BUE ACE1
Sustainable Vital Technologies in
Engineering & Informatics
8-10 Nov 2016
Solar Panels as an Efficient Energy Saving Tool in New
Housing Districts in Cairo
Karim, Kesseiba*
Cairo University, Cairo, Egypt
Abstract
Amid the horizontal expansion in new cities designed in Cairo suburbs, the dilemma of energy efficiency is re-questioned,
especially in the shadows of challenges of global warming and the limited non-renewable resources available. Thus, the
paper examines the use of solar panels positioned on roof tops of houses, precisely in new developments where horizontal
expansions of houses provide more roof tops to apply the solar panels for a fewer number of users, accordingly provide
better ratio of energy consumption in relation to production via the solar panels. The methodology followed in the paper
depends on the analysis of the capacity of energy produced by the solar panels in relation to energy consumed by users of
a single house in one of the new developments. This analysis highlights the amount of non-renewable energy saving
acquired by using more environmental friendly methods of energy production. Following that a comparative analysis is
highlighted between the extended applications of this system of energy production on a whole neighborhood to examine
the economics of energy saving in case of application on large scale projects. The paper concludes by a set of
recommendations for improving the methods of applying renewable energy production techniques in new cities.
© 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Global
Science and Technology Forum Pte Ltd
Keywords: solar panels, energy efficieny, horizontal urban expansion, new cities in Cairo.
1.
Introduction
The divert to using renewable energy resources is a real challenge which should be taken into
consideration nowadays amid the threats of global warming from an international perspective, in addition to
the local challenges a developing country like Egypt is currently facing. Those local challenges can be
grouped in relevance to the abundance of solar exposure which can be utilized for producing electricity in a
safe and clean approach. This is highly recommended in parallel with the increase in urbanization in Egypt
and the mega projects intended to take place which consequently require an increase in energy production.
Accordingly the paper will focus on one approach of producing electricity through an environmentally
friendly method, which is the utilization of photovoltaic cells, to be applied on housing use in the urban
* Corresponding author.
E-mail address: [email protected].
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sprawl around Cairo. In order to understand the mechanism discussed and analyzed in the case study, a brief
literature review about the solar energy production is primarily introduced, following that the analysis of the
use of solar panels in a single dwelling unit will be analyzed with reflections on the utilization of the same
system in a neighborhood. The paper concludes by a discussion of the possibility and future of solar cities in
Egypt.
2.
Literature Review of Solar Energy Use in Reducing Energy in Buildings:
Parida et al (2011) introduce photovoltaic conversion as a direct conversion of sunlight into electricity
without any heat engine to interfere. Photovoltaic devices are rugged and simple in design requiring very little
maintenance and their biggest advantage being their construction as stand-alone systems to give outputs from
microwatts to megawatts. Hence they are used for power source, water pumping, remote buildings, solar
home systems, communications, satellites and space vehicles, reverse osmosis plants, and for even
megawattscale power plants. With such a vast array of applications, the demand for photo-voltaic is
increasing every year, (Survey of Energy Resources 2007, World Energy Council).
Smith (2005) further exposes that the amount of energy supplied to the Earth by the sun is five orders of
magnitude larger than the energy needed to sustain modern civilization. One of the most promising systems
for converting this solar radiation into usable energy is the photovoltaic (PV) cell. PV materials generate
direct electrical current (DC) when exposed to light. The uniqueness of PV generation is that it is based on the
‘photoelectric quantum effect in semi-conductors’ which means it has no moving parts and requires minimum
maintenance. Silicon is, at present, the dominant PV material which is deposited on a suitable substrate such
as glass. Its disadvantages are that it is expensive; it is, as yet, capable of only a relatively low output per unit
of area, and, of course, only operates during daylight hours and is therefore subject to fluctuation in output
due to diurnal, climate and seasonal variation.
