Glossary of Technical Terms

AC
Alternating current. Electrical energy which reverses its direction at regular intervals.

AC Daily Power Budget
The daily amount of watts your AC appliances use.

AC Inverter and Battery Power Allowance
Running an inverter draws a small amount of power from your battery. So does keeping power stored. The inverter and battery allowance in your power calculations help make certain enough power will be produced to keep your battery from running in the red.

Adjusted Total Daily Power Budget
A total daily power budget may be changed to meet certain situations. For instance, if you spend only weekends at a house, then your adjusted total daily power budget will be lower.

Ampere or amp
Electric current is measured in amperes or amps. The ampere, in practice often shortened to amp, (symbol: A) is a unit of electric current, or amount of electric charge per unit time, in coulombs per second. The ampere is an SI base unit, and is named after André-Marie Ampère, one of the main discoverers of electromagnetism.

One ampere is defined to be the constant current which will produce an attractive force of 2×10–7 newton per metre of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one metre apart in a vacuum.The definition is based on Ampère's force law. The ampere is a base unit, along with the metre, kelvin, second, mole, candela and the kilogram: it is defined without reference to the quantity of electric charge.

The SI unit of charge, the coulomb, "is the quantity of electricity carried in 1 second by a current of 1 ampere." Conversely, an ampere is one coulomb of charge going past a given point in the duration of one second; that is, in general, charge Q is determined by steady current I flowing per unit time t

Amp Hours
The number of amps used or produced in a given hour. Batteries are rated in amp hours.

Array
A group of solar electric modules connected together in a power system.

Battery Bank
A group of batteries wired together to store power in a solar electric system. Allows you to use the stored power at night, on cloudy days or to run more power than the array can produce at one time.

Charge Controller
Regulates the current from solar panels to your battery bank. The charge controller ensures the batteries are not overcharged and provides protection from the current running backwards to the solar panels.

Coulomb
The coulomb (symbol: C) is the SI unit of electric charge. It is named after Charles-Augustin de Coulomb. In principle, the coulomb could be defined in terms of the charge of an electron or elementary charge. Since the values of the Josephson (CIPM (1988) Recommendation 1, PV 56; 19) and von Klitzing (CIPM (1988), Recommendation 2, PV 56; 20) constants have been given conventional values (KJ ≡ 4.835 979×1014 Hz/V and RK ≡ 2.581 280 7×104 Ω), it is possible to combine these values to form an alternative (not yet official) definition of the coulomb. A coulomb is then equal to exactly 6.241 509 629 152 65×1018 elementary charges. Combined with the present definition of the ampere, this proposed definition would make the kilogram a derived unit.

In everyday situations, positive and negative charges are usually balanced out. According to Coulomb's Law, two point charges of +1 C, one meter apart, would experience a repulsive force of 9×109 N, roughly the equivalent of 900,000 metric tons of weight.

Current
The rate of flow of an electric charge. Current is measured in amps.

DC
Direct current. Electrical energy flowing in one direction and of substantially constant value.

DC Daily Power Budget
The number of watts your DC appliances use daily.

Electron
The basic particle that orbits the nucleus of an atom. The flow of electrons produces electricity

Ground Mount
A piece of equipment upon which solar modules are mounted.

Hertz or HZ
The frequency of electrical current described in cycles per second. Appliances in the U.S. use 60 HZ. Appliances in other countries generally use 50 HZ.

Kelvin
The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero (0 K). The Kelvin scale and the kelvin are named after the British physicist and engineer William Thomson, 1st Baron Kelvin (1824–1907), who wrote of the need for an “absolute thermometric scale”. and its symbol was °K.

Incandescent bulb
A lightbulb that emits light due to the glowing of a heated filament inside it.

Inverter
An appliance used to convert independent DC power into standard household AC current.

Kilowatt or KW
A thousand watts. (see Watts)

LED
A light-emitting-diode (LED) , is a semiconductor diode that emits light when an electric current is applied in the forward direction of the device, as in the simple LED circuit. The effect is a form of electroluminescence where incoherent and narrow-spectrum light is emitted from the p-n junction.

LEDs are widely used as indicator lights on electronic devices and increasingly in higher power applications such as flashlights and area lighting. An LED is usually a small area (less than 1 mm2) light source, often with optics added to the chip to shape its radiation pattern and assist in reflection. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or ultraviolet. Besides lighting, interesting applications include using UV-LEDs for sterilization of water and disinfection of devices,and as a grow light to enhance photosynthesis in plants.

