# Feasibility Analysis and Development of Stand-Alone Hybrid Power Generation System for Remote Areas: A Case Study of Ethiopian Rural Area

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## Abstract

**:**

## 1. Introduction

#### 1.1. Related Work

_{2}emission limit for the greenhouse effect. Refer to [11] for a critical examination of hybrid renewable energy modeling tools—an emerging opportunity to include social indicators to optimize systems in small communities was done, but it had its own limitations as it did not show any modeling of renewable energy resources or feasibility analysis.

#### 1.2. Research Gap

#### 1.3. Contribution

- Compare the possibilities of solar, wind, and micro-hydro hybrid renewable energy resources with grid extension.
- Design a hybrid energy source from solar, wind, or micro-hydro and supply sufficient electricity for the people living in Maji town.
- Make a comparison between the hybrid system’s capital costs and the cost of electrifying the regions by extending the electric grid.

## 2. Case Study Area Description

#### 2.1. Renewable Energy Assessment

#### 2.1.1. Solar Energy System

#### 2.1.2. Equivalent Model of PV Cell

_{S}depends on the p–n junction depth, impurities, and contact resistance. In a perfect PV cell, RS = 0 and RSh = ∞.

#### 2.2. Wind Energy System and Potential Assessment of Study Area

_{j}is the median velocity in class j and f

_{j}is the frequency of occurrence in the same class. For k = 2, the Weibull PDF is commonly known as the Rayleigh density function, in which case Equation (2) may be rewritten as in Equation (3) [2]

_{r}is reference height (m), Z is height (m), Z

_{0}is measure of surface roughness (0.1 to 0.25 for crop land), v(z) is wind speed at height of Z m (m/s), and v(z

_{r}) is wind speed at the reference height (m/s). Using the power law wind speed at a certain height above ground level can be given as follows [2]:

^{3}), A is the swept area (m

^{2}), P

_{w}is power in the wind (W), and v is instantaneous wind velocity (m/s)

_{p}. The optimum (highest value for CP) of this function is 0.59 [2]. As a result, the wind turbine’s energy output can be stated as

_{w}out is the output power of wind turbine, ${\mathsf{\eta}}_{\mathrm{t}}$ is the overall efficiency of the transmission system, and C

_{p}is the power coefficient.

^{−1}K

^{−1}), and T is air temperature in 0 K. If the elevation Z′ (m) and temperature T at a site are known, then the air density can be calculated by [9]:

#### 2.3. Micro Hydro Power

#### 2.4. Electrical Load Calculation of Maji Town

#### 2.5. Load Forecasting

_{t}is the total present power, R is the annual electric growth (load factor), and N is number of forecasted years.

## 3. Overall System Design

#### 3.1. Solar Energy System Design

- The generated energy above showed the maximum load that will be used in the town. Therefore, the total AC load used is 5455.35 kWh/day.
- Multiply ${\mathrm{Ed}}_{\mathrm{pv}}$ by 1.25 to correct for inverter loss and battery efficiency. So, the corrected energy generated is 4931.84 kWh/day
- Choose the inverter DC input voltage, usually 12 V, 24 V, or 48 V.For energy up to 1 kWh, 12 V is used; energy up to 4 kWh, 24 V is utilized; and for energy greater than 4 kWh, 48 V is utilized. Therefore, in this work, 48 V is utilized as the total energy generated from the PV panel is about 4931.8 kWh/day.
- Divide corrected ${\mathrm{Ed}}_{\mathrm{pv}}$ by 48 V. This will provide the total amp hours per week used by AC loads, i.e., 102,746.55 Ah/day.

#### 3.1.1. PV Modules Calculation

_{pv}by 1.2–1.4. Therefore, the average amp hours per day are 123,295.86 Ah/day. The average sunshine hours per day are 8 h/day. The total solar array amps required is 15,411.98 A. Optimum or peak amps of the solar module used will be determined by the selected module specifications. Table 4 presents the PV module specifications.