Moreover, Smith (2005) explains that the growth in the manufacture of PVs has been accelerating at an
extraordinary pace. In 2002 it was 56 per cent in Europe and 46 per cent in Japan, greater than in 2001. We
are now seeing the emergence of large plants producing PVs on an industrial scale, that is, over 200 MW per
year. The result is that unit costs have almost halved between 1996 and 2002. Significant further cost
reductions are confidently predicted coupled with steady improvements in efficiency. One application of PVs
is its potential radically to improve the quality of life in the rural regions of developing countries. This is
certainly one area on which the industrialized countries should focus capital and technology transfer to less
and least developed countries.
In accordance to that, Roaf et al (2001) explain that photovoltaic cells convert sunlight directly into
electrical energy. The electricity they produce is DC (direct current) and can either be used directly as DC
power; converted to AC (alternating current) power; or stored for later use. The basic element of a
photovoltaic system is the solar cell that is made of a semiconductor material, typically silicon. There are no
moving parts in a solar cell, its operation is environmentally benign and, if the device is correctly
encapsulated against the environment, there is nothing that will wear out. Because sunlight is universally
available, with a specific high exposure in Egypt, photovoltaic devices have many additional benefits that
make them not only usable, but of great value in electricity production. PV cells are typically grouped
together in a module for ease of use. A PV system consists of one or more PV modules, which convert
sunlight directly into electricity, and a range of other system components that may include an AC/DC inverter,
back-up source of energy, battery to store the electricity until it is needed, battery charger, control centre,
mounting structures and miscellaneous wires and fuses, the different systems of which are presented in the
following figures (fig. 1-4).
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Fig. 1. Stand-alone DC system, Roaf et al (2001).
Fig. 2, Stand-alone DC/AC system,
Roaf et al (2001).
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Fig. 3, Hybrid system,
Karim Kesseiba/ BUE ACE1 SVT2016
Roaf et al (2001).
Fig 4, Grid Connected system,
Roaf et al (2001).
As Roaf et al (2001) explain, even in cloudy, northern latitudes, PV panels can generate sufficient
power to meet all, or part of, the electricity demand of a building. The Oxford Ecohouse, for example,
incorporates 48 PV panels on the roof that generate enough energy to lower the household electricity bills by
70 per cent. The flexibility of PV enables its use in many building products, such as solar roof tiles, curtain
walls and decorative screens, which can directly replace conventional materials in the building fabric. These
products serve the same structural and weather protection purposes as their traditional alternatives but offer
the additional benefit of generating the power to run the house.
Karim Kesseiba/ BUE ACE1 SVT2016
As Roaf et al. (2005 ) explain, working definition of a Solar City is a city that aims at reducing the
level of greenhouse gas emissions through a holistic strategy for the introduction of RES and the RUE to a
climate stable and thus sustainable level in the year 2050 (Kates et al., 1998; Droege, 2002). Some of the
stated goals of the emerging Solar Cities concept include lowering of greenhouse gas emissions by the year
2050 to an amount equal to a city’s 1990 population level multiplied by 3.3 tonnes of CO2 (Kates et al., 1998;
Droege, 2002). This target is based on fundamental equity calculations that each person has only an annual
3.3 tonnes emissions ‘allowance’, in order to allow oceans and forests to neutralise excessive carbon
emissions (Byrne et al., 1998). In addition to this, it includes identifying near- and medium-term milestones
for greenhouse gas reductions according to a schedule for the years 2005–2050. Roaf et al. (2005) also
exposed that identifying corresponding improvements in the transformation of energy production to solar and
other renewable systems, reduced energy consumption, reduced consumption of natural resources, protection
and improvement of urban environmental quality, improvement of social equity and improved quality of life.
