Cellular mobile technology has witnessed tremendous growth in recent times. One of the challenges facing the operators to extend the coverage of the networks to meet the rising demand for cellular mobile services is the power sources used to supply cellular towers with energy, especially in remote. Thus, switch from the conventional sources of energy to a greener and sustainable power model became a target of the academic and industrial sectors in many fields; one of these important fields is the telecommunication sector. Accordingly, this study aims to find the optimum sizing and techno-economic investigation of a solar photovoltaic scheme to deploy cellular mobile technology infrastructure cleanly and sustainably. The optimal solar-powered system is designed by employing the energy-balance procedures of the HOMER software tool. The problem objective is considered in terms of cost, but the energy system is constrained to meet the power demand reliably. Process simulations were performed to determine the optimum sizing, performance and monetary cost of the power system, using long-term meteorological datasets for a case study site with defined longitude (31° 25′ E) and latitude (30° 06′ N). From the observed results, the total net present cost (NPC) of the proposed system is $28,187. Indeed, these outcomes can provide profound economic, technical, and ecological benefits to cellular operators. It also ensures a sizeable reduction in greenhouse gas that supports sustainable green wireless network (WN) deployment in remote areas.

Cellular mobile technology has witnessed tremendous growth in recent times. The rising acceptance and accessibility of mobile broadband services are motivating a change in the engagement patterns of mobile users from basic voice to data-centric services. One of the challenges facing the operators to extend the coverage of the networks to meet the rising demand for cellular mobile services is the power sources used to supply cellular towers with energy, especially in remote areas. Accordingly, the growing demand for a sustainable energy system has made alternative power sources a promising field of investigation due to sustainability with negligible carbon emissions [

Mobile base stations (BSs) are the key consumers of the energy used by the operators, e.g., around 57%, as mentioned in [

Further, it is expected to rise immensely in the impending days due to the different sorts of IoT devices [

The researchers concentrate on several distinctive methodologies to decrease the energy consumption rate in WNs, notably effectual usage of radio transmission practice, energy-efficacy hardware modules, discerning operation of such modules, positioning heterogeneous cells, and employing renewable energy sources (RESs) [^{2} (December) to 7.44 kWh/m^{2} (June) [

However, the solar energy viability system depends on various factors comprising the mix of energy resources, distributed capacity, and control strategy. The HOMER model is used by developing an energy balance scheming for each hour of 8,760 h/year to overcome these issues. Moreover, it compares the actual load demand for every hour with generated energy. It also manages the charging and discharging features of the batteries and computes the installation and operating cost for the project's complete lifespan. Considering all these advantages, the HOMER platform is adopted to achieve the techno-economic viability of the PV-driven LTE-BS. The contributions of this work are summarized as follows:

Development of solar energy system for sustainable operation of modern cell sites.

To examine, analyze, and evaluate the energy balance for the proposed powered system.

To examine, analyze, and evaluate the feasibility of a standalone solar system to attain maximum energy harvest and cost savings to warrant both cost-effectiveness and sustainability.

The remaining of this article is organized as follows; Section 2 describes the associated literature studies. Section 3 demonstrates the system construction and mathematical modeling. Section 4 displays the study site, data, and configurations. Then, results and discussion are designated in Section 5. Section 6 concludes the work considering the observed outcomes.

The study [

Several studies have considered the capacity and efficiency problems of future wireless networks for sustainable energy management. The issues related to environmental concerns, high-power consumption, and insufficient energy-saving techniques are escalating rapidly in communication technologies. An insight into existing energy sustainable paradigms geared at obtaining highly sustainable and cost-effective networks was presented in [

Authors in [

Nevertheless, more comprehensive power models and advanced optimization techniques are currently needed. In this study, the optimum size and techno-economic examination of a PV system. The objective is to switch from the typical grid diesel hybrid to a greener and sustainable power alternative. The solar system is expected to satisfy the energy requirement of the cellular infrastructure at reduced cost with a high renewable portion.

