Solar energy: Solar energy: from basic knowledge from basic knowledge to some applicationsto some applications

Vyacheslav KhavrusVyacheslav Khavrus11, Ihor , Ihor ShelevytskyShelevytsky22

11 IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany IFW Dresden, P.O. Box 270016, D-01171 Dresden, GermanyE-mail: E-mail: vhavrus@yahoo.comvhavrus@yahoo.com

22 Kryvyi Rih State Pedagogical UniversityKryvyi Rih State Pedagogical University, , Haharin Av., 54, Kryvyi Rih Haharin Av., 54, Kryvyi Rih 50086, Ukraine; 50086, Ukraine; E-mail: E-mail: sheleviv@gmail.comsheleviv@gmail.com

Outline:Outline:

1. Introduction: what do we know about visible Sun movement and seasons at the Earth?

2. The simple parametrical model describing visible movement of the Sun

3. Exploring seasons and Sun paths using animated solar map

4. From prediction of Sun position to Solar energy. Some useful applications

5. “Shadow maps” and sundials

6. Conclusions

1. Introduction: what do we know about visible 1. Introduction: what do we know about visible Sun movement and seasons at the Earth? Sun movement and seasons at the Earth?

- Where do happen in Kyiv sunrise and sunset regarding - Where do happen in Kyiv sunrise and sunset regarding cardinal directions South-North, West-East in different cardinal directions South-North, West-East in different periods of year?periods of year?

- - Why do winter and summer (seasons) exist on Earth?Why do winter and summer (seasons) exist on Earth?

Absence answer = Absence application of solar energy

Why is so important Why is so important solar motion geometrysolar motion geometry?

Maximizing absorption of sunlight needs knowledge and prediction

of the Sun position in any moment of time

2. The simple parametrical model2. The simple parametrical model

describing visible movement of the describing visible movement of the

SunSun

DIERET: http://www.inforse.org/europe/dieret/Solar/solar.html

- obliquity, tilt ot the Earth axe regarding direction, which is perpendicular to rotational plane (current value: 23.45o)

- lattitude of fixed (!) observer (51.03o for Dresden; 50.45o for Kyiv)

Celestial (sky) sphereCelestial (sky) sphere

Latitude (Latitude () of place being considered ) of place being considered is the most important!!!is the most important!!!

sin

sin

tan

1440

2coscossinsincos

min1440,...2,1,0,1440

2sincos

...365,...2,1,0,25.365

2sin

yz

ty

tt

x

TT

– – latitude of observerlatitude of observer

-> Prediction of Sun position -> Prediction of Sun position on the sky for any time of year on the sky for any time of year

and point on the Earthand point on the Earth

20th of March: T=021th of March: T=1…30th of March: T=10…

The simple parametrical model describing visible The simple parametrical model describing visible movement of Sunmovement of Sun

3. Exploring seasons at different 3. Exploring seasons at different

points of Earth using animated solar points of Earth using animated solar

mapsmaps

Representation of 3D Sun movement at 2D planeRepresentation of 3D Sun movement at 2D plane

Solar time at the maps! Estimation difference between local Solar time at the maps! Estimation difference between local and solar time at solar noon:and solar time at solar noon:

1.1. The moment of the shortest shadows. They should be The moment of the shortest shadows. They should be directed to the north (for its estimation use the compass)directed to the north (for its estimation use the compass)

2.2. The middle time between sunrise and sunsetThe middle time between sunrise and sunset

Animated solar map of Dresden (Animated solar map of Dresden (=51.03=51.03oo) in different ) in different periods of year periods of year (Solar time! 12:00 (s.t.) corresponds ~13:10 (Solar time! 12:00 (s.t.) corresponds ~13:10

in summer time)in summer time)

Animated solar map of Kyiv (Animated solar map of Kyiv (=50.45=50.45oo) in different periods of ) in different periods of year year (Solar time! 12:00 (s.t.) corresponds ~13:00 in summer (Solar time! 12:00 (s.t.) corresponds ~13:00 in summer

time)time)

Dresden: observed angle between direction to Sun and Dresden: observed angle between direction to Sun and horizontal surface in different periods of yearhorizontal surface in different periods of year

4. From Sun angle to Solar energy. Some 4. From Sun angle to Solar energy. Some applicationsapplications

Insolation (irradiance)

= maxsin

Outside of atmospheremax~1366 W/m2

See level with transparent skymax~1000 W/m2

Weather with cloudsmax~200 W/m2

Average heat power of human bodymax~100 W/m2

What can you get using 1 kW-h of energy?What can you get using 1 kW-h of energy?

1 kW-h = 3600 kJ

* Lighting of energy-saving lamp (P=10 W) during 100 hours

* To raise temperature 40 l of water ~20 oC

* To heat an air in the room with volume 150 m3 (10x5x3) ~20 oC

Trombe wall Solar thermal collector

(efficiency is up to 80%) Solar panel

(efficiency is 15-18%)

Time dependence of ideal daily amount of energy (kW-h/mTime dependence of ideal daily amount of energy (kW-h/m22) which can ) which can harvested at different seasons from each side of “Solar cube”harvested at different seasons from each side of “Solar cube”

Winter timeWinter time: the south side gives : the south side gives the maximal amount of heatthe maximal amount of heat

South-oriented eaves in old Ukraine as elements of South-oriented eaves in old Ukraine as elements of energy-effective housesenergy-effective houses

Advantages:1. Protection of south windows of house in summer time against solar light.

Coolness in summer

2. Windows open to Sun in winter time. Barrier from the heat convection at the south wall

Novel GreenhouseNovel GreenhouseSunrise and sunset at winter solstice

(declination =-=-23.45o)

= arcsin(sin/cos)

Sunrise and sunset at winter solstice in Dresden

~ 39~ 39oo

Optimal distances between houses of solar Optimal distances between houses of solar panels? What is the length of shadows in panels? What is the length of shadows in

different seasons?different seasons?

55. “Shadow maps” and Sundials. “Shadow maps” and Sundials

HorizontalHorizontal sundial for Dresden sundial for Dresden

It is possible to calculate the main properties of any kind of sundials using the model

presented here

Sundial at the wall of ancient palace in the Pillnitz Sundial at the wall of ancient palace in the Pillnitz

(Dresden)(Dresden)

Horizontal sundial for KyivHorizontal sundial for Kyiv

Experimental tests performed in Kirovohrad Experimental tests performed in Kirovohrad region of Ukraine using unsophisticated region of Ukraine using unsophisticated

horizontal sundialhorizontal sundial

66. . Summary and outlooks Summary and outlooks based on the proposed model:based on the proposed model:

* always estimate at the sky the sector of the Sun shining!

* optimise position of thermal collector or solar panels in dependence on latitude;

* consider shadow areas

* sundials as useful and simple tools for popularization solar energy applications

Thank you for your attention!

Supplementary materials

Solar maps of different point of the Earth at summer Solar maps of different point of the Earth at summer solsticesolstice

Animated solar map of Murmansk (Animated solar map of Murmansk (=68.97=68.97oo) – the ) – the largest city beyond the polar circle (66.56largest city beyond the polar circle (66.56oo))

Animated solar map of Sohag (Animated solar map of Sohag (=26.55=26.55oo) in different periods ) in different periods of yearof year