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Ensuring adequate implementation of solar energy for providing environment-friendly energy to the household sector, which can considerably abate pollutants in the environment and make power industry structure sustainable, is necessary for developing countries. Comparison in terms of environmental and cost impacts of renewable energy (hybrid solar system) with non-renewable energy sources, water and planning development authority (WAPDA), and diesel generators (DGs) has been examined in the household sector of Pakistan. Primary data of hybrid solar systems have been obtained from 10 different households segregated them into two categories according to their income as medium-income households (MIHs) and lower income households (LIHs) containing 5 kW and 3 kW of hybrid solar energy systems, respectively. While operating with a hybrid solar energy system instead of a non-renewable energy system, in terms of average generated power and average running load, carbon dioxide (CO2) emissions can be reduced up to 8,446.6 kg CO2 and 6,131.725 kg CO2, respectively, in the next 25 years. Comparison of costs indicated that renewable energy has a comparatively low cost per electric unit. It can pay back its total installation cost in just 8 years and can save a sum of $4,936.4375, along with many more ecological, economic, and societal benefits. Pakistan can efficiently utilize solar energy to relegate CO2 emissions and general costs as it has distinct geographical features to access sunlight in most days of the year.
Keywords: CO2 emissions, Energy efficiency, Renewable energy, Hybrid solar, Household comparison, Cost analysis
The management of energy consumption and CO2 emission continued to be a major issue throughout the COVID-19 epidemic. The lack of public research to solve this real-time issue effectively was a big challenge as the previous literature could rarely help (Mohsin et al. 2021). The air pollution resulting from increased energy consumption has now become a global phenomenon. COVID-19 is declared to be a carrier of SARS-CoV-2 (Wen et al. 2022). Anthropogenic activities like fossil fuel burning, cement production, and deforestation escalated the CO2 emissions into the atmosphere and should be fetched to zero to overcome one of the most significant environmental issues called global warming. The longer it takes to do so, the warmer the globe will become (Pierrehumbert 2019). Carbon dioxide’s (CO2) atmospheric concentrations were recorded at the highest level in the last two million years, reported in Sixth Assessment Report (AR6) by Intergovernmental Panel on Climate Change (IPCC). Since the late 1800s, CO2 emissions have crossed 2400 billion tonnes. Human activities are mainly blamed for this exponential increase by the consumption of fossil fuels. The human interventions resulted in a warmer climate at an accelerated rate over 2,000 years. It is believed that the last decade has seen the hottest environmental temperature in global history recorded in the past 125,000 years. This temperature rise triggered many climatic factors like rising sea levels, droughts, extreme precipitation, rapid glacier melting, receding snowline, and extreme heat (IPCC 2019). In the global economic and social advancements, energy has always played a fundamental role. However, extensive energy usage has caused exceeding levels of air pollution and global warming, which is mainly produced through fossil fuel combustion (Zhang et al. 2019). The contribution to the global GHG emissions of the energy sector is approximately 75%, and the ever-increasing global energy demand has led to the multiplication of GHG emissions (Zaidi et al. 2018).
To mitigate the impacts of global warming, energy conservation is a very crucial tool for the household sector which consumes nearly 20% of energy worldwide, grabbing the interest of academia and government departments worldwide (Liu & Sun 2019). A similar scenario can be observed in Pakistan making the household sector lucrative for solar PV adoption, as this sector consumes nearly 48% of electricity produced in the country (Survey 2018–19). Due to increasing energy demands, the energy sector in Pakistan is the main recipient of governmental subsidies (Kessides 2013), pressurizing the economic and social sectors extensively. Practical measures to shift the household sector from fossil fuel energy to off-grid energy can provide alternative energy production sources which are environment friendly and reduce power outages (Qureshi et al. 2017). Pakistan is blessed with landscapes and areas with vast direct and natural reception of solar energy, which are not affected by the seasonal variations (Sadiqa et al. 2018). Despite having vast natural potential, the generation of solar energy is quite low in Pakistan, and its inclusion in the energy mix is nominal (Khalil & Zaidi 2014). A total of over 50% of electricity is produced by consuming fossil fuels in Pakistan, and these fuel combustions lead to massive GHG emissions, which is a precursor of climatic change (Tareen et al. 2018). The majority of the experts consider solar energy generation as a source to eradicate carbon-inclusive energy production to guarantee a sustainable and secure future (Hussain et al. 2018, 2019). In all the major power-consuming sectors like household, commercial, agricultural, and industrial, operational activities are gravely disturbed by frequent power outages, which could be avoided by deploying the latest technologies such as solar photovoltaic (PV) (Qureshi et al. 2017). A comprehensive assessment of the efficiency of the green economy and a comparative analysis of emission reductions are vital in achieving sustainable green economic development. The environmental aspects have been frequently ignored in most studies for the assessment of energy efficiency. However, the concept has been extensively used in the past (Hou1 et al. 2019).
