Solar Flashcards

Question

What is single axis tracking?

Answer 1

The collectors are turned to the east or west to track the sun’s position throughout the day. The rotation axis is the north-south plane to maintain an angle of incidence at 0°.

Answer 2

Energy output may be increased by 25%. Higher output reduces repayment period.

Answer 3

Complex electrical & mechanical equipment required; expensive. The motors/pneumatic cylinders use some power themselves to operate. Restricted to high solar radiation regions only. Panels need to be spaced far apart to avoid casting shadows on each other.

Answer 4

The sun moves across the sky at different angles during the year, explaining seasons. As the Earth is on a 23.5° tilt.

Answer 5

In winter, as the northern hemi is tilted away from the sun, it appears low in the sky, giving longer shadows & lower solar radiation values. Also a lower length of time per day solar radiation strikes the region. In summer, as the northern hemi is tilted towards the sun, it appears higher in the sky, giving shorter shadows and higher solar radiation values. Also more time per day when solar radiation strikes the region.

Answer 6

Higher energy output up to 35%. Higher outputs reduces repayment period.

Answer 7

Rotates collectors in the north-south plane to align with the sun in all seasons. The axis of rotation is in the east-west plane.

Answer 8

Complex electrical & mechanical equipment – expensive. Motors/pneumatic cylinders & tracking need some power/power loss to operate – more than single. Restricted to high solar regions – only direct. Overshading can easily occur so less are installed/work around than single.

Answer 9

flat plate and evacuated tube

Answer 10

LOOK IN BOOK

Answer 11

Cold water is pumped into the collector across low level pipes. It travels up heat-absorbing rise tubes. This correlates with natural convection currents. The heat-absorbing rise tubes are connected to an absorber plate painted black to maximise absorption. Under this absorber plate is insulation which reduces heat losses through conduction & convection. As water rises up the pipe it absorbs heat from the Sun and absorber plate, increasing the heat transfer fluid’s temperature. When this fluid reaches the top, it leaves the panel to be pumped to the hot water tank. Within it, a level gauge is installed.

Answer 12

For maintenance purposes, a bung is installed to easily remove or drain the fluid to clear any dirt or grit that may accumulate.

Answer 13

Increases solar radiation transmitted through it to the absorber plate. Reduces heat losses. Protects system from rain & weather.

Answer 14

Cheapest collector. Suitable for cooler environments — not snow. Good efficiency of solar to thermal at 80%.

Answer 15

Efficiency drops at or above 30°C. Installation requires at least 2 people. Flat surface only facing sun directly once per day. Panel filled with fluid can be heavy & cause structural damage.

Answer 16

LOOK IN BOOK

Answer 17

A double-walled glass cylinder called the evacuated tube contains an absorber plate connected to a copper heat pipe. The tube has a vacuum between the two glass walls, reducing heat loss to almost zero. Solar radiation is transferred from the absorber plate to the copper pipe. The pipe has an enclosed cavity filled with HTF (Heat Transfer Fluid). The HTF is heated at the lower end of the pipe. The HTF evaporates and rises up due to convection. The gas reaches the top of the copper pipe, which has water circulating through it. The high-temp vapour loses energy to the colder water in the copper manifold heat exchanger. The vapour condenses back into a liquid when sufficient energy is transferred. The HTF, now liquid, returns back down the pipe due to gravity. This cycle continues as long as solar radiation is incident.

Answer 18

Circular geometry means tube is perpendicular to the sun for most of the day. Heat losses are nearly 0 due to conduction & convection. Less load on structure, not totally filled with liquid. 90% efficiency can be maintained at high temp. Installed by one person. Stored vertically – minimal transport cost.

Answer 19

Higher cost than flat plate. Not able to melt snow due to lower heat losses.

