







































Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 
180-194 

180 

 

 

 

Article 

AI-enabled toward zero-emission buildings and 

clean mobility: PV–BIPV and battery storage 

integration: a case study of Diyala, Iraq 
Youssef Kassem1,2,3,4*, Hüseyin Çamur1,3, Ali Saad Aldayyeni1,  

Abdalla Hamada Abdelnaby Abdelnaby4 

1Department of Mechanical Engineering, Engineering Faculty, Near East University, 99138 Nicosia (via Mersin 10, Turkey), 

Cyprus  
2Energy, Environment, and Water Research Center, Near East University, 99138 Nicosia (via Mersin 10, Turkey), Cyprus 
3Science, Technology, Engineering Education Application, and Research Center, Near East University, 99138 Nicosia (via 

Mersin 10, Turkey), Cyprus 
4Department of Civil Engineering, Civil and Environmental Engineering Faculty, Near East University, 99138 Nicosia (via 

Mersin 10, Turkey), Cyprus 

A R T I C L E   I N F O 
 

Article history: 
Received 15 August 2025  
Received in revised form 
18 October 2025 
Accepted 19 November 2025 
 
Keywords:  
Iraq, Techno-economic, Rooftop PV system, BIPV, 
CO₂ emissions, Electric vehicles 
 
*Corresponding author 
Email address: 
yousseuf.kassem@neu.edu.tr 
youssef.kassem1986@hotmail.com 
 
DOI: 10.55670/fpll.futech.5.1.16 

A B S T R A C T 
 

Iraqi buildings continue to rely heavily on fossil fuels, which raises carbon 
emissions and energy costs. To address this knowledge gap, the primary 
objective of the present study is to assess the techno-economic and 
environmental performance of solar energy retrofitting for a two-story mixed-
use building in the eastern Iraqi province of Diyala, utilizing ERA5 reanalysis 
data for the first time. To this aim, three retrofit scenarios are considered ((1) 
the baseline scenario (BS) with no renewable systems, (2) the second scenario 
(SS) with a rooftop photovoltaic (PV) system, and (3) the third scenario (TS) 
combining rooftop PV, building-integrated photovoltaic (BIPV) glazing and a 30 
mm layer of Expanded Polystyrene (EPS) insulation). The simulations were 
conducted with and without battery storage (103.2 kWh capacity) to 
demonstrate grid independence and energy self-sufficiency. The findings 
demonstrate that the TS scenario achieved net-zero or carbon-positive 
operation, as evidenced by the reduction of annual CO₂ emissions from 39,122 
kg (BS) to –9,257 kg (TS), which represents net export of renewable energy to 
the grid. Economically, SPP ranged from 3.2 to 5.4 years without a battery and 
from 10 to 14 years with one, and LCOE ranged from 0.038 to 0.072 USD/kWh, 
demonstrating long-term viability. Furthermore, 90–120 electric vehicles might 
be charged each month using the extra daylight energy, encouraging 
sustainable mobility. This study shows that it is possible to create zero-
emission buildings that use integrated PV and BIPV systems to allow EV 
charging, improve grid stability, and lower CO₂ emissions all at once. Besides, 
the innovative potential of integrated PV-BIPV-battery systems for zero-
emission buildings to decarbonize Iraq's urban energy infrastructure is 
demonstrated in this study. 

1. Introduction 

Human activity is known to be the primary driver of 
climate change, particularly due to rising greenhouse gas 
emissions and environmental degradation [1].  The IPCC 
Climate Change Synthesis Report 2023 emphasizes the need 
for sustainable energy policies, noting that human activities, 
particularly unsustainable energy consumption, have 
elevated Earth's surface temperatures by 1.1°C relative to the 

pre-industrial levels [2]. According to the United Nations 
Climate Change [3], achieving these targets requires a 43% 
reduction in greenhouse gas emissions by 2030 and a peak in 
emissions by 2025. The Sustainable Development Goals 
(SDGs) [4] emphasize the significance of renewable energy in 
reducing global warming. One essential sustainable energy 
source is solar energy. Unlike fossil fuels, solar energy 
harnesses sunlight, an abundant and inexhaustible natural 

 

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ISSN 2832-0379 

February 2026| Volume 05 | Issue 01 | Pages 180-194 

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Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

181 

 

resource, converting it into electricity with minimal 
environmental impact [5]. The demand for solar photovoltaic 
(PV) systems is rising rapidly among renewable energy 
sources due to several factors, such as declining costs and 
high returns on investment [6]. Recently, rooftop solar 
photovoltaic (PV) systems have gained prominence as a 
powerful decentralized energy solution [7]. According to 
Poornima et al. [8], these systems can help minimize land-use 
conflicts, reduce transmission losses, and enable businesses 
and homes to generate their own electricity. 

Besides, PV technologies can be integrated into building 
envelopes as Building-Integrated Photovoltaics (BIPV) and 
have been considered a sustainable design solution for a built 
environment that is green and clean [9, 10]. Unlike 
conventional rooftop PV systems, BIPV technologies serve 
two functions: they act as building materials that can replace 
façades, skylights, windows, shading devices, and roofing 
elements while generating renewable electricity [11-13]. 
Additionally, BIPV offers significant aesthetic advantages, as 
photovoltaic components can be customized to meet 
architectural intent in terms of color, texture, transparency, 
and shape [11]. This ability facilitates a more natural 
integration of renewable technologies into dense urban 
environments, where cultural identity and visual coherence 
are crucial design factors [11, 14]. In addition to their 
aesthetic value, BIPV systems can generate electricity and 
replace conventional shading devices, providing a twofold 
advantage for energy-efficient design, as noted in Refs. [15, 
16]. A bifacial BIPV façade renovation raised the annual 
percentage of hours in the thermal comfort range by around 
8% in a real-world case study, according to Serrano-Lujan et 
al. [15]. Moreover, energy consumption can be significantly 
reduced without compromising architectural style when BIPV 
systems are used as double-skin envelopes in hot, dry 
locations. Additionally, buildings can become more valuable, 
have a smaller carbon footprint, and be certified LEED 
(Leadership in Energy and Environmental Design) when BIPV 
is used [17]. In addition to generating energy, BIPV systems 
can improve a building's acoustic and thermal insulation and 
provide other practical benefits. This dual use as a building 
material and an energy source represents a major 
advancement toward sustainable urban development [18, 
19].  

