A is an abbreviation for amps (see ‘Current’)



AGM refers to absorbed glass mat batteries. AGM batteries differ from flooded lead acid batteries in that the electrolyte is held in the glass mats, as opposed to freely flooding the plates.



An electric current is a flow of electric charge through an electrical conductor. Electric charge flows when there is voltage present across a conductor.



DPDR is an abbreviation for double pole double throw.



G4 is the definition given to the base of a bulb. A G4 base has 2 pins which are 4mm centre to centre.



A gel battery is also known as a gel cell. It is a VRLA battery with a gelified electrolyte. The sulphuric acid is mixed with silica fume, which makes the resulting mass gel-like and immobile. Unlike a flooded wet-cell lead-acid battery, these batteries do not need to be kept upright.



A joule is a derived unit of energy, work or amount of heat. It is equal to the energy expended (or work done) in applying a force of one newton through a distance of one metre (1 newton metre or Nm), or in passing an electric current of one ampere through a resistance of one ohm for one second.



LED is an abbreviation for light emitting diode.



Lead-acid batteries are the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and low energy-to-volume ratio, their ability to supply high surge currents means that the cells maintain a relatively large power-to-weight ratio.



Li-ion refers to lithium-ion batteries. These batteries are a member of a family of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge, and back when charging. Li-ion batteries use an intercalated lithium compound as the electrode material, compared to the metallic lithium used in the non-rechargeable lithium battery.



Lithium ferrophosphate is contained in lithium iron phosphate batteries. These rechargeable batteries use LiFePO4 as a cathode material. LiFePO4 batteries have a somewhat lower energy density than the more common LiCoO2 design found in consumer electronics. However, LiFePO4 batteries offer longer lifetime, better power density (the rate that energy can be drawn from them) and are inherently safer. LiFePO4 is commonly used in vehicles and backup power.



Maximum Power Point Tracking, and it relates to the solar cell itself. Each solar cell has a point at which the current (I) and voltage (V) output from the cell result in the maximum power output of the cell.



MR stands for multifaceted reflector, and 11 refers to the diameter in eighths of an inch across the front face. An MR11 is eleven eighths, or 1.375 inches (34.9 mm) in diameter.



MR stands for multifaceted reflector, and 16 refers to the diameter in eighths of an inch across the front face. An MR16 is sixteen eighths or 2 inches (51 mm) in diameter.



NC is an abbreviation for normal closed.



NO is an abbreviation for normal open.



OLED is an abbreviation for organic light emitting diode.



Pulse Width Modulation is the most effective means to achieve constant voltage battery charging by switching the solar system controller’s power devices. When in PWM regulation, the current from the solar array tapers according to the battery’s condition and recharging needs.


PV Array

PRV array, or photovoltaic array, refers to a linked collection of solar panels.



SMD is an abbreviation for surface mounted device.


Solar Panel

A solar panel is a packaged, connected assembly of photovoltaic cells. (Also referred to as solar module, photovoltaic module or photovoltaic panel). Solar panels use light energy (photons) from the sun to generate electricity through the photovoltaic effect.



SPDT is an abbreviation for single pole double throw.



SPST is an abbreviation for single pole single throw.



Voltage, otherwise known as electrical potential difference or electric tension, is the electric potential difference between two points — or the difference in electric potential energy of a unit test charge transported between two points. Voltage is equal to the work which would have to be done, per unit charge, against a static electric field to move the charge between two points.



VRLA is an abbreviation for value-regulated lead-acid battery, more commonly known as a sealed battery. Because of their construction, VRLA batteries do not require regular addition of water to the cells, and vent less gas than flooded lead-acid batteries.



A watt is a derived unit of power. The unit, defined as one joule per second, measures the rate of energy conversion or transfer.