The following questions pertain to solar energy facts. See how many you can answer correctly. Additional information is available by clicking on underlined terms within the answers. For books on solar energy subjects click a strawberry.
Solar Energy Facts Questions
1. What is solar energy?
2. What is a solar house?
3. What is the difference between a solar collector and a solar panel?
4. How much energy is in sunlight?
5. How much is solar energy worth?
6. How much does solar energy cost?
7. Why is solar energy so expensive?
8.
Why do other
countries use more solar energy than the
9. Can I install my own solar electric system?
10. Can I install my own solar hot water system?
11. Can I heat my house with sunlight?
12. How does a solar cell work?
13. How does a solar hot water system work?
14. How does a solar heating system work?
15. What is radiant solar heating?
16. Is an integrated system possible?
17. What is a solar greenhouse retrofit?
18. What is an energy independent house?
19. What is a multi tank heat storage vault?
20. What is a solar thermal roof?
21. What is a solar
thermal power?
1. SOLAR ENERGY: It's a fact that all life depends on and comes from the sun. The production of oxygen and food would be impossible without solar energy. Farmers know the value of a large field with a plentiful supply of sunlight, and now individuals all around the world are taking this boundless source of diffuse energy more seriously as the finite supply of fossil fuels dwindle.
Today less than 0.1% of our heating, transportation and power energy comes from direct sunlight although it is now possible to meet all our energy needs with this simple, renewable resource.
2. SOLAR HOUSE: A solar house is any house that makes good use of the suns energy. It's a solar energy fact that an ordinary house becomes a solar house when it gains more energy than it looses. Do you think the addition of skylights and large picture windows facing south make an ordinary house into a solar house? If these additions add a net heating value to a house that might be so, but if they lose more heat than they gain that will not be the case. Passive Solar greenhouse additions can transform ordinary houses into solar houses, but these additions are best suited for arid sunny areas. Active solar, hydronic systems are best suited for cold climates where sunlight is minimal and extended heat storage is critical.
3. SOLAR COLLECTORS AND SOLAR PANELS: Solar Collectors transform short wavelengths into long wavelengths and trap this energy in the form of heat which is transferred and transported into a heat storage vault. Solar panels convert selected wavelengths of light into electricity.
4. ENERGY IN SUNLIGHT: The energy from the sun varies from place to place and is very dependent on weather conditions. Without an atmosphere 1.4 KW/m2 per hour is available, but with an atmosphere we can only count on 1KW/m2 per hour in the absence of clouds. So, if asked how much 3 hours of sunlight on one square meter is worth what would you say?
5. $ VALUE OF SUNLIGHT $: How much is one hour of sunlight on three square meter worth? Let’s see, if we’re talking about electricity and we say that electricity is worth $0.10 per KWH than 3KWH’s are worth $0.30. The problem is that PV panels have a radiant energy conversion rate of about 20% or less so three hours of sunlight on one square meter of a solar panel is worth less than $0.06
How about heat? How much is 3 hours of sunlight on one square meter of a solar collector worth if we’re talking about heat? Well 1KWH = 3400 BTU so 3KWH = 10,200 BTU. Since one gallon of fuel oil contains 150,000 BTU 10,200 BTU’s are the equivalent of .07 gallons of fuel oil.
Now if fuel oil
is selling for $2.00/gallon which it soon will be the value 10,200 BTU’s is
about $0.14. You might think this is an unfair assumption since we're not taking
into account the heat
conversion efficiency factor like we did with the solar panel.
I’m glad to see
you’re paying attention and you are right about this.
The heat transfer
efficiency of a solar hot water system is between 50% and 70% the same as oil
burner heat transfer efficiency. Since the heat transfer efficiency for an oil
burner is about the same as solar collector and the price of oil is $2.00/gallon than the value of
3 hours of sunlight on one square meter is worth actually $0.14.
How about the
value of heat energy over the period of one year on a roof (20’ x 50’)
tilted south at a steep pitch designed to maximize heat gain?
The surface
area of the roof is 1000 sq ft or 95m2.
