This document discusses solar power and its various technologies including photovoltaics and concentrating solar power. It provides details on solar thermal energy applications like water heating, heating/cooling buildings, and cooking. Concentrated solar power plants using molten salt for thermal energy storage are also described. The document then discusses solar energy development and challenges in Bangladesh, noting most solar panels there have low efficiency and the government's renewable energy targets are modest compared to other countries.

1. Sustainable Resource Management Solar Power
Md Imran Hossain Rakib
Department of Environmental Science, Bangladesh University of Professional, Mirpur
Cantonment, Dhaka-1216, Bangladesh
Email: imranhossain.rakib38@gmail.com, mobile no-01941491597
Abstract:
Developing technologies that take advantage of the clean abundant energy of the sun is
important to reducing greenhouse gasses and helps stimulate the economy. Photovoltaic
cells, concentrating solar power technologies and solar water heaters are some of the solar
technologies being developed by the Department of Energy. Photovoltaic cells convert sunlight
directly into electricity and are made of semiconductors such as crystalline silicon or various
thin-film materials. Photovoltaics can provide tiny amounts of power for watches, large amounts
for the electric grid, and everything in between. Concentrating solar power technologies use
reflective materials to concentrate the sun's heat energy, which ultimately drives a generator to
produce electricity.
Keyword:
Solar power, Energy, Photovoltaics, renewable, solar radiation Thermal Energy, Green energy
etc.
1. Introduction:
Solar power is the conversion of energy from sunlight into electricity, either directly
using photovoltaics (PV), indirectly using concentrated solar power, or a combination.
Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large
area of sunlight into a small beam. Photovoltaic cells convert light into an electric current using
the photovoltaic effect.[1]
Photovoltaics were initially solely used as a source of electricity for small and medium-sized
applications, from the calculator powered by a single solar cell to remote homes powered by
an off-grid rooftop PV system. Commercial concentrated solar power plants were first developed

2. in the 1980s. The 392 MW Ivanpah installation is the largest concentrating solar power plant in
the world, located in the Mojave Desert of California.
The International Energy Agency projected in 2014 that under its "high renewables" scenario, by
2050, solar photovoltaics and concentrated solar power would contribute about 16 and 11
percent, respectively, of the worldwide electricity consumption, and solar would be the world's
largest source of electricity. Most solar installations would be in China and India.[2]
Solar energy is radiant light and heat from the Sun that is harnessed using a range of ever-
evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar
architecture, molten salt power plants and artificial photosynthesis.[3] [4]
It is an important source of renewable energy and its technologies are broadly characterized as
either passive solar or active solar depending on how they capture and distribute solar energy or
convert it into solar power. Active solar techniques include the use of photovoltaic
systems, concentrated solar power and solar water heating to harness the energy. Passive solar
techniques include orienting a building to the Sun, selecting materials with favorable thermal
mass or light-dispersing properties, and designing spaces that naturally circulate air.
The large magnitude of solar energy available makes it a highly appealing source of electricity.
The United Nations Development Programme in its 2000 World Energy Assessment found that
the annual potential of solar energy was 1,575–49,837 exajoules(EJ). This is several times larger
than the total world energy consumption, which was 559.8 EJ in 2012.[5] [6]
Fig.1. the source of Earth's solar power: the Sun
The Earth receives 174 pet watts (PW) of incoming solar radiation (insolation) at the
upper atmosphere.[7]
Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and
land masses. The spectrum of solar light at the Earth's surface is mostly spread across

3. the visible and near-infrared ranges with a small part in the near-ultraviolet.[6]
Most of the
world's population live in areas with insolation levels of 150–300 watts/m², or 3.5–7.0 kWh/m²
per day.[8]
Fig.2. Annual solar energy potential by region
2. Thermal Energy
Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to
generate thermal energy or electrical energy for use in industry, and in the residential and
commercial sectors.
2.1Early commercial adaptation
In 1878, at the Universal Exposition in Paris, Augustin Mouchot successfully demonstrated a
solar steam engine, but couldn't continue development because of cheap coal and other factors.
In 1897, Frank Shuman, a U.S. inventor, engineer and solar energy pioneer, built a small
demonstration solar engine that worked by reflecting solar energy onto square boxes filled with
ether, which has a lower boiling point than water, and were fitted internally with black pipes
which in turn powered a steam engine.

