Earthkeepers · Reference
Solar & Energy Glossary
Plain-language meanings for 50 common solar, battery and energy terms — the level-1 vocabulary used across the courses and in Solar Bingo.
Solar Basics 9
Irradiance
How strong the sunlight is on a surface, measured in watts per square metre.
Kilowatt (kW)
A measure of power. 1 kW = 1,000 watts. It tells you how big a system is.
Kilowatt-hour (kWh)
A measure of energy — using 1 kW for 1 hour. It's the unit on your power bill.
Photovoltaic (PV)
Technology that turns sunlight straight into electricity — "photo" means light, "voltaic" means electricity.
Renewable Energy
Energy from sources that never run out, like the sun, wind, and water.
Solar Array
A group of solar panels wired together to make more power.
Solar Cell
The small square inside a panel that turns sunlight into electricity.
Solar Energy
Power from the sun that we can turn into electricity or heat.
Solar Panel
Many solar cells joined into one flat unit; also called a module.
Panels & Equipment 9
Charge Controller
A device that protects batteries by controlling how fast they charge.
Inverter
The device that changes DC electricity from panels into the AC electricity homes use.
Microinverter
A small inverter on each panel, so one shaded panel won't slow the others down.
Monitoring
A system, often a phone app, that shows how much power your system is making.
Orientation
The compass direction panels face. In Canada, south faces the most sun.
Power Optimizer
A small device on a panel that boosts output when panels are partly shaded.
Racking
The metal framework that holds solar panels on a roof or the ground.
String Inverter
One inverter that handles a whole row, or "string," of panels.
Tilt
The angle panels are set at to catch the most sunlight.
Batteries & Storage 8
Backup Power
Using stored battery energy to keep the lights on during a power outage.
Battery Storage (BESS)
Batteries that store solar power for later — BESS means Battery Energy Storage System.
Capacity
How much energy a battery can hold, measured in kilowatt-hours (kWh).
Charge Cycle
One full charge and discharge of a battery.
Lithium-Ion
The most common modern battery type, used in phones, cars, and solar systems.
Load Shifting
Storing cheap or solar power and using it later when power costs more.
Off-Grid Battery
A battery setup that powers a building with no connection to the utility grid.
State of Charge (SOC)
How full a battery is right now, shown as a percentage.
The Grid & Power 9
Alternating Current (AC)
Electricity that flows back and forth — the kind homes and the grid use.
Amp (A)
A measure of how much electrical current is flowing.
Direct Current (DC)
Electricity that flows one way — the kind panels and batteries make.
Grid-Tied
A solar system connected to the utility grid (also called on-grid).
Net Metering
Earning bill credits for extra solar power you send back to the grid.
Off-Grid
A system that runs on its own, with no connection to the utility grid.
The Grid
The network of power lines that delivers electricity to homes and buildings.
Volt (V)
A measure of electrical "pressure" that pushes current through wires.
Watt (W)
A measure of electrical power, equal to volts times amps.
Install & Safety 8
Combiner Box
An enclosure where several panel strings are safely joined together.
Disconnect
A switch that fully cuts the power so a system can be worked on safely.
Grounding
Connecting equipment to the earth so stray electricity can flow away safely.
Permit
Official approval you need before installing a solar system.
PPE
Personal Protective Equipment — gear like gloves and safety glasses that keep workers safe.
Rapid Shutdown
A safety feature that quickly powers down rooftop panels for first responders.
Shading
Shadows from trees, chimneys, or buildings that lower a panel's output.
Site Assessment
Checking a roof or property to see if solar will work well there.
Projects & Money 7
Community Energy Champion
A trained local person who helps lead and care for a community's energy project.
EPC
Engineering, Procurement & Construction — the company that designs and builds the system.
Feasibility Study
An early check on whether a solar project makes sense for a site.
Incentive
Money from a government or utility that helps pay for going solar (also called a rebate).
O&M
Operations & Maintenance — the work of keeping a system running well after it's built.
Payback Period
How long it takes for energy savings to cover the cost of the system.
RFP
Request for Proposal — an invitation for companies to bid on doing a project.
Want these on the wall? Hit Print for a clean handout. Playing Solar Bingo? Every called term is defined here.