C

CAPACITANCE An electrical effect in AC circuits that results in amperage peaking before voltage.

CATHODE The electrode within a battery cell that undergoes the chemical process of reduction. Electrically, the cathode is the negative terminal of the cell.

CATHODIC PROTECTION Systems that protect metal from corrosion by running small electrical currents along the metal. Most often used to protect well heads, and oil, gas, and water pipelines.

CELL (battery) A single unit of an electro-chemical device capable of producing an electrical current by converting chemical energy into electrical energy. The cell is the basic unit used to store energy in the battery. The cell contains an anode, a cathode, and the electrolyte. A battery usually consists of several cells electrically connected together to produce higher voltages. (Sometimes the terms cell and battery are used interchangeably).

CELL (solar) The smallest, basic photovoltaic device that generates electricity when exposed to light.

CHARGE CONTROLLER A component of photovoltaic systems that controls the charging of the battery to protect the batteries from overcharge and over discharge. The charge controller may also indicate the system operational status. Standard charge controllers vary the current (A) based on preset voltage set points.

CHARGE RATE The current applied to a cell or battery to restore its available capacity, specified in relation to total battery size. A C/20 rate is a charge rate that is 1/20th of the total battery capacity. Also called a “20-hour rate.”

CIRCUIT A group of electrical components that make a complete electrical path, providing some function.

CIRCUIT BREAKER See BREAKER.

CLOSED LOOP SYSTEM A solar hot water system of which no part is vented to the atmosphere or fed with fresh liquid. The system liquid, usually some form of antifreeze solution, is re-circulated. Closed loop solar systems are also known as glycol systems and indirect systems.

COB CONSTRUCTION A traditional building technique using hand formed lumps of earth mixed with sand and straw.

COLLECTOR LOOP The plumbing loop in a solar hot water system that includes the solar collectors. The collectors heat the fluid in the collector, and the heated fluid can be used directly (if water) or the heat can be exchanged to a potable water loop.

COMBINER BOX A box where wires from individual PV modules or strings are combined into larger wires to run to the battery bank. Can also contain over current protection devices.

COMPACT FLUORESCENT LIGHT (CFL) A smaller version of standard fluorescent lamps that can directly replace incandescent lights. CFLs use 65 to 80 percent less energy, while producing the same lumens.

CONCENTRATOR A photovoltaic module that includes optical components, such as lenses, to direct and concentrate sunlight onto a solar cell of smaller area. Most concentrator arrays must directly face or track the sun.

CONDUCTION Heat transfer from a hot object to a colder object through direct contact.

CONDUCTOR A material with relatively low resistance through which electricity will readily flow—wires, cables, bus bars. The most common conductors are copper and aluminum.

CONDUIT Metal or plastic tubing designed to protect electrical conductors.

CONTINUOUS OUTPUT RATING The maximum amount of power an inverter may deliver to a load (or loads) for a sustained period of time.

CONVECTION — Heat transfer by the movement of fluid (usually air or water). — Heat transfer through either the natural or forced movement of air.

CONVERTER An electronic device for DC power that steps up voltage and steps down current proportionally (or vice-versa).

CRYSTALLINE SILICON A type of PV cell made from a single crystal or polycrystalline slice of silicon.

CURRENT Flow rate of electrons. See AMPERE.

CUTOFF VOLTAGE Electrical equipment setting for the voltage level at which a battery is considered to be empty, and the discharge process is terminated. Most commonly found in inverters and charge controllers that include a feature for low voltage disconnection.

CYCLE — One complete charge/discharge cycle of a battery. — An AC sine wave’s movement from zero to maximum positive, through zero, to maximum negative, and back to zero.

CYCLE LIFE Cycle life is the number of cycles a cell or battery will undergo before being considered “worn out.” This point is usually defined as when the battery’s capacity has decreased to 80 percent of its initial rated capacity.