Answer 20

A= RE/energy per m2 Where: A = Area of solar collector in m² RE = Renewable energy required in kWh Energy produced by 1m² panel per year = said in question

Answer 21

Location - near the equator have higher solar radiation intensity, and thus would require a smaller-sized solar collector area. Shading Type - Evacuated tubes require a smaller area than flat plates as they are more efficient Size - Larger families require more energy, and so a larger collector area. Lifestyle - People who run showers/baths more often, or who exercise more, will need a larger area solar collector.

Answer 22

Reduced Costs: Domestic hot water can be derived from the Sun while other households may have to pay for heating oil, natural gas, and electricity from the immersion on an annual basis. Energy Security: Protection from fluctuations in energy prices. Oil and natural gas prices were very volatile in certain geopolitical climates. Electricity will also always slowly rise due to inflation.

Answer 23

LOOK IN BOOK

Answer 24

Move electrons bond to the conduction bond where they can move an carry a charge leaving behind a hole.

Answer 25

To prove a driving force for the electrons from negative to positive. With phosphorus, the bond of electrons in P bonds with silicon’s outer electrons leaving one loosely held electron. As this doped layer has additional loosely held electrons it is referred to as an N-type (negative charge) product. = N-type layer A different layer is doped with boron. The 3 boron electrons covalently bond with the 3 silicon atoms but this leaves one region vacant, called a hole. These holes can be thought of as positive charge carriers as they move in the opposite direction to electrons = P-type Electrons in the N-type layer want to travel to the holes in the P-type layer. This process creates the depletion zone.

Answer 26

1. When solar radiation falls on the silicon p-n junction some of the photons can create electron-hole pairs through the photoelectric effect. 2. As the electrons move this creates a potential difference with net positive and negative charge at either side of the p-n junction. This region is called the depletion zone. 3. Contacts on either side of the PV cell connect to an external load and permit the electrons to travel around a loop back to neutralise the valency hole, at the opposite side

Answer 27

To give the electrons a path around the depletion zone along highly conductive metal contacts

Answer 28

Adding extra atoms of a single element?

Answer 29

→ Thick modules → Thin modules → Monocrystalline cells → Polycrystalline

Answer 30

Amorphous silicon Copper indium gallium diselenide Cadmium telluride Thinner (a few microns, 1×10⁻⁶ m) than the others, their enhanced ability to absorb photons allows much thinner cells to be produced. Can be applied to rigid backing or flexible backing, which facilitates their application to curved surfaces.

Answer 31

Exhibit a dark-blue or black colour which is uniform all over the cell. Other colours are possible in surface treatment. The vertical white lines and the much thinner horizontal lines are the metal contacts.

Answer 32

Mosaic-like; it has many individual crystals which differ in colour & contrast. The vertical white and thinner horizontal lines are the metal contacts.

Answer 33

Manufactured from a single, continuous silicon crystalline structure with no boundaries. Boundaries can cause holes to recombine with electrons, increasing the resistance. Most efficient PV cell at around 22 % and often used when little area is available

Answer 34

Manufactured using specialised equipment and personal which increases costs Time consuming to ensure no impurities Energy intensive which increases costs

Answer 35

Less complex, Less energy intensive and time consuming - lowering costs

Answer 36

Made from multiple smaller crystals (grains), between which are grade boundaries which increase resistance. Lower efficiency of a round 18-20%

Answer 37

Cost is between mono and poly crystalline Efficiency does not drop at high temps Can be applied to curved surfaces Can be transparent and used in passive systems

Answer 38

Much lower warranty than the others Lower efficiency that differs depending on material - 7 to 13% Amphorous silicon - lowest Copper indium gallium diselenide Cadmium telluride- Highest

Answer 39

1. No part of the panel exceeds the highest part of the roof. 2. No part of the panel protrudes more than 20 centimetres beyond the plane of a roof slope facing onto and visible from a road. 3. Panels do not exceed the boundary of the existing roof. 4. If you live in a house within a conservation area or World Heritage Site the roof slope on which the panels are fitted must not face onto and be visible from a road.

