Design and Analysis of an On-Grid Solar System House in Lahore, Pakistan

This paper investigates the economic and environmental benefits of installing a photovoltaic (PV) system in DHA Lahore using two distinct modeling tools: the System Advisor Model (SAM) and HOMER Pro. The study provides a comprehensive financial analysis by comparing the performance metrics of the PV system under both models. SAM analysis reveals a levelized cost of energy of 6.22 c/kWh nominal and 2.95 c/kWh real, with significant annual electricity bill savings of $1269 and a payback period of 2.7 years. Conversely, HOMER Pro highlights a high internal rate of return of 32.5% and a discounted payback period of 3.07 years, with a net present cost of $71,782.26, indicating considerable cost savings over the system’s lifetime. Although HOMER’s levelized cost of energy is reported at $0.125 per kWh, it reflects the system’s overall cost-effectiveness when combined with reduced operating expenditures. Both models underscore the PV system’s capacity to offer rapid financial returns, significant long-term savings, and substantial reductions in electricity costs. The study confirms that investing in solar technology in DHA Lahore is economically advantageous and environmentally beneficial, providing a sustainable solution for energy needs.

Introduction

The shift from the conventional energy source to renewable energy solutions has encouraged the installation of Photovoltaic (PV) systems, especially in residential settings [1], [2]. Solar energy, as a renewable energy source, has the potential to significantly decrease dependency on conventional fossil fuels, promote lower greenhouse gas emissions that contribute to the negative consequences of climate change, and provide efficient power [3]. Pakistan is now experiencing serious energy challenges as demand has consistently outstripped supply, resulting in frequent power outages and load sharing [4]. The national system, which relies heavily on imported fossil fuels, is characterized by power shortages and high operating costs [5], [6]. The current mismatch between energy supply and demand forces the government and business sector to seek alternative solutions to guarantee that the country has adequate energy both today and in the future [7]. Some of the energy challenges that still exist in Pakistan’s energy sector include insufficient generation capacity [8], aging infrastructure [9], and, most importantly, the country’s reliance on imported fossil fuels [10], making Pakistan unable to meet the nation’s energy needs.

Several studies have explored the utilization of simulation software to propose a PV system and its viability before the installation to analyze the performance and potential cost savings of PV systems. For instance, Ur Rehman et al. [11] provide an off-grid PV system for the power needs of a rural dwelling in Pakistan. When analyzing the system, HOMER software employs steady state modeling, which takes into account local irradiance, temperature, and humidity. The nominal power is 560 W of solar panels, 125 Ah of batteries, and a 1 kW inverter, which delivers 40 KWh each month. The statistics obtained from the HOMER simulation demonstrate the consistent nature of the necessary energy supply throughout the year, indicating the possibility for off-grid energy access in rural locations. Bhatti et al. [12] examine the design, optimization, and analysis of a stand-alone microgrid using hybrid resources for an Iraqi company. As a result, the research uses the PVsyst, HOMER Pro, and SAM software tools to conduct a thorough investigation of PV modules, inverters, battery storage technologies, and generators. HOMER Pro and SAM are utilized for detailed investigations and impact analysis, respectively, and PVsyst is used for system concept design.

The results suggest significant potential for renewable energy production with lower CO₂ emissions, as well as certain challenges with power generation during the winter season. The system has a reasonable normalized output rate but has a high potential for long-term environmental disruption. Khan et al. [13] used PVSyst software to simulate a grid-connected PV system in Pakistan and other SAARC nations. The investigation examines the efficiency of a Panasonic solar model cell, 320 kWp, 48 V, and a 1. 5 kW inverter for a 9. These losses, as well as the impacts of different tilt angles, were considered while designing the 6 kWp load. Thus, the research illustrates the potential for utilizing solar energy in the area and compares the energy generated, and the utility may be used in the management and selling of PV system components across SAARC countries. Ali et al. [14] conducted a techno-economic assessment of hybrid energy systems for RE integration in an isolated location of Pakistan using HOMER Pro software. To avoid the optimal tariff cost and associated energy poverty, the suggested systems combine wind and water power with battery storage. Energy consumption costs have been shown to fluctuate between 0. 0470–0. 0968 $/kWh, with significant environmental benefits such as glacier protection and the social cost of carbon. Thus, the given study underlines the need of establishing community-based hybrid systems to help provide sustainable energy to remote places. Aziz et al. [15] investigate the PV application at a commercial scale for agricultural estates in Punjab, Pakistan. To that end, 93 farmers’ load data were grouped using K-means, and HOMER Pro was used for techno-economic and environmental analysis. These findings show that PV installation is doable in all of the cities studied, with Attock and Multan having the lowest LCOE. The proposed PV systems demonstrate the ability to achieve significant emissions reductions, hence improving the green environment for sustainable agricultural systems. Overall, these studies envision and demonstrate the use of several simulation software packages, such as HOMER Pro, PVsyst, and SAM, in the design, performance, and assessment of PV systems. As a result, the degree of information provided by these tools, as well as the performance ratings that accompany them, aid in decision making concerning renewable energy investments, citing significant economic returns and environmental benefits.

This study focuses on the technical and economic evaluation of a 7.5 kW PV grid-tied hybrid system for a house in DHA Lahore. The aim of this study is to explore an assessment of the potential benefits, system’s performance as well as its cost-effectiveness using the System Advisor Model (SAM) and HOMER Pro. The analysis takes into account a number of different parameters, such as annualized costs, net present cost (NPC), electricity production patterns, and consumption patterns. Given the region’s high solar irradiance, the deployment of PV systems is particularly advantageous [16]. However, in order to achieve widespread adoption, it is essential to have a solid understanding of the economic implications and to guarantee the dependability of the system. This research not only evaluates the financial metrics but also investigates the operational performance, focusing on the contributions of the photovoltaic system to the overall energy mix as well as its interaction with the grid. A comprehensive case study of the photovoltaic (PV) system in DHA Lahore is going to be presented in this paper with the intention of contributing to the expanding body of knowledge regarding residential solar energy systems in Pakistan. This research was conducted with the purpose of providing homeowners, policymakers, and other stakeholders with information regarding the viability and benefits of incorporating solar photovoltaic technology into urban residential environments. The paper is structured as follows: Section 2 presents the methodology, section 3 presents and discusses the results obtained from the simulation software, and section 4 concludes the study.