#### 3.1.2. Steps for Sizing Battery

- Lead acid batteries model S1900
- Rated capacity = 1900 Ah
- Battery voltage = 12 V
- Number of batteries in parallel =$\frac{\mathrm{Required}\mathrm{Battery}\mathrm{Capacity}}{\mathrm{Capacity}\mathrm{of}\mathrm{selected}\mathrm{Battery}}$ = $\frac{231,179.74\mathrm{Ah}}{1900\mathrm{Ah}}$ = 121.67 batteries ≈ 122 batteries
- To determine the number of batteries required in series, divide the system voltage (48 V) by the voltage of the chosen battery (12 V).
- Number of batteries in series =$\frac{\mathrm{Nominal}\mathrm{System}\mathrm{Voltage}}{\mathrm{Nominal}\mathrm{Battery}\mathrm{Voltage}}$ = $\frac{48\mathrm{V}}{12\mathrm{V}}$ = 4
- Total number of the batteries needed = batteries in parallel × batteries in series =122 × 4 = 488 Batteries

#### 3.1.3. Charge Controller (MPPT)

#### 3.1.4. Inverter Sizing and Rating

#### 3.1.5. Area Covered by PV Modules

- Glass reflection factor or due to sun light striking panel straight is 5%;
- Allowance for panel being bellow specification and for aging is 5%;
- Dust particles are 10%.

#### 3.1.6. Area for PV Panel

^{2}/day). For this project, the data from NASA indicated that the average solar radiation in least sunny month is July, at 5.19 kWh/m

^{2}/day.

_{panel}= 0.95 × 0.95 × 0.9 = 0.82.

^{2}area; therefore, the area required by the PV farm is 9863.67 m

^{2}.

#### 3.2. Wind System Parameter Computation

_{p}is computed as 0.414. Based on the C

_{p}, the calculated wind power (P

_{w}) is 429.13 kW. The annual energy generation (${\mathrm{E}}_{\mathrm{generated}\mathrm{annually}}$) and capacity factor for the proposed wind system are 569,310.49 kWh and 0.39, respectively [21]. Table 6 presents the computed parameters of the wind generation system.

#### 3.3. Micro-Hydro Power Generation Design

#### Calculated Parameters of the Micro Hydro Power Plant

#### 3.4. Result and Discussion

#### 3.4.1. HOMER Input Data

#### 3.4.2. Economic Modeling

#### 3.5. Hybrid System Architectures

## 4. Results and Discussion

#### 4.1. Results

^{2}/day, an average flow rate of 1.6 m

^{3}/s, a wind operational reserve of 5%, and the highest allowable annual capacity shortfall of 5%. According to the above modeling, the fairest model for Maji town was a hybrid solar/battery/micro-hydro/converter with a 500 kW of solar, 18 kW × 9.28 wind turbines, 500 Hoppecke 16OPzS 2000 batteries (each 2000 Ah capacity), and a 916 kW bi-directional inverter (Figure 6, the final row). This “ideal” system used 100% renewable power, and the price of power was $0.81/kWh (a net present cost of $4,377,731), including capital depreciation and levelized operation and maintenance costs. Figure 7 shows the energy generation from various PV, wind, and micro-hydro elements of the overall main energy need (2,742,499 kWh/y). Wind turbines provided 498,380 kWh/day (18% of the total energy provided), solar PV provided approximately 37% of the total energy (1,003,250 kWh/y), and micro-hydro provided approximately 45% of the total energy (1,240,819 kWh/y) for this town. Even though there was a surplus of 2,113,023 kWh (77%) generated, there was only a capacity deficiency of 92,261 kWh (13.3%) over the year.

#### 4.2. Output of Economic Analysis

#### 4.3. Sensitivity Results

#### Comparative Analysis of the Cost of Standalone System and Grid Extension

#### 4.4. MATLAB/Simulink Validation

#### 4.5. Simulation Results and Discussion

^{2}and the average solar radiation in the least sunny month is 5.19kWh/m

^{2}/day for the case study areas, and the illuminance is 683,060.11 lux or 683,060 lm/m

^{2}. In Figure 11 for wind power generation, the average wind speed in the least windy season at a 10 m tower height is 3.6 m/s and at 50 m tower height is 4.44 m/s, which is sufficient to produce power as the minimum wind speed required to start to produce power is 3.5 m/s. Finally, in Figure 12, the flow rate of micro-hydro power is 1.6 m

^{3}/s. The simulation result of the designed standalone system is presented in the following figures.