Iraq faces severe power shortages due to decades of 
insufficient planning, aging infrastructure, and rapidly rising 
demand, despite having the fifth-largest oil reserves in the 
world and significant natural gas resources [20, 21]. As a 
result, there have been regular power outages, forcing homes 
and businesses to use expensive residential generators at 
significant personal financial expense [21]. According to the 
World Bank Group (Global Solar Atlas), specific photovoltaic 
power generation ranges from 4.34 to 5.26 kWh/kWp. Hence, 
Iraq currently has significant potential to generate solar 
energy.  Moreover, previous studies on solar power potential 
concluded that grid-connected and standalone PV systems 
can deliver reliable electricity, lower CO2 emissions, and 
achieve economic viability compared to fossil fuels [22-25]. 
According to the authors' review, most previous studies in 
Iraq have focused on small-scale solar applications, such as 
agricultural irrigation and residential water heating. Also, a 
few studies have analyzed grid-connected or integrated 
systems for large-scale power generation.  These studies have 
highlighted the potential of solar power to reduce CO2 
emissions and the electricity crisis. Consequently, the present 
study aims to assess the technical, environmental, and 
economic feasibility of battery storage, rooftop photovoltaic, 

and building-integrated photovoltaic systems in a mixed-use 
zero-emission building in the Diyala Governorate, Iraq. 
Besides, the current study aims to analyze the potential use of 
excess solar energy to charge electric vehicles, especially 
during daylight hours, thereby raising the possibility of 
sustainable transportation and energy independence.  To this 
aim, three retrofit scenarios are compared in this paper: 
Baseline Scenario (BS) with no renewable systems, Second 
Scenario (SS) with rooftop photovoltaic systems, and the 
Third Scenario (TS), which integrates all aforementioned 
systems besides 30 mm thick Expanded Polystyrene (EPS) 
insulation and BIPV glazing. The expected results of this study 
can provide a practical, replicable framework to reduce Iraq's 
electricity deficit, enable clean energy generation in buildings, 
and encourage the use of electric vehicles.  

 
2. Materials and methods  

2.1 Study area  
Figure 1 depicts the Diyala Governorate, located in 

eastern Iraq, northeast of Baghdad. This region, which is 
approximately 17,685 km² in size, is one of the most 
significant agricultural and habitation areas in Iraq, as it and 
its surrounding waters (River Diyala) provide water for 
cultivation and domestic use. The climate is characteristic of 
central and eastern Iraq; it is semi-arid to desert. Although 
winters are warm with mean temperatures between 8 and 
15°C, summers are hot and dry, with many days reaching over 
45°C in July and August. The annual rainfall ranges from 200 
mm on the plain to 400 mm in the northeastern foothills, with 
most rainfall occurring between November and March and 
being highly seasonal. Furthermore, solar irradiation data 
show that the mean values of direct normal irradiation, Global 
horizontal irradiation, and Diffuse horizontal irradiation are 
1835.3 kWh/m², 1944.3 kWh/m², and 778.8 kWh/m², 
respectively. The area experiences an average air 
temperature of about 24.3°C, with terrain at 120 m above sea 
level, both of which affect the performance of PV systems. In 
general, agriculture and water supplies are hampered by 
unpredictable rains and frequent droughts. Summertime also 
often brings dust storms and prolonged dry spells, which 
worsen environmental and human health impacts. The Water 
Crisis. The governorate is experiencing a growing water crisis 
due to several interconnected factors. Diyala is mostly 
dependent on transboundary floods from Iran via the Diyala 
River and its tributaries. In Iran, upstream dam construction 
and diversion have severely reduced inflows, while climate 
change has made droughts more frequent and severe. 
Excessive groundwater pumping in the area raises salinity 
and lowers water levels, reducing soil fertility and 
agricultural output. It has a direct effect on the rural economy 
of the governorate, which has historically been associated 
with date, wheat, barley, and citrus production. Additionally, 
domestic urban water supplies often run out, exacerbating 
social and political conflicts. Moreover, Diyala faces a serious 
electricity crisis in addition to a water deficit. Diyala is not an 
exception to the ongoing underperformance of Iraq's national 
grid. Power outages are common, lasting several hours each 
day and impacting homes, businesses, and critical services. 
Summertime and increased demand for electricity from 
cooling systems exacerbate the shortfall. Water and energy 
shortages are exacerbated by inadequate supplies of 
dependable electricity, which also make it difficult to run 
irrigation systems, water pumping stations, and other vital 
infrastructure. The majority of houses and businesses use 
expensive private diesel generators, which are harmful to the 
environment and not long-term viable. The region lies at the 



Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

182 

 

heart of Iraq's broader water-energy-food nexus challenges 
due to Diyala's physical and climatic features, transboundary 
water dependencies, climate change impacts, and energy 
constraints.  

 
Figure 1. Location map 

2.2 Dataset 
In this study, the global reanalysis, namely ECMWF's 

ERA5, is used. ERA5 is selected for its high spatial resolution 
and hourly temporal resolution, which are well-suited to 
capturing the local climate and topography of the Diyala 
region. ERA5 covers 1979 to the most recent 5 days, providing 
estimates of a large body of atmospheric, oceanic, and land 
climate data from many satellite and conventional 
instruments. The resolution in the horizontal grid is 0.25°, 
equal to about 31 km. ERA5 is correlated with uncertainty 
data for all variables at lower spatial and temporal resolutions 
[26]. The reliability of ERA5 reanalysis data for wind-
resource assessment is discussed in Ref. [27]. ERA5 has also 
been extensively tested, compared with previous reanalyses 
and with measurements at local and regional scales [28]. 
ERA5 surpasses MERRA-2 in every feature that was tested; 
the correlations are higher, and MAE and RMSE are by an 
average of 20 % smaller than MERRA-2 [29]. Ramon et al. [30] 
reported that ERA5 surface winds showed the best 
agreement, correlating and replicating the variance better 
than a multi-reanalysis mean at 35.1 % of the validation 
stations and were better than four reanalysis datasets (ERA-
Interim, JRA55, MERRA2, and the NCEP/NCAR R1). ERA5 
depicted the mean wind speed more realistically, was better 
correlated on flat surfaces, and performed better than the 
MERRA-2 and COSMO-REA6 reanalyses [31]. Pronk et al. [32] 
determined that ERA5 performs better than the Wind 
Integration National Dataset (WIND) Toolkit Long-term 
Ensemble Dataset (WTK-LED) according to the centered root-
mean-square error (cRMSE) and correlation coefficient for 
both the on-land and offshore scenarios under all 
atmospheric stability conditions. Further, ERA5 long-term 
winds were well consistent with in-situ altimeter 
measurements [33] and outperformed CFSR with a higher 
correlation coefficient and lower errors [34] and 
outperformed ERA-Interim by 20 % [35]. Further, ERA5 was 
the most reliable of the four reanalysis datasets considered 
(EMD-ERA, ERA5, CFSR2, and MERRA-2), with the highest 
correlation coefficient of 0.93 against in-situ LIDAR [36]. 

