A light-emitting diode (LED) lamp or bulb includes three basic elements: the LED chip or chips, a heat management system, and electronics. The LED chip produces light when electricity flows across the semiconductor releasing energy as a photon of light and different semiconductor materials produces different colors of light.
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Renewable Energy Glossary
LED Lamp or Bulb
Li-ion
Lithium ion (Li-ion) is a battery chemistry where a lithium salt in an organic solvent is used as the electrolyte, and lithium ions migrate from the cathode to the anode during discharge.
Light Pipes
Light pipes have three components: a round, domed plastic skylight that mounts on the roof; a cylindrical metal tube with a highly reflective interior surface; and a diffuser that mounts on the ceiling. Sunlight enters the skylight dome and reflects downward through the reflective tube to the diffuser, which delivers the light below.
Light Shelves
Highly reflective horizontal surfaces that bounce light toward the ceiling to help channel daylight deeper into the interior of a building. Typically installed toward the top of a high window exposed to sunlight where the bottom of the light shelf is above head height, they can be installed on the exterior, interior, or both.
Light-Emitting Diode Lamp or Bulb
A bulb that includes three basic elements: the LED chip or chips, a heat management system, and electronics. The LED chip produces light when electricity flows across the semiconductor releasing energy as a photon of light and different semiconductor materials produces different colors of light.
Line 1 (L1) and Line 2 (L2)
When referring to an AC split-phase system, these are the two “hot” waveforms which are 180 degrees out of phase and have a voltage potential between them of 240 Vac.
Lithium Ion
A class of batteries using a lithium salt as an electrolyte, where lithium ions migrate from the cathode to the anode through a membrane to produce current.
Litmus Paper
Used to measure the pH of an antifreeze solution.
Load Controllers
Devices that regulate the power from batteries to loads so that the batteries are not over-discharged.
Load Shedding
A process in which less-critical loads are turned off, allowing the more important loads to continue to operate. This can be programmed into some systems when the battery voltage reaches a certain level.
Load-Side Connection
Refers to using a circuit breaker in the main AC service panel to feed the power from a PV system to the grid.
Lockout/Tagout
Equipment that keeps power sources shut off for installation or maintenance by locking the disconnecting means in the off position and attaching a tag with contact name and notification that the system must not be turned on.
Low Iron Glass
Glass with the iron removed that has a higher transmittance than window glass; solar glass used on solar collectors and PV modules.
Low-E Glass
Panes of glass with a very thin metallic coating that has been applied to reduce radiant heat transfer and the overall U-value of the window unit.
Low-E Windows
Windows that reduce radiant heat transfer and have lower U-values or higher R-values. How a low-e window performs depends on which pane of glass the very thin metallic coating is applied.
Low-Head Site
A hydro-electric site with less than about 10 feet of vertical drop (head). Low-head sites need low-head turbines to produce useful amounts of power.
Low-Head Turbine
A hydro-electric turbine that can handle a high flow of water at a low head of pressure, for example a "propeller" type. Francis and crossflow turbines can also work at relatively low heads.
Low-Voltage Disconnect
A device that disconnects loads from the battery bank at a certain voltage, in order to prevent over-discharging and damage.
Lumen
A unit of measurement quantifying the amount of light emitted from a light source.
LVD
A low-voltage disconnect (LVD) disconnects loads from the battery bank at a certain voltage, in order to prevent over-discharging and damage.
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