Does solar technologyseem a bit technical for you? Well it doesn’t have to be. Let’s get you started on understanding some basic solar terms while expanding your vocabulary at the same time.


Alternating current (AC) – An electric current that reverses direction at regular intervals.

Ampere (A) or amp – The unit for the electric current; the flow of electrons. One amp is produced by an electric force of 1 volt acting across a resistance of 1 ohm.

Array – Any number of photovoltaic modules connected together to provide a single electrical output.

Azimuth – Horizontal angle measured clockwise in degrees from a reference direction, usually the north or south point of the horizon, to the point on the horizon intersected by the object’s line of altitude. As applied to the PV array, 180 degree azimuth means the array faces due south.


Balance of system (BOS) – Represents all components and costs other than the PV modules. It includes design costs, land, site preparation, system installation, support structures, power conditioning, operation and maintenance costs, and other related costs.

Breakers – Switches that automatically cut off electric current when an overload or some other anomaly occurs. They prevent circuits from overheating.


Carbon dioxide (CO2) – Well-known as a “green-house gas.” When people talk about “Carbon Footprint,” they are usually referring to CO2 emissions.


Diffuse insolation – Sunlight received indirectly as a result of scattering due to clouds, fog, haze, dust, or other obstructions in the atmosphere.

Direct current(DC) – Electric current in which electrons flow in one direction only.

Direct insolation – Sunlight falling directly upon a collector.

Distribution panel (MDP) – AKA breaker panel. This apparatus has a main breaker, which can cut power to the entire house, and as many circuit breakers as there are circuits in the house.


Electrical load schedule – is an estimate of the instantaneous electrical loads operating in a facility, in terms of active, reactive and apparent power.

Electric circuit – complete path of an electric current, including the generating apparatus, intervening resistors, or capacitors.

Electric current – A flow of electrons; electricity, amps.

Electrical grid – An integrated system of electricity distribution, usually covering a large area.

Energy – The ability to do work. Any source of usable power, as fossil fuel, electricity, or solar radiation


Grid-tied (PV system) – A PV system in which the PV array acts like a central generating plant, supplying power to the grid.

Gigawatt (GW) – 1,000,000,000 watts.


Hybrid system – A PV system that includes other sources of electricity generation, such as battery, generator set, wind or fossil fuel generators.


Incident light – Light that shines onto the face of a solar cell or module.

Insolation – Measure of solar radiation energy (direct or diffused) received on a given surface area in a given time. Maximum normal surface irradiance on earth is approximately 1000 W/m2 at sea level on a clear day.

Isolate – Todetach or separate so as to function alone.

Inverters – Devices that convert DC electricity into AC electricity (single or multiphase).


Junction box – protected enclosure for electrical wiring.


Kilowatt (kW) – 1000 watts.

Kilowatt-hour (kWh) – One thousand watts acting over a period of 1 hour. The kWh is a unit of energy (unit found on your electric bill to describe your electricity consumption).

Kilowatt peak (kWp) – This value specifies the output power achieved by a solar module under full solar radiation (under set STC). Solar radiation of 1,000 watts per square meter is used to define standard conditions.


Lightning arrester – A protective device for electrical equipment that reduces excessive voltage resulting fromlightning to a safe level by grounding the discharge.

Load – (1) the power consumed on an electrical circuit. (2) a power-absorbing device, such as a blender, light bulb, etc.


Megawatt (MW) – 1,000,000 watts. (Often used in solar farms) Module – A number of PV cells connected together; also called a panel; the smallest building block of the power generating part of a PV array.

Monocrystalline – Single silicon crystal; monocrystalline panels are made from one large, single silicon, usually dark in color.

Monolithic – Fabricated as a single structure.


Net-Metering – Allows the solar PV system to send excess electricity back through the electric meter to the utility. Defined by Philippine DOE as “Any electricity generated that is not consumed by the customer is automatically exported to the DU’s distribution system. The DU then gives a peso credit for the excess electricity received equivalent to the DU’s blended generation cost, excluding other generation adjustments, and deducts the credits earned to the customer’s electric bill.”


Off-grid system - Systems off of or have no access to the utility grid.

Ohm – The unit of electrical resistance.


Peak load; Peak demand – The maximum load, or usage, of electrical power occurring in a given period of time, typically a day.

PV – AKA Photovoltaic, pertains to the direct conversion of light into electricity.

PV array – An interconnected system of photovoltaic or ‘PV’ modules that function as a single electricity-producing unit. The modules are assembled as a discrete structure, with common support or mounting. In smaller systems, an array can consist of a single module.

PV efficiency – The ratio of electric power produced by a photovoltaic cell at any instant to the power of the sunlight striking the cell. This is typically about 9% to 14% for commercially available cells. Certain factors such as temperature can cause the efficiency rate to vary during the day.

PV system – A complete set of components for converting sunlight into electricity by the photovoltaic process, including the array and balance of system components.

Polycrystalline – Material that is solidified at such as rate that many small crystals (crystallites) form.

Pyronometer – An instrument for measuring total hemispherical solar irradiance on a flat surface, or "global" irradiance.


Radiance – Light from the sun; also called solar radiance.

Remote monitoring system – Capable of remotely monitoring, visualization and evaluating your solar PV system’s daily energy harvest.


Semiconductor – Any material that has a limited capacity for conducting an electric current. Generally falls between a metal and an insulator in conductivity. Silicon is a semiconductor.

Silicon (Si) – The basic material used to make solar cells. A common constituent of sand and quartz, it is the second most abundant element in the earth’s crust, after oxygen. It is an excellent semiconductor material.

Single line diagram – It is the blueprint for electrical system analysis. It will clearly show how the main components of the electrical system are connected, including redundant equipment and available spares.

Single phase (electric power) – a circuit having an alternating current using a system in which all the voltages of the supply vary in unison. It is commonly used in households.

Three phase (electric power) – a circuit generating, or using three alternating voltages of the same frequency, displaced in phase by 120°. It is commonly used for commercial applications (large businesses or manufacturing).

Solar constant – The strength of sunlight; 1000 watts per square meter at sea level at the equator at solar noon. It increases at higher altitudes.

Solar energy – Energy from the sun in the form of solar radiation.

Solar power – Energy from the sun that is converted into thermal or electrical energy.

Stand-alone (PV system) – An autonomous or hybrid photovoltaic system not connected to a grid. May or may not have storage, but most stand-alone systems require batteries or some other form of storage.

Stand-off mounting – Technique for mounting a PV array on a sloped roof, which involves mounting the modules a short distance above the pitched roof and tilting them to the optimum angle.


Transformer – Steps AC voltage up or down, depending on the application.


Volt (V) – A unit of measure of the force, or 'push,' given the electrons in an electric circuit. 1 volt produces 1 ampere of current when acting a resistance of 1 ohm.

Voltage – Potential energy that makes the electrical current flow in a circuit by pushing the electrons around (pressure).


Watt (W) – The unit of electric power, or amount of work (Joules), done in a unit of time. 1 ampere of current flowing at a potential of 1 volt produces 1 watt of power.