The solar
energy available (for north central
6. $
COST OF SOLAR ENERGY $:
Let’s take a close look at the cost requirements for a typical energy
independent house in a northeastern area of the
ELECTRICITY: We’ll need to produce 15,000KWH’s to meet our yearly household electrical requirements. That’s about 40KWH per day. Since an average of 4KWH/day is available we’ll need a 10KW system to meet our yearly electrical requirements. The electricity produced by this 10KW system would have a value of about $4.00/day and require about twenty five 2 m2 panels that would occupy a surface area in excess of 600 square feet. An installed system like this could easily cost $100,000 at $10/watt. Incentive rebates could cut this cost in half, but even at a cost of $5/watt the payback period would be about 30years. If your good friends with an electrical contractor or if you do your own work you might be able to do a little better, but this is still a major investment for a product that has a live expectancy of 20 years. If the price per watt comes down to $1/watt or the price of electricity increases to $1/KWH I’m sure the ugly power lines that cut across our towns would soon be replaced by roofs decorated with PV panels. Until that time I’ll be exploring the possibilities of solar thermal energy.
HEAT: For our well insulated house in the north east we’ll need 1000 gallons of oil per year. Some people will need more, but remember our budget is only $2,000/year for heat and hot water and we’re paying $2.00/gallon. OK the first thing we need to do is convert 1000 gallons of fuel oil into an energy equivalent expressed in terms of KWH’s. You should do this with me to make sure my calculations are correct. I like to round my numbers off to keep things simple. I hope you don’t find this confusing.
1000 x
150,000
= 150,000,000 BTU
150,000,000
BTU/3400
=
44,200 KWH
442,000 KWH is
our heat energy requirement for a year.
Since 1 m2
collector will harvest 1500 KWH/year.
44,200 KWH will
require a surface area of 29.5 m2 to harvest this much energy. Since
winter sunlight is more difficult to come by than summer sunlight lets change
this estimate to 40 m2. Since most commercial collectors are 2 square
meters you’d need 20 of them spread out over an area of 450 square feet to
collect this much heat. This many commercial collectors installed with a
sufficient number of commercial solar hot water tanks and a radiant heating
system would cost about $100,000. If you built and installed your own solar
heating system it would cost you about $10,000
SUMMARY: To summarize. I am saying that it will typically cost a person between $100,000 and $200,000 to convert their house into an energy independent house using commercially available solar application retrofit products and commercial installers. Even at a cost of $200,000 this kind of retrofit may not be feasible if the roof is too small or oriented in the wrong direction. Sounds like a lot of money huh? It is a lot of money. This is why most people don’t take solar energy seriously. You could dabble with a few solar toys if you like, but if you are seriously interested in declaring energy independence at a reasonable price you should consider designing and building an energy independent house from the ground up for not much more than a conventional house. The more involved you get with the process the more you will save.
7. Why
is solar energy so expensive?
There are many reasons why solar energy is so expensive. I’ll try to shed light on a few of them.
a.
Competition is
minimal.
b.
Government
regulations will not allow house owners to install their own systems.
c.
Architects are
reluctant to approve innovative unproven solar house designs.
d.
Builders find
that it is not profitable for them to spend excessive architectural
fees on
designs that are not mainstream and salable.
e. Our government, who should be demonstrating a leadership position in the promotion and use of solar energy, is the primary offender of energy conservation and has no interest in the promotion of a sustainable culture that might threaten the aristocracy.
f. The price of oil is maintained at an artificially low price by government subsidies and special interest groups.
g. Most people are too busy dealing with the problems of day to day survival to be concerned with the headache of a long range investment like solar energy.
h. Fossil fuel oil corporations, who control our economy are doing all they can to discourage the proliferation of alternative energies.
i.
We have become
addicted to fossil fuel energy concentrates the way a child becomes addicted to
candy.
8.
Why do other countries use more solar
energy than the
9. May I install my own
solar electric system?
Legally
speaking, most state regulations prohibit individuals from installing their own
system even though these installation fees are excessive. If you do install your
own system you could easily cut your bill in half, but than you wouldn’t be
entitled to a rebate.
11. Can I heat my house with
sunlight?