Site Data and System Analysis

In this section, we present site details, the proposed system, and the software used to simulate the PV setup on the house in Defence Housing Authority (DHA), Lahore, Pakistan.

Site Description

The site location coordinates are 31° 27′ 49.0″ N latitude and 74° 28′ 25.7″ E longitude. Fig. 1 depicts a satellite image of the site location. The PV setup at DHA Lahore is a system that includes both non-tender connections and has a capacity of 7.5 kVA. The installation is situated in a local house in the Defence Housing Authority (DHA) area of Lahore, Pakistan. The conditions for using solar energy are favorable at the site because there is plenty of space on the roofs, as well as the necessary conditions for project implementation. Because of its geographical location in DHA Lahore, solar insolation, which influences the performance and productivity of the PV system, is extremely favorable throughout the year.

Fig. 1. Site location on google maps (Latitude: 31° 27′ 49.0″ N, Longitude: 74°28′25.7″E).

Details of Installed Solar PV System

The local utility supply company in Lahore is offering net metering options to residential customers in order to encourage them to install rooftop solar PV units. The chosen house is outfitted with a grid-tied Solar PV unit, which provides electricity to the home while also feeding excess energy back into the grid during the day. A hybrid grid-tied system consists of three major components: an inverter, batteries, and solar PV panels. This Solar PV system includes an 8.2 kW hybrid inverter, 22 solar panels with 340 W each, and four batteries for emergency backup. The following are some details about the installed components.

Solar Panel

The Canadian Solar MaxPower CS6U-340M is a high-performance monocrystalline solar panel utilized in this study. Each panel has a 340-watt rated power output and a module efficiency of 17.37%. The open circuit voltage (Voc) is 46.8 V, the short circuit current (Isc) is 9.45 A, and the maximum power voltage (Vmp) is 38.6 V. The maximum power current (Imp) is 8.81 A. The panel has dimensions of 1960 mm × 992 mm × 40 mm and weighs 22.5 kg. It also has a temperature coefficient of −0.39%/°C and operates efficiently in temperatures ranging from −40°C to 85°C. Table I displays the electrical parameters of the solar panel.

Table I. Electrical Specification of Solar Panel

Specification	Value
Nominal Max. Power (Pmax)	340 W
Opt. Operating Voltage (Vmp)	37.9 V
Opt. Operating Current (Imp)	8.97 A
Open Circuit Voltage (Voc)	46.2 V
Short Circuit Current (Isc)	9.48 A
Module efficiency	17.49%
Operating temperature	−40°C~+85°C
Max. system voltage	1500 V (IEC) or 1500 V (UL)
Module fire performance	TYPE 1 (UL 1703) or CLASS C (IEC 61730)
Max. Series fuse rating	15 A
Application classification	Class A
Power tolerance	0~+5 W

The mechanical data of the utilized panel is shown in Fig. 2. It has a monocrystalline cell type with 6-inch cells arranged in a 72-cell configuration (6 × 12). The panel measures 1960 mm × 992 mm × 40 mm (77.2 × 39.1 × 1.57 inches) and weighs 22.4 kg (49.4 pounds). It features a 3.2 mm tempered glass front cover and a durable anodized aluminum alloy frame. The junction box is IP67-rated and includes three diodes to ensure consistent performance in a variety of environments. The panel measures 1160 mm (45.7 inches) and features PV1500DC-F1 4 mm² cables (IEC) and 12 AWG cables with a 2000 V (UL) rating. It connects via T4 or PV2 series connectors. Panels are shipped with 26 pieces per pallet, totaling 635 kg (1400 lbs), and a 40′ HQ container can hold 624 panels.

Fig. 2. Engineering drawing of Canadian Solar MaxPower CS6U-340M.

The Fig. 3 shows the I-V curves of the utilized PV for varying irradiance and temperature.

Fig. 3. I-V curve of Canadian Solar MaxPower CS6U-340M.

Inverter

For the proposed system, a Fronius Primo 8.2 pure sine wave hybrid inverter is utilized. It is a single-phase string inverter and was developed specifically for use in residential and small commercial photovoltaic (PV) systems. It has an efficiency rating of 98% and a maximum output power of 8.2 kW. A maximum input current of 33 A is supported by the inverter, which operates within a voltage range of 80 V to 1000 V within its input voltage range. The two MPP (Maximum Power Point) trackers that are included are designed to maximize the amount of energy that is harvested from the photovoltaic system by adjusting to different levels of sunlight. It is important to note that the nominal input voltage is set at 710 V, while the MPP voltage range extends from 270 V to 800 V. In addition to having two DC connections, the inverter is capable of supporting a maximum power of 12.3 kW from a PV generator. With a maximum output power of 8200 VA, it has an AC nominal output of 8200 W and a maximum output power of 8200 W. Operating within an AC voltage range of 180 V to 270 V, it is compatible with a grid connection of 1~NPE 220/230 V and operates properly within this range. In addition, the inverter has a broad frequency range that extends from 45 to 65 Hz and guarantees a minimal total harmonic distortion of less than 3% when operating at nominal power and voltage. The Fronius Primo 8.2 is designed to be long-lasting and has a protection rating of IP65, which makes it suitable for use in both indoor and outdoor settings. In addition to being able to function at altitudes of up to 4000 m, it is able to withstand temperatures ranging from −40°C to 55°C. Connections such as wireless local area networks (WLAN), Ethernet local area networks (LAN), Modbus TCP SunSpec, and USB are included for the purpose of data logging and firmware updates. Regulated air cooling is used to manage the cooling of the inverter, and it operates with a consumption of less than one watt during the nighttime hours. Furthermore, it provides a variety of protection devices, such as DC insulation measurement and reverse polarity protection, which guarantee the PV system’s operation in a dependable and risk-free manner.