4. Fig.3. 1917 Patent drawing of Shuman's solar collector
In 1908 Shuman formed the Sun Power Company with the intent of building larger solar power
plants. He, along with his technical advisor A.S.E. Ackermann and British physicist Sir Charles
Vernon Boys, developed an improved system using mirrors to reflect solar energy upon collector
boxes, increasing heating capacity to the extent that water could now be used instead of ether.
Shuman then constructed a full-scale steam engine powered by low-pressure water, enabling him
to patent the entire solar engine system by 1912.
Shuman built the world's first solar thermal power station in Maadi, Egypt, between 1912 and
1913. His plant used parabolic troughs to power a 45–52 kilowatts (60–70 hp) engine that
pumped more than 22,000 litres (4,800 imp gal; 5,800 US gal) of water per minute from the Nile
River to adjacent cotton fields. Although the outbreak of World War I and the discovery of cheap
oil in the 1930s discouraged the advancement of solar energy, Shuman's vision and basic design
were resurrected in the 1970s with a new wave of interest in solar thermal energy.([9]
2.2 Water heating
Solar hot water systems use sunlight to heat water. In low geographical latitudes (below
40 degrees) from 60 to 70% of the domestic hot water use with temperatures up to 60 °C can be
provided by solar heating systems. The most common types of solar water heaters are evacuated
tube collectors (44%) and glazed flat plate collectors (34%) generally used for domestic hot
water; and unglazed plastic collectors (21%) used mainly to heat swimming pools.[10][11][12]
As of 2007, the total installed capacity of solar hot water systems was approximately
154 thermal gigawatt (GWth). China is the world leader in their deployment with
70 GWth installed as of 2006 and a long-term goal of 210 GWth by 2020. Israel and Cyprus are

5. the per capita leaders in the use of solar hot water systems with over 90% of homes using them.
In the United States, Canada, and Australia, heating swimming pools is the dominant application
of solar hot water with an installed capacity of 18 GWth as of 2005.[13]
2.3 Heating, cooling and ventilation
In the United States, heating, ventilation and air conditioning (HVAC) systems account for 30%
(4.65 EJ/yr) of the energy used in commercial buildings and nearly 50% (10.1 EJ/yr) of the
energy used in residential buildings. Solar heating, cooling and ventilation technologies can be
used to offset a portion of this energy.[14][15]
Solar heating, cooling and ventilation technologies can be used to offset a portion of this energy.
Thermal mass is any material that can be used to store heat—heat from the Sun in the case of
solar energy. Common thermal mass materials include stone, cement and water. Historically they
have been used in arid climates or warm temperate regions to keep buildings cool by absorbing
solar energy during the day and radiating stored heat to the cooler atmosphere at night. However,
they can be used in cold temperate areas to maintain warmth as well. The size and placement of
thermal mass depend on several factors such as climate, daylighting and shading conditions.
When properly incorporated, thermal mass maintains space temperatures in a comfortable range
and reduces the need for auxiliary heating and cooling equipment.[16][17]
2.4Cooking
Solar cookers use sunlight for cooking, drying and pasteurization. They can be grouped into
three broad categories: box cookers, panel cookers and reflector cookers.[17]
Fig.3.Parabolic dish produces steam for cooking, in Auroville, India
2.5 Molten salt technology
Molten salt can be employed as a thermal energy storage method to retain thermal energy
collected by a solar tower or solar trough of a concentrated solar power plant, so that it can be
used to generate electricity in bad weather or at night. It was demonstrated in the Solar
Two project from 1995–1999. The system is predicted to have an annual efficiency of 99%, a

6. reference to the energy retained by storing heat before turning it into electricity, versus
converting heat directly into electricity.[18][19][20]
The molten salt mixtures vary. The most extended mixture contains sodium nitrate, potassium
nitrate and calcium nitrate. It is non-flammable and nontoxic, and has already been used in the
chemical and metals industries as a heat-transport fluid, so experience with such systems exists
in non-solar applications.
Fig.4: Some of the world's largest solar power stations: Ivanpah (CSP) and Topaz (PV)
3. Solar energy in Bangladesh
The installation of more than four million Solar Home Systems (SHS) in the last two
decades has made Bangladesh one of the biggest markets for SHS in the world. But these
numbers, often held up as a renewable energy success story, actually mask a grim reality.
Many of the solar systems are of a poor quality, contributing little to the solarization of
the country, say experts. High prices charged for inferior systems have emptied the
pockets of consumers, but have not had a lasting impact on the overall scenario of energy
generation. According to Engineer Mahbub Sumon, a renewable energy expert, the
average home solar system installed in Bangladesh in the last decade merely had a
generation capacity of 20-50 watt, which is good enough for lighting only a few bulbs
and fans. While modern solar panels used globally have energy efficiency of up to 22%,
the Bangladesh market is still stuck with 10-12% panel efficiency. As a result, even after
two decades of successful SHS dissemination throughout the country, the share of
renewable energy in total electricity generation in Bangladesh is only 0.07%. Engineer
B.D. Rahmatullah, the former Director General of Power Cell, said that due to the very
high prices charged for low-capacity solar systems, the concept of ‘renewable’ has