 
 

2.3 Case study description 
This study investigates the energy performance of a two-

story mixed-use building in Diyala, Iraq, with a gross floor 
area of approximately 600 m². This building is chosen as a 
representative typology of small- to medium-sized 
commercial buildings typical in the region, where energy 
consumption is highly dependent on climatic conditions, 
particularly hot, dry summers. The building's internal layout, 
occupancy time schedules, and internal load patterns were 
simulated in DesignBuilder, enabling a precise analysis of the 
building's thermal and energy performance across different 
retrofitting scenarios. The ground floor (see Figure 2) is 
primarily used as a supermarket, and the central Market Hall 
occupies most of the area. This space is intended to support 
basic retail functions, including product display, customer 
traffic, and cold storage. With extended operating hours and 
the use of high-intensity lighting and refrigeration machinery, 
the Market Hall experiences significant internal heat gains, 
which contribute to cooling loads, especially during summer. 
In addition to this central shopping area, there are three 
ancillary rooms: a manager's office, a storeroom, and a toilet 
facility. Each of these spaces was considered as an 
independent thermal zone during simulation to allow for 
variation in occupancy, equipment use, and internal heat 
generation. Internal partitions between zones were simulated 
using appropriate thermal properties to allow a realistic 
assessment of inter-zone heat transfer. All spaces on the 
ground floor are served by a centralized HVAC system 
designed to provide thermal comfort for the various 
functional spaces. Moreover, the first floor (Figure 2) is 
arranged as a residential area, with the best design for a 
household's normal occupancy. It has three bedrooms 
(Bedroom 1, Bedroom 2, and Bedroom 3), three bathrooms, a 
central living area, and an independent laundry room. The 
living room, the main common space, occupies the largest 
area and is used for prolonged periods beyond working hours. 
Each bedroom was modeled as an independent thermal zone 
to allow for varying occupancy schedules and internal gain 
profiles. Bathrooms and the laundry room were also defined 
as separate zones to account for their specific thermal and 
ventilation characteristics. Natural ventilation is achieved 
through operable windows on multiple façades, and space 
conditioning is provided by independent split-type air 
conditioners in the main rooms. The loads of plugs and 
lighting were distributed according to housing-use patterns 
typical for occupant behavior in Mediterranean climate 
regions. Interior partitions were constructed using materials 
with thermal properties typical of real materials to provide 
accurate thermal zoning within the space. To compare the 
effects of different energy-efficiency and renewable-energy 
measures, three retrofitting scenarios are proposed as 
follows. 

(a) The baseline scenario (BS) is the first one, where the 
building is simulated in its current condition with no envelope 
upgrading or renewable energy systems. The external walls 
are composed of two 10 mm-thick cement plaster layers, one 
on the inner side and one on the outer side, divided by a 200 
mm concrete block. Windows are depicted using single-pane 
glazing, and there are no photovoltaics. This condition is used 
as a basis for comparison for analyzing the building's energy 
consumption in its original, unchanged form. In the scenario, 
the energy consumption profiles for winter, spring, summer, 
and autumn are illustrated in Figure 3.  The results show that 
the highest demand is in the summer, especially during the 
8:00 to 22:00 time interval when cooling loads dominate. 



Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

183 

 

Winter and spring have relatively low and flat consumption, 
while autumn has an intermediate profile.  
(b) In the second scenario (SS), glazing and wall construction 
of the window are not altered from the baseline. However, 
rooftop photovoltaic panels are introduced. The panels are 
mounted in five rows with 19 modules each, providing a total 
of 95 PV panels on the roof. This scenario allows assessment 
of the solar energy production impact on energy performance 
without altering any thermal property of the building. The 
results indicate that the hourly consumption patterns by 
season are identical to those for the baseline, as the thermal 
envelope and drivers for loads are unchanged. The results 
demonstrate that summer and autumn remain the peak 
demand seasons, though overall energy balance is improved 
as some of the demand is met by renewable electricity, as 
shown in Figure 3.  
 

 
Figure 2. Description of the building  

(c) The third scenario (TS) goes a step further from the 
second by incorporating other indicators of energy efficiency. 
In this case, building-integrated photovoltaic systems (BIPVs) 
are applied to all windows' glazing surfaces. These consist of 
glazing with photovoltaic cells incorporated into the exterior 
layer so that electricity can be generated on-site by the 
windows. Further, an insulating thermal layer is incorporated 
into the building envelope to further its capacity to resist heat 
transfer. This combined approach combines active renewable 
energy generation with passive envelope changes in order to 
optimize overall energy efficiency, reduce cooling loads, and 
reduce reliance on grid electricity. Generally, energy 
efficiency measures are integrated by combining building-
integrated photovoltaics (BIPVs) with envelope insulation 
improvements (Figure 4). 

 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 



Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

184 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Figure 3. Energy consumption (EC) profiles for each scenario  

2.4 Estimating the potential of solar power systems 
Incident solar radiation on an inclined surface is a critical 

parameter in the design and performance assessment of solar 
energy systems. The tilted surfaces are oriented to capture 
the maximum possible solar radiation, based on the 
geographical location and seasonal solar path. It plays a 
significant role in the solar energy received, influencing the 
PV system's efficiency and energy yield. Thus, accurate 
estimation of solar radiation on tilted surfaces is crucial for 
the design of a solar power plant, as it depends on the optimal 
tilt angles. It is also crucial for determining an area's solar 
potential, enabling planners and engineers to estimate energy 
yields and ensure economic viability.  

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Moreover, the monthly output of the PV system can be 

calculated based on key factors such as the installed system 
capacity, the location's peak sun hours, and a derate factor 
that accounts for the combined effects of component 
efficiencies, system losses, and weather [38]. The amount of 
electricity to be generated by a photovoltaic system may be 
estimated on this basis.  The mathematical equations for the 
energy output of an array of PV panels (𝐸𝑃𝑉) as a function of 
incident global solar irradiance (𝑆𝑅𝑖) are given below [38]. 

