# TechnoEconomic Analysis of Standalone Solar PhotovoltaicWindBiogas Hybrid Renewable Energy System for Community Energy Requirement

## Abstract

Integrated renewable energy system (IRES) is integration of different energy sources to provide uninterrupted and viable solution for electrification especially for areas not connected to main grid due to difficult terrain and economic reasons. IRES has many advantages like non-depleting, non-polluting nature, better load matching and better renewable energy utilization. In the present study, mathematical modelling, size optimization and techno-economic analysis of standalone IRES have been carried out. Hybrid system is modelled to have maximum contribution from wind and solar energy with minimum net present cost (NPC) of system to meet electric load demand of CRC building, IIT Madras, India (13.01°N and 80.24°E). The results show that most feasible system configuration consists of 12 kW Photovoltaics, 3 kW wind turbine and 15 kW biogas generator with NPC and cost of energy equal to $117,098 and$ 0.09/kWh respectively. The IRES generates 71,826 kWh of energy to meet AC load of 64,396 kWh per year. The capacity factor and percentage contribution of PV, wind turbine and biogas generator are 17.8%, 6.57%, 39.1% and 26%, 2.4%, 71.6% respectively. The paper also presents sensitivity analysis of hybrid system with variation in capital cost of different components.

##### DOI: http://doi.org/10.5334/fce.72
Accepted on 09 Oct 2019            Submitted on 28 May 2019

## 1. Introduction

Uninterruptible and viable power supply to every household is one of the main challenge Indian government has taken, especially in rural and remote places which due to difficult terrain or due to economic reasons not connected to the main power grid. In such locations, renewable energy sources like Photovoltaics (PV) and wind energy are gaining attention due to easy installation, higher energy utilization rate, lower power transmission loss and lower operational cost. However, unpredictable and inconsistent nature are major drawback of some of the renewable sources to provide viable power energy. To counter this different renewable and non-renewable sources can be integrated together for increased system efficiency, greater balance of energy and viable power supply (Chauhan and Saini, 2014). However, selection of components of hybrid energy system and size optimization is very important to have reliable and cost effective system. The load demand and power generation with storage need to be optimally match, so that maximum utilization of energy sources and minimum investment can be assured. Various energy sources such as solar, wind, hydro, biomass and biogas etc. which are cost effective can be integrated together to meet viable electric load demand (Al-falahi et al., 2017). There are various advantages of IRES (i) better utilization of renewable energy (ii) better load matching (iii) better controllability (iv) less operational and maintenance cost (v) lesser environmental emission (Chong et al., 2016; Tezer et al., 2017).

Effective integration of hybrid energy sources has been gaining attention in the scientific community since past few decades to solve the technical and economic barriers for using renewable and distributed systems (Allison, 2017; Cano et al., 2017; Goel and Sharma, 2017; Kabalci, 2013; Perez-Navarro et al., 2016; Reddy et al., 2018, 2017; Yin et al., 2017). The study by Taele et al. (Taele et al., 2012) shows that installation of small scale solar PV systems at communities in Lesotho prevented frequent breakdowns, avoided large fuel storage and reduced power losses. Patil et al. (Patil et al., 2010) compared off-grid electrification of seven villages of Uttarakhand, India by integrating four different renewable energy sources to meet electrical and cooking needs. Baghadi et al. (Baghdadi et al., 2015) investigated the performance of hybrid PV-wind diesel battery system in Adrar climate of southern Algeria. The optimized system was able to meet 70% of energy demand by renewable PV-wind system and thereby reduced fossil fuel consumption. Singh et al. (Singh et al., 2017) examined technical and economic feasibility of hybrid hydrogen fuel cell and PV system to meet the energy demand of academic building at Bhopal, India. The analysis shows 3 kW hydrogen fuel cell with 5 kW of PV as most feasible system with minimum NPC and zero percentage energy shortage to meet load demand. Lau et al. (Lau et al., 2010) showed that integration of PV and diesel sources with battery can expressively reduce dependence on solely available diesel resource. Yilmaz and Selim (Yilmaz and Selim, 2013) reviewed different design techniques of biomass to energy conversion and integration of different renewable sources with biomass. The study shows that with appropriate integration of renewable energy resources and technologies, load demand can be met efficiently. Rahman et al. (Rahman et al., 2014) investigated technical and economic optimization of hybrid biomass and photovoltaic system to meet both thermal (cooking) and electric loads, replacing conventional facilities.

