**7. Proposed System Analysis**

*7.1. Cost Analysis*

In the past ten years, solar PV technology experienced a tremendous decrease in the levelized cost of energy (LCOE) every year which in turn increases its total installed capacity as well as the employment technology globally [36]. The cost breakup of the FPV system (see Table 7) is similar to the conventional PV system, with the additional cost requirement of complete transportation and installation of a floating structure which includes pontoons, mooring cables, anchors, screws and tensors.

In the year 2019, the global weighted average LCOE and the total installation cost of solar photovoltaic technology was 0.068 USD/kWh and 995 USD/kW, respectively, which is 13.1% and 17.6% lower compared to its value in the previous year [36]. This fall in the average LCOE as well as in the installation cost is experienced every year due to the newly commissioned utility-scale renewable energy power of solar PV technology. The capacity factor of the solar PV system is defined as the weighted average capacity factor (CF) of the solar PV system, which gained a step ahead every year: it was 18% in the year 2019, which is 23.3% higher in the last ten years range [36].


**Table 7.** Floating PV system cost component of different PV panels.

#### *7.2. Carbon Dioxide Analysis*

The prime consideration in switching to renewables from fossil fuel is to reduce carbon emission. From 1970 to 2017, Egypt experienced 422 Mt of CO2 emission, which is a 72.95% increase, mainly through coal and oil. In Egypt, the replaced renewable energy generation system avoided 7.14 million tons of CO2 emission, particularly through hydro and solar technology [36].

To assess the environmental benefits of the FPV system, the equivalent carbon dioxide emissions involved directly and indirectly in the manufacturing, installation and delivery of the entire FPV system is analyzed first. As per the report of climate transparency in the year 2018 on the country-specific electricity factors, the CO2 emission per kWh of generated power in Africa was 0.9609 kg. Thus, the CO2 emission avoided for power generating capacity of the present study is calculated and listed in Table 8. The CO2 savings from the solar energy production from the FPV fixed mount system and FPV system with single-axis tracking in portrait orientation in all three types of PV panels are calculated for a service life of 20 years, considering the specific carbon emission rate to be 0.9609 kg CO2/kWh for Aswan High Dam and Aswan Reservoir with HEPP of 2.1 GW cumulative power generation capacity.

**Table 8.** CO2 saving from fixed mount and single axis tracking FPV systems.


As the FPV system also has the added advantage of the reduction in water loss through evaporation, the reduction in carbon emission due to evaporation mitigation is also calculated, and the results are listed in Table 8. Besides this, the potential net/loss CO2 by reducing the water evaporation must also be taken into account. The specific energy (kWh/m3) is a potential energy use indicator of the embodied energy associated with water provision and storage in the irrigation reservoir and it is expressed as a ratio of energy consumption to water volume supplied [37]. The average value of specific electricity capacity (SEC) varies for different water sources [38], for the recycled water stored in the reservoir closer to the field location is an average of 0.5 kWh/m<sup>3</sup> [38]. Therefore, the energy saving from the reduction in water evaporation is straightforwardly calculated for the lifetime of the project. The amount of water saved by covering Aswan High Dam and Aswan Reservoir is 42,731.56 m3/year. The energy saving from the reduction in water evaporation over the lifetime of 20 years is 427315.6 kWh, with a reduction of 410.61 t CO2. Taking this into account, the total potential CO2 saving by the FPV systems with tracking are estimated as 44,270.61 t CO2 and it is 11.70% higher than the fixed mount FPV system.

#### *7.3. Water–Energy Nexus Analysis*

The water–energy nexus regulation is the notorious advantage of FPV, i.e., mitigating the potential water loss through evaporation while generating highly efficient power from the renewable energy source. This saved water without being lost from evaporation can be effectively used for the purpose of hydroelectric generation, irrigation or drinking. By directing the amount of water saved from evaporation for hydropower generation, the FPV covering system acts as a virtual battery and increases the energy yield from the hydro plants of the installed reservoir [18,30,33]. Thus, the cumulative renewable energy generation of the nation increases.

The installed hydropower generation capacity of the Aswan High Dam is 2100 MW, which produces 10,042 GWh annually. In the present study, by covering the 0.5 km<sup>2</sup> area of Aswan High Dam water surface, the annual water saving is about 137,252.86 m3, i.e., 0.1 million cubic meter (MCM) that increases by 63.56 MWh of hydropower production per year. Similarly, Aswan Reservoir has an installed hydropower plant of 592 MW capacity, and the average water saving by the FPV system increases by 21.76 MWh of hydropower annually.

#### **8. Discussion on the Limitations of the Study**

The present study analyzes the performance of the FPV system in reducing evaporation and hybrid power generation upon implementation in the HEPP reservoir. Being the first-ever study to analyze the FPV system in Egypt, the installed capacity of the system is limited to 5 MW to make it feasible for large scale analysis and real-time implementation. FPV projects covering entire reservoir areas in Agost, Spain and Silver Lake, USA results in a reduction in evaporation rate by 75% and 90%, respectively [21,39]. However, it is not advisable to cover the entire reservoir to completely eliminate the evaporation rate [40]. This is because the complete shading of the water surface with an FPV covering system affects the water quality and biodiversity [10,23,40]. As a trade-off, considering the water–energy demand, it is advisable to cover less than 40% of the entire surface of the water body [40]. In the present analysis, an average of 5000 m2 is required for installing an FPV system of 5 MW capacity. In such a case, covering 4% of the HD reservoir area of (5250 km2) by an FPV system tends to have an equal capacity as the hydroelectric power plant of 2.1 GW and it is possible to provide intermittent operation.

In the present study, the position of the FPV system is considered based on eliminating near and far shadows and area, which tends not to have the complete dry condition. However, proper mooring analysis on the water depth and soil type is essential to ensure the stability of the system. The FPV structure of the present study is considered as a single large structure and the cost of the mooring and anchoring system is calculated accordingly; however, for operational safety and maintenance, the existing system is divided into

small capacities. The system is analyzed only for a single-axis tracking mechanism to obtain a high energy yield. This is because dual-axis tracking on an FPV system is still challenging to implement due to the continuous action of mild waves [10]. Besides focusing the PV panel toward a high irradiation point, the tracking mechanism has to endure the persistent disturbances of the floating from the action of waves. In both sensor-based and astronomically calculated tracking types, inappropriate controller designs fail to find the brightest spot in the sky. This hunting condition of the tracking device extracts more power from the motor. Considering this condition, the single-axis tracking mechanism is cost effective and efficient for the floating PV system [41].

The power generation capacity and environmental benefits such as carbon footprint and evaporation mitigation are analyzed and implemented worldwide. The progress of the present study is to mainly focus on the panel interconnection topologies and multilevel inverter connection. Being in the initial stage of development, research on the FPV system related to standards of the structural components used and their impacts on the water quality on large scale implementation is needed. Besides lakes, reservoirs and hydropower plants, the future of the FPV is on the offshore platform [27,28,42]. Thin film PV modules are the growing technology that is suitable for potential FPV implementation in marine regions. However, the harsh marine environment is still slowing down the offshore FPV implementation and experimental studies [10,28].