This inverter has three different operational modes. This can be used as a stand-alone inverter by adding battery backup and disconnecting the utility supply, as a grid-tied inverter by only connecting solar panels and the utility supply, or as a hybrid inverter by connecting both the battery backup and the utility supply. The inverter also has dual outputs for smart load management, which means one of the outputs can be programmed as a noncritical load, turning off a certain level of battery backup at night. Table II displays the major technical specifications of the inverter as an online datasheet.

Table II. Technical Specifications of Inverter

Type	Rating
Maximum output power	8.2 kW
Efficiency	98%
Input voltage range	80 V–1000 V
MPPT voltage range	270 V–800 V
Maximum input current	33 A
Number of MPP trackers	2
Nominal input voltage	710 V
AC nominal output	8200 W
Maximum PV generator power	12.3 kW
Maximum output power	8200 VA
AC voltage range	180 V–270 V
Frequency range	45–65 Hz
Total harmonic distortion	<3%
Protection rating	IP65
Operating temperature range	−40°C to 55°C
Dimensions	645 mm × 431 mm × 204 mm
Weight	21.5 kg

Backup Setup

Additionally, the inverter comes with four batteries that can be used to supply power in the event that there is a surge in power. BAE Secura PVS BLOCK Solar 12 V 3 PVS 210 batteries are the ones that are utilized in this process. This particular battery is designed to provide dependable and sturdy energy storage, making it particularly well-suited for use in solar-powered applications. It has a rated capacity of 95 Ah at C1, 167 Ah at C10, 192 Ah at C20, and it can reach up to 211 Ah at C72, which means that it provides substantial performance over a wide range of discharge periods. The rated capacity of the battery reaches its highest point, 215 Ah at C100 and 217 Ah at C120, and it reaches its highest point of 222 Ah at C240. The internal resistance of this device is 6.27 mA, and it has the capacity to offer a short circuit current of 1.99 kA. In terms of its dimensions, the battery measures 380 mm in length, 205 mm in width, and 385 mm in height. It weighs 53.7 kg when it is empty and 71.4 kg when it is full. A high-impact SAN container that is rated HB according to UL-94 standards is used to house the battery. The lid of the container is made of grey SAN, and an ABS version is available as an option. The BAE Secura PVS BLOCK Solar batteries are designed for use inside, and they come equipped with robust construction features such as pole-bushing that is completely gas- and electrolyte-tight, as well as labyrinth plugs that are designed to arrest aerosols. Because the batteries are designed to have a high level of dependability and long cycle life, they are an excellent option for storing regenerative energy in environments that are both demanding and demanding.

System Layout

Fig. 4 provides a visual representation of the system layout. Twenty-two Canadian Solar MaxPower CS6U-340M panels are included in the system, and they are arranged in two strings of eleven panels each. As a result of the fact that each panel has a rated power output of 340 W, the total solar power capacity is 7480 W, which is equivalent to 7.48 kW. Inverter Fronius Primo 8.2 is a single-phase inverter that is capable of handling up to 8.2 kW of power. The panels are connected to this inverter. This inverter is equipped with two Maximum Power Point Tracking (MPPT) inputs, which enables it to manage power in an effective manner and maximize the amount of energy that can be harvested from solar panels. In order to create a 48 V battery bank, four BAE Secura PVS 12 V 3 PVS 210 batteries are connected in parallel to one another. These batteries are responsible for providing the system with the energy storage it needs. With a total capacity of 10.13 kWh, each battery has a capacity of 211 Ah, which results in a total store capacity of 10.13 kWh. Even during times when there is insufficient solar energy, such as when there is a power outage, this configuration guarantees that the system will be able to supply power to the loads regardless. The system is designed to manage two different kinds of loads: a high load and a normal load. This configuration allows it to handle both types of loads. The high load is connected to the system, and in order to conserve energy, it is turned off when there is a power outage. Because the normal load continues to operate with power coming from both the solar panels and the battery bank, it is possible to guarantee that essential functions will continue to be maintained. Table III shows the specification of overall setup, it includes 2 strings of 11 panels and an inverter along with 4 batteries in series.

Fig. 4. System layout.

Table III. Technical Specifications of Overall Setup

Component	Specification
Number of panels	22 (2 strings of 11 panels each)
Rated power per panel	340 W
Total solar power output	7480 W (7.48 kW)
Inverter	Fronius Primo 8.2
Maximum output power	8.2 kW
Number of MPPT inputs	2
Battery model	BAE Secura PVS 12 V 3 PVS 210
Number of batteries	4 (connected in parallel)
Total battery voltage	48 V
Battery capacity per unit	211 Ah
Total battery capacity	10.13 kWh

Given Lahore’s average annual solar insolation of approximately 5.3 kWh/m²/day, the system’s energy production can be estimated. Assuming a system efficiency of 90% (accounting for inverter losses, temperature losses, and other system inefficiencies):

$$\begin{array}{rl}& DailyEnergyProduction=TotalPVCapacity\\ & \times AverageSolarInsolation\times SystemEfficiency\end{array}$$

$$\begin{array}{rl}& DailyEnergyProduction=7.48kW\times 5.3kWh/m^2/day\\ & \times 0.9\approx 35.7kWh/day\end{array}$$

$$\begin{array}{rl}& AnnualEnergyProduction=DailyEnergyProduction\\ & \times 365\approx 35.7kWh/day\times 365\approx 13,031kWh/year\end{array}$$

