Solar Energy Glossary

A-Z guide to solar energy terms. Clear definitions for net metering, peak shaving, TOU rates, and 50+ more terms explained for Canadian homeowners.

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Azimuth

The compass direction a solar panel faces, measured in degrees from north. South-facing (180°) is optimal in Canada for maximum annual production.

Bifacial Panel

A solar panel that generates electricity from both its front and rear surfaces. Rear-side generation from reflected light can add 5-15% extra production, especially beneficial with snow reflection in Canada.

Capacity Factor

The ratio of actual energy output to maximum possible output over a period. Canadian residential solar typically has a 12-16% capacity factor, varying by province and season.

CCA (Capital Cost Allowance)

A Canadian tax deduction allowing businesses to write off the cost of solar equipment over time. Classes 43.1 and 43.2 offer accelerated depreciation for clean energy assets.

CEIP (Clean Energy Improvement Program)

An Alberta municipal financing program that attaches solar installation costs to property tax bills. Over 27 municipalities participate with varying rates and rebates.

DC-to-AC Ratio

The ratio of solar panel DC capacity to inverter AC capacity. A ratio of 1.2-1.3 is common, allowing panels to slightly oversize relative to the inverter for better energy capture.

Degradation Rate

The annual decrease in solar panel output, typically 0.5% per year. A panel rated at 500W will produce approximately 437W after 25 years (87.5% of original).

ESA (Electrical Safety Authority)

Ontario's regulator for electrical safety. ESA inspection is required before connecting a solar system to the grid in Ontario.

Feed-in Tariff (FIT)

A now-closed Ontario program that paid premium rates for solar electricity fed to the grid. Replaced by net metering and the HRS program.

GHI (Global Horizontal Irradiance)

The total amount of solar radiation received per unit area on a horizontal surface. Measured in kWh/m²/year, it's the primary metric for solar potential. Canada ranges from 900-1,350 kWh/m²/year.

Grid-Tied System

A solar system connected to the utility grid. Most residential installations are grid-tied, allowing import/export of electricity. These systems shut off during grid outages for safety unless paired with a battery.

HRS (Home Renovation Savings)

Ontario's incentive program offering up to $5,000 for solar panels and $5,000 for battery storage on zero-export (load displacement) systems.

Inverter

A device that converts DC electricity from solar panels to AC electricity used in your home. Types include string inverters, microinverters, and hybrid inverters (which also manage battery charging).

Irradiance

The power of solar radiation per unit area, measured in watts per square metre (W/m²). Standard Test Conditions (STC) use 1,000 W/m².

ITC (Investment Tax Credit)

A federal tax credit equal to 30% of the cost of eligible clean energy equipment. The Clean Technology ITC is refundable, meaning you receive the full credit regardless of your tax liability.

kW (Kilowatt)

A unit of power equal to 1,000 watts. Solar systems are rated in kW — a 10 kW system can produce 10 kW of power under standard conditions.

kWh (Kilowatt-hour)

A unit of energy equal to using 1 kilowatt for 1 hour. Electricity bills are measured in kWh. A 10 kW solar system might produce 12,000 kWh per year in Ontario.

Load Displacement

A system design where solar production is consumed on-site without exporting to the grid. Ontario's HRS program requires load displacement (zero-export) systems.

Microinverter

A small inverter attached to each solar panel individually. More expensive than string inverters but optimize per-panel output and are better for partially shaded roofs.

Mid-Peak

An Ontario TOU/ULO rate period with moderate electricity prices. Currently 15.7¢/kWh under both TOU and ULO plans.

N-type Cell

A newer solar cell technology using phosphorus-doped silicon. N-type cells (TOPCon, HJT) offer higher efficiency, lower degradation, and better performance in low light compared to older P-type cells.

Net Metering

A billing arrangement where surplus solar electricity is exported to the grid in exchange for credits that offset future consumption. Available in most Canadian provinces except Ontario.

NOCT (Nominal Operating Cell Temperature)

The cell temperature under standard conditions of 800 W/m² irradiance, 20°C ambient, and 1 m/s wind. Typically 45°C for modern panels.

Off-Peak

The lowest-cost period in time-of-use pricing. In Ontario TOU, off-peak is 9.8¢/kWh during nights and weekends. In ULO, off-peak is 9.8¢/kWh on weekends/holidays.

On-Peak

The highest-cost period in time-of-use pricing. TOU on-peak is 20.3¢/kWh (7-11AM, 5-7PM). ULO on-peak is 39.1¢/kWh (4-9PM weekdays).

Peak Shaving

Using battery storage to avoid purchasing electricity during expensive peak rate periods. Charge the battery at low rates and discharge during peak hours to maximize savings.

PV (Photovoltaic)

Technology that converts sunlight directly into electricity using semiconductor materials. Solar panels are PV devices.

PVGIS

Photovoltaic Geographical Information System — a European Commission tool providing free solar radiation data worldwide. Used in production estimates alongside NRCan data.

Self-Consumption

The percentage of solar production used directly in your home rather than exported to the grid. Higher self-consumption maximizes savings, especially in provinces where export credits are below retail rate.

STC (Standard Test Conditions)

Standardized conditions for rating solar panels: 1,000 W/m² irradiance, 25°C cell temperature, AM1.5 spectrum. Real-world output is typically 80-90% of STC ratings.

String Inverter

A central inverter that converts DC from multiple panels (wired in a "string") to AC. Most cost-effective option but entire string output is limited by the weakest panel.

Temperature Coefficient

The rate at which panel output changes with temperature. A coefficient of -0.30%/°C means output drops 0.30% for each degree above 25°C. Cold Canadian winters actually boost panel efficiency.

Tilt Angle

The angle of solar panels relative to horizontal. In Canada, the optimal annual tilt angle is approximately equal to the latitude (43° in Toronto, 51° in Calgary). Roof pitch often determines the actual tilt.

TOU (Time-of-Use)

An Ontario rate plan with three pricing tiers: off-peak (9.8¢/kWh), mid-peak (15.7¢/kWh), and on-peak (20.3¢/kWh). Prices vary by time of day and day of week.

ULO (Ultra-Low Overnight)

An Ontario rate plan with four tiers including an ultra-low overnight rate of 3.9¢/kWh (11PM-7AM) and a high on-peak rate of 39.1¢/kWh (4-9PM weekdays). Best for EV owners and battery systems.

Zero-Export System

A solar system designed so no electricity flows back to the grid. All production is consumed on-site or stored in batteries. Required for Ontario's HRS rebate program.