Solar Energy Basics

Question 1

Sun peak hours in Palestine

Answer 1

5.4 kwhlm2. Day (Solar irradiation)
Production in April to Sep is higher than other months.
A day with sunshine and no clouds in winter is better production than a day in June because high temps affect of efficiency of panels and production
Best sun hours from 10 AM to 2 PM
Sun angle is higher in summer than winter

Question 2

Solar energy uses

Answer 2

I-solar thermal: water heating and cooking
2- pv: electricity production

Question 3

Solar water heating

Answer 3

1-most water heating efficient way to use solar energy.
2- Solar panel to heat the water - cool water in _black water pipes with black background to absorb heat with transparent top - warm water out.
3- passive system in warm climates to heat water - active system have mechanical device such as pump

Question 4

Waves and colors

Answer 4

1-short waves get through - long waves are trapped.
2 - dark colors absorb alot and reflect little - light colors absorb little, reflect a lot

Question 5

Metal conductivity

Answer 5

1-copper: transfer heat quick and no heat losses.
2- iron: transfer heat in more time and heat losses.

Question 6

Solar cooking benefits

Answer 6

Consumes no fuel /wood - no air pollution - No GHG _ no smoke - no - fire danger - no daily search for wood-no risks for women and children _ no need to stir food - cook food slowly easy to clean.

Question 7

Solar electric systems

Answer 7

PV convert light energy directly into electricity

Question 8

How does solar electric system work

Answer 8

Sunlight is composed of photons, photons strike pv cell, they maybe reflected or absorbed, only absorbed photons generate electricity, when they are absorbed the energy of photons is transferredto electrons in the atoms of the solar cell.

Question 9

Solar cells

Answer 9

Made of two thin pieces of silicon, one piece of select has small amount of boron which gives it tendency to attract electrons - its called p-layer and its positive.
The other piece of silicon has phosphorous added to itto excess free electron, its called n-layer it because has tendency to give up -ve electrons.

Question 10

Best place for solar panels

Answer 10

South facing roof adequate space - no shading - roof structure

Question 11

Solar concentrators

Answer 11

Dishes with concentrators use an array of mirrors to focus sunlight into high efficiency solar cells - four supports hold the cells infront of mirrors - they supply cooling water and electrical connections