Solar Power: The Basics
Solar panels convert sunlight directly into electricity using a phenomenon called the photovoltaic effect. This process is remarkably simple and has no moving parts - light hits the panel, electrons move, and electricity flows.
Here's the 30-second version of how your solar system works:
- Sunlight hits the panels - Photons from the sun strike the solar cells
- Electrons are freed - The energy knocks electrons loose from atoms in the silicon
- Electricity flows - The freed electrons create a DC (direct current) electrical flow
- Inverter converts power - DC is converted to AC (alternating current) for home use
- Power your home - AC electricity flows to your breaker panel and powers your appliances
- Excess goes to grid - Any extra power flows to the grid, earning you credits
The Photovoltaic Effect
The photovoltaic effect was discovered in 1839 by French physicist Edmond Becquerel. Here's how it works in modern solar panels:
Solar Cell Structure
Each solar panel contains many individual solar cells made of silicon. Silicon is a semiconductor - it can conduct electricity under the right conditions.
- N-type layer (top): Silicon doped with phosphorus, creating extra electrons
- P-type layer (bottom): Silicon doped with boron, creating "holes" for electrons
- Junction: Where N and P layers meet, creating an electric field
The Process
- Sunlight (photons) hits the N-type layer
- Photon energy is absorbed by electrons
- Energized electrons break free from atoms
- The electric field at the junction pushes electrons toward metal contacts
- Electrons flow through an external circuit (your home) and return to the P-layer
- The cycle repeats continuously while light is present
No Fuel, No Emissions
Unlike fossil fuel generators, solar panels have no combustion, no fuel consumption, and no emissions. The only "fuel" is sunlight, which is free and unlimited. Once manufactured, a solar panel produces clean electricity for decades.
Solar System Components
1. Solar Panels (Modules)
Modern residential panels typically contain 60-72 solar cells wired together, producing 350-450 watts each. Key specs include:
- Wattage: Power output under standard test conditions (STC)
- Efficiency: How much sunlight is converted to electricity (18-22% typical)
- Temperature coefficient: How much efficiency drops in heat
- Warranty: Typically 25-30 years for production, 10-12 years workmanship
2. Inverter
The inverter converts DC power from panels to AC power for your home. Two main types:
- String Inverter: Single unit converts power from all panels. Cost-effective but entire string affected by shading.
- Microinverters: Small inverter on each panel. More expensive but better shade tolerance and panel-level monitoring.
3. Racking/Mounting
The structure that attaches panels to your roof or ground. Must be:
- Engineered for local wind and snow loads
- Waterproof at roof penetrations
- Oriented for optimal sun exposure
4. Electrical Components
- Wiring: Solar-rated cables connecting panels to inverter to panel
- Disconnects: Safety switches for maintenance and emergencies
- Meter: Bi-directional meter to track import/export
- Monitoring: System to track production and identify issues
Grid-Tied Systems
Most residential solar installations are "grid-tied" - connected to the utility grid without batteries. Here's how it works:
During the Day
- Panels produce electricity
- Your home uses what it needs
- Excess flows to the grid
- Your meter runs backwards (or tracks export)
- You earn credits from your utility
At Night or Cloudy Days
- Panels produce little or no power
- Your home draws from the grid
- Credits offset grid usage
- Net metering balances import/export
Net Metering Explained
Net metering is the policy that makes grid-tied solar work financially. In most Canadian provinces:
- You're credited for power you export at retail rates
- Credits offset power you import later
- Monthly billing shows net usage (import minus export)
- Annual true-up settles any remaining balance
Do You Need Batteries?
With net metering, most homeowners don't need batteries - the grid acts as your "battery." Batteries make sense if you want backup power during outages or if your utility doesn't offer good net metering rates.
Efficiency & Performance
What Affects Solar Panel Output?
- Sunlight intensity: More sun = more power. Panels are rated at 1000 W/m² (full sun).
- Temperature: Panels lose efficiency as they heat up. Cold, sunny days are optimal.
- Angle: Panels perpendicular to the sun produce most. Roof pitch affects annual production.
- Shading: Even partial shade significantly reduces output, especially with string inverters.
- Soiling: Dust, dirt, and debris reduce light reaching cells.
- Age: Panels degrade slowly over time (~0.5% per year).
Typical Production by Region
| Region | kWh per kW installed |
|---|
| Saskatchewan | 1,100-1,300 |
| Alberta | 1,100-1,250 |
| Ontario | 1,000-1,150 |
| British Columbia | 950-1,100 |