Answer 40

1. Panels do not extend more than 1.5 metres above the plane of the roof. 2. Panels do not exceed the boundary of the existing roof. 3. If you live in a house within a conservation area or World Heritage Site the panels must not be visible from a road.

Answer 41

1. Any part of the panel which is higher than 4 metres and closer than 3 metres to the property boundary does not protrude more than 20 centimetres from the plane of the wall. 2. Panels do not exceed the boundary of the wall. 3. No part of the solar panel installed on a wall of a chimney is higher than the highest part of the roof. 4. If you live in a house within a conservation area or World Heritage Site the wall must not face onto and be visible from a road.

Answer 42

1. There is only one freestanding solar panel installation within the boundary of the house. 2. The area of the free-standing solar panel does not exceed 14 square metres. 3. No part of the panel exceeds 2 metres in height. 4. No part of the panel is closer to a road than the part of the house nearest the road.

Answer 43

The Green Deal Feed-In-Tariff / NÍ renewable obligations certificate NÍ renewable heat incentive

Answer 44

Available in Great Britain, offers loans to households looking to install a solar panels. Must meet assessment criteria e.g. proper insulation and the fee must be paid upfront for this assessment. If approved the finance is granted and this loan will incur interest which can be paid back through fuel savings.

Answer 45

FTF in GB or the NÍ renewable obligations certificate involves the household selling electricity at a fixed price to the national grid. The contract lasts for 20 years and due to inflation electricity prices will rise each year.

Answer 46

Offered financial incentives to home owners who used: - Solar thermal products - Biomass - Geothermal - Air and ground source heat pumps Exploited by many businesses for financial gain

Answer 47

Window placement and orientation Size and glazing type Thermal mass Thermal insulation

Answer 48

Larger windows should be placed in more used rooms, where possible these should be located due south or within 15 degrees Rooms on the northern side should have smaller windows to minimise thermal losses.

Answer 49

Low emissivity glass reduces heat losses outside are critical Windows could use thin solar cells in the future

Answer 50

1. These materials, like marble, will absorb a huge amount of energy during the day. Preventing the room overheating. 2. At night, as the house cools, the marble transfers this energy into the rooms helping to maintain a higher temperature. Reducing heating requirements in the winter

Answer 51

High levels of thermal insulation will reduce heat losses through the walls, windows and roof Reducing the need for additional heating

Answer 52

1. Reflects solar radiation to a specific point where a HTF absorbs the energy. If water the HTF coverts to steam and if it’s antifreeze it transfers the water to a heat exchanger. 2. The steam drives a turbine as per a conventional power plant. The turbine turns a generator, which produces electricity through electromagnetic Induction

Answer 53

Concentrating solar power where solar radiation is used to heat a fluid which then is used to produce electricity

Answer 54

Look in book

Answer 55

A parabolic shaped mirror tracks the suns motion during the day as it relies on direct radiation from the sun. Parabolic - symmetrical U-shaped curve The curve reflects the sun’s radiation to a specific focal point rather than a plane. This point has a very small area. A receiver tube is located at the focal point, where a HTF circulates and absorbs the suns energy. During the day the HTF passes its energy to water via a heat exchanger The water evaporates to steam and turns a turbine which rotates a generator

Answer 56

Reflects the suns radiation to a fixed receiver tube with HTF. Contains more simplistic reflectors and a flat plate. HTF works the same but can be stored for a period of time in both systems before being used as system Offering the opportunity to produce power when there is no sunlight.

Answer 57

The generator is located at the focal point so no energy losses are incurred when it is transferred. Where the focal point is an engine is located, the energy heats a fluid inside the engine and under repeated expansion and contraction, a piston is forced to move backwards and forwards repeatedly. This motion is used to turn a generator which produces electricity Must track the sun during the day and has the highest efficiency of any solar solution- 30%

Solar Flashcards

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