Technical, Economic, and Environmental Analysis and Comparison of Different Scenarios for the Grid-Connected PV Power Plant

Abstract

Today, using systems based on renewable resources is a suitable alternative to fossil fuels. However, due to problems such as the lack of access in all the times needed to supply cargo and high-investment cost, it has not been well-received. Therefore, in this research, the modeling of the photovoltaic system with battery storage has been done to supply the required load, and various scenarios have been evaluated in terms of economic parameters and reliability indicators of the studied system for a better understanding of the comparison indicators. It has been evaluated from two modes, one connected to the network and one disconnected from the network. One of the important results is the supply of 56% of the load by the photovoltaic cell in the presence of the grid, which, in this scenario, the electrical load is supplied by the photovoltaic cell and the grid is 164.155 kWh/yr and 128.504 kWh/yr, respectively.

1. Introduction

Supplying the energy needed by humans is very important considering the economic and environmental aspects. About 1.3 billion people worldwide are still without electricity, 80% of whom live in rural areas [1,2]. Due to this growing demand for energy, and thus the burning of more fossil fuels, global warming has become one of the greatest problems associated to human consequences, with significant social, environmental, and economic consequences [3]. Today, the energy supply of countries depends on fossil fuels, which cause pollution in the environment [4]. On the other hand, the release of environmental pollution increases the cost of energy production [5]. Renewable energy is the best alternative energy to reduce environmental pollution [6,7].

Today, solar energy is one of the most stable and sustainable ways to generate electricity. Solar power generation systems do not produce any air pollutants when operating [8,9,10]. Most of the electricity generated now comes from coal-fired power plants, and in recent years, there has been much debate about using other energy sources to reduce greenhouse gases [9,10,11,12]. Other energy technologies also have environmental risks. Nuclear power is not suitable due to the production of hazardous nuclear waste by reactors. This nuclear waste accumulates in power plants around the world due to the lack of a solution for long-term storage (5) (modeling hub). Another concern in the field of nuclear energy is the failure of nuclear reactors, which can have devastating consequences for people and the environment [13,14,15]. A good example of this is the Chernobyl accident in 1987; another more recent example includes the Fukushima accident, when the Fukushima nuclear power plant caused a great deal of concern in 2011 due to an earthquake in Japan. Therefore, solar photovoltaic (PV) systems have emerged as an effective alternative in this field due to their many advantages [16,17,18].

These systems cover most PV applications in remote areas, as they are often the most cost-effective choice for off-grid applications [19,20]. Stand-alone systems typically have inherent disadvantages, such as a low-capacity factor, excessive battery cost, and limited power capacity, that result in wasted additional energy [21,22,23]. Baneshi and Hadianfard [24] investigated a hybrid energy system to meet the demand of large electricity consumers in Shiraz. Several off-grid and on-grid configurations of diesel generators, wind turbines, PV panels, and battery storage were investigated. Shabani et al. [25] studied the techno-economic effects of two battery-modeling scenarios on the sizing and optimization of a grid-connected PV-battery system. Scenario 1 was based on a simple common battery model and control strategy that showed the battery status without reflecting the dynamic behavior. In contrast, Scenario 2 was based on a complex battery model that involved estimating the current–voltage characteristics of the battery under different operating conditions. A law-based operational strategy associated with a nondominant genetic sorting algorithm was mostly used to simulate and optimize a multiobjective network-connected hybrid-PV-battery system.

PV modules are now widely used in developed countries to generate electricity in places that are difficult to access or where network power is expensive. These modules often charge the batteries to ensure consistent use by the consumer. However, in most developing countries, electricity grids either do not exist or have not been developed (especially in rural areas) and are expensive [26,27]. In this case, photovoltaic systems are highly competitive with other energy sources (especially in countries with high levels of solar radiation) and their use is increasing rapidly [28,29,30].