𝐸𝐺 = ∑ 𝜂𝑃𝑉𝑃𝑆𝑇𝐶 (
𝑆𝑅𝑖

𝐺𝑆𝑇𝐶
) [1 − 𝛼𝑝(𝑇𝐶 − 𝑇𝑆𝑇𝐶)]𝑁∆𝑡𝑖

𝑛
𝑖=1          (1) 

𝑆𝑅𝑖 = 𝐺𝑏 + 𝐺𝑑 + 𝐺𝑟               (2) 

 

 

 

 

 

0
200
400
600
800

1000
1200
1400

1 3 5 7 9 11 13 15 17 19 21 23

EC
 [

kW
h

]

Hour [-]

BS

0
200
400
600
800

1000
1200
1400

1 3 5 7 9 11 13 15 17 19 21 23

EC
 [

kW
h

]

Hour [-]

SS

0
200
400
600
800

1000
1200

1 3 5 7 9 11 13 15 17 19 21 23

EC
 [

kW
h

]

Hour [-]

TS
Winter Spring Summer Autumn

0
700

1400
2100
2800
3500
4200

1 3 5 7 9 11 13 15 17 19 21 23

EC
 [

kW
h

]

Hour [-]

Annual
BS SS TS



Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

185 

 

 
Figure 4. Building envelope insulation 

For estimating the beam component from direct sunlight on 
the tilted surface (𝐺𝑏) [38, 40, 41]:  

𝐺𝑏 =
𝐺𝐷𝐻

𝑐𝑜𝑠𝜃𝑧
𝑐𝑜𝑠𝜃𝑖              (3) 

𝑐𝑜𝑠𝜃𝑧 = 𝑠𝑖𝑛𝜙 ∙ 𝑠𝑖𝑛𝛿 + 𝑐𝑜𝑠𝜙 ∙ 𝑐𝑜𝑠𝛿 ∙ 𝑐𝑜𝑠𝜔  

𝑐𝑜𝑠𝜃𝑖 = 𝑠𝑖𝑛𝛿 ∙ 𝑠𝑖𝑛𝜙 ∙ 𝑐𝑜𝑠𝛽 − 𝑠𝑖𝑛𝛿 ∙ 𝑐𝑜𝑠𝜙 ∙ 𝑠𝑖𝑛𝛽 ∙ 𝑐𝑜𝑠𝛼 +
𝑐𝑜𝑠𝛿 ∙ 𝑐𝑜𝑠𝜙 ∙ 𝑐𝑜𝑠𝛽 ∙ 𝑐𝑜𝑠𝜔 + 𝑐𝑜𝑠𝛿 ∙ 𝑐𝑜𝑠𝜙 ∙ 𝑠𝑖𝑛𝛽 ∙ 𝑐𝑜𝑠𝛼 ∙ 𝑐𝑜𝑠𝜔 +
𝑐𝑜𝑠𝛿 ∙ 𝑠𝑖𝑛𝛽 ∙ 𝑠𝑖𝑛𝛼 ∙ 𝑠𝑖𝑛𝜔              (4) 

𝜔 = 15(12 − 𝐿𝐴𝑇)             (5) 

𝐿𝐴𝑇 = 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑡𝑖𝑚 (𝑐𝑙𝑜𝑐𝑘 𝑡𝑖𝑚𝑒) ±
4(𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑡𝑖𝑚𝑒 𝑙𝑜𝑛𝑔𝑖𝑡𝑢𝑑𝑒 − 𝑙𝑜𝑛𝑔𝑖𝑡𝑢𝑑𝑒 𝑜𝑓 𝑙𝑜𝑐𝑎𝑡𝑖𝑜𝑛) +
𝐸𝑂𝑇               (6) 

𝐸𝑂𝑇 = 229.18(0.000075 + 0.001868 ∙ 𝑐𝑜𝑠(𝐵) − 0.032077 ∙

𝑠𝑖𝑛(2 ∙ 𝐵) − 0.014615 ∙ 𝑐𝑜𝑠(2 ∙ 𝐵) − 0.04089 ∙ 𝑠𝑖𝑛(2 ∙ 𝐵))  

             (7) 

𝐵 =
360∙(𝑁𝑑−1)

365
             (8) 

For calculating the diffuse component (𝐺𝑑) and reflected 
component (𝐺𝑟)  [38, 42, 43] 

𝐺𝑑 = [𝐺𝐻𝐼 − 𝐺𝐷𝑁𝑐𝑜𝑠𝜃𝑖  ] (
1+𝑐𝑜𝑠𝛽

2
)          (9)  

𝐺𝑟 = 𝜌𝑔𝑟𝑜𝑢𝑛𝑑𝐺𝐻𝐼 (
1−𝑐𝑜𝑠𝛽

2
)         (10) 

Where, 𝛿: sollar declination angle, 𝜙: Location's latitude, 
𝜔: Hour angle, 𝛽: Surface tilt angle concerning the horizontal 
plane, 𝛼: Surface azimuth angle, 𝐺𝐷𝐻 and 𝐺𝐷𝑁: Direct 
horizontal solar irradiance and Direct Normal solar 
irradiance, respectively, 𝐺𝐻𝐼: Global horizontal solar 
irradiance, 𝜂𝑃𝑉: Individual PV module derating factor (𝜂𝑃𝑉 = 
0.85), PSTC: Nominal power of an individual PV module, G: 
Plane-of-array irradiance, 𝐺𝑆𝑇𝐶: Reference plane of-array 
irradiance under STC = 1 kW/m2, 𝜌𝑔𝑟𝑜𝑢𝑛𝑑: Ground reflectance 

(albedo), typically 0.1–0.3 (dimensionless), 𝛼𝑝: PV panel 

temperature coefficient of power, 𝑇𝐶: Operating cell 
temperature, 𝑇𝑆𝑇𝐶: STC operating cell temperature = 25℃, 𝑁: 
Number of installed PV modules, 𝑁𝑑 is the day of the year and 
∆𝑡𝑖: Duration of the n time steps considered. 

Additionally, one of the most important factors in 
determining the solar system's performance is the capacity 
factor.  It is the ratio of the annual energy (𝐸𝑃𝑉) produced by 

the solar system to the annual maximum energy generation 
under optimal operating conditions.  The expression for 
calculating it is shown in Eq. (11) [38].  

𝐶𝐹 =
𝐸𝑃𝑉

𝐼𝑛𝑠𝑡𝑎𝑙𝑙𝑒𝑑 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 ×8760
         (11)  

2.5 Estimating energy production from a BIPV system 
using PVGIS 
The Photovoltaic Geographical Information System 

(PVGIS) is a web-based, free tool that aims to predict solar 
resources and the performance of PV systems in most 
countries worldwide [39]. PVGIS estimates monthly and 
yearly totals of electricity generation for various sun-tracking 
systems.  PVGIS has implemented satellite-based 
meteorological databases, including the PVGIS climate 
monitoring satellite application facility (CMSAF), PVGIS-
ERA5, PVGIS surface solar radiation dataset heliosat (SARAH), 
and PVGIS-COSMO. Solar radiation data for Europe, Asia, and 
Africa are obtained from the PVGIS-CMSAF and PVGIS-SARAH 
datasets; US data are obtained from the National Renewable 
Energy Laboratory (NREL) National Solar Radiation Database 
(NSRDB); and high-latitude region data are obtained from 
reanalysis products (PVGIS-COSMO and PVGIS-ERA5). In the 
current study, PVGIS 5 is used, and the PVGIS-ERA 5 dataset 
is used to simulate PVGIS 5. From satellite measurements, 
ERA5 provides global direct solar irradiation, the optimal 
angle for global irradiation, and average temperature.  

