| M100 | 100 percent (neat) methanol used as a motor fuel in dedicated methanol vehicles, such as some heavy-duty truck engines. |
| M85 | a blend of 85 percent methanol and 15 percent unleaded regular gasoline, used as a motor fuel. |
| Magma | hot, thick, molten (liquid) rock found beneath the Earth’s surface; formed mainly in the mantle. |
| Magnet | A piece of material that has the natural ability to attract iron. |
| Magnetic Declination | The number of degrees east or west of true south from magnetic south. |
| Magnetic Field | A detected force that exists around a magnet or electrical field. |
| Magneto Hydro Dynamics (Mhd) | A means of producing electricity directly by moving liquids or gases through a magnetic field. |
| Maintenance Free Battery | A sealed battery to which water cannot be added to maintain the level of the electrolyte solution. |
| Maintenance-Free Battery | A sealed battery to which water cannot be added to maintain electrolyte level. |
| Major Natural Gas Producer | any person who produces natural gas in amounts determined by the commission as having a major effect on energy supplies. MAJOR MARKETER |
| Majority Carrier | Current carriers (either free electrons or holes) that are in excess in a specific layer of a semiconductor material (electrons in the n-layer, holes in the p-layer) of a cell. |
| Mantle | the semi-molten interior of the Earth that lies between the core and the crust making up nearly 80% of the Earth’s total volume; extends down to a depth of about 1800 miles (2,900 kilometers) from the surface. |
| Marginal Cost | In the utility context, the cost to the utility of providing the next (marginal)kilowatt-hour of electricity, irrespective of sunk costs. |
| Market Clearing Price | The price at which supply equals demand. The Day Ahead and Hour Ahead Markets. |
| Market Participant | An entity, including a Scheduling Coordinator, who participates in the energy marketplace through the buying, selling, transmission, or distribution of energy or ancillary services into, out of, or through the ISO-controlled grid. |
| Market-Based Price | A price set by the mutual decisions of many buyers and sellers in a competitive market. |
| Marketer | An agent for generation projects who markets power on behalf of the generator.The marketer may also arrange transmission, firming or other ancillary services as needed. Though a marketer may perform many of the same functions as a broker, the difference is that a marketer represents the generator while a broker acts as a middleman. |
| Marsh Gas | A common term for gas that bubbles to the surface of the water in a marsh or swamp. It is colorless, odorless and can be explosive. |
| Master File | A file maintained by the PX for use in bidding and bid evaluation protocol that contains information on generating units, loads, and other resources eligible to bid into the PX. |
| Maximum Power Point | The point on a PV module’s voltage/amperage curve where the product of current and voltage is a maximum (measured in watts). |
| Maximum Power Point (MPP) | Operating a PV array at that voltage will produce maximum power. The point on the current-voltage (I-V) curve of a module under illumination, where the product of current and voltage is maximum. [UL 1703] This corresponds to the point on an I-V curve that represents the largest area rectangle that can be drawn under the curve. For a typical silicon cell panel, this is about 17 volts for a 36 cell configuration. |
| Maximum Power Point Tracker (MPPT) | A power conditioning unit that automatically operates the PV generator at its MPP under all conditions. An MPPT will typically increase power delivered to the system by 10% to 40%, depending on climate conditions and battery state of charge. |
| Maximum Power Point Tracking (Mppt) | Electronically tracking the maximum power point of a PV module to achieve the highest possible output, by (in simplest terms) using surplus voltage to boost amperage. |
| Maximum Power Tracking | Operating a photovoltaic array at the peak power point of the array’s I-V curve where maximum power is obtained. Also called peak power tracking. |
| MCF | One thousand cubic feet or natural gas, having an energy value of one million Btu. A typical home might use six MCF in a month. |
| Mean Power Output (Of A Wind Turbine) | The average power output of a wind energy conversion system at any given mean wind speed. |
| Mean Wind Speed | The average wind speed over a specified time period and height above the ground. |
| Mechanical Energy | the energy an object has because of its motion or position and the forces acting on it. |
| Mechanical System | See HVAC system. |
| Median Wind Speed | The wind speed with 50% probability of occurring. |
| Megawatt | 1,000,000 watts of power or 1,000 kilowatts. |
| Megawatt (MW) | 1,000 kilowatts, or 1 million watts; standard measure of electric power plant generating capacity. |
| Megawatt Hour (MwH) | One thousand kilowatt-hours, or an amount of electricity that would supply the monthly power needs of 1,000 typical homes in the Western U.S. (This is a rounding up to 8,760 kWh/year per home based on an average of 8,549 kWh used per household per year [U.S. DOE EIA, 1997 annual per capita electricity consumtpion figures]). |
| Megawatt-Hour | 1,000 kilowatt-hours or 1 million watt-hours. |
| Megawatt-Hour (MwH) | 1,000 kilowatt-hours or 1 million watt-hours. |
| Met Tower | Meteorological towers erected to verify the wind resource found within a certain area of land. |
| Meter | A device which measures and records the production or consumption of electrical energy. |
| Methane | A light hydrocarbon that is the main component of natural gas and marsh gas. It is the product of the anaerobic decomposition of organic matter, enteric fermentation in animals and is one of the greenhouse gases. Chemical formula is CH4. |
| Methane (Ch4) | the simplest of hydrocarbons and the principal constituent of natural gas. Pure methane has a heating value of 1,1012 Btu per standard cubic foot. |