Azaroual et al. [31] presented an optimum energy flow management of a grid-tied photovoltaic-wind-battery system considering the cost, reliability, and CO₂ emissions. Sahu et al. [32] presented a techno-economic analysis of a hybrid renewable energy system with energy storage for rural electrification. Shaikh et al. [33] presented a techno-enviro-economic assessment of a stand-alone parabolic solar dish Stirling system for electricity generation. Singh et al. [34] presented green-energy-technology-based energy-efficient appliances for buildings. In other studies, a photovoltaic system connected to the grid was evaluated to supply the load required by residential buildings and different cities [7,30,35].

The applications of these systems include PV water pumping and PV refrigerators to store vaccines in health centers, PV systems for homes and community centers to produce lighting, radio, and audio–visual systems, power telecommunications systems, and street lighting. In a photovoltaic system connected to the grid, several DC to AC converters are used to convert the DC voltage of the output of the PV modules to the AC voltage corresponding to the grid.

The input of each DC to AC converter is a set of vertical rows of PV modules to which it is connected, as shown in Figure 1. These vertical rows consist of modules that are connected in a series.

In this research, photovoltaic-cell-system modeling has been done, and the purpose of this modeling is to investigate different scenarios in energy storage for depeaking, which have been evaluated in the direction of depeaking, economic and environmental parameters, and reliability.

2. Materials and Methods

In this study, a grid-connected photovoltaic system to supply load to an agricultural area in a village in northwestern Iran has been investigated. The type of connection to the network is suitable due to the variable load of the desired location, so that it is a complement to the network during peak times and sells its electricity to the network during off-peak times.

2.1. Methodology

Economic analyses related to the proposed renewable system, along with analyses related to pollution-reduction using the HOMER simulator software, are presented [36]. Finally, using the optimization method described in the previous section with the optimal design of the grid photovoltaic system, the best modulus values, the best modulus inclination angle, and the best distribution of PV modules among the inverters are obtained by considering the structure of the supports. The HOMER software is an accurate tool for designing and analyzing hybrid systems, which includes a combination of traditional power generators, cogeneration, wind turbines, PVs, hydropower, batteries, fuel cells, biomass, and other inputs. A very important feature of the Homer software that distinguishes it from other software is the sensitivity analysis that considers the effect of variables that are out of user’s control, such as wind speed, fuel cost, etc., which helps determine how to optimize the system due to the above-mentioned parametric changes.

2.2. Load Profiles

The profile of the electrical load is the most important parameter for this type of study. The two studied areas are a residential–agricultural area in one of the villages of Saveh, located in central Iran. This area has a relatively good radiation intensity (7.8 kWh/m². day).

The village has a population of about 30 families and most of them are engaged in agriculture. The load profile of this area has been obtained by considering various factors and an attempt has been made to obtain the real-load profile of this area. For this purpose, the load profile is divided into two categories. The basis of the category of the load consumption is based on the seasons when the people in this area are engaged in agriculture.

Due to the low rainfall in this area during the hot seasons, high-pressure-irrigation systems are used to irrigate the lands. The daily consumption of each household is about 1.1 kW, which includes their use of lighting, radio, and television, and this consumption has little change during the year. The peak load of the area when there is enough rain is about 33 kW, and the pump is not used for irrigation. Figure 2 shows the load profiles in the low-rainfall seasons.

In the hot seasons when the amount of rainfall is low, high-pressure irrigation is performed for 12 h a day, from 6 a.m. to 6 p.m., with low fluctuations in the load profiles, in turn, for the landowners. In fact, the load profiles are divided into two categories based on the months of the year. Rainy months (January, February, March, April, October, and December) and low-rain months (May, June, July, August, and September). The load profile for low-rainfall months, which is an approximately fixed value for 5 months, is shown in Figure 3 and Figure 4, and is shown as monthly load profiles.

The graph of the load changes during the year is shown in Figure 4. In the middle 5 months of the year, the consumption increases by about 50 kW, and the important role of the grid photovoltaic system plays out in this time interval.