Ozden and Tari (Ozden and Tari, 2016) studied exergy and energy analysis of hybrid solar-hydrogen system in Ankara, Turkey. The result shows that overall hybrid system efficiency and hydrogen cycle efficiency are 6.21% and 4.06% respectively. The authors also suggested that PV-hydrogen hybrid system is better than PV-battery system. Using inspired coevolutionary algorithm shi et al. (Shi et al., 2015) designed hybrid energy system with PV, wind turbines, batteries and diesel generator. The optimization of the system includes minimization of annualized cost of the system, loss of power supply probability and fuel usage. A multi-objective receding horizon optimization is proposed by Forough and Roshandel (Behzadi Forough and Roshandel, 2017) to determine optimal scheduling of hybrid energy system. Diesel fuel cost and battery wear cost were considered as two objective functions. Castellanos et al. (Castellanos et al., 2015) studied various combination of PV, anaerobic digester and combined heat and power unit using micro-grid modelling simulations to power a small village in West Bengal, India. The result shows that IRES containing PV, anaerobic digester, and a micro turbine has lower capital and electricity cost over the life of the project. The design and evaluation of PV-hybrid systems by M. Muselli et al. (Muselli et al., 1999) and M.R. Borges Neto et al. (Borges Neto et al., 2010) analysed the optimal contribution of system components to serve the demand. Giatrakos et al. (Giatrakos et al., 2009) presented sustainable planning of renewable based energy system by replacing existing diesel generator with hybrid PV-Wind and hydrogen system for Karpathas island of Dodecanese, Greece.

From the literature study, it has been observed that considerable work has been done on optimization of integrated system considering different configuration and optimization technique. However, most of the study did not optimize the system, considering seasonal variation in energy load demand. This is important for accurate designing of hybrid system to have maximum resource utilization with minimum system cost to meet load demand all time. Present study focus on size optimization and economic analysis of hybrid integrated renewable energy system with seasonal load demand. Mathematical modelling, feasibility study and control strategy of all the system component has been done. Also, sensitivity analysis of hybrid system with variation in system component cost has been carried out. The optimization of integrated system has been carried out using HOMER software.

The paper is organized as follows, Section 2 describes the proposed hybrid integrated renewable energy system. Section 3 explains specification and mathematical modeling of components of proposed IRES system and seasonal electric load demand. Section 4 explains methodology, constraints and control strategy implemented in present system. Section 5 discuss size, economic and energy analysis of optimized IRES configuration and section 6 discusses sensitivity analysis of system with variation in cost of system components.

## 2. Description of proposed IRES

The integrated energy system must be feasible and viable, i.e. at each time step some or the other energy system i.e. primary generation, backup system or storage system must be available to meet electric load demand. To achieve this, there are many possible configurations in which system components can be designed and integrated. Probabilistic approach of simulations of system components has been carried out for sizing based on wind speed, solar radiation, biogas specification, electric load demand and certain technical and physical parameter. The schematic of proposed IRES is shown in Figure 1. Different component of hybrid energy system includes wind turbine, solar PV, solar charge controller, inverter, battery, control panel, and biogas generator. In the present study, wind speed, solar radiation, ambient temperature, PV temperature, wind speed, fuel property of biogas and load reading are measured by various equipment and weather monitoring system available in the solar energy research laboratory at IIT Madras, India.

Figure 1

Schematic of integrated hybrid renewable energy system.

For validation, modelling has been carried out similar to done by Baghdadi et al. (Baghdadi et al., 2015) using HOMER software. The simulation and calculation shows similar results to those of Baghdadi et al.

## 3. Specification and Mathematical modeling of IRES components

### 3.1. Wind energy system

The power output of the wind turbine depends upon wind speed at the location and turbine specification and is calculated by Eq. (1) (Chedid et al., 1998).

(1)

Where V(t) is speed of wind at time t, Pr is wind turbine rated power and Vci, Vr, and Vco are respectively wind turbine cut in, rated and cut out speed (Tito et al., 2016).

By knowing wind profile at reference height, wind speed at any other height can be calculated by Eq. (2).

(2)
${V}_{h}={V}_{ref}{\left(\frac{H}{{H}_{r}}\right)}^{\alpha }$

Where Vh is wind speed at height H, Vref is wind speed at reference height Hr, and α is wind speed power law coefficient. The overall effective electrical power output of wind turbine (PWeff) can be expressed as Eq. (3).