Performance Analysis in System Advisor Model (SAM)

The National Renewable Energy Laboratory (NREL) created the Systems Advisor Model (SAM), which is available to the public for free. Its goal is to encourage the examination and financial analysis of renewable energy projects such as photovoltaic (PV) systems. SAM provides detailed, real-time information on the aptitude and profitability of a particular solar power system to project developers, policymakers, and research scientists. The simulation results may also be selected by an hour of the day, as well as input factors such as weather, system type, building layouts, and operating settings. Furthermore, SAM communicates with a big meteorological database to get accurate solar radiation as well as the weather of the location where the PV project is situated. This ensures that the simulation’s findings are specific to the actual environmental conditions in Lahore. Users may describe PV system aspects in detail, such as panel type, inverter efficiency, degree of shadowing, and component deterioration. It enhances the accuracy of performance projections. Another benefit of the SAM method is that it includes basic economic modeling capability, allowing users to undertake not just performance assessments but also rudimentary tests of the enterprise’s economic viability. This integrated method improves the appraisal of the project’s prospects by considering numerous variables and their combinations.

The overall setup was modeled in SAM to evaluate the performance and financial analysis of the proposed system. Fig. 5 illustrates the I-V cure for PV in SAM, while Fig. 6 shows the inverter efficiency with respect to rated output power. Since there are two different electricity rates in Pakistan for peak hours and off-peak hours, the two rates are also incorporated in the SAM. Fig. 7 illustrates the two rates setup in SAM. The electricity rates are at $0.18/kWh and $0.22/kWh for off-peak and peak hours respectively. Figs. 8 and 9 show the simulated yearly load in SAM in terms of hourly as well as daily load, respectively.

Fig. 5. I-V curve of solar panel simulated in SAM.

Fig. 6. Inverter efficiency with respect to output voltage.

Fig. 7. Electricity rates: Rate 1 at $0.18/kWh and Rate 2 at $0.22/kWh in SAM.

Fig. 8. Hourly electrical load over period of a year.

Fig. 9. Daily electrical load over a year.

System Modeling in HOMER Pro

HOMER Pro, developed by UL’s HOMER Energy division, is an outstanding program for planning and assessing hybrid renewable energy systems. They may, however, integrate technical characteristics with financial data, which is unknown in most other HOMER Pro scenarios, when determining optimum system designs. HOMER Pro is known for its ability to examine numerous system configurations in order to determine which is the most resource efficient. This includes calculating the required number of PV arrays, inverters, and storage devices for a certain energy need. The tool HOMER Pro can calculate the net present value (NPV), profit per share (or cost/benefit ratio), particular internal rate of return (IRR), levelized cost of energy (LCOE), and payback periods. This helps stakeholders understand the economic feasibility of the currently planned project. Furthermore, it is established that HOMER Pro is widely used in financial modeling, and its great efficacy has been proven in a variety of academic and commercial applications. It should also be emphasized that the program includes an optimization mechanism, and the fundamental financial calculations are based on established procedures that are compared to real-world data. Because of the precise cost inputs used in the HOMER Pro tool and the capacity to oversee multiple simulations, the financial results are realistic and valuable for decision-making. Fig. 10a illustrates the irradiance and clearness index of the selected site provided to HOMER Pro for analysis, while Fig. 10b shows the temperature of the selected site.

Fig. 10. Irradiance (a) and Temperature (b) of the selected site provided to HOMER Pro.

Fig. 11 shows the designed system structure in Homer Pro. This diagram shows 7.63 kW solar panels connected to a DC busbar and 8.2 kW PV inverter along with backup batteries connecting the system to household and power grid. Household load is also designed as per annual energy consumption data of the house collected through electric bills.

Fig. 11. System structure in homer pro.

Fig. 12 illustrates the monthly load profile of attached load at the site location.

Fig. 12. Monthly load profile of load at site location in HOMER Pro.

Like SAM, HOMER Pro is provided with two distinct rates to get a comprehensive study of the suggested configuration. The rates that were simulated in HOMER Pro are shown in Fig. 13. During off-peak and peak hours, grid prices are $0.18/kWh and $0.22/kWh, respectively, while the sellback cost is $0.08/kWh for both schedules. Grid rates are determined by the grid. In addition to including the power outage behavior, HOMER Pro includes four hours of scheduled power outages throughout the year. Fig. 14 illustrates the schedule of power interruptions that will occur.

Fig. 13. Grid rate in HOMER Pro: Grid Price 1 at $0.18/kWh and grid price 2 at $0.22/kWh. While the sellback rate is at $0.08/kWh for both schedules.

Fig. 14. Grid schedule outages simulated in HOMER Pro.

Results and Discussion

This section presents the results of the system performance analysis using the System Advisor Model (SAM) and the financial analysis using HOMER Pro for the 7.5 kW PV system installed in DHA Lahore.

Simulation Results by SAM

SAM needs basic parameters to simulate the projected energy and ROI of the desired system. In general, SAM requires simple statistics to estimate the projected energy and ROI of the desired system. SAM requires online data on solar irradiance for the above-mentioned locations. These selected location weather data were downloaded and added to the software’s weather data library. SAM’s libraries contain a variety of brands of solar panels and inverters, but users can add a new product if the part numbers are not listed.

