1.8 Solar Flashcards
explain how an automated tracking system can maximise energy output from solar devices.
Answer to make reference to the fact that a solar tracking device must be able to track the relative motion between the Earth and the Sun and make reference to at least three of the following design parameters;
• Daily variations of the position of the sun during day light hours (earth spinning on its own axis).
• Annual variations in the position of the sun in the sky depending on the season / time of the year (Earths elliptical orbit around the Sun).
• Variations in positioning in the Northern and Southern hemisphere (Earths tilt on its own axis is 23.45 degrees and elliptical orbit).
• Tracking device must be able to change tilting angle and rotate on its own axis to achieve optimum tracking.
Outline two ways in which automated solar tracking can maximise the energy output from solar collectors
It can tilt and rotate on its own axis to achieve optimum tracking.
• It can track the variations in the sun’s position during daylight hours (earth spinning on its axis).
• It can track the annual variations in the sun’s position during years/seasons (earth orbiting the sun).
• It can adjust according to location in northern or southern hemispheres.
Outline two methods by which automatic solar tracking maximises the energy output from solar collectors.
Tilts and rotates on its own axis to achieve optimum tracking
• Tracks the variations in the Sun’s position during daylight hours (Earth
spinning on its axis)
• Tracks the annual variations in the Sun’s position during year/seasons
(Earth orbiting the sun)
• Adjusts according to location in northern or southern hemispheres
State three factors which should be considered when calculating the roof area required to install flat plate thermal solar panels on a house.
Solar radiation levels of site / roof.
• Shading.
• Proposed collector type and performance specifications.
• Family size and hot water requirements.
• Lifestyle of users and hot water requirements.
State three issues which should be considered when calculating the amount of roof space required for a flat plate thermal collector.
Solar radiation levels of the site / roof
• Shading
• Proposed collector type and performance specification.
• Family size and hot water requirements.
• Lifestyle of users and hot water requirements.
Identify two factors, other than cost, that should be taken into consideration by the occupants when deciding whether to install the solar collector.
*Solar radiation levels
*shading
*roof orientation
Explain the main benefit to households of installing a flat plate solar collector
Economic reasons. Cost more important in the application than efficiency
State one benefit to households of installing a flat plate
collector.
Reducing environmental impact.
• Financial benefit – reducing energy costs.
• Improved energy security.
State one benefit that the occupants would get from installing the flat plate solar collector.
*Reducing environmental impact
*Financial benefit – reducing energy costs
*Improved energy security [
The purpose of the antireflective coating.
Maximises the efficiency of the cell by reducing the reflection of light (photons) from the surface.
The role of the metal contacts
Necessary to allow for circuitry necessary to facilitate the flow of electrons in the circuit from the p to the n layer of the cell.
The operation of the PV cell.
When light falls on a silicon p-n junction some of the photons can create electron hole pairs through the photoelectric effect.
As the electrons move, this creates a potential difference with net positive and negative charge at each side of the junction (pn junction).
Contacts on either side of the cell connect the cell to an external load and permit the electrons to travel around the circuit loop back to neutralise the valency hole on the opposite side of the potential barrier.
Explain the purpose of the anti-reflective coating on a PV cell.
The anti-reflective coating maximises the efficiency of the cell and hence
the panel by reducing the reflection of light from the surface of the cell.
Name two of the main material types of PV module.
Monocrystalline
Polycrystalline
Thin-Film
Thick-Film
Solar power can also be used for microgeneration of electricity in PV panels. List the four material types of PV panels.
Monocrystalline
Polycrystalline
Thick-film
Thin film
Describe one advantage monocrystalline PV modules.
Advantage; Most efficient type of PV module.
Disadvantage; Cost – Expensive manufacturing techniques required to ensure efficiency
Name two other material types of PV modules
Polycrystalline
Thick-film
Thin-film
State one advantage and one disadvantage of monocrystalline PV modules.
Advantage: It is more efficient than other PV cells.
Disadvantage: It is more expensive.
Name and briefly explain any two financial incentives that are available to homeowners considering the installation of solar panels.
Green deal; Financial assistance towards cost of installing solar panels.
• Feed-in-Tariff for Solar PV Where homeowners are paid for the amount of electricity they generate and feed back into the grid.
• Renewable heat incentive; Where homeowners are paid for the amount of heat they generate using their own solar thermal panels
Explain briefly any two passive solar design techniques that can be applied to new and existing buildings.
Orientation {1}; Main glazed ‘dayrooms’ orientated South (or within 15 degrees of South) Non-habitable rooms towards north {1}.
• Windows to be appropriately sized; To provide good day-lighting and prevent excessive heat loss / heat gain.
• Use low emissivity glazing; To reduce heat loss through windows.
• Provide eaves overhangs / bris-soleil; to reduce summer heat gain through windows.
• Heavy construction / high thermal mass; will absorbs heat in winter and even out temperature fluctuations.
• High levels of thermal insulation {1}; will reduce the heat loss of the building
Describe any two passive solar design techniques that could be applied to the design of a new house
Main glazed ‘dayrooms’ to be orientated towards South (or within 15 degrees of south); Non-habitable rooms (bathrooms, stores etc) orientated towards North.
- Windows to be appropriately sized to provide good day lighting and also prevent excessive heat loss / heat gain
- Use low emissivity / double / triple glazing tp reduce heat loss through windows.
- Provide eaves overhangs / bris-soleil to reduce summer heat gain through windows.
- Heavy construction / high thermal mass; will absorb heat in winter to even out temperature fluctuations.
- High level of thermal insulation; will reduce the heat loss of the building.
Name two types of concentrating Solar Power (CSP) systems;
*Parabolic troughs.
• Fresnel Reflectors.
• Solar Dishes.
Explain how Concentrating Solar Power (CSP) systems may be used in power plants.
CSP plants produce electricity by converting the suns energy into high-temperature heat (steam) using various mirror configurations.
The steam is then sent through a generator to produce electricity.
Outline how Concentrating Solar Power (CSP) systems may be used in power plants to convert the Sun’s energy into electricity.
Concentrating Solar Power (CSP) plants use mirrors to focus the Sun’s energy for conversion into high grade heat (steam) ; the steam drives a turbine which turns a generator creating electricity
