Photovoltaic Solar Energy: A Comprehensive Guide
Photovoltaic Solar Energy
Photovoltaic solar energy is a method of extracting energy from sunlight and converting it into electricity using solar panels. Advancements in this technology have led to its widespread use in various applications, including:
- Powering homes and businesses
- Providing electricity in remote areas
- Agricultural and livestock applications
- Lighting and communication technology
Renewable Energy
Definition
Renewable energy sources are inexhaustible and derived directly or indirectly from the sun. They are consistently available to humans.
Advantages
- Improve energy security
- Environmentally friendly
- Encourage industrial and regional economic development
Disadvantages
- Availability issues: not always available when needed
- High initial investment cost, potentially making the system unprofitable in the short term
- Internalizing social or environmental benefits could make them less competitive than conventional energy sources
Applications of Photovoltaic Solar Energy
There are two main application groups:
1. Off-Grid Facilities
These include homes and businesses located away from the conventional power grid, public lighting, agricultural and livestock applications, and signaling and communication systems.
2. Grid-Connected Facilities
- Photovoltaic power plants: Generate electricity and deliver it directly to the grid.
- Photovoltaic systems in buildings and industries: Connected to the grid, these systems utilize generated energy for on-site consumption, with excess energy fed back into the grid.
Benefits of Photovoltaic Solar Energy
- No combustion, resulting in zero air pollution at the point of use
- No contribution to acid rain, greenhouse gas emissions, or other environmental problems
Disadvantages of Photovoltaic Solar Energy
- Environmental impact during the manufacturing process of solar panels
Solar Cells
Photovoltaic conversion relies on the photoelectric effect, which converts light energy from the sun into electrical energy. Solar cells are made from semiconductor materials with an artificially created electric field.
Manufacturing Process
- Quartz-rich rocks are melted.
- Crystallization is initiated to form crystalline silicon ingots.
- The ingots are cut into wafers (this step is crucial as up to 50% of the material can be lost).
- Wafers undergo a stripping process to remove irregularities, defects, dust, and debris.
Definitions
Solar Radiation
Energy from the sun in the form of electromagnetic waves.
Irradiance
Power density incident on a surface, representing the incident energy per unit time and unit area.
Irradiation
Energy incident on a surface per unit area over a specific period.
Typical Meteorological Year (TMY)
A set of hourly irradiation values for one year, constructed using hypothetical data.
Solar Cell or Photovoltaic Cell
A device that converts solar energy into electrical energy.
Cell Technology Equivalent (CTE)
Solar cell manufacturing technology and packaging identical to that of photovoltaic modules used in a photovoltaic generator.
Photovoltaic Module
A collection of interconnected solar cells encapsulated between protective materials to withstand weathering effects.
Photovoltaic String
A subset of interconnected photovoltaic modules.
PV Generator
A parallel association of photovoltaic strings.
Standard Test Conditions (STC)
Conditions of irradiance and temperature used as a reference to characterize cells, modules, and photovoltaic generators.
Maximum Power Point (Peak Power)
The maximum power a module can deliver under STC.
NOCT (Nominal Operating Cell Temperature)
The temperature reached by solar cells under standard operating conditions.
Battery
An electrochemical device that stores energy.
Battery Bank
A DC voltage source formed by a group of interconnected batteries.
Self-Discharge
Loss of battery power when it remains open circuit.
Nominal Capacity C20 (Ah)
The amount of charge that can be drawn from a battery over 20 hours.
Capacity
The available or usable capacity of a battery.
State of Charge (SOC)
The ratio of the remaining capacity of a partially discharged battery to its rated capacity.
Depth of Discharge (DOD)
The ratio of the charge extracted from a battery to its rated capacity.
Charging (or Discharging) Scheme
A parameter relating the nominal battery capacity and the value of the current flow.
Cell
A basic electrochemical unit within a battery.
Charge Controller
A device that protects the battery from overcharging and over-discharging.
Low Battery Disconnect Voltage
The battery voltage below which the supply of electricity to loads is interrupted.
Final Charge Voltage
The battery voltage above which the connection between the PV generator and battery is interrupted.
Inverter
A power converter that transforms DC electricity to AC electricity.
VRMS
The root mean square value of the output AC voltage.
Rated Power (VA)
The power output specified by the manufacturer, which the inverter can deliver continuously.
Overload Capacity
The inverter’s ability to deliver power exceeding its rated power for specific durations.
Inverter Efficiency
The ratio of output power to input power of the inverter.
Power Factor
The ratio of active power (W) to apparent power (VA).