Most
definitely. If you live in the south west all you need is a simple passive solar
greenhouse. Northern climates require lots of insulation as well as an entire
solar thermal roof dedicated to the process of gathering heat and an enormous
heat storage vault for storing it. The labor and materials required to heat a
house with sunlight are minimal compared with the government regulations and the
building permit headaches.
12. How does a solar
cell work?
13. How does a solar hot water system work?
14. How does a solar heating
system work?
Hydronic
solar heating systems work
the same way as solar hot water systems except that the stored hot water is used
for house heating rather than domestic hot water systems. Hydronic solar heating
systems are typically ten or more times larger than domestic hot water systems.
In mild, sunny areas the hot air from solar
greenhouses are often used for house heating, but hydronic systems are
more suited for cold climates.
15. Is an integrated system
possible?
Solar
heating and solar hot water systems may share the heat from the same heat
storage vault.
16. What is radiant solar
heating?
Radiant
heating is a method of
heating slab of material. Since the temperature of stored solar hot water is low
radiant heating is preferred. This is true because the large surface area of a
radiant heating system is required to obtain the same results of a conventional
concentrated heat source. A warm floor is a warm house. Radiant solar heating
systems circulate hot water through a network of plastic tubes into the flooring
of a concrete slab. Plastic tubes are used because they will not corrode in the
presence of concrete.
17. What is a solar
greenhouse retrofit?
A
retrofit is sort of an after thought. After a house is built the owner decides
to add something. If a house is oriented properly and landscaping permits a fair
amount of sunlight into the proposed solar greenhouse a practical method of heat
gain is possible. Solar greenhouses are different than standard greenhouses in
that they have a net heat gain effect on the house.
18. What is an energy
independent house?
An
energy
independent house is exactly what you think
it is. It’s a house without power lines hanging over the back yard. It’s a house
without an oil tank attached to the side of the house, buried in the ground
or occupying valuable basement space. A well planned solar house can supply all
the electrical household needs and 80% of the heating requirements. Additional
heating requirements can be supplemented with a well insulated, wood stove
designed to burn (wood, cardboard, cereal boxes, milk cartons, and other
household waste products) at a high temperature. High temperature burning
results in complete oxidation without polluting the atmosphere. A well insulated
wood stove releases most of its heat through the chimney. This is where heat
should be collected and added to the multi tank heat storage vault.
19. What is a multi tank
heat storage vault?
A
multi
drum heat storage vault system is a practical,
efficient, method of collecting, storing and distributing large quantities of
heat at low cost.
20.
What is a solar thermal roof?
A
solar thermal roof is basically a roof converted into one giant collector. A
solar thermal roof 50’x20’ or 1000 sq ft could easily harvest the fuel oil
equivalent contained in 3,000 gallons of fuel oil/year. The materials needed to
make a solar thermal roof of this size cost about $4,000. It takes two men two
days to assemble. A 3,000 gallon heat storage vault takes a full day to build.
The plumbing and radiant heating system could take another day. The material
cost of the entire system would be about $6,000. The problem is that most roofs
are not oriented south with the steep pitch needed to maximize winter heat gain
so a radical roof and house reconstruction might be necessary to make a solar
thermal roof practical. This is why more thought should go into new construction
and house builders should be educated about the possibilities of a solar thermal
house.
21.
What is a solar thermal power?
Commercial
solar power plants use superheated steam to generate electricity. A residential
solar hot water storage vault stores hot water system operates at a much lower
temperature. Is it possible to use this low temperature to generate electricity?
As
long as a there's a temperature difference electricity may be generated.
Sterling engines can operate at temperature differences of less than 150
F although the power they generate is not very significant. To increase the
efficiency of power generation and use the waste heat to generate hot water for house
heating we need a low temperature turbine generator but that could take a
lot of government research dollars to develop.
Contact...
Strawberry Fields Solar Book
Store
How to Build a Solar Hot Water System
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Alternative Housing for the 21st Century
Active Solar
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Greenhouse Effect and the Solar Greenhouse
Solar Energy the Alternative Energy of Choice
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Gallery of Solar Houses
Photovoltaic Electricity Animation
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Our Sun and Our Future
Five Solar Thermal Principles
