6.8: Solar Energy

Question 1

Passive Solar

Answer 1

Absorbing or blocking heat from the sun, without use of mechanical or electrical equipment

Question 2

Examples of passive solar

Answer 2

• Using the sun’s heat to cook food in a solar oven
• Orienting buildings to block sunlight in warmer months and allow sunlight in during colder months (double paned windows, southern facing windows, deciduous shade trees

Question 3

Active Solar

Answer 3

Capturing the sun’s heat using mechanical/electrical equipment

Question 4

Active Solar Examples

Answer 4

Solar water heaters (capture sun’s heat in water or circulating fluid and transfer heat to warm water for home in place of electric /gas water heater), Concentrated Solar Thermal, PV cells to convert light rays directly into electricity

Question 5

Photovoltaic Cells

Answer 5

Solar Panels that contain semiconductor (usually silicon) that emits low voltage electrical currents when exposed to sunlight

Question 6

What goes on inside PV cells?

Answer 6

• Photons (particles carrying energy from the sun) cause separation of charges between two semiconductor layers
• Electrons separate from protons and flow through circuit to load, delivering energy as electricity

Question 7

PV Cells use

Answer 7

PV cells on a roof can directly power the building or send excess electricity back to the grid for other users which can earn you a credit from your utility company

Question 8

Drawback of pv cells

Answer 8

Intermittency (solar energy can only be generated during the day) and currently aren’t cost effective

Question 9

Solution to drawbacks of pv cells

Answer 9

Can be solved by cheaper, larger batteries that can store energy generated during the day for use at night

Question 10

Concentrated Solar Thermal (CST or CSP)

Answer 10

Heliostats reflect sun’s rays onto a central water tower in order to heat water to produce steam to turn a turbine to generate electricity

Question 11

Drawback of CST

Answer 11

Habitat destruction and light beams can kill birds in mid air

Question 12

Community Solar Farm vs Rooftop Solar

Answer 12

Large scale solar farms can generate lots of electricity, but do take up land and cause habitat loss and fragmentation. On the other hand, rooftop solar doesn’t take up land, but it produces little electricity

Question 13

Pros of solar energy

Answer 13

• No air pollutants (PM, Nox, Sox) released during electricity production, no carbon dioxide released
• Renewable

Question 14

Cons of solar energy

Answer 14

• Semicondutor metals need to be mined to produce PV cells/ indirect GHG emission
  1. Mining can disrupt habitats and pollute water with mine tailings and the air with particulate matter
  2. Silicon is a limited resource
  3. Solar panel farms can displace animals and habitats