2.3. Radiation Information

The study area is located at 34.45° north latitude and 49.15° east longitude. By entering latitude and longitude along with time parameters in the HOMER software, it receives the radiation information of the desired location along with the resolution index from the database. As shown in Figure 5, the intensity of the daily radiation is in good condition, and its average value is 7.8 kW h/m². day, which is a good value for the energy production through the PV system.

A noteworthy point in comparing the intensity of the radiation and the load diagram is that the amount of radiation is higher when the amount of load consumed is high. Moreover, this increases the share of the charge feeding through the grid photovoltaic system during peak load and reduces the pressure on the public electricity grid during peak times.

2.4. The Purchase Price and the Sale of Electricity (Economic Parameters)

The energy purchase and sale prices from the grid are entered in the HOMER grid section in three parts, the peak, intermediate, and nonpeak times. The selling price of electricity to the consumer is 0.140 USD/kWh. The selling price of the photovoltaic system to the network is 0.11 USD/kWh.

How to apply these values in the software, along with the load-consumption schedule, can be seen in Figure 6. It can be seen that the peak amount occurs in the middle five months of the year and from 6 a.m. to 6 p.m. The interest rate for Iran in 1990 was 11.4 percent (10), and this amount is included in the HOMER economic sector along with the system life of 25 years. The cost that will be shown in the output to build the system is the net present cost (NPC).

In the process, the net metering mode is considered. Net metering is a billing scheme that allows a grid photovoltaic system to retail (low power) the grid. In fact, the electrometer does the opposite when we sell to the grid. At the end of the period (monthly or yearly) the amount of energy used will be calculated as the energy purchased minus the energy sold to the grid. If the net amount purchased from the network is negative, it means that the amount of system sales to the network in that period was more than the amount purchased from the network, and the network will pay for it according to the rate determined.

2.5. Specifications of the Desired System

The system includes PV panels, batteries, inverters, mains, and load (Figure 7). PV panels absorb solar energy and convert it to DC voltage. The DC voltage generated by the inverter is converted to AC voltage. The output of the inverter connected to the AC line is a three-phase 415 VAC. The load is single- or three-phase depending on how the consumer connects. The batteries are charged when the power from the PV power supply is left full.

This is called a load-tracking strategy. The battery bank is used at low-radiation times to increase the output power. At night, without radiation, the network enters into operation. The two-way arrows show the ability to move current in both directions. The grid photovoltaic system can either use batteries to store energy or it cannot use it and injects all the extra electricity into the grid. In the obtained results, the condition with and without batteries will be investigated.

2.6. Technical Specifications of the Equipment

2.6.1. PV Array

In the HOMER software, in the section related to the photovoltaic system, the required amount of power and initial cost, replacement, repair, and maintenance, along with the life of the PV system, are entered. Depending on the load and condition of the system that is connected to the network, two values of 80 kW and 100 kW have been entered. Each of the PV modules used to form the PV presentations is W 170 with a rated voltage of 24 V. The specifications of the PV module used can be seen in

Table 1. Specifications of the equipment used.

Components	Characteristics	Amount
PV array	Size	100 kW
	Initial cost	3882 USD/kW
	Replacement fee	3000 USD/kW
	Maintenance cost	100 USD/yr
	Lifetime	25 year
Inverter	Size	100 kW
	Connection mode	Three-phase
	Initial cost	429 USD/k
	Network voltage and frequency	415 VAC50/60
	Maintenance cost	0 USD/yr
	Lifetime	16 year
	Efficiency	95%
Battery	Rated voltage	6 v
	Nominal capacity	1156 Ah
	Initial cost	USD 1200
	Replacement fee	USD 1000
	Maintenance cost	10 USD/yr

. The cost of each module is USD 660, so the initial cost of PV is considered to be 3882 USD/kW. Due to the fact that the lifespan of the modules is 25 years, which is equal to the operating time of the system, the cost of replacement is not considered. The maintenance cost of each module will be 0.01 of their initial cost for each year. The panels are mounted at a fixed angle, although the software has the ability to detect solar radiation to absorb the most power.