(3)

Where Aw is wind turbine swept area, ηw is wind turbine efficiency and ηinv is invertor’s efficiency. The wind speed for the complete year at height of 10 m above ground at IIT Madras, India is shown in Figure 2. The specification of wind turbine (Luminous Whisper 500) used for present study is summarized in Table 1.

Figure 2

Wind speed profile at IIT Madras, India.

Table 1

Specification of wind turbine (Chauhan and Saini, 2016).

Parameter Unit Value

Rated Power kW 3
Rated wind speed ms–1 12
Cut-in wind speed ms–1 3.1
Cut-out wind speed ms–1 24
Rated voltage V 240
Rotor diameter m 4.5
Swept area m2 15.1

### 3.2. Solar photovoltaic system

The basic element of solar PV module is a solar cell that converts incident solar radiation directly into electrical energy (DC current) (Derrouazin et al., 2017; Khanna et al., 2017). The power output of PV array depends upon PV module specification and is calculated by Eq. (4) (Koutroulis et al., 2006).

(4)
${P}_{pv}={N}_{s}{N}_{p}{V}_{oc}{I}_{SC}FF$

Where Np and Ns are respectively numbers of PV modules connected in parallel and series, Isc is short circuit current (A) of PV module, Voc is open-circuit voltage (V) of PV module, and FF is fill factor of panel.

The overall effective power from PV array is calculated by Eq. (5).

(5)
${P}_{ar}={\eta }_{\mathrm{mod}}{\eta }_{inv}{P}_{pv}$

Where ηmod is PV module efficiency, ηinv is inventor efficiency.

The effects of solar irradiance at tilted PV (IT), solar irradiance coefficient (γc), average temperature of PV (TPV,avg), temperature coefficient (βc), efficiency of PV panel at standard test conditions (ηSTC) and area of PV (APV) on the electrical output (Epv) of the systems can be calculated by Eq. (6) (Khanna et al., 2018).

(6)
$Epv={\eta }_{stc}\left\{1+{\beta }_{c}\left({T}_{pv-avg}-25\right)+{\gamma }_{c}ln\left(\frac{{I}_{T}}{1000}\right)\right\}{I}_{T}{A}_{pv}$

The temperature of PV cell can be calculated by Eq. (7).

(7)
${T}_{PV-avg}={T}_{amb}+\left(NOCT-20\right)\frac{{S}_{\mathrm{mod}}}{{S}_{stc}}$

Where Tamb is ambient temperature, NOCT is nominal operating cell temperature (°C), Smod is solar incident radiation (Wm–2) on the PV module and Sstc is incident solar radiation at standard test condition (Wm–2).

The power obtained from PV panel is directly related to the slope at which panel is installed. The maximum incident radiation on the solar panel for the given location is calculated by equation (8) (Sukhatme and Sukhatme, 1996).

(8)
${S}_{mod}= {S}_{inc} sin\left(\left[90-\phi +\delta \right] + \gamma \right)$

Where declination angle δ is given by,

(9)

The yearly solar radiation at CRC building, IIT Madras is calculated and compared with the Indian Meteorological Department (IMD) solar radiation database (“Indian Meteorological Department,” n.d.). The average hourly month wise solar radiation profile at CRC, IIT Madras is shown in Figure 3. The specification of PV (Bosch solar module CSi-P 60) used for present study is summarized in Table 2.

Figure 3

Table 2

Specification of PV module (Bosch Solar Energy, n.d.).

Parameters Value Parameters Value

Cell Configurations (Nos.) 60 Maximum System Voltage (DC) 1000
Pmax (W) (Tolerance: +3%) 250 Series Fuse Rating (A) 15
Voc (V) (Tolerance ±3%) 37.00 Nominal Operating Cell Temp. (°C) 44.6
Isc (A) (Tolerance ±3%) 8.55 Temp. Coefficient of Pmax (%/°C) –0.45
Vmax (V) (Tolerance ±3%) 30.95 Temp. Coefficient of Voc (%/°C) –0.36
Imax (A) (Tolerance ±3%) 8.08 Temp. Coefficient of Isc (%/°C) 0.043