| Methane Gas | A chemical compound that is a major part of natural gas. |
| Methanol (Also Known As Methyl Alcohol, Wood Alcohol, Ch3oh) |
a liquid formed by catalytically combining carbon monoxide (CO) with hydrogen (H2) in a 1:2 ratio, under high temperature and pressure. Commercially it is typically made by steam reforming natural gas. Also formed in the destructive distillation of wood. |
| Methyl Tertiary Butyl Ether (MTBE) | an ether manufactured by reacting methanol and isobutylene. The resulting ether has a high octane and low volatility. MTBE is a fuel oxygenate and is permitted in unleaded gasoline up to a level of 15 percent. It is one of the primary ingredients in reformulated gasolines. |
| Microburst | A strong localized downdraft from a thunderstorm. Also called a downburst. |
| Microgroove | A small groove scribed into the surface of a cell which may be filled with metal for contacts. |
| Microhydro | Hydro-electric plants producing more than 100 watts and less than 2,000 watts. |
| Micrometer | One millionth of a meter. |
| Microwave | Electromagnetic radiation with wavelengths of a few centimeters. It falls between infrared and radio wavelengths on the electromagnetic spectrum. The radio wave beam can deliver electrical energy over long distances. |
| Mil | One-tenth of one cent $0.001. |
| Milliamps | One Thousandth of an amp. |
| Mineralized | containing minerals; for example, mineralized geothermal water contains dissolved minerals from inside the Earth. |
| Minimum Generation | Generally, the required minimum generation level of a utility systemós thermal units. Specifically, the lowest level of operation of oil-fired and gas-fired units at which they can be currently available to meet peak load needs. |
| Minority Carrier | A current carrier, either an electron or a hole, that is in the minority in a specific layer of a semiconductor material; the diffusion of minority carriers under the action of the cell junction voltage is the current in a photovoltaic device. |
| Minority Carrier Lifetime | The average time a minority carrier exists before recombination. |
| Mistral | A penetrating, stormy, dry and cold wind that blows through the Rhone Valley of France toward the Mediterranean coast. |
| Modified Sine Wave | A waveform that has at least three states (i.e., positive, off, and negative). Has less harmonic content than a square wave. |
| Modularity | The use of complete sub-assemblies to produce a larger system. Also the use of multiple inverters connected in parallel to service different loads. |
| Module | An encapsulated panel containing a number of electrically connected PV cells. |
| Module Derate Factor | A factor that lowers the photovoltaic module current to account for field operating conditions such as dirt accumulation on the module. |
| Module De-Rating Factor | A factor that lowers the power output of a module to account for field operating conditions e.g. Dirt build-up on the module. |
| Molecule | The smallest group of atoms held together by electrostatic forces. |
| Molecules | extremely tiny particles of which all materials are made . |
| Monocrystalline Solar Cell | A form of solar cell made from a thin slice of a single large crystal of silicon. |
| Monolithic | Fabricated as a single structure, as used to describe thin film series interconnected PV cells on a single sheet substrate. |
| Monopoly | The only seller with control over market sales. |
| Monopsony | The only buyer with control over market purchases. |
| Monsoon | Any seasonal wind that blows toward a continent in summer and away from it in winter. |
| Motor | A device that converts electrical energy into mechanical energy. |
| Movistor | Metal Oxide Varistor. Used to protect electronic circuits from surge currents such as those produced by lightning. |
| MTBE (Methyl Tertiary-Butyl Ether) | A clean- burning oxygenate with high octane and low volatility added to unleaded gasoline to reduce carbon monoxide emissions. |
| Mud Pot (Paint Pot) | thermal surface feature which occurs where there is not enough water to support a geyser or hot spring even though there may be some hot water below. Steam and gas vapors bubble up through mud formed by the interaction of gases with rock. |
| Multi-Bladed | More than two blades. |
| Multicrystalline | A material that has solidified at a rate such that many small crystals (crystallites) form. The atoms within a single crystallite are symmetrically arranged with a particular orientation, whereas the crystallites themselves are differently oriented. The multitude of grain boundaries in the material (between the crystallites) reduce the cell efficiency. Multicrystalline is also referred to as polycrystalline. |
| Multicrystalline Cell | See POLYCRYSTALLINE CELL |
| Multijunction Device | A high-efficiency photovoltaic device containing two or more cell junctions, each of which is optimized for a particular part of the solar spectrum. |
| Multi-Junction Device | A PV device containing two or more cell junctions each of which may be different in nature and optimized to absorb a particular part of the solar spectrum in order to achieve higher overall cell efficiency. |
| Multi-Stage Controller | A charge controller that allows different charging currents as the battery approaches full state of charge. |
| Municipal Electric Utility | A power utility system owned and operated by a local jurisdiction. |
| Municipal Solid Waste | Locally collected garbage, which can be processed and burned to produce energy. |
| Municipal Utility | A provider of utility services owned and operated by a municipal government. |
| Municipalization | The process by which a municipal entity assumes responsibility for supplying utility service to its constituents. In supplying electricity, the municipality may generate and distribute the power or purchase wholesale power from other generators and distribute it. |