#### 4.6. Practical System versus Ideal System

## 5. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## Abbreviations

AC | Alternating current |

Ah | Ampere hour |

COE | Cost of energy |

CP | Power coefficient |

CROM | Center for Research on Microgrids |

D | Rotor diameter |

DC | Direct current |

DFIG | Doubly fed induction generator |

HOMER | Hybrid optimization model for energy renewables |

ILSFA | Illinois Solar for All |

kWh | Kilo watt hour |

MPPT | Maximum power point tracker |

NPC | Net present cost |

NREL | National Renewable Energy laboratory |

° | Degree |

O&M | Operation and maintenance |

OPGW | Optical fiber ground wire |

Probability density function | |

PGF | Panel generation factor |

PV | Photovoltaic |

SNNPRs | South nation, nationality, and peoples regional state |

USD | United States Dollar |

WP | Watt peak |

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**Figure 2.**A PV cell equivalent electrical circuit [2].

**Figure 7.**Monthly average electric production of Maji town for the PV/wind/micro-hydro hybrid system.

Renewable Resource | Availability | Installed Cost | Control | Environmental Effect |
---|---|---|---|---|

Solar power | More | Less | Uncontrollable | No effect |

Wind power | Medium | Medium | Uncontrollable | No effect |

Hydro power | Medium | High | Controllable | No effect |

Biomass power | Medium | Very high | Controllable | Pollution deforestation |

Water Pumps for | Item | Rating (W) | Total Power (kW) | Usage (h/day) | Usage (day/week) | Energy (kWh/day) |
---|---|---|---|---|---|---|

Community | 6 | 15,000 | 90 | 6 | 6 | 540 |

Public service | 3 | 15,000 | 45 | 2 | 5 | 90 |

Reserve for community | 3 | 15,000 | 45 | 18 | _ | 810 |

Reserve for public service | 2 | 15,000 | 30 | 6 | _ | 180 |

Total | 210 | _ | _ | 1620 |

Loads | Working Time for Monday–Friday | Rating (W) | Power (kW) | Usage (h/day) | Usage (day/week) | Energy (kWh/day) | |
---|---|---|---|---|---|---|---|