### 3.3. Battery Bank system

The charging of battery takes place when power produced by wind turbine and PV is more than electric load demand. Battery bank is used to serve load demand when the power output of wind turbine and PV system is less than threshold value and is insufficient to meet load demand. Battery bank capacity is selected based on total power needed and autonomy period of operation in a day. The battery bank cost for complete duration of the project has three components: capital cost, operation & maintenance (O&M) cost, and replacement cost. The capital cost of battery bank depends on its size and specification, O&M cost includes maintenance cost at regular interval whereas replacement cost is cost of replacing battery after particular duration (lifetime). Thus selection of right battery bank is important during integration of system. The tabular lead acid batteries are largely used for solar application in India because of their low cost and robust usage. Thus, authors have considered tabular lead acid batteries for present analysis. The characterization of battery to know its charge and discharge status is determined by its state of charge (SOC). The SOC is defined as the ratio of current capacity to nominal capacity of the battery. When battery is fully charged, SOC is one and when the battery is empty, SOC is zero. The instantaneous SOC of battery can be calculated by Eq. (10) (Chiasson and Vairamohan, 2005).

(10)
$SOC\left(t\right)=SOC\left(t-1\right)\left(1-\frac{\sigma \Delta t}{24}\right)+\left(\frac{{I}_{bat}\left(t\right).\Delta t.{\eta }_{bat}}{{C}_{bat}}\right)$

Where SOC(t) is state of charge of battery at time t, SOC(t–1) is state of charge at (t–1) hours, σ is battery self-discharge rate, Ibat is battery current at time t (A), ηbat is battery charge efficiency and Cbat is capacity of battery bank.

The instantaneous battery current is given by Eq. (11) (Chiasson and Vairamohan, 2005).

(11)
${I}_{bat}\left(t\right)=\frac{{P}_{pv}\left(t\right)+{P}_{w}\left(t\right)-{P}_{load}\left(t\right)}{{V}_{bat}\left(t\right)}$

Where Ppv(t) and Pw(t) are respectively instantaneous power generated by PV and wind turbine system, Pload(t) is instantaneous load demand and Vbat(t) is terminal voltage of battery bank. The capacity of the battery bank Cbat is given by Eq. (12) (Singh et al., 2017).

(12)
${C}_{bat}=\left({E}_{L}{}_{oad}AD\right){\eta }_{inv}{\eta }_{bat}DOD$

Where Eload is total energy demand, AD is daily autonomy, DOD is depth of discharge of battery, ηinv is inventor efficiency, and ηbat is battery efficiency.

### 3.4. Biogas generator system

The biogas generator (Bio-Gen) is used as secondary power source for the proposed IRES system. The generator is used to meet peak load and when PV, wind turbine and battery power are insufficient to fulfill load demand. Biogas is used as fuel by biogas generator to produce electrical power. The biogas is produced by biodegradation of organic material fed into gasifier. The power output of biogas generator is given by Eq. (13) (Liu et al., 2018).

(13)

Where B is amount of biomass, CVBG is calorific value of biogas (kJ-kg–1), ηBG is efficiency of biogas generator and ηgas is efficiency of gasification of gasifier. The specification of generator considered for present study is listed in Table 3 (Specification, Test generator. Sawafuji Electric Co., Ltd, ELEMAX Generator SH7600EX: Owner’s Manual, n.d.).

Parameter Specification

Model ELEMAX SH5300EX Generator
Engine type 4 stroke, single cylinder, side valve, Spark Ignition engine
Ignition system Transistorized Coil Ignition (TCI)
Rated Power 6.3 kW @ 3600 rpm
Generator AC output 5.3 kVA @ 220 V, 60 Hz
Cooling system Forced Air Cooling

### 3.5. Converter system

Power converter is required to maintain flow of energy from different power sources of IRES to electric load by converting electric energy from one form to another (AC to DC and vice versa) (Zahboune et al., 2016). The power generated by wind turbine, solar PV and power stored in battery bank is in DC form. Whereas, power generated by biogas generator and electric load is in AC form. Converter is a combination of both inverter (DC to AC) and rectifier (AC to DC), which operate as per the requirement of flow of energy (Kabalci, 2013).

The electric load profile is the main influencing factor for designing and optimizing of integrated hybrid energy system. So, it is very important to know how load vary from weekdays to weekends and from season to season for accurate designing of hybrid system to have maximum utilization of resources and minimum system cost. The electric loads considered for present study are computers, fans, lights, electronic devices and machinery. The load demand of the building varies with weather condition. Chennai has three major seasons’ summer, monsoon and winter. March to August is summer season, September to October is monsoon season and November to February is winter season. The seasonal average electric load profile and frequency histogram of load for CRC building, IIT Madras is shown in Figure 4.