2.6 Economic viability and carbon mitigation analysis 
Evaluating the economic viability of renewable energy 

projects, such as solar energy systems, is essential to ensure 
financial sustainability and environmental stewardship. 
Simple Payback Period (SPP) and Levelized Cost of Energy 
(LCOE) are important metrics that are used in this evaluation. 
The SPP provides investors and policymakers with a clear 
indicator of risk and return by clearly defining the time it will 
take for the initial capital to be recovered, either as savings or 
revenues. Eq. (12) can be used to estimate the SPP value for 
the proposed system [44]. 

𝑆𝑃𝑃 =
𝐼𝑛𝑣𝑒𝑠𝑡𝑚𝑒𝑛𝑡 𝑐𝑜𝑠𝑡

 𝐴𝑛𝑛𝑢𝑎𝑙 𝑆𝑎𝑣𝑖𝑛𝑔
          (12) 

The LCOE (Eq. 13) is a useful benchmark compared to 
traditional energy sources since it enables a thorough 
assessment of the unit cost of energy produced over the 
system’s lifespan [38].   

𝐿𝐶𝑂𝐸 =
𝑆𝐶𝑙𝑖𝑓𝑡𝑒𝑖𝑚𝑒

𝑆𝐸𝐺𝑙𝑖𝑓𝑡𝑒𝑖𝑚𝑒  
           (13) 

where 𝑆𝐶𝑙𝑖𝑓𝑡𝑒𝑖𝑚𝑒: Sum of cost over lifetime, and 𝑆𝐸𝐺𝑙𝑖𝑓𝑡𝑒𝑖𝑚𝑒: 

Sum of electricity generated over the lifetime. 
In addition to these cost-effective strategies, a carbon-
reduction analysis is required to highlight the solar systems' 
positive environmental impacts, as they significantly lower 
greenhouse gas emissions compared to energy derived from 
fossil fuels.  The carbon mitigation analysis can be estimated 
using the following equations [45]. 

𝐶𝑂2 − 𝑀𝐷𝑆𝑏𝑦 = 𝐴𝐸𝑃𝑉 × 𝐸𝑓          (14) 

𝐶𝑂2 − 𝑀𝐷𝑆𝑓𝑟𝑜𝑚 = 𝐴𝐸𝑃𝑉  × 𝐶𝑂2 − 𝑀𝐷𝑆𝑏𝑦        (15) 

𝑁𝐶𝑂2𝑅 = 𝐶𝑂2 − 𝑀𝐷𝑆𝑏𝑦 − 𝐶𝑂2 − 𝑀𝐷𝑆𝑓𝑟𝑜𝑚        (16) 

where 𝐶𝑂2 − 𝑀𝐷𝑆𝑏𝑦: 𝐶𝑂2 mitigation by a developed system, 

𝐴𝐸𝑃𝑉: Annual energy generation, 𝐸𝑓: emission factor (0.7 
kg/kWh),   𝐶𝑂2 − 𝑀𝐷𝑆𝑓𝑟𝑜𝑚: 𝐶𝑂2  mitigation from the 

developed system,  𝑁𝐶𝑂2𝑅: Net 𝐶𝑂2 reduction. 



Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

186 

 

3. Results and discussion 

3.1 Comparison of thermal behavior across building 
scenarios 
Figure 5 shows the monthly variation of heating, cooling, 

and solar gains over the three building scenarios. The largest 
heating and cooling loads are shown in the reference scenario, 
suggesting that the building envelope, in its original 
configuration before any alterations, permits significant 
winter heat loss and significant summer solar heat gain. 
Besides, the energy consumption is slightly lower in the 
second scenario, where the wall structure and windows 
remain unmodified, but other minor modifications are 
implemented. This is particularly relevant for cooling loads 
during the summer. When BIPV glazing is used for all window 
orientations, the third scenario (TS) shows the most 
significant drop. Compared with the baseline, the zone and 
total sensible cooling loads are reduced by up to 15–20% 
during the summer months thanks to the BIPV glazing, which 
also significantly reduces solar heat transmission through the 
windows. Similarly, improved insulation qualities and less 
heat loss through window surfaces minimize the need for 
winter heating by about 20–25%. Additionally, solar gains 
over the windows drop by 20–30% as compared to the 
baseline method, especially during the hottest summer 
months. By preventing overheating in the summer and 
reducing heat loss in the winter, the TS configuration delivers 
superior overall thermal performance. This results in 
increased interior comfort, less annual energy consumption, 
and more potential for renewable energy generation through 
the integrated BIPV system. This outcome demonstrates that 
BIPV glazing can effectively maximize thermal and energy 
performance across all climatic seasons when used as part of 
an integrated, energy-efficient building envelope approach. 

Moreover, the temperature profile shows the annual 
performance of interior and outdoor thermal conditions for 
the BS, SS, and TS scenarios, as shown in Figure 6. The outdoor 
dry-bulb temperature ranges from about -1°C in January to 
about 28°C in July, following a typical yearly pattern. The 
interior air, radiant, and operating temperatures are all 
directly impacted by this external variance, and all three 
exhibit similar yearly trends. Once more, the adoption of 
efficiency measures results in little but significant changes. 
Higher solar heat gain from the building enclosure is 
indicated by the baseline case (BS), which records the highest 
summertime radiant and room air temperatures. Although 
there are slight improvements in the second case (SS), the 
pattern remains identical because the glazing qualities 
remain the same.  

Additionally, the third scenario (TS) demonstrates the 
maximum indoor thermal stability, using BIPV glazing to 
lower air, radiant, and operating temperatures by roughly 0.5 
to 1°C during the hottest summer months. This shows that the 
window surfaces reduce heat gain, improving indoor comfort 
and lowering cooling loads. Interestingly, winter 
temperatures remain essentially unchanged, indicating that 
the BIPV glazing has no significant effect on passive solar 
heating. By reducing summer overheating without sacrificing 
pleasant winter conditions, the TS case more effectively 
achieves year-round thermal balance, increasing indoor 
thermal comfort and total building energy efficiency. 
 

