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Definition

solar panel

A solar panel, also known as a photovoltaic (PV) panel, is an interconnected assembly of solar cells encased in a common frame that converts sunlight into electricity. The solar cells within a panel contain photovoltaic material, usually silicon, that absorbs photons from sunlight and converts them into electrical current via the photovoltaic effect.

This photovoltaic effect, in which voltage and electric current is generated from exposure to light, is a physical property of certain semiconductor materials. When sunlight strikes the solar cell’s surface, its energy knocks electrons loose within the cell allowing them to flow freely, generating DC current.

Components

Solar panels are made up of many individual solar cells wired together in a close-packed array. Each cell consists of thin layers of semiconductor material, usually silicon, finely treated to form a p-n junction capable of separating charges. Conductive metal plates are attached to the positive and negative sides to collect and move current.

In addition to the solar cells, panels include a transparent top cover of tempered glass to allow light to pass while protecting against weather, an aluminum frame providing structural support, and a junction box on the back with wiring and connector terminals. Bypass diodes are also integrated to minimize shading effects.

Types

There are three main types of solar panels defined by the type of photovoltaic material used in their solar cells:

  • Monocrystalline – Made from single crystal silicon. Highest efficiencies at 15-22%. Distinctive uniform black color.
  • Polycrystalline – Made from multiple silicon crystal fragments melted together. Slightly lower efficiency but cheaper manufacturing. Blue color.
  • Thin Film – Constructed by depositing extremely thin layers of photosensitive materials like cadmium telluride onto substrates. Lower efficiencies but very flexible and lightweight.

Efficiency

Solar panel conversion efficiency is defined as the percentage of sunlight energy striking the panel that gets converted into usable electricity. There are losses from light reflection, heat, electrical resistance, and other factors.

Typical residential solar panels have efficiencies in the range of 15-22%. Higher efficiency ratings mean more power output from the same panel surface area, but also higher costs. Laboratory testing under optimal conditions can produce efficiencies over 40%, but real-world performance is lower.

Applications

Solar panels are used in installations of all sizes to produce renewable solar electricity. For residential homes, panels are commonly mounted on rooftops or ground stands. Multiple panels are wired together to form an array sized to match energy needs.

Commercial businesses may utilize larger rooftop or ground mount arrays to power their facilities. At the utility scale, vast arrays with hundreds of thousands of panels spread over hundreds of acres can feed into the grid to power thousands of homes.

Solar power provides clean, renewable electricity from an abundant resource, the sun, helping reduce fossil fuel dependence. It can play a major role in decarbonizing the world’s power grids as part of the global transition toward sustainability.

Installation

Installing solar panels requires mapping out the layout, mounting equipment, wiring, and siting considerations like sun exposure and shading. Permits are usually required and panels must be interconnected and grounded properly per electrical code.

Rooftop installations utilize racking systems bolted into roof rafters to securely fasten panels. Ground mounts use driven posts, concrete footings, or ballasted mounts. Professional installation is recommended.

Advantages

Benefits of solar panels include:

  • Renewable – Unlimited free fuel from the sun
  • Clean – Zero emissions during operation
  • Cost savings – Lower electric bills with free sunlight
  • Energy independence – Reduce reliance on grid
  • Low maintenance – Minimal upkeep required
  • Tax credits and incentives – Available in many regions
  • Grid security – Extra power generation capacity

Disadvantages

Drawbacks of solar panels include:

  • Higher upfront cost – Installation expense amortized over many years
  • Intermittency – Limited during night, cloudy weather, winter
  • Space requirement – Large arrays need substantial roof or land area
  • Aesthetics – Some find panels visually unappealing

 

Published On: 2023年9月13日Categories: ,