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Energy Glossary

Essential terms for understanding home energy efficiency, solar power, and savings.

15
Terms Defined
10
Categories

Categories

UnitsSolarHeating & CoolingFinancialIncentivesSmart HomeEnvironmentInsulationAssessmentStorage

Units

kWh (Kilowatt-hour)

A unit of energy equal to using 1,000 watts for one hour. Your electricity bill is measured in kWh. The average US home uses about 900 kWh per month.

Example: If you run a 100-watt light bulb for 10 hours, you use 1 kWh of electricity.
Related: Watt • Electricity Rate • Energy Consumption

Solar

Solar Panel (Photovoltaic Panel)

A device that converts sunlight directly into electricity using semiconductor materials. Most residential panels produce 300-400 watts each and last 25-30 years.

Example: A typical home installation uses 15-25 solar panels to offset most electricity usage.
Related: Photovoltaic Effect • Solar Inverter • Net Metering

Net Metering

A billing arrangement where solar panel owners receive credit for excess electricity they send to the grid. Your meter spins backward when you produce more than you use.

Example: With net metering, electricity generated during sunny days offsets nighttime usage.
Related: Feed-in Tariff • Grid-Tie System • Utility Credit

Grid-Tie System

A solar power system connected to the utility grid, allowing you to use grid power when needed and sell excess back to the utility.

Example: Most residential solar installations are grid-tie systems without battery storage.
Related: Off-Grid • Battery Storage • Net Metering

Heating & Cooling

Heat Pump

A device that transfers heat from one place to another, providing both heating and cooling. Heat pumps are 2-4 times more efficient than traditional furnaces because they move heat rather than generate it.

Example: An air-source heat pump can reduce heating costs by 50% compared to electric resistance heating.
Related: SEER Rating • COP • HVAC

SEER Rating (Seasonal Energy Efficiency Ratio)

A measure of air conditioner and heat pump cooling efficiency. Higher SEER ratings mean lower energy consumption. Modern efficient units have SEER ratings of 15-25.

Example: A SEER 20 unit uses about 33% less energy than a SEER 15 unit for the same cooling.
Related: EER • HSPF • Energy Star

Financial

ROI (Return on Investment)

A measure of profitability calculated as (Net Profit / Cost of Investment) × 100. In home energy, ROI tells you how quickly your upgrade pays for itself and continues saving money.

Example: A $10,000 solar system that saves $2,000/year has a 20% annual ROI.
Related: Payback Period • Net Present Value • Cost-Benefit Analysis

Payback Period

The time required for an investment to pay for itself through savings. Shorter payback periods indicate better investments.

Example: A $6,000 heat pump that saves $1,200/year has a 5-year payback period.
Related: ROI • Break-Even Point • Total Cost of Ownership

Incentives

ITC (Investment Tax Credit)

A US federal tax credit for solar installations, currently set at 30% of system cost through 2032. This directly reduces your tax liability.

Example: A $20,000 solar system qualifies for a $6,000 federal tax credit.
Related: Tax Incentive • Rebate • MACRS Depreciation

Feed-in Tariff (FIT)

A policy mechanism that pays renewable energy producers a set rate for electricity fed into the grid, often higher than retail rates to encourage adoption.

Example: Germany's feed-in tariff helped make it a world leader in solar adoption.
Related: Net Metering • Renewable Energy Credit • Power Purchase Agreement

Smart Home

Smart Thermostat

A programmable thermostat that learns your schedule and preferences, automatically adjusting temperature for comfort and efficiency. Can reduce heating/cooling costs by 10-15%.

Example: A Nest or Ecobee thermostat learns when you leave for work and reduces heating automatically.
Related: Home Automation • Zoning • Setback Temperature

Environment

Carbon Footprint

The total greenhouse gas emissions caused by an individual, organization, or activity, usually measured in tons of CO2 equivalent per year.

Example: The average US household has a carbon footprint of about 7.5 tons of CO2 per year from electricity alone.
Related: Greenhouse Gas • Carbon Offset • Emissions

Insulation

R-Value

A measure of insulation's ability to resist heat flow. Higher R-values indicate better insulating properties. Required R-values vary by climate zone.

Example: Attic insulation in cold climates should have R-49 to R-60.
Related: Thermal Resistance • U-Value • Insulation

Assessment

Energy Audit

A professional assessment of your home's energy use, identifying inefficiencies and recommending improvements. Many utilities offer free or subsidized audits.

Example: An energy audit might reveal that air leaks are costing you $200/year in wasted energy.
Related: Blower Door Test • Thermal Imaging • Home Performance

Storage

Battery Storage (Home Battery)

A rechargeable battery system that stores electricity for later use, typically paired with solar panels. Provides backup power and can maximize solar savings.

Example: A Tesla Powerwall stores 13.5 kWh and can power an average home for several hours.
Related: Solar + Storage • Backup Power • Time-of-Use

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