Therefore, to overcome the power shortage and reduction of CO2 emissions, the deployment of PV in all sectors of life is vital. In the current research study, the PV application in the household sector is targeted. The investigation into household behaviors and norms is primarily conducted through household consumption and expenditure surveys (HCEs), which can play a vital role in achieving carbon reduction targets (Yuan et al. 2019). Like many developing countries, Pakistan has a large growing population with the generation of a significant amount of CO2 emissions in the atmosphere. An energy-based HCE can be the most effective way of presenting the findings on energy consumption and expenditure of households. In our previous study, we took an organization as a sample of study and discussed cost comparison, output analysis, and different properties of solar energy and non-renewable energy. This exclusive study presents a comprehensive comparison of CO2 emissions among renewable energy sources (hybrid solar energy systems) with non-renewable energy sources and their economic and climatic impacts on the household sector.
The main purpose of this research project is to present a realistic picture of measures to reduce CO2 emissions by providing analysis and comparisons in terms of efficiency and cost of deploying a hybrid solar system in Pakistan’s household sector for green and clean Pakistan. Similarly, the application of probability simulation presented in this study will enable the researchers to forecast the future of solar energy while casting pleasant impacts on the community and atmosphere. The global impact of this study is that it frames the outlines to reduce non-renewable energy usage, decrease long-term costs of energy generation costs, and minimize GHG emissions altogether for sustainable development of society.
The household sector was taken as a sample for this research study, as 48% of the energy in Pakistan is consumed by households and is considered the main consumer of electricity (Survey 2018–19). To compete with the economic powers of the world, Pakistan also has to promote non-fossil fuels and renewable energy sources as measures are being carried out to generate electricity from these renewable sources across the globe. The higher the consumption of electricity by households, the higher the CO2 emissions, causing extensive adverse climatic impacts. The seasonal variations and geographical location of Pakistan present a promising potential to generate electricity from renewable energy sources (Sadiqa et al. 2018). A total of 4,500 kWh/m 2 and 2,500 to 3,500 kWh/m 2 tilted solar radiations received by 60% and 40% of the country respectively per annum (Ashfaq & Ianakiev 2018). About 95% of Pakistan’s total stretch of land is the recipient average irradiation of 5–7 kWh/m 2 per day (Solangi et al. 2011) which indicates the potential for harvesting solar energy to meet household energy needs.
Following a mixed-method approach, primary and secondary data collection sources were utilized for energy system evaluation in Pakistan, particularly hybrid energy systems. To achieve research objectives, preliminary data was attained from 10 households from different regions of the Punjab province of Pakistan, as the province is the recipient of direct sunlight almost throughout the year. The selected households were further subdivided into two different categories based on their income, i.e., lower income households (LIHs) and medium-income households (MIHs). The comparison and evaluation showed that MIHs use more electricity (nearly double of LIHs) as these households use high energy-consuming electric appliances such as air conditioners, irons, and deep freezers. On the other hand, LIHs consume a lower level of electricity through low-power-consuming appliances such as fans, refrigerators, and televisions. The preliminary data was useful in densifying the study with accurate readings of energy usage, building micro-comparisons, and ensuring the authenticity of the research.
A typical hybrid solar energy system, presented in Fig. 1 , was chosen to be presented as the ideal solar energy generation tool for households due to its enhanced efficiency, low cost, reduced emissions, and high reliability (Ingole & Rakhonde 2015). This hybrid solar energy system combines the on-grid solar system (GTSS) and off-grid solar system (OGSS) which are powered through solar heat. The produced energy is directly fed into the main grid, and firstly charges the battery power bank; when this power bank is full, the excessive power is fed into the main grid with net metering (Ingole & Rakhonde 2015; Sultan et al. 2018). As displayed in Fig. 1 , an excessive amount of electricity produced by solar panels would reduce the power input from other energy sources including WAPDA and DG. Since the hybrid solar energy system can provide accurate readings of generation and usage from each of the energy sources, the study was able to present a comprehensive comparison which is discussed in the latter part of this study. Furthermore, careful considerations were taken in the selection of the hybrid energy based on the validity and reliability of each system and associated system spheres including high-quality reliable solar plates, well-tamed manpower, wire quality along with connection, and solar rays tilting angle.
System diagram of the hybrid solar system (Kit & Kit, 2019)
The medium-income households and low-income households carefully installed the hybrid energy systems containing 5 kW and 3 kW hybrid inverters respectively along with installed solar panels that can power up nearly 3 and 1.5 kW, respectively. In the 5-kW system, 12 solar modules were connected in two strings containing 6 modules each in the series, and both strings were connected parallelly with four batteries of 220amp/12 V connected for backup. Similarly, in the 3-kW system, a string having 6 modules in series was connected with two backup batteries 220amp/12 V. Furthermore, the class of solar panels used in the system enabled the power of each panel at 250 W with each solar module having 8.1 amp and 31 V. Grade A (highest quality) polycrystalline solar modules were installed with the help of blocks that are easily moveable on the top of the roof in cubic meters as shown in Fig. 2 . Since the efficiency of polycrystalline solar modules is much higher at high temperatures than monocrystalline solar cells, a pure sine wave solar inventor with an output factor of 1, called Axpert V Off-Grid Inverter, was deployed. The power from solar panels was fed into the grid inverter where maximum power point tracking (MPPT) charge controller was used with a direct connection (DC) to a pure copper wire of 10 mm for longevity and sustainability of the hybrid energy system. The installed inverter came with premier functionalities including an optional anti-dusk kit, cold start function, overload, short circuit protection, auto restart while AC is recovering, wide DC input range, and selectable input voltage range for home appliances and personal computers (Kit & Kit 2019).
