question: how solar panels actually generate power from the sun
comment: Solar Cells consist of two layers of material. In-between is a thin interface that cannot be simply passed by electrons. Sunlight however provides enough energy to push electrons over this barrier. These electrons want to go back to their original side, but can't because of the barrier. So their only option is to move all the way through the circuit connected to the solar cell.
passages: The sun's rays can be used to produce electrical energy. The direct user of sunlight is the solar cell or photovoltaic cell, which converts sunlight directly into electrical energy without the incorporation of a mechanical device. This technology is simpler than the fossil-fuel-driven systems of producing electrical energy. A solar cell is formed by a light-sensitive p-n junction semiconductor, which when exposed to sunlight is excited to conduction by the photons in light. When light, in the form of photons, hits the cell and strikes an atom, photo-ionisation creates electron-hole pairs. The electrostatic field causes separation of these pairs, establishing an electromotive force in the process. The electric field sends the electron to the p-type material, and the hole to the n-type material. If an external current path is provided, electrical energy will be available to do work. The electron flow provides the current, and the cell's electric field creates the voltage. With both current and voltage the silicon cell has power. The greater the amount of light falling on the cell's surface, the greater is the probability of photons releasing electrons, and hence more electric energy is produced.
   Section::::Theory.
  
  The solar cell works in several steps:
  
  BULLET::::- Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon.
   BULLET::::- Electrons are excited from their current molecular/atomic orbital. Once excited an electron can either dissipate the energy as heat and return to its orbital or travel through the cell until it reaches an electrode. Current flows through the material to cancel the potential and this electricity is captured. The chemical bonds of the material are vital for this process to work, and usually silicon is used in two layers, one layer being doped with boron, the other phosphorus. These layers have different chemical electric charges and subsequently both drive and direct the current of electrons.
   BULLET::::- An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.
  
  BULLET::::- An inverter can convert the power to alternating current (AC).
   Ohmic metal-semiconductor contacts are made to both the n-type and p-type sides of the solar cell, and the electrodes connected to an external load. Electrons that are created on the n-type side, or created on the p-type side, "collected" by the junction and swept onto the n-type side, may travel through the wire, power the load, and continue through the wire until they reach the p-type semiconductor-metal contact. Here, they recombine with a hole that was either created as an electron-hole pair on the p-type side of the solar cell, or a hole that was swept across the junction from the n-type side after being created there.
   In a slightly updated version of the film, the "solar battery" is discussed. Based on the work of scientists Daryl Chapin, Calvin Fuller, and Gerald Pearson at Bell Labs, this device can turn sunlight directly into electricity. A cartoon version of Dr. Research dressed as a pastry chef shows how the solar battery can be manufactured by "cooking-up" a wafer of silicon with a boron coating. (This became the predecessor of today's ubiquitous solar cells).
   Assemblies of solar cells are used to make solar modules that generate electrical power from sunlight, as distinguished from a "solar thermal module" or "solar hot water panel". A solar array generates solar power using solar energy.
  
  Section::::Applications.:Cells, modules, panels and systems.
   Section::::Research in solar cells.:Bifacial solar cells.
   Section::::Nanoparticle processing.
   Micro-inverted solar panels are wired in parallel, which produces more output than normal panels which are wired in series with the output of the series determined by the lowest performing panel (this is known as the "Christmas light effect"). Micro-inverters work independently so each panel contributes its maximum possible output given the available sunlight.
  
  Section::::Technology.
   When a photon hits a piece of silicon, one of three things can happen:
  
  BULLET::::1. The photon can pass straight through the silicon — this (generally) happens for lower energy photons.
  
  BULLET::::2. The photon can reflect off the surface.
  
  BULLET::::3. The photon can be absorbed by the silicon if the photon energy is higher than the silicon band gap value. This generates an electron-hole pair and sometimes heat depending on the band structure.
   Solar panel
  
  Photovoltaic solar panels absorb sunlight as a source of energy to generate electricity. A photovoltaic (PV) module is a packaged, connected assembly of typically 6x10 photovoltaic solar cells. Photovoltaic modules constitute the photovoltaic array of a photovoltaic system that generates and supplies solar electricity in commercial and residential applications. 
  
  The most common application of solar energy collection outside agriculture is solar water heating systems.
  
  Section::::Theory and construction.
   A fluid (also called heat transfer fluid) passes through the receiver and becomes very hot. Common fluids are synthetic oil, molten salt and pressurized steam. The fluid containing the heat is transported to a heat engine where about a third of the heat is converted to electricity.
   Section::::The p-n junction.
  
  The most commonly known solar cell is configured as a large-area p-n junction made from silicon. As a simplification, one can imagine bringing a layer of n-type silicon into direct contact with a layer of p-type silicon. In practice, p-n junctions of silicon solar cells are not made in this way, but rather by diffusing an n-type dopant into one side of a p-type wafer (or vice versa).
   Section::::"Solar Impulse 1" (HB-SIA).:Operational history.:International and intranational flights.:Belgium and France (2011).
   The most commonly known solar cell is configured as a large-area p–n junction made from silicon. Other possible solar cell types are organic solar cells, dye sensitized solar cells, perovskite solar cells, quantum dot solar cells etc. The illuminated side of a solar cell generally has a transparent conducting film for allowing light to enter into active material and to collect the generated charge carriers. Typically, films with high transmittance and high electrical conductance such as indium tin oxide, conducting polymers or conducting nanowire networks are used for the purpose.
  
  Section::::Efficiency.
   Section::::Connection to an external load.
   Solar cells are devices that convert sunlight into electricity by the photovoltaic effect. Electrons in a solar cell absorb photon energy in sunlight which excites them to the conduction band from the valence band. This generates a hole-electron pair, which is separated by a potential barrier (such as a p-n junction), and induces a current. Organic solar cells use organic materials in their active layers. Molecular, polymer, and hybrid organic photovoltaics are the main kinds of organic photovoltaic devices currently studied.
  
  Section::::Theory.:Hybrid solar cell.
   BULLET::::2. Electrons (negatively charged) are knocked loose from their atoms as they are excited. Due to their special structure and the materials in solar cells, the electrons are only allowed to move in a single direction. The electronic structure of the materials is very important for the process to work, and often silicon incorporating small amounts of boron or phosphorus is used in different layers.
  
  BULLET::::3. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.
  
  Section::::Photogeneration of charge carriers.
   Photovoltaic modules use light energy (photons) from the Sun to generate electricity through the photovoltaic effect. The majority of modules use wafer-based crystalline silicon cells or thin-film cells. The structural (load carrying) member of a module can either be the top layer or the back layer. Cells must also be protected from mechanical damage and moisture. Most modules are rigid, but semi-flexible ones based on thin-film cells are also available. The cells must be connected electrically in series, one to another. 
   Section::::Silicon processing.:Nanocrystalline solar cells.
   Section::::Research in solar cells.
  
  Section::::Research in solar cells.:Perovskite solar cells.
   The whole structure of solar lamp is shown in Figure 2. 
  
  Section::::Components.:Solar panels.
  
  Most solar panels are made out of single crystalline silicon, a semiconductor material. A solar cell has two different layers of silicon. The lower layer has less electrons and hence has a slight positive charge due to the negative charge nature of electrons. In addition, the upper layer has more electrons and has slightly negative charge. A potential barrier is created between these two layers. 
   Section::::History.:Research and industrial production.
   In addition, most solar panels on spacecraft are also made of high efficient multi-junction photovoltaic cells to derive electricity from sunlight when operating in the inner Solar System.
  
  Section::::Emerging technologies.:Floatovoltaics.
  