 

 

 

 

 

 

 

Figure 5. Monthly thermal Behavior for three building Scenarios 

 
 

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Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

187 

 

 

 

 

 

Figure 6. Monthly indoor and outdoor temperature behavior for 
three building Scenarios (AT: Air Temperature,  RT: Radiant 
Temperature, OT: Operative Temperature, ODBT: Outside Dry-Bulb 
Temperature) 

3.2 Optimal orientation and slope angle for rooftop PV 
system  
In general, there are several types of solar panels 

available on the market, and new models are always being 
released due to the rapid advancement of technology. For the 
proposed system, the Tiger Neo N-type JKM570N-72HL4-BDV 
monocrystalline solar panel was selected for the rooftop PV 
system due to its robust power output, durable design, and 
exceptional efficiency. The specifications of the selected solar 
panel can be found in Table 1. Besides, AS-B60 320W Bifacial 
was selected for the BIPV system, and the specifications of it 
are listed in Table 2. The association between tilt angle, 
orientation, and annual energy yield on north-, south-, east-, 
and west-facing surfaces is determined by the analysis of the 
54 kW rooftop PV system as shown in Figure 7 and Table 3.  

 

 

Table 1. Specification of the selected solar panel (JKM570N-72HL4-
BDV) at STC 

Specification  Value 
Maximum Power (Pmax) 570Wp 

Maximum Power Voltage (Vmp) 42.29V 

Maximum Power Current (Imp) 13.48A 

Open-circuit Voltage (Voc) 51.07V 

Short-circuit Current (Isc) 14.25A 

Module Efficiency STC 22.07% 

Operating Temperature -40℃~+85℃ 

Nominal operating cell temperature  45±2℃ 

Temperature coefficients of Isc 0.046%/℃ 

Temperature coefficients of Voc -0.25%/℃ 

Temperature coefficients of Pmax -0.30%/℃ 

 
Table 2. Specification of the selected solar panel (AS-B60 320W 
Bifacial) at STC 

Specification  Value 
Maximum Power (Pmax) 320 Wp 

Maximum Power Voltage (Vmp) 36.5 V 

Maximum Power Current (Imp) 8.8 A 

Open-circuit Voltage (Voc) 44 V 

Short-circuit Current (Isc) 9.34 A 

Module Efficiency STC 19.4% 

Operating Temperature -40 - 85 °C 

Temperature coefficients of Pmax 0.41 %/°C 

 

For all tilt angles, the south-facing orientation yields the 
most PV energy output of any arrangement, confirming its 
ability to maximize solar energy extraction in the research 
area. According to the findings, the north-facing panels' ideal 
slope angle is around 30°, at which the PV energy yield peaks 
at about 96,000 kWh/year, in line with the observed peak 
capacity factor (CF). The output gradually decreases as the 
slope exceeds 30° because the panels receive less direct 
sunlight throughout the summer. However, in winter, when 
there is less sun incidence, shallower angles (less than 20°) 
also result in poorer efficiency. Due to their limited exposure 
to direct sunlight, the north-facing panels produce the least 
amount of energy, with production steadily decreasing as the 
slope angle increases. At lower tilt angles (10° to 20°), which 
capture more morning or afternoon sun, respectively, the 
east- and west-facing orientations perform mediocrely, with 
slightly higher generation. However, they drastically decline 
after 30°. In conclusion, the findings demonstrated that a 
north orientation with a tilt angle of 30° is the best 
compromise between system efficiency and annual solar 
radiation harvesting, aligning with the location's solar 
geometry and optimizing the potential energy yield. 

3.3 Monthly energy balance and contribution from PV 
systems 
The monthly energy data shown in Table 4 reveal trends 

in grid dependency and PV generation across the BS, SS, and 
TS scenarios. Due to high cooling loads, grid energy 
consumption varies seasonally, peaking in the summer (June 
to August) and falling in the spring and autumn months. As 
mentioned before and shown in Table 4, the BS consistently 
exhibits the highest rate of grid power dependence, while the 
SS shows a fractional decrease in grid energy demand due to 
minor efficiency gains.  

 
 
 

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Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

188 

 

 

 

 

 

Figure 7. Annual value of energy production from a rooftop PV 
system and capacity factor with various orientation angles  
 
Table 3. Monthly variation of energy demand and production 

Variable 
Slop 

angle  
[°] 

Orientation azimuth angles [°] 
North-

facing 

South-

facing 

East-

facing 

West-

facing 

PV energy 

production 

[kWh] 

10 90003 74785 82470 83140 

20 94340 64388 80432 81668 

30 96303 53553 77538 79174 

40 95845 44270 73959 75896 

50 92980 35452 69503 71643 

CF [%] 10 19.03 15.81 17.43 17.58 

20 19.94 13.61 17.00 17.26 

30 20.36 11.32 16.39 16.74 

40 20.26 9.36 15.63 16.04 

50 19.66 7.49 14.69 15.15 

 

 

 

Table 4. Monthly variation of energy demand and production 

Month 
Energy from the grid Energy production from PV 

BS SS TS Rooftop BIPV Total 
Jan 3219 3219 3196 7024 1220 8244 

Feb 2883 2883 2862 7188 1238 8426 

Mar 3218 3218 3195 8605 1464 10069 

Apr 3044 3044 3023 8520 1433 9953 

May 3467 3447 3437 8721 1451 10172 

Jun 4539 4460 4378 8303 1376 9679 

Jul 5861 5775 5446 8539 1408 9947 

Aug 5931 5837 5475 8977 1473 10451 

Sep 4108 4039 4005 8686 1434 10119 

Oct 3330 3321 3334 8064 1350 9414 

Nov 3107 3107 3085 7016 1198 8214 

Dec 3155 3155 3133 6800 1177 7977 

 

Besides, TS exhibits the lowest grid energy consumption 
and evaluates the effectiveness of combined renewable 
energy installations in reducing electricity consumption. As 
shown in Table 4, the rooftop PV system provides the 
maximum monthly energy during March-August, ranging 
from approximately 8,300 to 8,900 kWh (Figure 8), while the 
BIPV system adds 1,200–1,470 kWh per month, depending on 
solar irradiance conditions. The combined PV generation is 
highest in August (10,451 kWh) and is always more than 
9,000 kWh from March to September. However, due to lower 
solar radiation, generation is at its lowest in December (7,977 
kWh) and January (8,244 kWh). In the TS scenario, where 
total PV generation meets the majority of building energy 
demand, the combined rooftop and BIPV system contribution 
significantly reduces grid dependence each month. These 
findings clearly show that combining BIPV with traditional 
rooftop PV expands building energy independence, optimizes 
overall renewable energy production, and permits a 
reduction in annual grid electricity demand and related 
greenhouse gas emissions. The integration of rooftop PV and 
BIPV systems in the TS scenario not only reduces reliance on 
the grid but also yields substantial energy savings throughout 
the year. The surplus generated energy (Figure 9), 
particularly during months with high solar radiation such as 
April to September, can exceed the building's operating 
demand, thus providing potential for secondary uses such as 
charging electric vehicles (EVs).  

