The document discusses the sun as an energy source. It explains that the sun's angle changes with the seasons, causing variations in day length and seasonal temperatures. It also notes that sunlight is more spread out when hitting the Earth at shallower angles, covering more area with the same energy. Additionally, it provides guidelines for optimal solar panel orientation for different purposes, such as maximizing energy in summer versus winter.

1. Sun as an Energy Source

2. Lecture 8
Sun as an Energy Source
E-101 - Energy and Sustainability
Professor Lonnie Gamble
Sustainable Living Department
Maharishi University of Management
This presentation was prepared on solar powered computers

3. What Causes Seasons?

4. What Causes Variations in Day Length?

6. Photo of sun rising at road
Sun angle with the season

10. Orientation
Thermal Gains by Window Orienta
Btus / Square Foot Glass/Day - 320 Latitude
North
2030 NOW
CASE STUDY

11. The Nature of Sunlight - Sunlight Density
One sunbeam one mile wide shines on the ground at a 90° angle, and another
at a 30° angle. The one at a shallower angle covers twice as much area with the
same amount of light energy.

13. For Max Summer gain:
Latitude -15
For max winter gain:
Latitude +15
Rule of Thumb:
PV = Latitutde
Hot Water = Lat+15
If in doubt: Latitude

14. Use of PV Watts
http://pvwatts.nrel.gov/version_5.php