It has been argued (Capello, 1999; Droege, 2002) that a number of scientific and technical objectives
of Solar Cities are needed to achieve the overall goals,1 and that some key activities are needed to ensure that
the objectives are met (www. solarcitiesineurope.nu). Some activities have already been implemented. The
use of renewable energy and micro-power systems is already on the rise, but the current speed of change is
still too slow to meet the global goals for CO2 reduction in time to avert the pending serious crises threatened
by climate change and fossil fuel depletion (Droege, 2002). Cities and towns are increasingly regarded as
settings for co-ordinated policy implementation programmes aimed at global renewable energy technology
introduction. Against this background a number of ‘Solar City’ projects and initiatives have been established
as global or regional networks in Europe and America. For example, in Ashland, Oregon, in 1996 the
municipal utility supported a net metering law that established a simple grid-interconnection policy that
guaranteed the purchase of exported electricity at full retail price of up to 1000 kW of excess electricity per
month. On a larger scale San Francisco, spurred on by the power crisis of 2000/2001, plans to place as much
as 50 mW of photovoltaic (PV) panels on city rooftops, financed by the sale of revenue bonds agreed by the
electorate (www.e-coop.org/news529.cfm). In Europe the strong coalition of Solar Cities, reinforced by
European research funding (www.solarcitiesineurope.nu) includes London and Berlin, and also Barcelona, a
city where every new building must have a solar hot water system and where the local municipality has
invested heavily in PV systems on public buildings. In 2002, a group of local Oxford Councillors, council
employees, consultants and academicians put together a team to promote Oxford as a leading Solar City in the
UK, and the following sections detail their approach to this challenge.
Thus, according to Roaf et al. (2005) , the overall objective of the OSI is to find the best ways to
introduce Solar Energy Technologies (SET) and the RUE in Oxford. The initiative contains several clear
goals including:
● Goal One: 10% of all houses in Oxford will have solar systems by the year 2010.
● Goal Two: To implement a capacity building program for local government to provide information,
training and other services oriented to CO2 mitigation strategies.
● Goal Three: To establish strategic alliances with, and participation of local government, households,
business organisations, energy supply companies and community organisations to fulfil Oxford ’s CO2
reduction targets.
● Goal Four: To initiate and implement a solar campaign to support local CO2 reduction initiatives at every
level within the Oxford community from primary school children to business leaders.
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Roaf et al. (2005) further expose that the OSI has been designed to use a community-based approach
to develop Oxford as a pioneering Solar City. The ultimate aim of the project is to build local partnerships to
implement actions to reduce CO2 emissions from the buildings of the city, by up to 90%. The project aims in
turn to stimulate local industry and to ensure that the citizens of Oxford are future-proofed, in safe and
comfortable homes, against the twin challenges of climate change and increasingly expensive fossil fuels. To
date, the first phase of the project has demonstrated that energy efficiency measures are more popular among
householders, being cheaper and better understood technologies. The householders are however, also very
keen to have solar hot water systems installed, and many of them would like (eventually) to have solar PV
panels on their roofs. It is estimated that with time, the take-up rate for solar systems will increase as the
technology becomes more familiar.
Stemming from the above discussions it is crucial to reflect to the state of the Arab Countries in the
utilization of the clean energy resources. According to Chedid el al (2003), the following table shows
respectively the solar and wind energy resources, biomass potential, and status of hydropower stations in Arab
Countries. Despite the promising data shown in these tables, RE has never been a priority for Arab
governments. During the past two decades, most RE activities in Arab Countries were mainly linked to the
Research and Development activities of the academic communities, and were not considered as an integral
element of the national energy plans. In all Arab countries, renewable energy development is being taken care
of by universities, research centers and by departments within relevant ministries such as ministries of energy,
electricity, water and environment. A few countries like Egypt, Jordan, Syria, Libya, Morocco and Tunisia
have taken steps towards the formulation of policies and plans for RE development. The government in Egypt
formulated, in the early 1980s, a national strategy for the development of RE applications and energyconservation measures as an integral element of its national energy-planning.