2.6.2. Inverter

The 100 kW inverter with AC output and DC input is used in the design. The output of the three-phase inverter is 425 VAC 50/60. The initial cost of this inverter is USD 42,900 (429 USD/kW). The cost of operation and maintenance of the inverter is considered zero. Its yield is 95.5% with a lifespan of 16 years. This means that the system is replaced once during operation. The cost of replacing the inverter is USD 40,000 (400 kW/USD). The inverter selected for the system must have features that make the system stronger. Good control systems can be used for the designed system, such as multilevel inverter control schemes that can be used in multilevel inverter structures in any type of renewable energy sources [11].

2.6.3. Battery Bank

In the HOMER batteries section, various models with different powers and capacities can be seen. The type of battery used is surette 6cs25P [12]. The battery voltage is 6 volts and its capacity is 1156 Ah. To have a 24 V output (nominal panel voltage), which is a DC bus voltage, 4 batteries are connected in a series in each row. Batteries can be discharged in about an hour during low-light or shady conditions. The minimum charge mode is 40% and the upper limit is 80%. The initial cost and replacement of each battery is USD 1200 and USD 1000, respectively. The cost of operation and maintenance of each battery is estimated at 10 USD/yr. In terms of the HOMER size for the battery, values of 0, 2, 3, and 4 are placed to show the best result. In the combinations shown for the system, the values 0, 4, 12, and 16, will be seen due to the fact that there are 4 batteries in each row. Table 1 shows the specifications of the equipment used in the grid-connected PV power plant.

2.7. Pollution

Under the Kyoto Protocol, an agreement was reached between member countries to reduce greenhouse-gas emissions [13]. Greenhouse gases, such as methane, carbon dioxide, water vapor, and nitrous oxide, in the Earth’s atmosphere will raise the Earth’s temperature, which will cause unpleasant changes to the environment. Recently, another international conference was held in Durban, South Africa, which extended the provisions of the Kyoto Protocol for another five years (until 2016). Under the provisions of this regulation, industrialized countries pledged to emit greenhouse gases within 10 years up to 5% and support developing countries in using renewable energy. The grid power supply has its own pollution from conventional methods [14].

Table 2. Pollution parameters.

Network Infection Rate (g/kWh)	Expense (USD/Ton)	Type of Pollutant
692	24	CO2
1	45	CO
2.84	4400	SO2
0.1	10,000	pm
2.63	1400	NO

shows the amount of pollution generated per kilowatt hour at a cost per ton. Pollution values and their costs are entered in the HOMER network pollution section. Therefore, the costs that are spent on the production of electricity in the public grid are also applied to pollution in this simulation, so we will have more realistic prices than the cost of energy production. The use of a grid photovoltaic system will not lead to pollution costs, which will be a significant amount in the 25 years of the system operation. In the results section, these values will be determined according to the energy produced by the grid photovoltaic system.

3. Results

To perform the simulation by the HOMER software, taking into account the load of the study site and the technical specifications of the equipment for each part of the system, the values were selected as follows: For the network, the value of 200 kW was considered, and the required value is proportional to the amount. The renewable system used will be selected. Obviously, more use of the renewable system will lead to less network use. For the inverter, two values of 80 and 100 kW have been entered, which is proportional to the energy produced by the PV modules. The amount of batteries is also given as zero, two, four, and six, which, due to the fact that there are four 6-volt batteries in each row, the values of 0, 8, 16, and 24 will be displayed for the batteries. These values are seen in different combinations with one of the 80 kW and 100 kW values for the photovoltaic system, as shown in the simulation results in

Table 3. Optimization results obtained from the HOMER software.