 

Figure 8. Monthly variation of surplus generating energy (SRi: 
Incident global solar irradiance) 

 
 

 

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Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

189 

 

Based on monthly generation, PV systems generate 
9,500–10,000 kWh/month, and the building's grid energy 
requirement under the TS configuration decreases 
significantly compared to the baseline. This indicates that a 
portion of the renewable electricity can be directed toward 
charging electric vehicles, supporting sustainable transport 
initiatives without increasing the overall energy profile. 
Additionally, in this investigation, a lithium-ion battery 
storage system with a total capacity of 103.2 kWh was used to 
store extra energy generated by the PV system during the day. 
The technical specifications of the battery module are shown 
in Table 5. In this study, it is assumed a depth of discharge 
(DoD) of 80%, a round-trip efficiency of 90%, and a hybrid 
inverter efficiency of 99.9%. It should be noted that the hybrid 
inverter (XG50KTRL) with a power rating of 80kW is used in 
this study.  The number of batteries used at night and for 
energy storage for the selected construction is displayed in 
Figure 10. The results show that a maximum of 35 batteries is 
required for the BS and SS, and 32 for the TS. BIPVs and 
energy-saving techniques can effectively reduce nighttime 
energy dependence and enhance system performance, as 
evidenced by the TS example, which reduced the number of 
batteries required. 

3.4 Results of estimating the number of EVs and chargers  
The most available electric vehicles (EVs) in Iraq are 

theCar#1: Tesla Model 3 (60 kWh), Car#2: Jaguar I-PACE (92 
kWh), Car#3: Tesla Model S (100 kWh), Car#4: BYD DOLPHIN 
(44 kWh), Car#5: MG ZS EV (72.6% kWh), and Car#6: 
HYUNDAI KONA ELECTRIC (64 kWh). A 22 kW 
commercial/public charger was employed in this 
investigation. Figure 11 displays the number of EVs that are 
charged by the surplus energy generated during the daytime 
period for six different car models (Car#1–Car#6) for the 
three scenarios.  

 
Figure 9. Monthly variation of surplus-generating energy   

 

Table 5: Specification of Lithium Battery 

Specification  Value  
Cell type LFP48173170E-120Ah 

Module type HJESLFP-38240 

Combination (192S~240S) 2P 

Nominal Voltage (V) 614.4~768 

Nominal capacity (Ah) 240 

Nominal energy (kWh) 147.46~184.32 

Standard charge current (A) 120 (0.5) 

Maximum charge current (A) 150 (0.625C)@5S 

Standard discharge current (A) 120 (0.5) 

Maximum discharge current (A) 150 (0.625C) @5S 

Operating voltage (V) 500~850 

 

 

 

Figure 10. Monthly variation of energy demand at night and the 
number of batteries  

The results indicate that the TS case consistently yields 
the highest number of EVs charged across all months and car 
types, followed by the SS and BS cases. This improvement in 
the TS scenario results from the addition of BIPV systems, 
which significantly increase overall energy generation and 
reduce building energy consumption, yielding more surplus 
energy for EV charging. Seasonally, the maximum EVs that can 
be charged are in the spring and early summer months 
(March–May), which coincide with more solar radiation and 
more PV system production. June and July have the lowest 
number of charged EVs, primarily due to higher cooling 
demand and reduced excess energy available for charging. Of 
all car types, Car#1 and Car#4 carry the highest charging 
potential, charging up to around 100–120 EVs per month, 
whereas Car#3 and Car#5 show fairly low values. Based on 
annual charging, the TS scenario shows the highest total 
count of EVs charged, followed by the SS and BS cases, which 
represent the overall energy efficiency gains achieved when 
incorporating BIPV.  

These findings underscore the twofold benefits of PV 
systems: not only providing building energy needs but also 
facilitating clean transportation by supplying renewable 
electricity to charge electric vehicles during the daytime. 

 

 

 
 
 
 
 
 

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Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

190 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 
 
 
 
 
 
 
 
 

3.5 Results of economic viability   
Based on prior research and literature on Iraq, some 

assumptions have been made to evaluate economic viability. 
The proposed system's initial investment, with and without a 
battery, is USD 53652 and USD 466548, respectively. Note 
that, according to the TS case, there are 32 batteries. This 
includes 31 solar panels (AS-B60 320W Bifacial) at USD 75 
each and 95 PV panels (JKM570N-72HL4-BDV) at USD 91 
each. The price of a hybrid inverter is USD 8,000. The cost of 

the seven public chargers is USD 3,000 apiece, for a total of 
USD 21,000.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The remaining expenses are 0.6% for engineering and 
feasibility, 8.6% for installation and spare parts, and 3% for 
contingencies. This carefully considered cost breakdown 
guarantees that all important expenses and levies are 
included in the project budget. According to local economic 
projections and other studies on investments in renewable 
energy, a 9% discount rate has been used for financial 
computations to account for the time value of money. In 

  

 
 

 

 

 

Figure 11. The number of electric vehicles that are charged by the surplus energy generated during the daytime period 

0

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Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

191 

 

accordance with regional economic patterns, a 3% inflation 
rate was also anticipated. Operational and maintenance 
(O&M) expenses were accounted for at a standard rate of 
1.5% of the annual total cost of capital, which is typically used 
in feasibility studies for renewable energy worldwide.  

Figure 12 shows the relationship between the electricity 
selling price (USD/kWh) and the Simple Payback Period (SPP) 
of the proposed PV system in two working conditions, with 
storage and without storage. The results indicate a strong 
negative correlation between the selling price and payback 
period in both conditions, with extremely high coefficients of 
determination (R² = 0.9731), which confirms an excellent 
model fit. The payback period for a system without battery 
storage is comparatively short, ranging from one to five years, 
depending on the electricity's selling price. This is mostly 
because there is no extra expense for purchasing and 
maintaining batteries, and the initial capital expenditure is 
relatively low. The system's sensitivity to market energy 
prices is demonstrated by the payback period increasing as 
the selling price of electricity declines. However, when the 
battery storage facility is taken into account, the payback 
period rises significantly to roughly 10 to 45 years. This is 
because the battery units and related energy management 
systems demand a larger initial investment. However, adding 
batteries improves long-term operational redundancy and 
energy autonomy, particularly for areas with intermittent 
grid supplies or time-of-use electricity prices. According to 
the research's findings, battery-integrated systems are more 
reliable and energy-independent over the long run, without 
battery systems offering more financial advantages in the 
short term. In order to make judgments for investors and 
policymakers when assessing PV projects with or without 
storage, the quadratic regression formulas shown in the 
figure can be used to estimate the payback period for different 
power selling prices. 

