Evaluation of PV-Wind Hybrid Energy System for a Small Island DOI: http://dx.doi.org/10.5772/intechopen.85221

sensitivity variables at which optimal system solutions have been obtained. Project life of system A (15 years) is less than that of system B (25 years), which is also one of the reasons for low NPC of system A.

Table 6 displays the selected size of each component for both systems. Both systems consist of one wind turbine and system converter of almost 1000 kW size. PV panel size for system B (3,157 kW) is higher than system A (2,504 kW), that is why NPC of system B is higher than system A. By selecting an appropriate model of wind turbine according to the wind conditions of Deokjeokdo island, both system architectures might be different from present cases. But, a right choice of wind


• System A: HRES with lowest overall net present cost (NPC)

Wind Solar Hybrid Renewable Energy System

• System B: HRES with lowest overall levelized cost of energy (LCOE)

Table 5 shows the basic characteristics of both of the optimized system solutions. It is to be noted that both systems have batteries as default option for storing surplus electricity. System A has the lowest overall NPC (11.3 million \$) whereas LCOE is lowest in case of system B (\$ 0.123). Table 5 also displays the values of

Average load (kWh/day) Discount rate (%) Project lifetime (years)

Variable Unit System A System B NPC Million \$ 11.3 17.61 LCOE \$/kWh 0.158 0.123 Total load scaled average kWh/day 20,000 20,000 Nominal discount rate % 8 4 Project lifetime years 15 25

Component Model Unit Size (system A) Size (system B)

Leonics MTP-413F 25 kW kW 1006 1009

HOMER cycle charging N/A N/A N/A

Battery Surrette 6 CS 25P Strings 7197 6269 Wind turbine STX 93/2000 ea. 1 1

kW 2504 3157

24,720 8 25 20,000 6 20 30,000 4 15

Breakdown of multiple solutions obtained from HOMER simulations.

Table 4.

Figure 16.

Table 5.

System converter

Dispatch strategy

Systems architecture.

Table 6.

176

Basic information about both system solutions.

PV panels Canadian Solar Max Power CS6X-

325P

Sensitivity variables.

Figure 17. Daily PV power output for both systems (a) system A (b) system B.

turbine depends on the detailed wind data analysis of local site, which is beyond the scope of current study; therefore not performed here.

of the other alternate system solutions on the basis of economic evaluations. In order to achieve this goal, Figure 18 has been prepared which shows multiple

Figure 18 shows a total of 27 optimal system solutions obtained by varying the

The present study provides a basic information about the working methodologies of a hybrid renewable energy system (HRES) consisting of wind and solar as primary energy resources. Two case studies of HRES have also been included to

First case study deals with the analysis of a small HRES consisting of wind turbines and PV panels with batteries as energy storage system (ESS). This small HRES is being installed at Deokjeokdo island in South Korea and its performance have been monitored for two consecutive years (2016 and 2017). Analysis showed that the prevailing wind direction at Deokjeokdo island is either north-east or south-west, with mean wind speed of 3.6 m/s at 10 m height. Similarly, average value of daily solar radiations was estimated to be 4.13 kWh/m2 with mean clearness index of 0.5. The total capacity of this small HRES is 6 kW; with two Darrieus

Second case study finds an optimum HRES to fulfill the yearly electricity demand of Deokjeokdo island, which corresponds to approximately 7.296 MWh/ year. Over 8760 simulations were performed to find out two optimum HRESs based on lowest NPC (system A) and lowest LCOE (system B), respectively. The overall NPC of system A was calculated to be 11.29 million USD, whereas for system B, it was 17.61 million USD. On the other hand, LCOE for system A was slightly higher than system B as it was 0.158 \$/kWh for system A and 0.123 \$/kWh for system B. Both systems can independently provide electricity to Deokjeokdo island through-

This study was supported with major project funding from the Korea Institute of Civil Engineering and Building Technology. We would also like to thank the KMA for providing long-term measured wind data at all proposed wind farm sites.

system solutions obtained by superimposing NPC over LCOE.

further clarify the economic aspects of such energy systems.

VAWTs of 1.5 kW size each and 3 kW size of PV panels.

out the year without any external assistance such as grid, etc.

The authors declare no actual or potential conflicts of interest.

values of all sensitivity variables mentioned in Table 4.

Evaluation of PV-Wind Hybrid Energy System for a Small Island

DOI: http://dx.doi.org/10.5772/intechopen.85221

4. Conclusions

Acknowledgements

Conflict of interest

179

Finally, Table 7 shows the annual amount of pollutant gases emissions due to operation of both systems.

Figure 17 displays the graphical representation of power produced by PV panels in both cases. Both the images of Figure 17 indicate that summer is the ideal season for harvesting energy from sun in South Korea, as the average day-time is almost 14–15 hours in Deokjeokdo island. The average hourly power generated by PV panels in case of system A is 425 kWh whereas this value corresponds to 536 kWh for system B.