Table 1, Solar-energy resources (kWh/m2/day), Chedid el al (2003)
Country
Solar energy
Country
Solar energy
Algeria
5–7
Oman
5–6
Bahrain
5–8
Palestine
4–6
Egypt
5–9
Qatar
5–6
Iraq
5–6
Saudi Arabia
6–8
Djibouti
4–6
Sudan 5–8
5–8
Jordan
5–7
Somalia
6–9
Kuwait
5–8
Syrian Arab Republic
5–6
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Lebanon
4–6
Tunisia
5–7
Libya
5–7
United Arab Emirates
5–6
Mauritania
6
Yemen
4–6
Morocco
5–7
Thus, according to Chedid el al (2003), the only advanced solar thermal power plant in the region is
in Egypt. A large scale 150 MW integrated solar combined cycle system, using parabolic trough solar
technology with a conventional gas turbine combined cycle, is currently under implementation by the New
and Renewable Energy Authority (NREA) with financial support from GEF. Its operation is expected in early
2003. PV technologies are not widely spread in the AC due to many reasons including their high capital costs
and the low level of awareness about their values. The total installed capacity of PV systems in all AC is
estimated at 10 MW spread over countries including Egypt, Jordan, Syria, Palestine, Saudi Arabia, Tunisia,
Morocco and Algeria. The PV projects in Egypt have a total capacity of 2 MW including: (1) more than 10
water-pumping projects with capacities varying between 2 and 10 kWp; (2) a 200 kWp central electrification
system for a land reclamation farm at Owinat; and (3) a remote-village electrification project with a total
capacity of 28 kWp serving 20 households with street lighting and water pumping.
3.
Case Study Analysis: Using Solar Panels in Electricity Saving in Residential Units:
3.1. Model Description
The model investigated in the case study is the implementation of the grid connected system previously
explained in figure 4 and shown below in figures (5, 6). The solar panels are connected to a smart inverter
which is connected to AC output. The smart inverter supplies electricity generated from the solar panels
directly into the AC output to be used during day for appliances usage, and to be stored when not in use for
later usage during night.
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Fig. 5, Solar Panels Installation in a Home in Sheikh Zayed, Author, 2016.
Karim Kesseiba/ BUE ACE1 SVT2016
Fig. 6, Smart Inverter Converting Electricity from the Solar Panels to AC current, Author, 2016.
The maximum production of a single solar panel is 250 watt per hour when installed facing south
with an inclination of 30 degrees. The average sunny hours in Cairo is calculated to be 5.5 hours daily.
3.2. Energy Saving Solutions for a Singly Dwelling Unit:
According to data collected from monthly electricity bills for a four family members residing in a single
storey dwelling in a new community around Cairo, the average energy consumption per month for electricity
usage is 300 Kilo Watt. Thus, the average production of electricity by the solar panels per month if applied
according to the model described will be the following,
300 Kwatt/ 30 days= 10 Kwatt per day.
10 Kwatt/ 5.5= 2 Kwatt/ day.
Accordingly, to achieve clean electricity from the applied solar panels only, the home will be in need for 8
panels according to the model described above.
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3.3. Energy Saving Solutions for a Typical Residential Neighborhood:
Given the average number dwelling units in a typical neighborhood in the outskirts of Cairo as of 70 units, the
following electricity saving solutions will be implemented;
The Need for 8 panels* 70 homes= 560 solar panel.
Average saving of 300 Kwatt* 70= 21,000 Kwatt per month.
Thus, the economics of use of such solar panel units (fig. 7) will be of great value for both the
government to sustain clean electricity production as well as dwellers who will benefit from the reduced
monthly consumption.
Fig. 7, Applications of Solar Panels Installation in Sheikh Zayed, Author, 2016.
4.
Discussion: Future of Solar Cities:
As exposed in the literature review and the analysis of the electricity consumption when applying solar
panels in a typical neighbourhood, it is obvious that due to Egypt’s location and potentials of the solar energy
use, the wide spread of solar panels can lead to a great deal of energy saving. The future of solar cities can be
further implemented through governmental incentives and raise of awareness for the potentials of applying
this method of clean and sustainable energy production.
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5.
Conclusion:
The paper explored the efficiency of creating energy in atypical neighbourhood in one of Cairo’s outskirts.
The use of the solar panels system on a wide range can lead to a considerate energy saving way for the
challenges facing governments, especially in the developing world. The wide spread of the system especially
in the Egyptian context can be a great set of renewable resources. It is highly recommended to implement
further future research on the economics and design potentials associated with the spread of the system.
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211–220
Droege, P. (2002) Solar City, Retrieved on 30 May 2016 from the World Wide Web: http://www.solarcity.org/ solarcity/contents.htm
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