|
|
| Line 1: |
Line 1: |
| − | Introduction<br/> = | + | = Introduction<br/> = |
| | | | |
| − | '''Photovoltaics''' ('''PV''') is the field of technology and research related to the application of [[Solar Cells and Modules|solar cells]] for energy production by converting Sun energy (sunlight, including Sun ultra violet radiation) directly into electricity by the [http://en.wikipedia.org/wiki/Photovoltaic_effect photovoltaic effect]. The latter refers to the process of converting light (photons) to electricity (voltage). Solar cells are photovoltaic devices that use semi-conducting materials to convert sunlight directly into electricity. When sunlight is absorbed by these materials, it causes electrons to flow through the material generating electric currents. Solar cells produce direct current (DC) electricity. There are two broad categories of solar cells; thin film and crystalline<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>. | + | '''Photovoltaics''' ('''PV''') is the field of technology and research related to the application of [[Solar Cells and Modules|solar cells]] for energy production by converting Sun energy (sunlight, including Sun ultra violet radiation) directly into electricity by the [http://en.wikipedia.org/wiki/Photovoltaic_effect photovoltaic effect]. The latter refers to the process of converting light (photons) to electricity (voltage). Solar cells are photovoltaic devices that use semi-conducting materials to convert sunlight directly into electricity. When sunlight is absorbed by these materials, it causes electrons to flow through the material generating electric currents. Solar cells produce'''direct current (DC) '''electricity. There are two broad categories of solar cells; thin film and crystalline<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>. |
| | | | |
| | The key components of a photovoltaic power system are the photovoltaic cells (also called solar cells) interconnected and encapsulated to form a photovoltaic module (the commercial product), the [[Module Mounting|mounting structure]] for the module or array (several modules mounted and interconnected together to produce a desired voltage and current (power capacity)), the inverter (essential for grid-connected systems and required for many off-grid systems), the storage [[Batteries|battery]] and the [[Charge Controllers|charge controller]] (for off-grid systems only). Solar cells are typically combined into modules that hold up to 40 cells to generate substantial voltages (typically 12 V or 24V) and currents that can be used to power various devices. The power output of a module is measured under standardized test conditions in Watt Peak (Wp). | | The key components of a photovoltaic power system are the photovoltaic cells (also called solar cells) interconnected and encapsulated to form a photovoltaic module (the commercial product), the [[Module Mounting|mounting structure]] for the module or array (several modules mounted and interconnected together to produce a desired voltage and current (power capacity)), the inverter (essential for grid-connected systems and required for many off-grid systems), the storage [[Batteries|battery]] and the [[Charge Controllers|charge controller]] (for off-grid systems only). Solar cells are typically combined into modules that hold up to 40 cells to generate substantial voltages (typically 12 V or 24V) and currents that can be used to power various devices. The power output of a module is measured under standardized test conditions in Watt Peak (Wp). |
| | | | |
| | Performance of PV modules depends on the amount of solar irradiation received which varies by location and season. For this reason, systems normally need to be carefully designed. A typical commercial solar cell has an efficiency of 15%. The first solar cells, built in the 1950s, had efficiencies of less than 4%<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>. | | Performance of PV modules depends on the amount of solar irradiation received which varies by location and season. For this reason, systems normally need to be carefully designed. A typical commercial solar cell has an efficiency of 15%. The first solar cells, built in the 1950s, had efficiencies of less than 4%<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>. |
| | + | |
| | + | |
| | | | |
| | = Applications and Efficiency<br/> = | | = Applications and Efficiency<br/> = |
| Line 11: |
Line 13: |
| | PV technology can be employed in a variety of applications: Typical applications of PV technology include remote telecommunications, cathodic protection of pipelines, PV home systems, vaccine refrigeration, water pumping, grid connected or [[Building Integrated Photovoltaics (BIPV)|building integrated systems]], miniature electronic devices and toys<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>: | | PV technology can be employed in a variety of applications: Typical applications of PV technology include remote telecommunications, cathodic protection of pipelines, PV home systems, vaccine refrigeration, water pumping, grid connected or [[Building Integrated Photovoltaics (BIPV)|building integrated systems]], miniature electronic devices and toys<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>: |
| | | | |
| − | '''Off-grid domestic''' PV systems like [[Solar Home Systems|solar home systems]]: | + | <u>'''Off-grid domestic''' PV systems like [[Solar Home Systems|solar home systems]]:</u> |
| | | | |
| | *Provide electricity to households and villages that are not connected to the utility electricity network (also referred to as the [[Grid|grid]]) | | *Provide electricity to households and villages that are not connected to the utility electricity network (also referred to as the [[Grid|grid]]) |
| Line 17: |
Line 19: |
| | *Are often the most appropriate technology to meet the energy demands of off-grid communities | | *Are often the most appropriate technology to meet the energy demands of off-grid communities |
