Solar power Flashcards
Features of Solar energy
renewable, intermittent, predictable (to some degree), low energy density, local constraints due to amount of sunlight received in different parts of the world
The problems with solar power
daily and seasonal intermittency, changes in solar intensity caused by cloud cover, low energy density, conflict with land use
Passive solar architecture
design of building to maximise absorption of solar energy, elongated south facing walls. Many windows on south facing walls, dark, textured surfaces.
Photothermal
A system that converts light into heat. Cells heat water
Photovoltaic (PV)
A system that converts light into electricity. Cells produce electricity
How does a photovoltaic cell work?
Cells made of silicon, one side is doped with phosphorus and is electronegative and has excess electrons, the other side is doped with boron, is electropositive and is lacking in electrons, excited electrons move from one side to another and produces an electric current.
How do heat pumps work?
Heat pumps use a liquid with a low boiling point, the liquid evaporates at a low temperature, the gas is captured and compressed. Compression converts the gas back to a liquid and releases heat energy.
Environmental impacts of solar power
Mining and extraction of materials for photovoltaics, toxic waste produced from the manufacture of photovoltaics e.g. cadmium, energy and water required for cleaning, conflict in land use e.g. agriculture.
New technologies solar
Concentrating solar power, Anti-reflective surfaces, multi junction photovoltaic cells, photovoltaic/thermal hybrid cells, transparent photovoltaic cells, Heliostats, self cleaning panels
Concentrating solar power (CSP)
A method of increasing the intensity of solar energy by using a parabolic array of mirrors to reflect the light onto a smaller area, often filled with molten salt that will retain high temperatures for later use (to boil water)
Multi-junction photovoltaic cells
made of multiple layers of material which can absorb different wavelengths of light, a greater amount of light is absorbed and converted to electricity.
Anti-reflective surfaces
smooth surfaces reflect 30% of light. Grooved and textured surfaces reflect more light into the cell. Example of biomimetics - built like moth eyes
Photovoltaic/thermal hybrid systems
Hybrid cells heat water which can be used for space heating as well as produce electricity, the water also cools the solar cell which can increase the efficiency of the photovoltaic
Transparent PV cells
can be incorporated into window space, some look like ordinary windows, some can provide shade.
Heliostats
alters the angle of the solar panel to follow the path of the sunlight and increase absorption of sunlight