Figure 4

## 4. Optimization and Operational methodology

### 4.1. Component sizing and optimization

The optimization of integrated hybrid system has been done by HOMER software. The software simulates all possible system configurations to find the optimum combination of hybrid system to match seasonal electric load demand (Al Garni et al., 2018). Various details like global solar radiation, ambient temperature, wind speed, specification of components, electric load demand are given as input for the simulation. The specification of system component and load demand of proposed IRES are described in section 3. The HOMER software determine various system combination in terms of economic and technical parameters. In present work optimization is done on the basis of net present cost of hybrid system.

#### 4.1.1. Net present cost

The proposed optimisation process is based on lowest NPC of the system which is total of capital cost, O&M cost, replacement cost and salvage cost of the integrated system over the project life. The net present cost of the system calculated by HOMER is given by Eq. (14) (Dalton et al., 2008).

(14)
${C}_{NPC}=\frac{{C}_{ann}}{CRF\left(i,{R}_{proj}\right)}$

Where Cann is annualized cost, CRF is capital recovery factor, i is annual real discount rate, Rproj is project lifetime (25 years).

#### 4.1.2. Capital recovery factor

The capital recovery factor is ratio used to calculate present value of an annuity that is amount of cash flow annually over the lifetime of the project and is given by Eq. (15) (Li et al., 2013).

(15)
$CRF\left(i,{R}_{proj}\right)=\frac{i{\left(1+i\right)}^{{R}_{proj}}}{{\left(1+i\right)}^{{R}_{proj}}-1}$

Where i is nominal discount rate.

#### 4.1.3. Cost of energy

The levelized cost of energy (COE) is average cost to generate per kWh of useful electrical energy by integrated system. It is one of the important economic assessment factor considered while optimizing integrated energy system. It is the ratio of total annualized cost (Cann) of system to useful energy served (Eser) by the system and is calculated by Eq. (16) (Li et al., 2013).

(16)
$COE=\frac{{C}_{ann}}{{E}_{ser}}$

#### 4.1.4. Salvage cost

Salvage cost (Csal) is value of the components of integrated system at the end of the project. The salvage cost is calculated by Eq. (17) (Munuswamy et al., 2011).

(17)
${C}_{sal}={C}_{rep}\frac{{R}_{rem}}{{R}_{comp}}$

Where Crep is component’s replacement cost, Rrem is component’s remaining life, Rcomp is the lifetime of the project.

The real discount rate is used to convert between one-time cost and annualized cost and is calculated by Eq. (18) (Li et al., 2013).

(18)
$i=\frac{{i}^{\prime }-f}{1+f}$

Where i’ is nominal discount rate and f is expected inflation rate.

Present operational strategy aim at maximizing wind and solar PV energy utilization and reducing operational duration of biogas generator and thereby reducing pollutant emission. Economic data and operation life of different components of integrated hybrid energy system are listed in Table 4.

Table 4

Economic data and operational life of components of IRES.

## Nomenclature

 Aw Wind turbine swept area (m2) Cbat Capacity of battery CVBG Calorific value of biogas (MJ/kg) CNPC Net present cost Cann Annualized cost Crep Component’s replacement cost Epv Electrical output of PV system (W) Eload Energy demand (kWh) f Expected inflation rate Isc Short circuit current of PV module (A) Ibat Battery current (A) IT Solar irradiance at tilted PV (W/m2) I Annual real discount rate i’ Nominal discount rate Ns PV modules connected in parallel Np PV modules connected in series Pw Power output of Wind turbine (kW) PWeff Effective electrical power output of wind turbine (kW) Ppv Power output of solar PV array (W) Par Effective power output from PV array (W) Pbio Power generation by biogas generator (W) Pload Power load demand (W) Rproj Project lifetime Rrem Component’s remaining life Rcomp Lifetime of the project Sstc Incident solar radiation at standard test condition (W/m2) Smod Solar radiation incident on the module (W/m2) Sinc Solar radiation perpendicular to the sun (W/m2) TPV,avg Average Temperature of PV (°C) Tamb Ambient temperature (°C) t Duration of operation Voc Open circuit voltage of PV module (V) Vci, Wind turbine cut in speed (m/s) Vr Wind turbine rated speed (m/s) Vco Wind turbine cut out speed (m/s) Vbat Terminal voltage of battery (V)