A light-emitting-diode (LED) is a semiconductor diode that emits light when an electric current is applied in the forward direction of the device, as in the simple LED circuit. The effect is a form of electroluminescence where incoherent and narrow-spectrum light is emitted from the p-n junction.

LEDs are widely used as indicator lights on electronic devices and increasingly in higher power applications such as flashlights and area lighting. An LED is usually a small area (less than 1 mm2) light source, often with optics added to the chip to shape its radiation pattern and assist in reflection. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or ultraviolet. Besides lighting, interesting applications include using UV-LEDs for sterilization of water and disinfection of devices, and as a grow light to enhance photosynthesis in plants.

High-Powered LED
High power LEDs from Philips Lumileds Lighting Company mounted on a star shaped heat sinkHigh power LEDs (HPLED) can be driven at more than one ampere of current and give out large amounts of light. Since overheating is destructive, the HPLEDs must be highly efficient to minimize excess heat; furthermore, they are often mounted on a heat sink to allow for heat dissipation. If the heat from a HPLED is not removed, the device will burn out in seconds.

A single HPLED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp. LEDs have been developed that can run directly from mains power without the need for a DC converter. For each half cycle part of the LED emits light and part is dark, and this is reversed during the next half cycle. Current efficiency is 100 lm/W.

Load
An appliance or fixture that consumes or uses the energy harvested or stored by the solar system.

Lumens
Is the amount of light measured from a light source, typically 6" from the source. Often Lumens are a specified requirement of light hitting a specific surface. The amount of photons existing the light source determine this lumen measurement value.

MA
Milliamps, 1000 MA = 1 amp.

Megawatt
1,000,000 watts of power or 1,000 kilowatts.

Module
Modular solar electric charger; used interchangeably with solar electric panel.

Neutron
A basic particle in an atom’s nucleus that has a neutral electrical charge.

Proton
A basic particle in an atom's nucleus that has a positive electrical charge.

Photovoltaic
Converting light into electricity. Photo means "light" voltaic means "electric". Often referred to as "PV" for short. More commonly referred to as "solarelectric".

Photon
The smallest measurement of light (quanta) energy known to man.

SI
The International System of Units (abbreviated SI from the French Le Système International d'Unités) is the modern form of the metric system and is generally a system devised around the convenience of the number ten. It is the world's most widely used system of measurement, both in everyday commerce and in science.

The older metric system included several groups of units. The SI was developed in 1960 from the old metre-kilogramsecond (mks) system, rather than the centimetre-gram-second (cgs) system, which, in turn, had a few variants. Because the SI is not static, units are created and definitions are modified through international agreement among many nations as the technology of measurement progresses, and as the precision of measurements improves.

The system is nearly universally employed, and most countries do not even maintain official definitions of any other units. A notable exception is the United States, which continues to use customary units in addition to SI. In the United Kingdom, conversion to metric units is government policy, but the transition is not yet complete. Those countries that still recognise non-SI units (e.g., the US and UK) have redefined their traditional non-SI units in SI units.

Solar Blanket
A floating polyethylene material that insulates the pool surface and allows light to pass through into the pool.

Solar Cell
The smallest basic solar electric device which generates electricity when exposed to light.

Solar Electric
The preferred term used to describe something which uses sunlight to produce electricity. "Photovoltaic" is the more technical term.

Thermal Blanket
A floating foam cover that insulates well but does not allow light to pass into the swimming pool.

Total Daily Power Budget
In a DC system, the daily amount of watts your DC appliances use, plus the battery power allowance. In a DC and AC system, the daily amount of watts DC and AC appliances use, plus battery and inverter power allowances.

Voltage or Volts
Voltage is the rating of the amount of electrical pressure that causes electricity to flow in the power line. If electricity were water, voltage would measure the amount of pressure at the faucet.

Watts
A watt is a measurement of total electrical power. Volts x amps = watts. The watt (symbol: W) is the SI derived unit of power, equal to one joule of energy per second. It measures a rate of energy conversion.

A human climbing a flight of stairs is doing work at a rate of about 200 watts. A typical automobile engine produces mechanical energy at a rate of 25,000 watts (approximately 33.5 horsepower) while cruising. A typical household incandescent light bulb uses electrical energy at a rate of 25 to 100 watts, while compact fluorescent lights typically consume 5 to 30 watts.

Watt Hour
The quantity of electrical energy used or produced when one watt is used for one hour.