The type of electricity used by standard household outlets.
Most plug-in household appliances use AC power. Batteries and solar panels are usually DC internally, so conversion may be needed.
A unit of heat energy used for HVAC and appliance ratings.
Heat pump and air conditioner capacity is often expressed in BTU per hour. Efficiency ratings compare BTU moved to electrical energy consumed.
Bill impact: Higher BTU capacity does not automatically mean lower operating cost; efficiency and runtime matter.
A measure of how much energy a generator actually produces compared with its maximum possible output.
The CPUC glossary explains capacity factor as actual energy produced divided by the maximum energy the unit could produce over the same period.
Bill impact: More relevant to power plants than home bills, but it helps explain why solar, wind, gas, and nuclear resources have different grid roles.
COP
Coefficient of Performance
A heat pump efficiency ratio for heat delivered compared with electricity consumed.
ENERGY STAR defines COP as the average rate of space heating delivered divided by the average rate of electrical energy consumed under a specific test condition.
Bill impact: A COP of 3 means roughly three units of heat moved for each unit of electrical energy used at that condition.
Electricity that flows in one direction, used inside batteries and many electronics.
Solar panels and batteries produce or store DC power. Running AC loads from DC storage requires an inverter.
EER2
Energy Efficiency Ratio 2
A cooling efficiency ratio at a specific operating condition.
ENERGY STAR describes EER2 as average space cooling delivered divided by average electrical energy consumed, expressed in Btu per Wh.
Bill impact: Useful for comparing efficiency under hotter or specific test conditions, not just seasonal averages.
Grid
Also called: Power grid
The interconnected system of power lines, substations, and generators that delivers electricity.
The CPUC glossary describes the grid as interconnected power lines and generators managed so generation can meet customer needs reliably.
Bill impact: Delivery charges and some fixed charges pay for the local infrastructure that connects your home to the grid.
Equipment that moves heat instead of creating heat directly from electric resistance.
A heat pump can heat and cool a home by moving heat between indoors and outdoors. Its performance depends on temperature, equipment design, and installation.
Bill impact: A heat pump can increase electric usage while reducing gas usage, making TOU plan choice more important.
HSPF2
Heating Seasonal Performance Factor 2
A seasonal heating efficiency rating for heat pumps.
ENERGY STAR describes HSPF2 as seasonal heating required divided by electricity consumed by the heat pump system during the same season.
Bill impact: Higher HSPF2 can reduce winter heating kWh for the same comfort level.
HVAC
Heating, ventilation, and air conditioning
The heating and cooling equipment and ductwork that conditions indoor air.
HVAC can refer to central air conditioning, heat pumps, furnaces, ducts, filters, fans, and controls. In San Diego, HVAC runtime often drives summer peak usage.
Bill impact: HVAC load is often large enough that TOU timing, thermostat schedules, and equipment efficiency materially affect the bill.
Electronics that convert DC battery or solar power into AC power for household devices.
Inverters have power limits, surge limits, and efficiency losses. A 1 kWh battery cannot deliver a full 1 kWh to AC loads after conversion losses.
Bill impact: Inverter losses reduce the savings from charging a battery and using it later.
A unit of power equal to 1,000 watts.
Power is the rate at which electricity is being used or produced. A 1 kW load running for one hour uses 1 kWh.
Bill impact: Residential SDGE energy charges are usually based on kWh, not instantaneous kW demand.
A unit of energy equal to using 1 kilowatt for 1 hour.
If a device uses 500 watts for 2 hours, it uses 1 kWh. SDGE residential energy prices are usually shown as dollars per kWh.
Bill impact: Most bill calculators multiply kWh in each rate period by the applicable price.
LFP
Lithium iron phosphate
A lithium battery chemistry common in modern portable power stations and home batteries.
LFP batteries are often marketed for longer cycle life and improved thermal stability compared with some other lithium-ion chemistries.
Bill impact: Cycle life matters if you plan to charge and discharge a battery daily for TOU savings.
The amount of electric power a device, home, or system requires at a point in time.
A home load rises when major appliances turn on. Utilities also use load to describe system demand.
Bill impact: On residential SDGE plans, when the load occurs matters because TOU periods price kWh differently.
A vehicle fuel-economy metric showing miles traveled per gallon of fuel.
MPG is useful for gasoline vehicles, but can be misleading when comparing EVs because fuel prices and energy units differ.
Bill impact: EV-vs-gas comparisons should convert both sides to cost per mile rather than comparing MPG directly with kWh.
MPGe
Miles per gallon equivalent
An EPA fuel-economy label metric for comparing EVs and other non-gas vehicles with gasoline vehicles.
FuelEconomy.gov explains MPGe as similar to MPG, but based on the distance a vehicle can travel using energy equivalent to a gallon of gasoline.
Bill impact: MPGe helps compare vehicle efficiency, but your actual EV fuel cost still depends on kWh used and the electricity rate you pay.
MPPT
Maximum Power Point Tracking
Solar charging electronics that help extract more usable power from solar panels.
MPPT controllers adjust operating voltage and current to keep solar panels near their best power point as sunlight and temperature change.
Bill impact: Relevant when using portable solar to reduce grid charging.
Photovoltaic
Also called: PV
Solar technology that converts sunlight directly into electricity.
PV panels produce DC electricity, which is usually converted by an inverter before it is used by household AC loads or exported to the grid.
Bill impact: PV export value depends heavily on whether the account is under NEM, SBP/NBT, and the applicable TOU period.
Electricity from naturally replenished resources such as solar, wind, geothermal, hydro, and biomass.
Renewable resources are replenished over time but still vary in availability by weather, season, and location.
Bill impact: CCA and SDGE generation products can differ in renewable content, but the delivered bill still includes delivery and other utility charges.
SEER2
Seasonal Energy Efficiency Ratio 2
A seasonal cooling efficiency rating for air conditioners and heat pumps.
ENERGY STAR describes SEER2 as total heat removed during the cooling season divided by total electrical energy consumed during that season.
Bill impact: Higher SEER2 usually means less electricity for cooling, but installation quality and usage patterns still matter.
A unit of electrical potential, often used for outlets, batteries, and solar equipment.
Voltage is part of the electrical compatibility picture. A 120-volt household outlet and a DC battery system may both involve electricity, but they are not interchangeable without the right equipment.
Bill impact: Voltage does not directly set your SDGE bill, but it matters when checking whether a device can safely connect to a home outlet, inverter, or solar input.
A unit of power for how fast a device uses electricity.
A 100 W device uses electricity at one-tenth of a kilowatt while it is running.
Bill impact: Watts become billable energy only over time: watts multiplied by hours becomes watt-hours.
A small unit of energy equal to 1 watt used for 1 hour.
Battery capacity is often listed in Wh. 1,000 Wh equals 1 kWh.
Bill impact: Useful for translating portable battery capacity into grid energy cost.