| | | | |
| − | '''Off-grid non-domestic''' PV installations: | + | |
| | + | |
| | + | <u>'''Off-grid non-domestic''' PV installations:</u> |
| | | | |
| | *Are used in locations where small amounts of electricity have a high value | | *Are used in locations where small amounts of electricity have a high value |
| Line 24: |
Line 28: |
| | *Make PV commercially cost competitive with other small generating sources | | *Make PV commercially cost competitive with other small generating sources |
| | | | |
| − | '''Grid-connected''' '''distributed''' PV systems: | + | |
| | + | |
| | + | <u>'''Grid-connected''' '''distributed''' PV systems:</u> |
| | | | |
| | *Provide power to grid-connected customers or directly to the electricity network (specifically where that part of the electricity network is configured to supply power to a number of customers rather than to provide a bulk transport function) | | *Provide power to grid-connected customers or directly to the electricity network (specifically where that part of the electricity network is configured to supply power to a number of customers rather than to provide a bulk transport function) |
| | *May be on or integrated into the customer's premises, often on the demand side of the electricity meter, on public and commercial buildings, or elsewhere in the built environment | | *May be on or integrated into the customer's premises, often on the demand side of the electricity meter, on public and commercial buildings, or elsewhere in the built environment |
| | | | |
| − | '''Grid-connected''' '''centralized''' PV systems: | + | |
| | + | |
| | + | <u>'''Grid-connected''' '''centralized''' PV systems:</u> |
| | | | |
| | *Perform the functions of centralized power stations | | *Perform the functions of centralized power stations |
| Line 38: |
Line 46: |
| | | | |
| | To design a system for PV application the following information is required: daily energy requirement, voltage and current draw of appliances, average insolation (kWh/m2 day), the yearly variation in insolation levels for the specific area and the equipment type, availability and costs to enable appropriate selection<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>. | | To design a system for PV application the following information is required: daily energy requirement, voltage and current draw of appliances, average insolation (kWh/m2 day), the yearly variation in insolation levels for the specific area and the equipment type, availability and costs to enable appropriate selection<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>. |
| | + | |
| | + | |
| | | | |
| | = Capability and Limitations<br/> = | | = Capability and Limitations<br/> = |
| Line 46: |
Line 56: |
| | *Experiences show that security is essential for most PV installations. In remote unguarded locations, there is risk of the modules and other system components being stolen or vandalized<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>. | | *Experiences show that security is essential for most PV installations. In remote unguarded locations, there is risk of the modules and other system components being stolen or vandalized<ref name="Energy Technology">GTZ (2007): Eastern Africa Resource Base: GTZ Online Regional Energy Resource Base: Regional and Country Specific Energy Resource Database: I - Energy Technology</ref>. |
| | | | |
| − | = Links to further reading<br/> =
| |
| | | | |
| − | [http://en.wikipedia.org/wiki/Photovoltaics http://en.wikipedia.org/wiki/Photovoltaics]<br/>[http://www1.eere.energy.gov/solar/photovoltaics.html http://www1.eere.energy.gov/solar/photovoltaics.html]<br/>[http://www.greenenergy.org.uk/pvuk2/technology/index.html http://www.greenenergy.org.uk/pvuk2/technology/index.html] | + | |
| | + | = Further Reading<br/> = |
| | + | |
| | + | *[http://en.wikipedia.org/wiki/Photovoltaics http://en.wikipedia.org/wiki/Photovoltaics] |
| | + | *[http://www1.eere.energy.gov/solar/photovoltaics.html http://www1.eere.energy.gov/solar/photovoltaics.html] |
| | + | *[http://www.greenenergy.org.uk/pvuk2/technology/index.html http://www.greenenergy.org.uk/pvuk2/technology/index.html] |
| | + | |
| | + | |
| | | | |
| | = References<br/> = | | = References<br/> = |
The key components of a photovoltaic power system are the photovoltaic cells (also called solar cells) interconnected and encapsulated to form a photovoltaic module (the commercial product), the mounting structure for the module or array (several modules mounted and interconnected together to produce a desired voltage and current (power capacity)), the inverter (essential for grid-connected systems and required for many off-grid systems), the storage battery and the charge controller (for off-grid systems only). Solar cells are typically combined into modules that hold up to 40 cells to generate substantial voltages (typically 12 V or 24V) and currents that can be used to power various devices. The power output of a module is measured under standardized test conditions in Watt Peak (Wp).
Performance of PV modules depends on the amount of solar irradiation received which varies by location and season. For this reason, systems normally need to be carefully designed. A typical commercial solar cell has an efficiency of 15%. The first solar cells, built in the 1950s, had efficiencies of less than 4%[1].
PV technology can be employed in a variety of applications: Typical applications of PV technology include remote telecommunications, cathodic protection of pipelines, PV home systems, vaccine refrigeration, water pumping, grid connected or building integrated systems, miniature electronic devices and toys[1]:
To design a system for PV application the following information is required: daily energy requirement, voltage and current draw of appliances, average insolation (kWh/m2 day), the yearly variation in insolation levels for the specific area and the equipment type, availability and costs to enable appropriate selection[1].