 

 

Figure 12. Relationship between electricity selling price and simple 
payback period  

3.6 Results of Emission Reduction Analysis    
The monthly variation in CO₂ emissions (kg) for the three 

scenarios under investigation is shown in Figure 13. The 
findings clearly show that combining energy-efficient 
procedures and BIPV systems can significantly reduce 

emissions. In BS, when no efficiency measures are performed, 
monthly CO₂ emissions range from around 2,148 to 5,159 kg, 
with higher values in January and July months when heating 
and cooling demand is greater.  Emissions in SS drop 
dramatically, even going negative for every month but 
November and December (April to October), when 
improvements in building envelope and system efficiency are 
taken into account.  This shows that the system produces 
extra clean energy to offset emissions from other sources in 
addition to meeting the building's energy requirements. The 
TS shows the most significant environmental positive impact 
when energy-saving measures and BIPV installations are 
implemented. Except for a few cold months (January, 
February, and December), CO₂ emissions are negative for 
practically the whole year. Net-zero or carbon-positive 
operation is represented by negative emission numbers, 
when the system generates more renewable energy than the 
building consumes, hence negating the need for fossil fuel-
based grid electricity. June's lowest emission estimate, 
roughly -2,733 kg CO₂, indicates the system's greatest 
renewable generating capability when solar radiation is at its 
strongest. In the SS and TS scenarios, the building's PV system 
generated more renewable energy than the building's overall 
energy consumption, as indicated by the negative CO₂ 
emission values. In certain cases, the extra electricity 
produced by the BIPV or PV systems is fed back into the grid, 
effectively offsetting CO₂ emissions that would otherwise be 
attributed to fossil fuel-based grid-provided electricity 
generation.  

Figure 13. Monthly variation of CO2 emission reduction 

4. Discussion  

The study's findings provide a comprehensive 
demonstration that rooftop PV-BIPV systems can significantly 
improve the technical, environmental, and financial 
performance of Iraq's building sector, particularly when 
integrated with enhanced thermal envelope measures.  These 
findings are closely aligned with previous international and 
regional studies emphasizing the role of integrated 
renewable systems in achieving near-zero energy buildings 
(NZEBs) and ensuring sustainable energy transitions in 
developing countries. The findings indicated that the Third 
Scenario (TS), which includes rooftop PV, BIPV glazing, and 
EPS insulation, provides higher thermal performance and 
more energy savings. BIPV glazing successfully lowers solar 
heat gain in the summer and limits heat loss in the winter, as 
demonstrated by a 15–25% decrease in heating and cooling 
loads. Similar findings were found in previous studies [46-
48]. These studies concluded that BIPV façades' low solar heat 
gain coefficient and accompanying energy generation can 
lower building cooling requirements by up to 20% in hot 
climate areas.   Furthermore, in line with the improvements 

y = 0.0363x2 - 0.3066x + 0.7353
R² = 0.9731

0

0.2

0.4

0.6

0 1 2 3 4 5 6

Se
lli

n
g

p
ri

ce
 [

U
SD

/k
W

h
]

Simple Payback Period  [Year]

Without bettery

y = 0.0005x2 - 0.0353x + 0.7353
R² = 0.9731

0

0.2

0.4

0.6

0 5 10 15 20 25 30 35 40 45

Se
lli

n
g

p
ri

ce
 [

U
SD

/k
W

h
]

Simple Payback Period  [Year]

With bettery

-3000

-1000

1000

3000

5000

C
O

2
Em

is
si

o
n

s 
[k

g]

BS SS TS



Y. Kassem et al. /Future Technology                                                                                 February 2026| Volume 05 | Issue 01 | Pages 180-194 

192 

 

shown in the TS scenario, Amani [49] and Lazaro et al. [50] 
demonstrated that installing EPS insulation in buildings can 
reduce energy consumption and improve thermal comfort. 
Moreover, it is found that systems without battery storage 
have a shorter return period (between 1 and 5 years) than 
systems integrated with batteries, which have a longer return 
period (between 10 and 45 years). These findings are 
supported by previous studies [51,52].  They revealed that 
storage solutions enhance system resilience and grid 
independence. However, in regions such as Iraq, which are 
susceptible to grid instability, integrating batteries provides 
long-term resilience and energy autonomy. The study also 
emphasizes the potential of excess solar energy in EV 
charging, which is an innovation.  Furthermore, the TS 
scenario was able to achieve almost net-zero or even negative 
CO2 emissions, with a maximum monthly decrease of about –
2,733 kg CO2. According to the International Energy Agency, 
solar systems can reduce about 0.38 kg CO2 per kWh in areas 
dependent on fossil fuel-based power generation; this 
estimate is comparable with Iraq's energy mix. The current 
study concluded that Iraq's sustainability and 
decarbonization goals can be achieved by combining the 
environmental viability of PV and BIPV technologies with the 
significant emission reduction observed in this investigation.  

5. Conclusion  

This study examined the technical, environmental, and 
financial results of an integrated rooftop-BIPV solar system 
designed for residential use in Iraq. According to the findings, 
the proposed system significantly reduced greenhouse gas 
emissions and reliance on fossil fuels, thereby supporting 
Iraq's climate and sustainability objectives. In addition, the 
results demonstrated the potential for substantial energy cost 
savings and emissions reductions over the system's lifetime. 
Also, the study could contribute to enhancing energy security 
and supporting Iraq's transition to cleaner energy sources by 
integrating solar technologies into buildings' energy systems. 
The study emphasized how design parameters-tilt angle, 
orientation, and capacity-should be optimized in pursuit of 
maximum efficiency. Further areas of research should include 
long-term monitoring and sensitivity analyses regarding 
climate variability, dust accumulation, and fluctuations in 
energy demand. In general, these results will be helpful to 
policymakers, engineers, and households to promote the 
adoption of renewable energy and to further sustainable 
development in Iraq and other regions with high solar 
potential. 

Ethical issue 
The authors are aware of and comply with best practices in 
publication ethics, specifically regarding authorship 
(avoidance of guest authorship), dual submission, 
manipulation of figures, competing interests, and compliance 
with research ethics policies. The authors adhere to 
publication requirements that the submitted work is original 
and has not been published elsewhere. 

Data availability statement 
The manuscript contains all the data. However, more data will 

be available upon request from the authors. 

Conflict of interest 

The authors declare no potential conflict of interest. 

 

 

 

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