## Abbreviations

 AD Daily autonomy CRC Classroom complex CRF Capital recovery factor DOD Depth of discharge of battery FF Fill factor of PV panel HOMER Hybrid optimization of multiple energy resources IRES Integrated renewable energy system NOCT Nominal operating cell temperature (°C) PV Photovoltaics SOC State of charge of the battery

## Greek symbol

 βc PV panel temperature coefficient γc Solar irradiance coefficient δ Latitude degrees σ Battery self-discharge rate ηbat Battery charge efficiency ηbat Battery efficiency ηBG Efficiency of biogas generator ηgas Efficiency of gasification of gasifier ηw Efficiency of wind turbine ηinv Efficiency of invertor ηmod PV module efficiency ηstc Efficiency of PV module at standard test condition

## Competing Interests

The authors have no competing interests to declare.

## References

1. Al-falahi, MDA, Jayasinghe, SDG and Enshaei, H. 2017. A review on recent size optimization methodologies for standalone solar and wind hybrid renewable energy system. Energy Convers. Manag., 143: 252–274. DOI: https://doi.org/10.1016/j.enconman.2017.04.019

2. Al Garni, HZ, Awasthi, A and Ramli, MAM. 2018. Optimal design and analysis of grid-connected photovoltaic under different tracking systems using HOMER. Energy Convers. Manag., 155: 42–57. DOI: https://doi.org/10.1016/j.enconman.2017.10.090

3. Allison, J. 2017. Robust multi-objective control of hybrid renewable microgeneration systems with energy storage. Appl. Therm. Eng., 114: 1498–1506. DOI: https://doi.org/10.1016/j.applthermaleng.2016.09.070

4. Baghdadi, F, Mohammedi, K, Diaf, S and Behar, O. 2015. Feasibility study and energy conversion analysis of stand-alone hybrid renewable energy system. Energy Convers. Manag., 105: 471–479. DOI: https://doi.org/10.1016/j.enconman.2015.07.051

5. Behzadi Forough, A and Roshandel, R. 2017. Multi objective receding horizon optimization for optimal scheduling of hybrid renewable energy system. Energy Build, 150: 583–597. DOI: https://doi.org/10.1016/j.enbuild.2017.06.031

6. Borges Neto, MR, Carvalho, PCM, Carioca, JOB and Canafístula, FJF. 2010. Biogas/photovoltaic hybrid power system for decentralized energy supply of rural areas. Energy Policy, 38: 4497–4506. DOI: https://doi.org/10.1016/j.enpol.2010.04.004

7. Bosch Solar Energy. n.d. Properties of Bosch Solar Module c-Si M 60. Bosch Solar Energy Corporation.

8. Cano, MH, Agbossou, K, Kelouwani, S and Dube, Y. 2017. Experimental evaluation of a power management system for a hybrid renewable energy system with hydrogen production. Renew. Energy, 113: 1086–1098. DOI: https://doi.org/10.1016/j.renene.2017.06.066

9. Castellanos, JG, Walker, M, Poggio, D, Pourkashanian, M and Nimmo, W. 2015. Modelling an off-grid integrated renewable energy system for rural electrification in India using photovoltaics and anaerobic digestion. Renew. Energy, 74: 390–398. DOI: https://doi.org/10.1016/j.renene.2014.08.055

10. Chauhan, A and Saini, RP. 2014. A review on integrated renewable energy system based power generation for stand-alone applications: configurations, storage options, sizing methodologies and control. Renew. Sustain. Energy Rev., 38: 99–120. DOI: https://doi.org/10.1016/j.rser.2014.05.079

11. Chauhan, A and Saini, RP. 2016. Techno-economic optimization based approach for energy management of a stand-alone integrated renewable energy system for remote areas of India. Energy, 94: 138–156. DOI: https://doi.org/10.1016/j.energy.2015.10.136

12. Chedid, R, Akiki, H and Rahman, S. 1998. A decision support technique for the design of hybrid solar-wind power systems. IEEE Trans. Energy Convers., 13: 76–83. DOI: https://doi.org/10.1109/60.658207

13. Chiasson, J and Vairamohan, B. 2005. Estimating the State of Charge of a Battery. IEEE Trans. Control Syst. Technol., 13: 465–470. DOI: https://doi.org/10.1109/TCST.2004.839571

