic Module: composed of multiple PV cells (usually 60 or 72) wired in series and/or parallel (usually series). 

Solar Photovoltaic Array: composed of multiple PV modules that are wired together in series and/or parallel 

Solar Panel: A number of solar PV modules mounted onto a rack.  The term "solar panel" is often misused to mean both a solar PV module and a solar thermal collector. A solar thermal collector creates heat for water or air.  It is preferable that the term "solar panel" be discontinued in order to avoid the confusion that it is causing.  Instead the term "solar PV module", or "PV module" should be used for a solar photovoltaic device, and the term "solar thermal collector" or "solar collector" should be used for a solar heating device.

Tracker: A solar PV array receives the greatest amount of solar radiation when it is perpendicular to the rays of the sun. A tracker insures that the PV array faces the sun by mechanically adjusting its angle throughout the day and the year. Every project can be assessed to determine if the amount of extra solar energy that will be received, is worth the extra cost of the tracker and small amount of electricity needed to move the array. Typically it is not economically worthwhile under most electricity generation pricing structures.

Net metering: A net metering system utilizes a single meter that measures energy flow through the meter regardless of whether the flow is imported (to the customer) or exported (to the grid). At the end of the month the meter will provide a single "net" reading where: Import – Export = Your Bill.  

Import happens when consumption is greater than generation. 

Net Consumption > Generation

Export happens when generation is greater than consumption.

Net Generation > Consumption

A net metering program effectively values real-time import and real-time export at the same price.  In a net metering program the monthly net exported energy and monthly net imported energy can be assigned the same price or different prices.  Although some jurisdictions in North America use net metering Alberta has a net billing system.  

Net billing: Net billing is the method by which micro-generators in Alberta are billed for all the energy imported from the grid (and not just the net monthly energy imported) and paid for the all the electricity exported to the grid (and not just the net monthly energy exported).  Net billing employs a meter with two registers - one for electricity exported to the grid and one for electricity imported from the grid. In a net billing arrangement the total imported electricity is priced as per any energy imported by a customer that does not have any generation.  The total exported electricity can be valued in any of three ways:  discounted (less than import), equal (equal to import) or premium (greater than import). [5]

Bi-directional meter: A bi-directional type of meter is a special meter, that separately measures imported and exported electrical energy. Under Alberta’s Micro-Generation Regulations, your Wire Service Provider (electricity delivery company) is required to supply and install a bi-directional meter at no additional cost. 

Watt (W): A watt (W) is a unit of power, and power is the rate at which energy is produced or consumed. Think of watts as a measure of electrical flow. Does an electrical device need a big flow or a small flow to work? For example, a 100 W light bulb uses energy at a higher rate than a 60 W bulb; this means that the 100 W light bulb needs a bigger “flow” to work. Likewise, the rate at which your solar energy system “flows” power into your home is measured in watts.  One Megawatt (MW) is 1,000,000W. [8]

CE Code: (Canadian Electrical Code) The CE Code governs the accepted practice for electrical installations in Canada.  Section 64 specifically addresses the acceptable installation of components of renewable energy systems.  Other sections address the acceptable installation of the wiring of these systems.

Electrical Utility Grid: The electrical utility grid distributes electricity from generators to users.  The generators can be large centralized generating units such as coal, methane, hydro, and wind farm facilities as well as numerous distributed micro-generation generating units such as solar, wind, biomass and hydro generating units on residences, buildings and farms.   

Inverter: An inverter converts the DC (direct current) electricity created by solar PV arrays into the AC (alternating current) electricity that is used by households, buildings and the grid.

Gridconnected Inverter (AKA grid-tie or synchronous inverter): A gridconnected inverter is an inverter that is permitted to generate electricity into circu0its that also operate in parallel with the electrical grid or a standalone generator.  The inverter feeds electric current into circuits that are already energized by another source.  These inverters incorporate power, quality, and anti-islanding features that stand-alone inverters do not provide.  Some gridconnected inverters are energized solely from a PV array (and are called grid dependent inverters), and some are energized solely from a battery bank (regardless of from where the energy comes).

Module inverter: A module inverter is a small grid-dependent inverter that converts the electricity from one or more PV modules into AC electricity.  Module inverters are attached to the back of a PV module.   A popular module inverter that the manufacturer has assigned the brand "microinverter" tends to make everyone believe that all module inverters are called "microinverters", but this is merely a brand name.

Deep Cycle Battery: A deep cycle battery is a type of electrochemical battery that has been designed to withstand a high depth of discharge without significant damage to its plates.  A typical battery withstand only 50 to 150 discharges before failure, and likely only 6 deep discharges before failure, whereas a deep cycle battery, such as utilized in solar PV systems, is able to withstand 1200 deep discharge cycles without damage. [6]

Charge Controller: A charge controller is a device that regulates battery charge by controlling the charging voltage and/or current from a DC power source, such as a solar PV array. [1]

Standard Test Conditions (STC): STC is the most common internationally accepted set of conditions for rating PV module capacity.  STC consists of three test conditions: a solar irradiance of 1000W/m2, an air mass of 1.5, and a PV cell temperature of 25°C. [1]

References:

[1]Dunlop, J.P. (2010). Photovoltaic systems (2nd ed.). USA: American Technical Publishers. 

[2]Hamidi, R. (2012). Introduction to photovoltaic technology.  Retrieved from http://www.deanza.edu/faculty/hamidiridha/esci61/pdf/esci-61-spring-2012...

[5] Government of Alberta. (2015). What is micro-generation? Retrieved from http://www.energy.alberta.ca/electricity/microgen.asp

[7] Linak. (2015). Solar tracking. Retrieved from http://www.solar-tracking.com

[8]Enphase. (2015). Energy production. Retrieved from http://enphase.com/myenlighten-help/tip/what-is-the-difference-between-a...

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