Solar Energy Basics
Understanding the fundamentals of solar power and PV systems
The Photovoltaic Effect
Solar panels work through the photovoltaic effect, a process where certain materials generate an electric current when exposed to sunlight. This effect was first observed by French physicist Alexandre-Edmond Becquerel in 1839.
When photons (particles of light) from the sun strike a solar cell, they can knock electrons loose from their atoms. If conductors are attached to the positive and negative sides of a cell, it forms an electrical circuit. When electrons flow through such a circuit, they generate electricity.
From Sunlight to Electricity
- Absorption: Solar panels absorb photons from sunlight.
- Electron Release: These photons knock electrons free from atoms in the semiconductor material (typically silicon).
- Electric Field: The solar cell's electric field forces these free electrons to flow in a certain direction.
- Current Generation: This flow of electrons is an electric current, which can be drawn off for external use.
- Conversion: Inverters convert the DC electricity produced by solar panels into AC electricity used by most household appliances.
Types of Solar Technologies
- Photovoltaic (PV) Systems: Directly convert sunlight into electricity using semiconductor materials.
- Concentrated Solar Power (CSP): Uses mirrors or lenses to concentrate sunlight onto a small area, generating heat that drives a steam turbine connected to an electrical generator.
- Solar Thermal: Captures heat from the sun for water heating or space heating and cooling.
Key Solar Energy Terms
Photovoltaic (PV)
The conversion of light into electricity using semiconducting materials.
Kilowatt (kW)
A unit of power equal to 1,000 watts, used to measure the capacity of solar systems.
Kilowatt-hour (kWh)
A unit of energy equal to one kilowatt of power sustained for one hour, used to measure electricity production and consumption.
Solar Insolation
The amount of solar radiation energy received on a given surface area during a specific time period, typically measured in kWh/m².
Net Metering
A billing mechanism that credits solar energy system owners for the electricity they add to the grid.
Grid-Tied System
A solar system connected to the utility grid, allowing for the export of excess electricity and import when needed.
Off-Grid System
A solar system not connected to the utility grid, typically using batteries to store energy for use when the sun isn't shining.
Hybrid System
A solar system that is connected to the grid but also includes battery storage for backup power or self-consumption optimization.