Fig. 15 shows the monthly load profile for one of the PV systems in the SAM simulation study. The profile depicts the demand for electricity (blue), the PV system’s background electricity production (orange), and the electricity purchased from the grid (brown) over the course of a year. Energy consumption is measured in kWh, with values ranging from 0 to 20 kWh. As shown in the figure, the load (blue) remains constant month after month, with an increase from March to September. Furthermore, the orange line depicts the PV system’s generated electricity, which varies throughout the year: the highest generation occurs in the summer (June–August), while the lowest generation occurs in the winter (December–February). Also, in the figure, the brown line represents electricity taken from the grid, and just like the PV, the amount of electricity taken from the grid is greater in winter and less in summer. This appears to imply that the PV system is capable of supplying current that meets load requirements, particularly during the summer season, though there is a reliance on the grid for additional power during the winter. As a result, the above profile implies that the PV system installed is capable of supplying power equal to or greater than the load demand during some months of the year but not all.

Fig. 15. Monthly load profile simulated in SAM.

The system yields an annual AC energy output of 10,026 kWh in its first year, with a DC capacity factor of 15.30%, indicating the proportion of total possible energy that was actually captured. The energy yield of 1339 kWh/kW and a performance ratio of 0.69 reflect the system’s efficiency in converting available solar energy into usable electrical power. The system’s capability to produce and utilize energy efficiently throughout the year is evident from the monthly data, where periods of high solar production, such as in March, significantly contribute to reducing reliance on grid electricity. Table IV provides the summary of the results extracted from SAM.

Table IV. Summary of Cost of Proposed System over One Year

Metric	Value
Annual AC energy in Year 1	10,026 kWh
DC capacity factor in Year 1	15.30%
Energy yield in Year 1	1339 kWh/kW
Performance ratio in Year 1	0.69
LCOE Levelized cost of energy nominal	6.22 ¢/kWh
LCOE Levelized cost of energy real	2.95 ¢/kWh
Electricity bill without system (year 1)	$1638
Electricity bill with system (year 1)	$370
Net savings with system (year 1)	$1269
Net present value	$56,825
Simple payback period	2.7 years
Discounted payback period	3.1 years
Net capital cost	$5989
Equity	$5989

Fig. 16 shows the monthly AC power produced by PV as well as the monthly power utilized by the load. It is evident that January, July, and September are the months with loads where the PV setup cannot meet the required energy needs of the house.

Fig. 16. Monthly AC power produced by PV as well as the monthly power utilized by load.

Fig. 17 shows the electricity flow to and from the grid over a year. The x-axis of the graph shows the month, and the y-axis shows the net electricity (in kW) that is either exported to the grid (positive values, red) or imported from the grid (negative values, blue). The house generates the most solar energy (positive values on the y-axis) during the summer months (May to September), which is consistent with Lahore’s climate. The house imports the most energy from the grid (negative values on the y-axis) during the winter months (December to February) when there is less sunlight. The house generates more electricity than it consumes from the grid throughout the year. This suggests that the 7.5 kW PV system is a net producer of electricity.

Fig. 17. Electricity flow to and from the grid over a year in SAM.

Table V shows the DC energy produced by the solar panels prior to conversion to AC, as well as the total AC energy produced by the solar panels per month. The table also shows the power consumed by the load, as well as the net difference between the energy produced by the solar panels and the electricity consumed by the home. Positive values indicate excess energy fed back into the grid, while negative values represent the amount of electricity imported from it. All figures are in kWh per month. Table VI compares the approximate electricity bills and consumption before and after installing the Solar PV system. Table VI shows perfect examples of reduced electricity bills following the installation of a solar PV system. Every month, the electricity bill paid with the system will be lower than the electricity bill paid without the system. All costs and figures are expressed in US dollars per month. The variations in such electricity tariffs are as follows: The difference in electricity bills can range $2. The expenses decreased from $34 in March to $203.11 in July. Table VI also shows that the amount of electricity drawn from the grid decreases after the solar PV system is installed. Specifically, the bar graph shows that the number of units of electricity used is lower with the system in place in most months than without it. The highest reduction in electricity use occurs in July, at 2461. The reduction from the base year is the greatest, confirming the implication of unproportional electricity consumption resulting in a reduction by the specified measures. 04 kWh, with the lowest consumption recorded in February at 79 kWh. 4 kWh. The following cash flow statement expresses all currency values in kWh per month. According to usage and bills, the maximum amount of electricity savings and consumption reduction is recorded during the summer months, which run from May to September. This is due to the sweetspot, which occurs when the solar panels generate the most electricity in a day, enough to meet the house’s needs without having to purchase electricity from the grid. Certain months, particularly the three winter months of December, January, and February, result in higher additional electricity use with the system than without it. This is because the solar panels produce insufficient electricity, forcing the house to draw power from the grid during these months. As a result, the paper demonstrates that incorporating a solar PV system reduces electricity costs and demand in establishments, particularly in areas with high sun exposure in a given calendar year.

Table V. Energy Flow from PV to Load and Grid

Month	DC energy	AC energy	Load	Electricity to/from grid
Jan	708.674	674.497	1293	−618.503
Feb	702.061	668.041	589	79.0414
Mar	1067.86	1019.53	299.5	720.027
Apr	1013.28	965.1	646.3	318.8
May	1074.28	1023.35	714.1	309.246
Jun	944.115	898.251	612.75	285.501
Jul	789.571	748.419	1033.2	−284.781
Aug	823.888	781.482	730.85	50.632
Sep	882.857	840.705	924.15	−83.4447
Oct	863.086	822.264	619.15	203.114
Nov	898.49	857.817	470.6	387.217
Dec	761.551	726.436	521.05	205.386

Table VI. Monthly Comparison of Electricity Bills and Usage with and without PV System

Month	Electricity billwithout system	Electricity billwith system	Electricity usewithout system	Electricity usewith system
Jan	250.28	127.34	1293.00	618.50
Feb	114.04	33.40	589.00	−79.04
Mar	58.02	2.34	299.50	−720.03
Apr	124.36	38.06	646.30	−318.80
May	137.00	38.59	714.10	−309.25
Jun	120.67	0.00	612.75	−285.50
Jul	203.11	0.00	1033.20	−1427.84
Aug	143.09	0.00	730.85	−50.63
Sep	176.87	54.89	924.15	−1395.02
Oct	118.75	39.75	619.15	−203.11
Nov	91.13	35.36	470.60	−387.22
Dec	100.99	0.00	521.05	−205.39

Fig. 18 depicts the cost of electricity over the lifetime of the PV setup. It is obvious that without a PV system, electricity would cost around $25,000 over 25 years, whereas with a PV system, it would cost less than $3500 over 25 years. This results in an 86% reduction in electricity costs over the course of 25 years.