a 3-kW solar system installed. b 5-kW solar system installed
The solar system, displayed in Fig. 2a and andb, b , was installed at specified angles, normally at 30–45°, to maximize the power generation output and electricity generation, which heavily depends on the intensity of heat. These types of energy-efficient hybrid solar energy systems are being promoted in Punjab where mercury can cross 40 °C during summer (Sajjad et al. 2015). However, due to landscape indifferences and seasonal variations, the solar modules and structural integrity can be moved towards an optimized angle (Rehman et al. 2012). The considerable point in these systems is that the angle should be set where maximum solar output lies and moved appropriately.
The record of daily energy generation and consumption readings in kilowatt-hour (kWh) from 7 am to 5 pm for 15 days enabled us to obtain energy data from these solar hybrid energy systems. There is an app and a monitoring system to monitor the solar system provided by the inverter companies. The data presented in this study was obtained by the monitoring system. The aforementioned calculations have been derived from data obtained from the Axpert V Off-Grid Inverter (Tesla produced inverter) in June 2020. The data logger is basically generated by the data collection, which is connected with hardware. The data logger is further connected with the inverter, which updates the data on the cloud and is connected to MATLAB. MATLAB provides access to the data for analysis. The obtained data is real and correct, attained from the inverters connected online through WiFi devices. Hence, there is no chance of any biases in the data as the data is received online on MATLAB and further analyzed. The model of probability simulation enabled us to determine the energy contribution from the solar hybrid systems, after calculating the average daily and yearly energy contribution. Following the preliminary calculations, the projection of CO2 emissions caused by WAPDA, DG, and hybrid solar energy for the coming 25 years was made by applying a probability-based simulation model. Additionally, detailed efficiency and cost comparisons were made by applying the cost–benefit ratio formula. To develop a precise understanding of emissions, costs, and efficiency, online resources were used to collect the secondary data including Google Scholar, Web of Science, Science Direct, and the online library of the university.
The main objective to obtain the preliminary facts (primary data) was to understand the ground realities regarding all the sources of energy in households, particularly the impact of solar energy. Comprehensive comparisons and analysis of already available secondary data enabled us to have a critical understanding of the energy spectrum of emissions, cost, and efficiency in this research project. The findings of this study will advocate securing a future of sustainable energy development by exploring crucial options like solar energy through awareness and disseminating its broader understanding. In addition to the probability-based simulation model and cost–benefit ratio, frequency analysis and descriptive analysis were also applied for presenting data analysis and comparisons through Microsoft Excel, MATLAB and Origin Pro 9.0.
The study sample of middle-income households and lower income households contained 5 kW and 3 kW hybrid inverters with the installed solar panels powering nearly 3 kW and 1.5 kW respectively. In accordance with the suggested load, the solar energy supplied by the solar panel for the sake of this study is presented in graphical form in Figs. 3 and and4. 4 . The mentioned figures also indicate the consumed energy distributed with the contribution of other energy generation resources. As mentioned earlier, the daily energy in kWh was calculated from 7 am to 5 pm for continuous 15 days and the entire data set of 10 systems is illustrated in Figs. 3 and and4 4 which displays the maximum energy generation, average running load, and saving backup. In system I, the average energy generation of MIHs and LIHs turned out to be 2.235 kW and 1.143 kW respectively, average running load 1.658 kW and 0.80 kW, while the average backup was 0.578 kW and 0.343 kW respectively. In the case of LIHs, the 6th and 13th day displayed negative saving backup which meant that energy consumption was much higher on those specific days and/or bad weather was experienced causing low generation of energy. In system II, the average energy generation of MIHs was found to be 2.315 kW and of LIHs to be 1.151 kW, the average running load was 1.664 kW and 0.674 kW, and the average backup was 0.651 kW and 0.478 kW respectively. In the case of MIHs, average energy generation was comparatively high as compared to other systems with the highest energy saving on the 8th day, and in case of LIHs, the 1st, 7th, 10th, 11th, and 15th days usage and backup were consistent. In system III, the average energy generation of MIHs which was 2.289 kW and LIHs which was 1.133 kW, average running load was 1.662 kW and 0.585 kW, and the average backup was 0.627 kW and 0.548 kW. As we can see in the case of LIHs, in the majority of the days 1, 2, 4, 5, 7, 9, 10, 11, and 15, the average backup is higher as compared to the average running load which means this house used energy efficiently, as displayed in Fig. 1 .