(kW)		(kW)	(kW)	Initial Capital	Operating Cost (USD/yr)	Total NPC	COE (USD/kWh)	Ren. Frac.
			200	USD 0	40,480	USD 432,116	0.174	0.00
	8	80	200	USD 43,92	41,452	USD 486,410	0.196	0.00
	8	100	200	USD 52,500	41,580	USD 496,358	0.200	0.00
	16	80	200	USD 53,520	41,911	USD 500,913	0.202	0.00
	16	100	200	USD 62,100	42,039	USD 510,861	0.206	0.00
	24	80	200	USD 63,120	42,370	USD 515,415	0.207	0.00
	24	100	200	USD 71,700	42.499	USD 525,363	0.211	0.00
80		80	200	USD 276,640	24.483	USD 537,990	0.216	0.47
80		100	200	USD 285,220	24,611	USD 547,938	0.220	0.47
80	8	80	200	USD 286,240	24,943	USD 552,505	0.222	0.47
100		80	200	USD 337,220	20,615	USD 557,280	0.224	0.56
80	8	100	200	USD 294,820	25,072	USD 562,453	0.226	0.48
100		100	200	USD 345,800	20,705	USD 566,816	0.228	0.56
80	16	80	200	USD 295,840	25,404	USD 567,025	0.228	0.48
100	8	80	200	USD 346,820	21,075	USD 571,793	0.230	0.56
80	16	100	200	USD 304,420	25,532	USD 576,973	0.232	0.48
100	8	100	200	USD 355,400	21,165	USD 581,331	0.234	0.56
80	24	80	200	USD 305,440	25,865	USD 586,548	0.234	0.48
100	16	80	200	USD 356,420	21,536	USD 586,310	0.236	0.56
80	24	100	200	USD 314,120	25,994	USD 591,496	0.238	0.48
100	16	100	200	USD 365,000	21,626	USD 595,849	0.240	0.56
100	24	80	200	USD 366,020	21,997	USD 600,831	0.242	0.56
100	24	100	200	USD 374,600	22,087	USD 610,371	0.246	0.56

.

3.1. Energy-Generation System without the Use of Renewable Sources

Among the results, it can be seen that the cheapest combination of power generation mode with the grid without the use of photovoltaic system. The total cost of the NPC in this case is USD 432,116 and the cost of energy production is 0.174 USD/kWh (COE). The operating cost of the system is 40,480 yr/USD, which is obtained by multiplying the total energy purchased from the grid by the purchased price. The initial cost of this mode is zero due to the use of any PV panel, inverter, and battery. Figure 8 and Figure 9 and

Table 4. Energy-generation system without the use of renewable sources.

Production	kWh/yr	%	Consumption	kWh/yr	%	Quantity	kWh/yr	%
Grid purchases	232,870	100	AC primary load	232,870	100	Excess electricity	0.00	0.00
Total	232,870	100	Total	232,870	100	Unmet electric load	0.00	0.00
						Capacity shortage	0.00	0.00
				Quantity		Value
				Renewable fraction		0.00

show the cost of the network along with the costs of pollution. It can be seen that USD 84,098 of the total system cost is related to pollution, which is a significant amount. The total energy used is 232,870 kWh/yr, which is supplied only through the network, of which the participation rate of the renewable system in this case is zero.

It is quite clear that the amount of purchases from the network will peak in the middle 5 months of the year, as shown in Figure 9. The purpose of this article is to add a grid photovoltaic system to the grid during this period as a supplement to prevent any voltage drop during peak times, and also to sell the extra amount of PV-produced energy to the grid during low-consumption months. This is not the case, because the goal is to develop the use of renewable systems and also because of the mentioned pollutants and dependence on fossil fuels.

3.2. Energy-Generation System Using a Renewable System

Modes in which the renewable system plays a role in the production of energy as a complement to the grid are the modes in which the values of 80 kW and 100 kW of the PV panels are used. Considering the amount of load, and considering that, in this article, we want the grid photovoltaic system to play an important role in energy production, we examine the amount of 100 kW of the PV system. The cheapest combination that can be seen for the 100 kW panel in the results is the 100 kW panel with the 80 kW inverter. In this case, the battery is not used. The initial cost for this system is USD 337,220, the operating cost is 20,615 yr/USD, and the total NPC is USD 557,280. The cost of energy production in this combination is 0.224 kWh/USD and the participation rate of the renewable system in this case reaches 56%. Figure 10 and

Table 5. Economic analysis for the energy-generation system using a renewable system.