Fig. 18. Cost of electricity over the lifetime period of PV setup.

The System Advisor Model (SAM) findings provide a thorough perspective of the technical and economic performance of the 7.5 kW PV system installed at DHA Lahore. The system’s primary performance parameters include an annual AC energy production of 10,026 kWh in its first year and a DC capacity factor of 15.30%.

The energy output, computed at 1339 kWh/kW, and a performance ratio of 0.69 demonstrate the system’s efficiency in converting solar into electricity. The financial study shows a very good economic consequence. The solar installation is cost-effective, with an LCOE of 6.22 ¢/kWh nominal and 2.95 ¢/kWh real. The power bill reductions are significant, with an annual drop of $1,638 to $370, resulting in a net savings of $1269 in the first year alone. Over the system’s lifetime, the net present value (NPV) is expected to be $56,825, with a basic payback period of 2.7 years and a discounted payback period of 3.1 years. The system has a net capital cost of $5989 and is fully financed by equity.

Monthly examination of power output and consumption demonstrates the system’s performance over seasons. For example, in March, the PV system generates 1,019.53 kWh of AC energy and meets a considerable percentage of the household’s power needs, resulting in a surplus of 720.027 kWh put back into the grid. Conversely, during months such as January and July, the grid fills the household’s power demands owing to lower PV output or increased electricity consumption. The monthly breakdown of power costs demonstrates the significant savings realized with the PV system. For example, in January, the power bill dropped from $250.28 to $127.34, demonstrating the PV system’s effect on lowering grid reliance. In July, the cost is decreased to zero, indicating the solar panels’ peak output season.

The SAM findings highlight the significant advantages of installing a 7.5 kW PV system in Lahore, both in terms of energy output and cost savings. Thus, when paired with consistent AC energy generation throughout the year, it is possible to conclude that the MaxPower CS6U-340M Canadian Solar panel and Fronius Primo 8 efficiency are optimal. To address this issue, two inverters play a significant role in integrating solar energy in Lahore’s specific climatic circumstances. Accounting-wise, it has shown to be a financially viable method. The LCOE is low, and large power bill savings, along with a short payback period, indicate that homes may benefit both in the near term and during the system’s lifespan. This allows for the maximization of net present value, which improves the financial viability of a solar system. Focusing on the variability of aggregated energy production and consumption data with monthly resolutions suggests that seasonal features should be taken into account to the greatest extent possible when building and sizing PV systems. In this manner, the additional energy needed for consumption during the other months is generated when there is enough sunshine, while grid power supplements the energy produced by the system during the other months of the year.

HOMER Pro Results

The HOMER Pro simulation findings for the base and suggested systems focus on economic, technological, and environmental factors. The exploratory investigation reveals that there is significant improvement and increased benefits with the integrated PV system. The projected internal rate of return (IRR) for the proposed system is 32.5%, indicating a high degree of profit and, as a result, the company’s appeal for investment. Based on this significant IRR, it can be concluded that the proposed PV system is more financially viable than the base system. This indicates that the payback term for the proposed system can be calculated using the aforementioned information by deducting the original expenditure from the discounted payback period of 3.07 years. Because of these low payback periods, it is clear that the initial investment in the proposed PV system would be repaid in the shortest time feasible, resulting in speedy returns. The suggested system has a substantially smaller NPC ($71,782) than the basic system ($98,337). This suggests a lower NPC, which reduces the system’s cost during its whole life cycle, boosting its economic viability. The suggested system’s installation cost is $5340, known as Capital Expenditure (CAPEX), plus $3240 for the basic system. Similarly, the suggested system has a lower OPEX of $1,585 than the basic system, which is $2268. This implies that, even while the initial expenditures are more than offset in the second year, operational expenses are far lower, making the project more cost-effective in the long term. The suggested system’s levelized cost of energy is $0.125 per kWh, which is much cheaper than the basic system, which is $0.277 per kWh. This drop in LCOE demonstrates the cost-effectiveness of the proposed system for producing energy at a lower price per kWh. As shown in Fig. 19, the investment in the proposed compared to base systems in terms of cash flow is clear. Thus, the suggested system is less expensive and generates considerable savings over a 25-year period. Fig. 20 illustrates the projected cash flow (year-wise) for 25 years. The replacement of batteries results in around $1240 every four years. Fig. 21 shows the PV setup output power over the period of one year. Table VII provides a summary of the annual production of electricity for the proposed PV system integrated with grid support. The PV panel represents the energy produced by the PV system, contributing 10,130 kWh per year. This accounts for 65.8% of the total energy production. The grid purchases denote the amount of electricity purchased from the grid, totaling 5262 kWh per year, which makes up 34.2 of the total production. This indicates that while the PV system provides a substantial amount of energy, there is still a reliance on the grid to meet the total energy demand.

Fig. 19. Cash flow comparison with base system and proposed system in HOMER Pro.

Fig. 20. Projected cash flow for 25 years.

Fig. 21. PV output power over the period of one year.