The architecture and model of the hybrid energy system, as presented in

This backhaul network configuration has different sub-units such as DC-DC Power supply, radio-frequency (RF), multiple transceivers (TRXs), power amplifier (PA), Base band (BB) and cooling systems. Specifically, TRXs encompass PA that amplifies the signal power received from the Base band units. Further, the internal processing and programming are performed using base band units. The BS (cellular) comprises several equipment and components and can be adapted to communicate with cellular modules. Also, a comprehensive description of the BS modules can be referred in [

Elements | Parameters | Unit | Power consumption |
---|---|---|---|

PA | Watts | 102.60 | |

RF | Watts | 10.90 | |

BB | Watts | 14.80 | |

Loss factor 1 (_{DC} |
% | 06.00 | |

Loss factor 2 (_{cool} |
% | 10.00 | |

Watts | 151.65 | ||

No. of transceivers _{TRX} = N_{Sect} _{Ant} _{Carr} |
06.00 | ||

Total power of the BS _{BS} = N_{TRX} × Total power/TRX |
Watts | 909.93 |

It consists of numerous interconnected solar cells (both series and parallel connections) to design PV modules. The developed module produces DC power by means of shortwave irradiance on the panel surfaces. The net annual energy extraction from the solar PV arrangement (_{PV}_{PV}_{PV}

The capacity of the battery banks used in BS purely hinges on the depth of discharge (DOD) estimated using _{min}_{batt}_{batt} and V_{nom}_{nom}_{prim, ave}

It is a known fact that the lifetime of the battery modules plays a vital role. It can be anticipated considering the operating conditions of the complete system. Pointedly, the DOD of the battery module during each diurnal charge-discharge phase exhibits a leading role in the battery life, and it can be calculated as [_{lifetime}_{thrpt}_{battf}

The net inverter capacity (_{inv}_{AC} _{sf}

The arrangement of PV-powered base station is considered based on the following factors: the vital components that must be used in the system design; a number of components adopted; the size of the individual component. To attain an optimum PV system with lesser net present cost (NPC), the HOMER Micro-power optimization tool is adapted. The NPC covers all incurred expenditures and profits throughout the venture lifetime, and it can be computed using the below equation:

The term TAC signifies a total annualized cost representing the cost of complete arrangement in $/year. It encompasses various costs such as operation and maintenance (O & M) costs, initial capital (IC) costs, and replacement costs.

Similarly, _{NPC}

The full NPC is reduced markedly owing to salvage value (S) precisely at the end of the venture lifetime, and it can be computed using the below equation;
_{comp}_{rem}_{rep}

This work examines to reduce the total NPC considering several constraints. Further, the objective function of the NPC can be computed using the below equation to accomplish system optimization.

The above-mentioned objective function is exposed to the succeeding constraints:

It is essential to maintain the power generation of the available sources (_{PV}_{Battery}_{BS}_{Losses}

The anticipated region for PV-powered BSs is usually in the mid-latitudes between 30° north and south. Specifically, low latitudes are recognized as the most lucrative regions for solar PV-based BSs [

Considering the economic factors, the net NPC is taken as $28,187 that encompasses 4.5 kW solar PV modules and 64 batteries, and they are connected in 8 parallel arrangements along with an inverter of 0.1 kW. The total energy output is observed from the designated system as 7,372 kWh (4.5 kW × 5.28 h × 0.85 × 365 days/year), which is estimated using

The optimum capacity of the battery bank that is computed by the HOMER software for the designated system is 64 units. Pointedly, the voltage rating of a single battery is estimated to be 6 V_{dc} (Trojan L16P), and its capacity is determined as 360 Ah. To attain the required ratings, a total of 64 batteries are associated in both series and parallel that could maintain the constant voltage of 48 V_{dc} connected in the bus bar. The roundtrip efficiency of the battery reached 85%, calculated between the ratios of yearly energy output and input, i.e., 4,369 and 5,139 kWh, respectively. Approximately, the battery bank feeds the energy to the load for nearly 106 h, notably during the failure of the PV array. Based on the inferences from