14. Chong, LW, Wong, YW, Rajkumar, RK, Rajkumar, RK and Isa, D. 2016. Hybrid energy storage systems and control strategies for stand-alone renewable energy power systems. Renew. Sustain. Energy Rev., 66: 174–189. DOI: https://doi.org/10.1016/j.rser.2016.07.059

15. Dalton, GJ, Lockington, DA and Baldock, TE. 2008. Feasibility analysis of stand-alone renewable energy supply options for a large hotel. Renew. Energy, 33: 1475–1490. DOI: https://doi.org/10.1016/j.renene.2007.09.014

16. Derrouazin, A, Aillerie, M, Mekkakia-Maaza, N and Charles, JP. 2017. Multi input-output fuzzy logic smart controller for a residential hybrid solar-wind-storage energy system. Energy Convers. Manag., 148: 238–250. DOI: https://doi.org/10.1016/j.enconman.2017.05.046

17. Giatrakos, GP, Tsoutsos, TD, Mouchtaropoulos, PG, Naxakis, GD and Stavrakakis, G. 2009. Sustainable energy planning based on a stand-alone hybrid renewable energy/hydrogen power system: Application in Karpathos island, Greece. Renew. Energy, 34: 2562–2570. DOI: https://doi.org/10.1016/j.renene.2009.05.019

18. Goel, S and Sharma, R. 2017. Performance evaluation of stand alone, grid connected and hybrid renewable energy systems for rural application: A comparative review. Renew. Sustain. Energy Rev., 78: 1378–1389. DOI: https://doi.org/10.1016/j.rser.2017.05.200

19. Indian Meteorological Department [WWW Document]. n.d. URL http://www.imd.gov.in/Welcome%?20To%20IMD/Welcome.php.

20. Kabalci, E. 2013. Design and analysis of a hybrid renewable energy plant with solar and wind power. Energy Convers. Manag., 72: 51–59. DOI: https://doi.org/10.1016/j.enconman.2012.08.027

21. Khanna, S, Reddy, KS and Mallick, TK. 2017. Performance analysis of tilted photovoltaic system integrated with phase change material under varying operating conditions. Energy, 133: 887–899. DOI: https://doi.org/10.1016/j.energy.2017.05.150

22. Khanna, S, Reddy, KS and Mallick, TK. 2018. Effect of climate on electrical performance of finned phase change material integrated solar photovoltaic. Sol. Energy, 174: 593–605. DOI: https://doi.org/10.1016/j.solener.2018.09.023

23. Koutroulis, E, Kolokotsa, D, Potirakis, A and Kalaitzakis, K. 2006. Methodology for optimal sizing of stand-alone photovoltaic/wind-generator systems using genetic algorithms. Sol. Energy, 80: 1072–1088. DOI: https://doi.org/10.1016/j.solener.2005.11.002

24. Lau, KY, Yousof, MFM, Arshad, SNM, Anwari, M and Yatim, AHM. 2010. Performance analysis of hybrid photovoltaic/diesel energy system under Malaysian conditions. Energy, 35: 3245–3255. DOI: https://doi.org/10.1016/j.energy.2010.04.008

25. Li, C, Ge, X, Zheng, Y, Xu, C, Ren, Y, Song, C and Yang, C. 2013. Techno-economic feasibility study of autonomous hybrid wind/PV/battery power system for a household in Urumqi, China. Energy, 55: 263–272. DOI: https://doi.org/10.1016/j.energy.2013.03.084

26. Liu, G, Li, M, Zhou, B, Chen, Y and Liao, S. 2018. General indicator for techno-economic assessment of renewable energy resources. Energy Convers. Manag., 156: 416–426. DOI: https://doi.org/10.1016/j.enconman.2017.11.054

27. Munuswamy, S, Nakamura, K and Katta, A. 2011. Comparing the cost of electricity sourced from a fuel cell-based renewable energy system and the national grid to electrify a rural health centre in India: A case study. Renew. Energy, 36: 2978–2983. DOI: https://doi.org/10.1016/j.renene.2011.03.041

28. Muselli, M, Notton, G and Louche, A. 1999. Design of hybrid-Photovoltaic power generator, with optimization of energy management. Sol. Energy, 65: 143–157. DOI: https://doi.org/10.1016/S0038-092X(98)00139-X