Lighting | 13:00–17:00 | 11 | 18.194 | 5 | 7 | 90.97 | |

Television | 12:00–16:00 | 60 | 14.46 | 4 | 7 | 57.84 | |

Radio rating | 03:00–11:00 | 5 | 2.93 | 8 | 7 | 23.44 | |

Cell-phone recharge | 13:00–15:00 | 3 | 1.56 | 2 | 7 | 3.12 | |

Refrigerator | Café | 00:00-23:00 | 475 | 2.85 | 24 | 7 | 68.4 |

Home | 00:00−23:00 | 70 | 0.84 | 24 | 7 | 20.16 | |

Clinic | 00:00−23:00 | 80 | 0.08 | 24 | 7 | 1.92 | |

Electric stove | 01:00–02:00, 13:00–15:00 | 2000 | 200 | 3 | 7 | 600 | |

Electric mitad | 01:00–02:00 | 3000 | 240 | 1 | 3 | 720 | |

Hotels | 02:00–14:00 | - | 1.53 | 12 | 7 | 18.36 | |

Barber shop | 03:00–12:00 | - | 0.408 | 9 | 7 | 3.672 | |

Good shops | 02:00–14:00 | - | 0.515 | 12 | 7 | 2.22 | |

Computer | Desktop | 03:00-06:00, 08:00−11:00 | 120 | 6.48 | 6 | 5 | 38.88 |

Printer | 03:00−05:00, 08:00−10:00 | 100 | 0.8 | 4 | 6 | 3.2 | |

Copy | 03:00−06:00, 07:00−11:00 | 120 | 0.96 | 7 | 6 | 6.72 | |

School | 03:00–06:00, 08:00–10:00 | 12.09 | 7 | 7 | 84.63 | ||

Clinic | 13:00–00:00 | 1.512 | 12 | 7 | 17.664 | ||

Municipality | 02:00–06:00, 07:00–11:00 | 5.241 | 8 | 7 | 41.928 | ||

Religious institution | 00:00–02:00,11:00–13:00 | 2.445 | 5 | 7 | 12.225 | ||

Flour-making mill | 02:00–12:00 | 12,500 | 250 | 10 | 7 | 2500 | |

Total | 762.89 | 3835.35 |

PV Module Model | Topsun TS-S420TA1 |
---|---|

Max Power | 420.0526 W |

Max Current | 8.62 Amps |

Max Voltage | 48.73 V |

Nominal Output Voltage | 48 Volts |

Lead Acid Batteries Model | S1900 |
---|---|

Rated Capacity | 1900 Ah |

Battery voltage | 12 V |

Parameters | Calculated Value |
---|---|

Shaft power (P_{w}) | 429.13 kW |

Diameter of turbine blades (D) | 128.74 m |

Radius of turbine blades (R) | 64.37 m |

Swept area (A) | 13,011.39 m^{2} |

Tip speed ratio (λ) | 4 |

Number of blades | 3 |

Starting torque (T) | 71,730.18 Nm |

Shaft speed | 0.27 rad/s |

Maximum torque (T_{max}) | 664.44 × 10^{3} Nm |

Height of tower (2.5 × R) | 160.93 m |

Spacing between towers | 643.72 m |

Width of hub | 18.93 m |

Mass of blade | 27,272.56 kg |

Parameters | Computer Values |
---|---|

Design flow rate (Q) | 1.6 m^{3}/s |

Head (H) | 30 m |

Efficiency of the turbine (${\mathsf{\eta}}_{\mathrm{t}}$) | 0.85 |

Efficiency of the generator (${\mathsf{\eta}}_{\mathrm{g}}$) | 0.76 |

Electric power (P) | 306 kW |

Runner diameter (D) | 3.12 mm |

Runner length (L) | 245.76 m |

Space between the blades (s) | 0.54 mm |

Number of blades (B) | 18 |

Radial rim width (α) | 0.53 mm |

Radius of blade curvature (${R}_{c}$) | 0.51 mm |

Static pressure (Ps) | 4.26 Psi |

Economical diameter (De) | 0.79 m |

Minimum thickness of the penstock (t_{min}) | 1.64 mm |

Component | Capital ($/kW) | Replacement ($) | O&M ($/year) |
---|---|---|---|

Solar (1 kw) | 2200 | 2200 | 0 |

Wind (1 kw) | 48,740 | 30,000 | 1000 |

Micro-hydro (1 kw) | 750,000 | 250,000 | 800 |

Inverter | 700 | 700 | 0 |

Battery (1 Qty) | 900 | 600 | 0 |

Component | Capital (USD) | Replacement (USD) | O&M (USD) | Fuel (USD) | Salvage (USD) | Total (USD) |
---|---|---|---|---|---|---|

PV | 220,000 | 0 | 0 | 0 | 0 | 220,000 |

SW Skystream 3.7 | 2,437,000 | 0 | 533,739 | 0 | 0 | 2,970,739 |

Hydro | 750,000 | 0 | 8540 | 0 | 0 | 758,540 |

Hoppecke 16 0PzS 200 | 7200 | 1030 | 2562 | 0 | −526 | 10,266 |

Converter | 282,800 | 89,150 | 0 | 0 | −13,765 | 358,186 |

Other | 60,000 | 0 | 0 | 0 | 0 | 60,000 |

System | 3,757,000 | 90,180 | 544,840 | 0 | −14,290 | 4,377,731 |

Name | Nearest Substation | Voltage Level | Unit Cost/km ($) | Total Transmission Line Cost ($) | O& M Cost | Total Cost ($) of Grid |
---|---|---|---|---|---|---|

Maji | Mizan Aman | 132 kv | 125,000 | 21,750,000 | 435,000 | 22,185,000 |

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## Share and Cite

**MDPI and ACS Style**

Bayu, E.S.; Khan, B.; Hagos, I.G.; Mahela, O.P.; Guerrero, J.M.
Feasibility Analysis and Development of Stand-Alone Hybrid Power Generation System for Remote Areas: A Case Study of Ethiopian Rural Area. *Wind* **2022**, *2*, 68-86.
https://doi.org/10.3390/wind2010005

**AMA Style**

Bayu ES, Khan B, Hagos IG, Mahela OP, Guerrero JM.
Feasibility Analysis and Development of Stand-Alone Hybrid Power Generation System for Remote Areas: A Case Study of Ethiopian Rural Area. *Wind*. 2022; 2(1):68-86.
https://doi.org/10.3390/wind2010005

**Chicago/Turabian Style**

Bayu, Endeshaw Solomon, Baseem Khan, Issaias Gidey Hagos, Om Prakash Mahela, and Josep M. Guerrero.
2022. "Feasibility Analysis and Development of Stand-Alone Hybrid Power Generation System for Remote Areas: A Case Study of Ethiopian Rural Area" *Wind* 2, no. 1: 68-86.
https://doi.org/10.3390/wind2010005