Component	Capital (USD)	Replacement (USD)	O & M (USD)	Fuel (4)	Salvage (USD)	Total (USD)
PV	302,900	0	53,374	0	0	356,274
Grid	0	0	130,383	0	0	130,383
Converter	34,320	7005	0	0	−1533	39,792
Other	0	0	30,831	0	0	30,831
System	337,220	7005	214,588	0	−1533	557,280

show the costs associated with the PV system, inverter, network, and pollution. In the replacement section, only the inverter, which has a lifespan of 16 years, is charged, and its maintenance cost is zero.

The operating cost of the system in this case is 19,865 yr/USD, which is less than in the previous case, because some of the extra energy that is out of demand is sold to the network during the day when there is a lot of radiation. The photovoltaic system shows a network reducing the cost of the energy produced in the future. In this case, there is also a significant reduction in pollution, which will reduce costs by USD 53,267. The amount of energy produced by the photovoltaic system is shown in Figure 11 and

Table 6. The amount of electrical energy produced by the photovoltaic system.

Production	kWh/yr	%	Consumption	kWh/yr	%	Quantity	kWh/yr	%
PV array	164.155	56	AC primary load	232.870	84	Excess electricity	266	0.09
Grid purchases	128.505	44	Grid tables	43.134	16	Unmet electric load	0.00	0.00
Total	292.660	100	Total	276.004	100	Capacity shortage	0.00	0.00
				Quantity		Value
				Renewable fraction		0.561

. Of the total energy produced by the PV system in this case (239,594 kWh/yr), there are 43,134 kWh annual electricity sales to the grid. It can be seen that electricity sales to the network are made during nonpeak times.

Table 7. The amount of energy sold and purchased from the grid.

Month	Energy	Energy	Net	Peak	Energy	Demand
	Purchased	Sold	Purchases	Demand	Charge	Charge
	(kWh)	(kWh)	(kWh)	(kW)	(USD)	(USD)
January	8949	4743	4206	38	589	0
February	7218	4925	2293	36	322	0
March	7640	7465	175	38	97	0
April	6952	7708	−756	38	−8	0
May	14,957	58	14,899	63	2086	0
June	14,542	23	14,519	63	2033	0
July	14,814	33	14,781	56	2069	0
August	14,883	82	14,800	57	2072	0
September	13,697	254	13,443	58	1882	0
October	7641	8017	−377	35	39	0
November	8191	5576	2615	37	366	0
December	9021	4249	4772	37	668	0
Annual	128,505	43,134	85,371	63	12,214	0

show the amount of energy sold and purchased from the grid.

Considering that net metering is included in the network section, the energy charge is obtained according to Equation (1) [29,30]:

$$C_{grid,energy}={\displaystyle \sum _i^{rates}{\displaystyle \sum _j^{12}\left\{\begin{array}{l}{E}_{netpurchases,i,j}.C_{power,i}if{E}_{netpurchases,i,j}\ge 0\\ E_{netpurchases}.C_{sellback,i}if{E}_{netpurchases,i,j}<0\end{array}\right.}}$$

(1)

E_{netpurchases,i,j} is equal to the energy purchased from the grid minus the amount of energy sold on it in the jth month and in the ith period (peak, intermediate, nonpeak);

C_power (USD/kWh) is the purchase price of the electricity from the network in the period i;

C_sellback,i is the price of the electricity sold to the grid in period i.

Due to the significant amount of electricity sold to the grid, for the development of such small PV systems connected to the grid in similar areas across the country, the lack of energy is compensated, and, as a result, with the influence of production on consumption, the price of energy production will decrease. Although the consumer has to pay more than the grid for energy (COE) per kilowatt, this structure has a large share of clean renewable energy, and the amount of pollution emitted by the fuel due to the use of conventional methods such as diesel for he generator is reduced. In the meantime, the government can legislate to promote renewable energy. In the long run, the amount of COE will be reduced by changing tariffs and providing more support for the renewable system, as well as reducing equipment costs.