Table VII. Production of Proposed System

Component	Production (kWh/year)	Percentage
CanadianSolar MaxPower CS6U-340M	10,130	65.8
Grid purchases	5262	34.2
Total	15,392	100

Table VIII provides a summary of the annual consumption of electricity for the proposed PV system integrated with grid support. AC Primary Load represents the main energy consumption by the household or facility, amounting to 8453 kWh per year, which constitutes 61.5% of the total energy consumption. It indicates the primary usage of electricity to meet the household’s or facility’s needs. DC Primary Load shows zero consumption, indicating no direct current (DC) loads are being served in this system and similarly, there are no deferrable loads, which means there are no loads that can be delayed optimizing energy use. Grid Sales indicates the amount of energy sold back to the grid, totaling 5282 kWh per year, which makes up 38.5% of the total consumption. This signifies that the excess energy produced by the PV system is fed back into the grid, contributing to the overall energy supply.

Table VIII. Consumption Summary of Proposed System in HOMER Pro

Component	Consumption (kWh/yr)	Percent
AC primary load	8,453	61.5
DC primary load	0	0
Deferrable load	0	0
Grid sales	5,282	38.5
Total	13,735	100

The battery system shows that the average cost of energy is $0.129 per kWh, demonstrating the cost-effectiveness of storing energy in these batteries vs buying power from the grid. The overall energy input into the battery system is 1063 kWh per year, which represents how much energy is stored in the batteries over the course of a year. Meanwhile, the battery system generates a total of 905 kWh every year. The storage depletion rate is 1.23 kWh per year, suggesting that the battery system is efficient at maintaining stored energy. Additionally, the system loses 160 kWh of energy every year owing to inefficiencies in the charging and discharging procedures. The battery system has an annual throughput of 981 kWh, which is the total energy cycled through the battery over the course of a year. Furthermore, the battery system has a capacity of 8 hours. The storage wear cost is $0.0997 per kWh, which reflects the expense of battery deterioration over time. The overall nominal capacity of the battery system is 9.65 kWh, which is the greatest amount of energy that the batteries can store. Fig. 22 depicts the status of charge of a battery backup over a one-year period. Fig. 23a illustrates the energy purchased from grid (kW) over the period of one year, while Fig. 23b shows the energy sold to grid (kW) by the proposed system.

Fig. 22. State of charge of backup batteries for the proposed system in HOMER Pro.

Fig. 23. Flow of energy between PV and grid: (a) Energy purchased from grid, (b) Energy sold to grid.

Under Grid Rate 1, as shown in Table IX, the total energy purchased throughout the year is 3704 kWh, while 4796 kWh of energy is sold back to the grid. This results in a net energy purchase of −1092 kWh (negative sign shows that more energy is sold than purchased), with an annual energy charge totaling −$7.24. Notable months include July, with a high net energy purchase of 453 kWh and an energy charge of $81.62, and March, where more energy is sold than purchased, leading to a negative net energy purchase of −463 kWh and an energy credit of −$37.07.

Table IX. Grid Rate 1 Monthly and Annual Energy Transactions and Charges

Month	Energy purchased (kWh)	Energy sold (kWh)	Net energy purchased (kWh)	Energy charge
January	444	405	39.0	$7.01
February	141	369	−229	−$18.29
March	69.2	533	−463	−$37.07
April	247	478	−231	−$18.49
May	258	453	−196	−$15.66
June	339	254	85.3	$15.35
July	622	169	453	$81.62
August	432	209	224	$40.24
September	389	420	−31.1	−$2.49
October	286	537	−251	−$20.09
November	196	521	−324	−$25.94
December	280	448	−168	−$13.43
Annual	3704	4796	−1092	−$7.24

For Grid Rate 2 as illustrated in Table X, the total energy purchased annually is 1,558 kWh, and the energy sold back to the grid amounts to 486 kWh. The net energy purchased for the year is 1072 kWh, resulting in a higher annual energy charge of $281. Significant months under this rate include January, with a net energy purchase of 292 kWh and an energy charge of $64.35, and June, where energy sold exceeds energy purchased, resulting in a negative net energy purchase of −159 kWh and an energy credit of −$12.76.

Table X. Grid Rate 2 Monthly and Annual Energy Transactions and Charges

Month	Energy purchased (kWh)	Energy sold (kWh)	Net energy purchased (kWh)	Energy charge
January	292	0	292	$64.35
February	83.9	0.898	83.0	$18.27
March	45.2	5.10	40.1	$8.83
April	144	0	144	$31.71
May	162	0	162	$35.63
June	28.3	188	−159	−$12.76
July	75.4	131	−55.5	−$4.44
August	53.6	161	−107	−$8.59
September	252	0	252	$55.54
October	135	0	135	$29.81
November	111	0	111	$24.32
December	174	0	174	$38.32
Annual	1558	486	1072	$281.00

The HOMER Pro study offers a full comparison between the base system and the proposed system. The results of this comparison demonstrate that the proposed photovoltaic (PV) system offers considerable benefits in terms of economic performance, operational efficiency, and environmental effects. The system that is being presented has a high internal rate of return (IRR) of 32.5%, which highlights the fact that it is financially viable and appealing for investment purposes. When compared to the simple payback period of 3.07 years, the discounted payback period of 2.86 years indicates that the original investment will be recovered in a short amount of time, which will result in swift financial returns. With a net present cost (NPC) of $71,782, the proposed system is much less expensive than the basic system, which has a cost of $98,337. This indicates that the suggested system will result in significant cost savings over the course of its lifespan. However, the operating expense (OPEX) dramatically decreased to $1585 from $2268, showing long-term savings. This is despite the fact that the capital expenditure (CAPEX) for the proposed system is greater at $5340 compared to $3240 for the basic system. The proposed system has a levelized cost of energy (LCOE) of $0.125 per kWh, which is much lower than the base system’s LCOE of $0.277 per kWh. This highlights the cost-effectiveness of the proposed system in terms of producing electricity at a lower price per kWh.

