Reading Practice
Photovoltaics on the rooftop
A natural choice for powering the family home
A
In the past, urban homeowners have not always had much
choice in the way electricity is supplied to their homes. Now, however, there
is a choice, and a rapidly increasing number of households worldwide are
choosing the solar energy option. Solar energy, the conversion of sunlight into
energy, is made possible through the use of ‘photovoltaics’, which are simple
appliances that fit onto the roof of a house.
B
The photovoltaics-powered home remains connected to the
power lines, but no storage is required on-site, only a box of electronics (the
inverter) to the interface between the photovoltaics and the grid network.
Figure 1 illustrates the system. During the day, when the home may not be using
much electricity, excess power from the solar array is fed back to the grid, to
factories and offices that need daytime power. At night, power flows the
opposite way. The grid network effectively provides storage. If the demand for
electricity is well matched to when the sun shines, solar energy is especially
valuable. This occurs in places like California in the US and Japan, where
air-conditioning loads for offices and factories are large but heating loads
for homes are small.
C
The first systematic exploration of the use of
photovoltaics on homes began in the US during the 1970s. A well-conceived
program started with the sitting of a number of residential experiment
stations’ at selected locations around the country, representing different
climatic zones. These stations contained a number of ‘dummy’ houses, each with
different solar-energy system design. Homes within the communities close to
these stations were monitored to see how well their energy use matched the
energy generated by the stations’ dummy roofs. A change in US government
priorities in the early 1980s halted this program.
D
With the US effort dropping away, the Japanese Sunshine
Project came to the fore. A large residential test station was installed on
Rokko Island beginning in 1986. This installation consists of 18 ‘dummy’ homes.
Each equipped with its own 2-5 kilowatt photovoltaic system (about 20 – 50
square meters for each system). Some of these simulated homes have their own
electrical appliances inside, such as TV sets, refrigerators and air
conditioning units, which switch on and off under computer control providing a
lavish lifestyle for the non-existent occupants. For the other systems,
electronics simulate these household loads. This test station has allowed being
explored in a systematic way, under well-controlled test conditions. With no
insurmountable problems identified, the Japanese have used the experience
gained from this station to begin their own massive residential photovoltaics
campaign.
E
Meanwhile, Germany began a very important ‘1,000 roof
program’ in 1990, aimed at installing photovoltaics on the roofs of 1,000
private homes. Large federal and regional government subsidies were involved,
accounting in most cases for 70% of the total system costs. The program proved
immensely popular, forcing its extension to over 2,000 homes scattered across
Germany. The success of this program stimulated other European countries to
launch a similar program.
F
Japan’s ‘one million roof program’ was prompted by the
experience gained in the Rokko Island test site and the success of the German
1,000 roof program. The initially quoted aims of the Japanese New Energy
Development Organization were to have 70,000 homes equipped with the
photovoltaics by the year 2000, on the way to 1 million by 2010. The program
made a modest start in 1994 when 539 systems were installed with a government
subsidy of 50 percent. Under this program, entire new suburban developments are
using photovoltaics.
G
This is good news, not only for the photovoltaic industry
but for everyone concerned with the environment. The use of fossil fuels to
generate electricity is not only costly in financial terms, but also in terms
of environmental damage. Gases produced by the burning of fossil fuels in the
production of electricity are a major contributor to the greenhouse effect. To
deal with this problem, many governments are now proposing stringent targets on
the amount of greenhouse gas emissions permitted. These targets mean that all
sources of greenhouse gas emissions including residential electricity use will
receive closer attention in the future.
H
It is likely that in the future, governments will develop
building codes that attempt to constrain the energy demands of new housing. For
example, the use of photovoltaics or the equivalent may be stipulated to lessen
demands on the grid network and hence reduce fossil fuel emissions. Approvals
for building renovations may also be conditional upon taking such energy-saving
measures. If this were to happen, everyone would benefit. Although there is an
initial cost in attaching the system to the rooftop, the householder’s outlay
is soon compensated with the savings on energy bills. In addition, everyone
living on the planet stands to gain from the more benign environmental impact.
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Questions 1-6
The Reading Passage has nine paragraphs A-H
Which paragraph contains the following information?
Write
the correct letter A-H, in boxes 1-6 on your answer sheet.
NB You may
use any letter more than once.
1..................... examples of countries where electricity use
is greater during the day than at night
2..................... a detailed description of an experiment that
led to photovoltaics being promoted throughout the country
3..................... the negative effects of using conventional
means of generating electricity
4..................... an explanation of the photovoltaic system.
5..................... the long-term benefits of using
photovoltaics
6..................... a large campaign inspired by a country's
successful example
Questions 7-13
Do the following statements agree with the information
given in Reading Passage?
In
boxes 7-13 on your answer sheet,
write
TRUE if the statement is true
FALSE if the statement is false
NOT GIVEN if the information is not given in the
passage
7..................... Photovoltaics are used to store electricity.
8..................... Since the 1970s, the US government has
provided continuous support for the use of photovoltaics on homes.
9..................... The solar-powered house on Rokko Island is
uninhabited.
10..................... In 1994, the Japanese government was
providing half the money required for installing photovoltaics on homes.
11..................... Germany, Italy, the Netherlands and
Australia all have strict goals with regard to greenhouse gas emissions.
12..................... Residential electricity use is the major
source of greenhouse gas emission.
13..................... Energy-saving measures must now be included
in the design of all new homes and improvements to buildings.
Solution:
|
1. B |
8. FALSE |
|
2. D |
9. TRUE |
|
3. G |
10. TRUE |
|
4. B |
11. NOT GIVEN |
|
5. H |
12. NOT GIVEN |
|
6. E |
13. FALSE |
7.
FALSE
PASSWORD: GETBAND7
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