3.3. Analysis of Grid-Connected Photovoltaic System with Energy Storage

The task of energy storage is to store excess energy from energy sources and to support energy when the PV output is low due to low radiation. The type of battery used is the surette 6cs25p. In the simulation, a load-tracking strategy is used in which the battery is charged when the PV meets the load requirements and the excess value remains. According to Figure 12 and

Table 8. Economic analysis for the electrical-energy-generation system using a renewable system with energy storage.

Component	Capital (USD)	Replacement (USD)	O & M (USD)	Fuel (4)	Salvage (USD)	Total (USD)
PV	302,900	0	53,374	0	0	356,274
Grid	0	0	130,398	0	0	130,398
Surrette 6CS25P	9600	5326	854	0	−1285	14,495
Converter	34,320	7005	0	0	−1533	39,792
Other	0	0	30,834	0	0	30,834
System	346,820	12,332	215,460	0	−2818	571,793

, for the results obtained for the PV kW 100 system and the 80 kW inverter, the system cost also increases with the increase in the number of batteries, so the use of eight batteries in this combination will have the lowest cost. The initial cost in this structure is USD 346,820, its operating cost is 21,075 USD/yr, the total NPC is USD 571,793, and its COE is 230 USD/kWh. It is clear that the cost of energy production in this case is higher than the cost of the previous case.

Table 9. The amount of energy produced by the photovoltaic system and energy storage.

Production	kWh/yr	%	Consumption	kWh/yr	%	Quantity	kWh/yr	%
PV array	164.155	56	AC primary load	232.870	84	Excess electricity	266	0.09
Grid purchases	128.504	44	Grid tables	43.124	16	Unmet electric load	0.00	0.00
Total	292.659	100	Total	275.994	100	Capacity shortage	0.00	0.00
				Quantity		Value
				Renewable fraction		0.561

shows the amount of energy produced by the photovoltaic system and the energy storage.

As shown in Figure 13, the amount of energy sold is reduced by a small amount compared to the previous case. The share of renewable energy is similar to the state without storage, at about 56 percent. By analyzing the obtained results, the amount of power with the cost of energy production for three modes is shown. Now, considering the objectives of the article, which is to produce energy with a clean source at a reasonable cost, the 100 kW mode of the photovoltaic system and the 80 kW inverter without energy storage is a suitable combination for the connection to the grid because this mode does not produce pollution in the energy production through the network and also because its cost is less than the mode of the photovoltaic system with storage.

As can be seen, the use of batteries does not have much effect on the amount of power and the cost of energy production in this case increases. Therefore, the 100 kW PV mode with the 80 kW inverter without energy storage with a power of 164,155 kWh/yr is considered as the best combination available.

4. Conclusions

Due to declining fossil fuel reserves due to population growth, the use of alternative sources is inevitable. Meanwhile, solar energy is one of the potential sources for electricity generation due to its availability in all parts of the Earth. Renewable resources can be used in two ways: systems connected to the network and disconnected from the network. Therefore, using renewable grid-connected systems where the grid is available may be a better option. One of the important results of this research is the low-investment cost of the grid-connected system compared to the grid-disconnected system, in which case the cost of each unit of energy is significantly reduced and the system is economically viable. From an environmental point of view, using a grid-connected system is a good option for two reasons: the lack of a backup system and, on the other hand, injecting excess electrical energy into the grid because, in this case, it significantly prevents the release of polluting gases. After checking the results, it was found that, for producing energy with a clean source at a reasonable cost, the 100 kW mode of the photovoltaic system and the 80 kW inverter without energy storage is a suitable combination for connection to the grid, as, in this scenario, 56% of the required load was provided by renewable energy sources. Some future work includes:

• Load management from the demand side to depeak and reduce the cost of energy production.
• Exergy analysis of production resources to increase overall system efficiency.
• Using intelligent optimization algorithms to reduce costs and increase reliability.