7. gradually become unpopular among rural people. He said, “Instead of pushing each rural
household to pay a very high price for solar home systems, the Power Development
Board could have built countrywide solar based minigrid and microgird systems which
would drive down the price for the poor by ensuring economies of scale.” The bulk of the
solar home system installations in the country was undertaken either by the government-
owned Infrastructural Development Company Limited (IDCOL) and its partner
organizations or by private-sector companies. According to several officials of IDCOL
partners, the commercial market which expanded during the solar home installation boom
of the last twenty years severely lacked government monitoring and regulation, leading to
a flood of poor quality hardware entering the market. Currently, new installations of solar
systems are encouraged by the government under a ‘Free of Cost’ program within the
framework of KABITA (Kajer Binimoye Taka) or Money for Work. An executive at an
IDCOL partner claimed that the ‘Free of Cost’ program of the government not only
disrupted the existing business model, it also led to widespread corruption within the
system of distribution. Allegations are common that the solar panels under KABITA are
normally distributed to locally influential people, and hence fail to reach the bona fide
non-electrified households.(21)
Despite the hype about renewable energy in Bangladesh, the current installed capacity of
solar, wind, and biomass in Bangladesh is mere 242 MW. The government has declared a
plan to install a total of only 2,666 MW renewable capacity by 2021, when the total
energy generation capacity of the country will reach 24,000 MW. In contrast, the recent
Indian figures of renewable energy installation show a striking escalation of electricity
generation from renewable sources. India has set a course to install as much as 160,000
MW capacity of solar and wind power plants by the year of 2022. While the recent Power
Sector Master Plan (PSMP-2016) of Bangladesh government has shown the potential of
renewable-based electricity generation to be as low as 3% by 2041, India sets a target to
achieve as much as 40% of its electricity generation from non-fossil fuel renewable
sources by 2030. Similarly, Germany is now producing 31% of its electricity from
renewable sources and set a target to achieve 35-40% of its required electricity from
renewable sources by 2025. At a time when heavily industrialized countries like Germany
and France and even developing countries like India drastically shifted from fossil fuel to
renewable sources, Bangladesh government has been criticized for its inclination towards
coal and nuclear energy. The PSMP-2016 has fixed a target of generating as much as 35%
of electricity from coal and 10% from nuclear energy by 2041. Meanwhile, 15% of
electricity generation is expected to come from a combination of renewable sources and
imported power by 2041. This particular combination of energy sources makes it difficult
to figure out the exact share of renewable electricity from the energy mix. According to
Professor Anu Muhammad, the member secretary of National Committee to protect Oil
Gas Mineral Resources Power and Ports, this is a deceptive character of the PSMP’s
renewable energy target. In this way, the renewable based power generation quota can
easily be replaced by pumping imported electricity into the system. Sheikh Reaz Ahmed,
the Director of Sustainable and Renewable Energy Development Authority (SREDA) has
identified ‘the lack of empowerment of SREDA’ as an obstacle to boosting renewable
energy in Bangladesh. “Although SREDA is the nodal agency for renewable energy, it

8. has limited authority to contribute to the expansion of renewable energy in Bangladesh,”
he said. This was echoed by BD Rahmatullah who referred to SREDA as a ‘toothless
tiger’ whose real potential has been restricted by the Ministry of Power, Energy and
Mineral Resources. Moshahida Sultana, Associate Professor of Economics at Dhaka
University, said: “Clean energy transition is an evolving process requiring not only new
investments and infrastructure, but also price regulation, government interventions,
subsidies and local innovation incentives. While sensible governments around the world
are adopting appropriate policies to make major shifts towards renewable, the Bangladesh
government is going in a flawed direction.”
Fig.5. solar Panel in rural area of Bangladesh
4. Conclusion
Renewable energy technologies are essential contributors to sustainable energy as they generally
contribute to world energy security, reducing dependence on fuel resources, Solar heating systems
are a well-known second-generation technology and generally consist of solar thermal collectors,
a fluid system to move the heat from the collector to its point of usage, and a reservoir or tank for
heat storage and subsequent use. The systems may be used to heat domestic hot water,
swimming pool water, or for space heating By participating in a green energy program a
consumer may be having an effect on the energy sources used and ultimately might be helping to
promote and expand the use of green energy. They are also making a statement to policy makers
that they are willing to pay a price premium to support renewable energy. Green energy
consumers either obligate the utility companies to increase the amount of green energy that they

9. purchase from the pool (so decreasing the amount of non-green energy they purchase), or
directly fund the green energy through a green power provider. If insufficient green energy
sources are available, the utility must develop new ones or contract with a third party energy
supplier to provide green energy, causing more to be built. However, there is no way the
consumer can check whether or not the electricity bought is "green" or otherwise. Innovative
green energy trends and solutions were at the center of discussion at EXPO 2017 in Astana,
Kazakhstan. Specialized Expo 2017 was themed "Future Energy" and brought together
representatives of 115 countries and 22 international organizations.[22]

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