Elements | Parameters/factors | Values |
---|---|---|

Control factors | Interest rate-annual (Jul. 2021) | 8.5% |

Project lifetime | Ten years | |

Inverter | Sizes considered | 0.1, 0.2, 0.3, 0.4 kW |

Efficiency | 95% | |

Operational lifespan | 15 years | |

IC price | $ 0.4/Watt | |

Replacement cost | $ 0.4/Watt | |

O & M price per year | $ 0.01/Watt | |

Solar-PV | Sizes considered | 2, 2.5, 3, 4, 4.5, 5 kW |

Operational lifespan | 25 years | |

Efficiency | 85% | |

IC price | $ 1/Watt | |

Replacement cost | $ 1/Watt | |

O & M price/year | $ 0.01/Watt | |

Trojan L16P battery | Number of batteries | 24, 32, 40, 64, 72 |

Round trip efficacy | 85% | |

Minimal operational lifetime | Five years | |

IC | $ 300 | |

Replacement | $ 300 | |

O & M price/year | $ 10 |

The total inverter capacity is considered as 0.1 kW, and its efficacy is figured between the input (837 kWh) and output energy (795 kWh) annually and perceived as 95%. Also, the net operating hours are found to be 8,759 h/year (24 h × 365 days/year).

The total capital of the PV array is $4,500, which is computed as 4.5 kW (size) × $1,000/1 kW (cost). The O&M cost of the PV array considered low is $450 which is computed as 4.5 kW (size) × $10/1 kW (cost) × 10 years (macro LTE-BS lifetime). Due to the higher lifetime of PV panels (25 years) compared with project lifetime (10 years); the replacement cost of the solar system is zero. Further, the PV array's salvage value is $2,400, calculated using

Further, the total capital of the battery is $19,200, which is computed as 64 (units) × $300/1 unit (cost). The O&M price of the battery units is considered high at about $6,400, which is computed as 64 (units) × $10/1 unit (cost) × 10 years (macro LTE-BS lifetime). Also, the battery pack's replacement cost is considered zero since the battery bank has a lifespan of 10 years, i.e., the macro LTE-BS lifetime. Thus, the normal net NPC of battery bank is $25,600, i.e., $19,200 (capital cost) + $6,400 (O&M cost) – $0 (salvage).

Similarly, the total capital of the inverter is evaluated and found to be $40 (0.1 kW (size) × $400/1 kW (cost)). The O&M price of the inverter is $10, which is computed as 0.1 kW (size) × $10/1 kW × 10 years (macro LTE-BS lifespan). The replacement cost again becomes zero because the inverter has a lifespan of 15 years higher than the project lifespan or macro LTE-BS lifetime of 10 years. The salvage value is $13. Thus, the normal net NPC of inverter is found to be $37, i.e., $40 (capital cost) + $10 (O&M cost) – $13 (salvage).

Consolidating the above inferences, the total NPC for the proposed solar system is $28,187. Notably, the battery bank evidently represents the bulk cost compared with other components. Nonetheless, this cost depends on the battery numbers used in the system. In this study, the optimum number of batteries was found to be 64 evaluated through HOMER software. Thus, the number of batteries used in the proposed case can be reduced significantly. However, the load autonomy declines, and it is considered a vital concern, specifically in off-grid areas. Further, the replacement cost of the entire cost is zero-based on the observed results because all the significant components, notably battery bank, PV panes, and inverter unit, have a higher lifetime than the project lifespan.

This work proposed a framework for an energy-efficient RES-based cellular network for Egypt off-grid sites using a PV module that acts as the primary and standalone source for the base stations to minimize the OPEX. Moreover, the architecture of the system, energy yield investigation, and economic exploration was discussed. From the observed results, it is revealed that the suggested PV-based system could possibly meet the net energy demand of the macro LTE-BS. Furthermore, the battery bank could meet the power demand of the macro LTE-BS load autonomy for 106 h; this figure is considered an adequate time to fix the solar PV array during malfunction scenarios. Regarding the economic aspect, the simulation outcomes exhibited that the anticipated solar PV system could achieve OPEX savings with a reliable energy supply. These results indicate that the PV-based power system is a good and effective choice for wireless network operators.