Chapter 6-part 1 Passive Solar
• Incident Solar Radiation-Effects of Latitude
and Season
• Solar Heating through Time
• Uses of Passive Solar Heating Today
– Passive Solar Houses
– Solar Hot Water Heaters
Energy in the News
US Renewable Energy Use
Share in 1999:
How is this mix
Different from that
In Developing
Countries?
Brazil?
India?
Other?
Expected Growth in Renewables: Bush
Admin. 2001 Report
Is this right, especially given the relative costs of different sources?
Renewables: Second Best Growth
Can nuclear continue to outstrip
Renewables, why or why not?
What is the growth rate of wind power
In Europe?
Solar Radiation vs Infrared Radiation
Why do the sun
And the earth emit
Different types of radiation?
Why does the mix of
radiation change from the top
to the bottom of the
atmosphere?
What is insolation?
What are absorption bands?
What is albedo?
What is the greenhouse
effect?
Seasonal and Latitudinal Insolation Variations
Why does solar insolation at
High latitudes decrease during
Winter months?
What happens between the
Tropics of Cancer and
Capricorn?
Angle of Incidence of Solar Insolation
Why does the optimum
Angle from horizontal for
A solar panel vary with the
Season (at high latitudes)?
What happens near
The equator?
Seasonal Sunrise and Sun Angle at 40°N
Why is this variation
In angle important
For passive solar
design?
What happens at the
Equator?
At South Pole station?
Insolation on a Solar Collector: 40°N
What season does
The flat collector
Get the most
insolation?
What season does the
Vertical collector
Get the most
insolation?
What would this graph
Look like near the
equator?
Types of Solar Insolation
Physics of cloud
Cover: still not
Well known
Big problem in
Climate models
How does total
Insolation
depend on the
Solar constant?
(Precambrian
Equatorial
Glaciations)
Types of Solar Insolation
Direct
Reflected
Diffuse
Where do you get the most reflected insolation, on land
Or on the water? Why?
What type of weather gives you more diffuse insolation,
Cloudy or clear? Why?
How much of the incident solar radiation reaches the
Earths surface?
US Mean Annual Solar Insolation
Where is insolation
greatest?
Where is insolation
Least?
What is the ratio of
The greatest to
Least insolation
In the US?
Is this surprising?
Solar Printing Press
Invented by August
Mouchat: 1878
A: Solar Collector
B: Steam Engine
C: Water Tank
Printing Press turned
By steam engine
Parabolic Solar Collector
How does using
water as the working
fluid limit the
collectors efficiency?
If outside air is at
293K, what is the
Theoretical
efficiency?
Solar Pot
Mouchots solar pot
Could boil 3 liters of
Water in 1.5 hours.
Based on your problem
Set, about how long would it
Take to just bring the water
To 100°C?
Adams solar cooking pot
Where in
The developing
World would these
Pots be easiest
For people to
accept?
Least easy to
accept?
(Think cuisine
Not income levels)
Telkes Oven
Why can this solar oven
Reach higher temperatures
Than the previous oven?
What features of passive solar
Design does it incorporate
That make it more efficient?
Solar Water Distiller
Research vessels get water from evaporators. Why is it so hard to
distill water in the Red Sea? Why does the ship need to be moving
To distill water? (Dredging leg in the Red Sea.)
General Features of Solar Heating
What uses a fan:
Active or passive
Solar heating
Systems?
Flat Plate Solar Collector
How is this
Solar collector
like a greenhouse?
Why should it
Absorb more heat
Than a typical
Greenhouse
(three reasons)
Types of Solar Flat Plate Collectors
Which types are most
Likely to be passive?
Why?
Active solar hot water system
Why is active solar more common at high latitudes?
Types of Solar Collectors
Thermosiphon Hot Water Heater
Passive Solar System
Water Collection Tank
Must be above the solar
Collector. Why?
Very popular in the
Middle East.
Why are these systems
Impractical at higher
Latitudes?
Bread Box or Batch Water Heater
Hot water is removed
Whenever tap is turned on.
Payback time: 5 to 10 years.
Very inexpensive for
Preheating water.
Solar shower used in Gulf
War: very similar.
Increasing Systems Energy Efficiency
of Hot Water Systems
Reduce water temperature to 120°F (depends on dishwasher)
Insulate heater to R-19
Use low flow showerhead and aerators (payback time 1 year)
Reduce use by 50%
Install a graywater system (illegal in some areas)
Special detergents needed
Install a timer on water heater so is only on when being used.
Install a tankless water heater system (some use open flame
But so do gas driers).