The PV system plan provides an annual output summary of 15,392 kWh; the PV panels generate 10,130 kWh (65.8%), while the grid purchases 5262 kWh (34.2%). This shows that the PV system has contributed significantly to decreasing the amount of electricity needed from the grid while remaining heavily reliant on it. According to the consumption summary, the home consumes 13,735 kWh per year, with 8453 kWh (61.5%) going to the AC’s main load and 5282 kWh (38.5%) going to the grid. This implies that most of the energy produced is used to power the home or facility, with the remainder being supplied back into the grid.

Furthermore, the battery system’s performance points of energy cost an average of $0.129 per kWh, which is less than the cost of grid power. The overall energy input charged into the battery system is 1260 kWh each year, whereas the total energy output is 905 kWh per year. The depletion of storage is modest at 1.23 kWh per year, illustrating the effective energy saving demonstrated by this palm oil product. Given the impacts of charging and discharging, energy losses total 160 kWh each year. The battery system throughput is 981 kWh per year, and its autonomy is 8 hours. The utilized storage wear cost is $0.0997 per kWh to account for the battery deterioration costs incurred when utilizing the Electricity Storage System. The battery system’s nominal capacity is 9.65 kWh, with a usable nominal capacity of 7.72 kWh.

Net Grid Rate figures reveal a yearly energy purchase of 5262 kWh and energy sales of 5282 kWh, for a net energy purchase of −20 kWh (indicating higher sold than purchased) and an annual energy charge of $273.75. Although the energy sold is higher than purchased (−20 kWh), the higher rate of Grid Rate 2 results in $273.75 cost annually. Significant months include July, which had a large net energy buy of 398 kWh and an energy charge of $77.19, and March, which had a negative net energy purchase of −423 kWh and an energy credit of −$28.24.

Comparative Analysis of SAM and HOMER Pro

A demonstration of the cost-effectiveness of the solar system is provided by the findings of the SAM, which indicate that the levelized cost of electricity (LCOE) is 6.22 ¢/kWh nominal and 2.95 ¢/kWh real. LCOE is reported to be $0.125 per kWh in the HOMER study. The basic payback period is estimated to be 2.7 years by SAM, while the discounted payback period is estimated to be 3.1 years. HOMER suggests a similar payback period with a discounted payback time of 2.86 years and a simple payback period of 3.07 years.

Within the context of SAM, the net present value (NPV) is assessed to be $56,825, which highlights the profitability of the investment in the PV system over the course of its lifespan. Having a positive net present value (NPV) suggests that the system provides more value than it costs to operate. HOMER, on the other hand, places an emphasis on the net present cost (NPC), which is much cheaper for the suggested system, coming in at $71,782, in comparison to the basic system, which would cost $98,337. Despite the fact that HOMER does not directly give NPV, the huge decrease in NPC indicates that there will be significant cost savings and financial gains from the system over the course of its operating duration. For the photovoltaic (PV) system, which is financed fully by equity, SAM estimates a net capital cost of $5,989 for the construction. HOMER, on the other hand, reveals that the suggested system would incur a greater capital expenditure (CAPEX) of $5,340, but it highlights that the operational expenses (OPEX) will be reduced, coming in at $1585 per year.

The photovoltaic system offers an immediate financial advantage in the form of savings on electricity bills. SAM reports that the yearly power cost has been lowered from $1638 to $370, which results in a net savings of $1269 in only the first year alone. This translates into significant financial advantages for homeowners over the course of the system’s lifespan. Although HOMER offers comprehensive monthly data on energy purchases and sales, it does not give a concise summary of yearly savings in the same way that SAM does. The data, on the other hand, suggests that large savings may be achieved by decreasing dependence on grid power and selling extra energy back to the generation system. Regarding the photovoltaic (PV) system that has been suggested, HOMER has reported an internal rate of return (IRR) of 32.5%, which highlights the system’s financial feasibility and appeal for investment. In spite of the fact that SAM does not explicitly give IRR, the short payback time and high NPV both suggest that there is a significant return on investment.

Conclusions

This research provides a thorough examination of the economic, operational, and environmental performance of a photovoltaic (PV) system using two different modeling approaches: the System Advisor Model (SAM) and HOMER Pro. The SAM study evaluates the system’s performance and highlights its cost-effectiveness, with a low LCOE of 6.22 ¢/kWh nominal and 2.95 ¢/kWh real. The findings show a beneficial economic outcome, with a basic payback time of 2.7 years and a discounted payback period of 3.1 years. The large decrease in the yearly power expenditure, from $1638 to $370, results in a net savings of $1269 in the first year. These data highlight the PV system’s strong ROI and financial appeal. In contrast, the HOMER Pro study focuses on the planned PV system’s long-term financial benefits. The system’s economic feasibility is shown by its high internal rate of return of 32.5% and discounted payback time of 2.86 years. The suggested system’s net present cost is $89,447, which is much lower than the standard system’s $98,337, indicating significant cost savings during the system’s operating lifetime. Although HOMER’s levelized cost of energy is higher at $0.125 per kWh than SAM’s results, the proposed system’s lower operating expenses and short payback time highlight its long-term financial advantages and operational efficiency. Both the SAM and HOMER evaluations show that the PV system provides significant economic and environmental benefits. SAM’s simple indicators and emphasis on immediate financial savings provide a clear picture of the system’s efficacy in lowering power costs and generating rapid profits. HOMER, on the other hand, emphasizes the system’s long-term economic advantages and overall efficiency via its full cost breakdown.