29. Ozden, E and Tari, I. 2016. Energy-exergy and economic analyses of a hybrid solar-hydrogen renewable energy system in Ankara, Turkey. Appl. Therm. Eng., 99: 169–178. DOI: https://doi.org/10.1016/j.applthermaleng.2016.01.042

30. Patil, ABK, Saini, RP and Sharma, MP. 2010. Integrated renewable energy systems for off grid rural electrification of remote area. Renew. Energy, 35: 1342–1349. DOI: https://doi.org/10.1016/j.renene.2009.10.005

31. Perez-Navarro, A, Alfonso, D, Ariza, HE, Carcel, J, Correcher, A, Escriva-Escriva, G, Hurtado, E, Ibanez, F, Penalvo, E, Roig, R, Roldan, C, Sanchez, C, Segura, I and Vargas, C. 2016. Experimental verification of hybrid renewable systems as feasible energy sources. Renew. Energy, 86: 384–391. DOI: https://doi.org/10.1016/j.renene.2015.08.030

32. Rahman, MM, Hasan, MM, Paatero, JV and Lahdelma, R. 2014. Hybrid application of biogas and solar resources to fulfill household energy needs: A potentially viable option in rural areas of developing countries. Renew. Energy, 68: 35–45. DOI: https://doi.org/10.1016/j.renene.2014.01.030

33. Reddy, KS, Mudgal, V and Mallick, TK. 2017. Thermal performance analysis of multi-phase change material layer-integrated building roofs for energy efficiency in built-environment. Energies, 10. DOI: https://doi.org/10.3390/en10091367

34. Reddy, KS, Mudgal, V and Mallick, TK. 2018. Review of latent heat thermal energy storage for improved material stability and effective load management. J. Energy Storage, 15: 205–227. DOI: https://doi.org/10.1016/j.est.2017.11.005

35. Shi, Z, Wang, R and Zhang, T. 2015. Multi-objective optimal design of hybrid renewable energy systems using preference-inspired coevolutionary approach. Sol. Energy, 118: 96–106. DOI: https://doi.org/10.1016/j.solener.2015.03.052

36. Singh, A, Baredar, P and Gupta, B. 2017. Techno-economic feasibility analysis of hydrogen fuel cell and solar photovoltaic hybrid renewable energy system for academic research building. Energy Convers. Manag., 145: 398–414. DOI: https://doi.org/10.1016/j.enconman.2017.05.014

37. Specification, Test generator. Sawafuji Electric Co., Ltd. ELEMAX Generator SH7600EX: Owner’s Manual, n.d.

38. Sukhatme, K and Sukhatme, SP. 1996. Solar energy: principles of thermal collection and storage, 2nd ed. Tata McGrawHill.

39. Taele, BM, Mokhutsoane, L, Hapazari, I, Tlali, SB and Senatla, M. 2012. Grid electrification challenges, photovoltaic electrification progress and energy sustainability in Lesotho. Renew. Sustain. Energy Rev., 16: 973–980. DOI: https://doi.org/10.1016/j.rser.2011.09.019

40. Tezer, T, Yaman, R and Yaman, G. 2017. Evaluation of approaches used for optimization of stand-alone hybrid renewable energy systems. Renew. Sustain. Energy Rev., 73, 840–853. DOI: https://doi.org/10.1016/j.rser.2017.01.118

41. Tito, SR, Lie, TT and Anderson, TN. 2016. Optimal sizing of a wind-photovoltaic-battery hybrid renewable energy system considering socio-demographic factors. Sol. Energy, 136: 525–532. DOI: https://doi.org/10.1016/j.solener.2016.07.036

42. Yilmaz, S and Selim, H. 2013. A review on the methods for biomass to energy conversion systems design. Renew. Sustain. Energy Rev., 25: 420–430. DOI: https://doi.org/10.1016/j.rser.2013.05.015

43. Yin, C, Wu, H, Locment, F and Sechilariu, M. 2017. Energy management of DC microgrid based on photovoltaic combined with diesel generator and supercapacitor. Energy Convers. Manag., 132: 14–27. DOI: https://doi.org/10.1016/j.enconman.2016.11.018

44. Zahboune, H, Zouggar, S, Krajacic, G, Varbanov, PS, Elhafyani, M and Ziani, E. 2016. Optimal hybrid renewable energy design in autonomous system using modified electric system cascade analysis and Homer software. Energy Convers. Manag., 126: 909–922. DOI: https://doi.org/10.1016/j.enconman.2016.08.061