2. Review of the Literature
The utilization of photovoltaics is older than that of hydro energy and wind energy. According to the statistical data of BP, the utilization of solar energy first appeared in the United States, but the production was small; however, it rose by 22% in 2018. After 2000, large-scale development and utilization began. The world’s total solar energy production has rapidly increased from 0.27 Mtoe in 2000 to 314.44 Mtoe in 2021, accounting for 12.6% of the world’s total renewable energy consumption [
1]. The future development potential of agrivoltaic technology is huge. Although developed countries began to actively encourage the development of PV systems very early, the utilization of solar energy in various countries did not increase significantly before 2008. From 2010 to 2020, the annual renewable electricity consumption of solar PV in the European Union (EU) was 8.8 Mtoe in 2015, and the following year it increased by 9.28 Mtoe; however, there was a noticeable drop in consumption in 2017 (5.44 Mtoe). In 2015, the share of electricity from solar PV in the EU was 28.8% [
2]. Since 2009, solar energy utilization has increased rapidly, reaching 23.88 Mtoe in 2020, almost 70 times higher than in 2009, accounting for 18% of global solar energy consumption [
3]. The long-term policy of encouraging the development of photovoltaic systems in the United States has begun to take effect [
4,
5]. Japan’s “new sunshine plan” and “new energy promotion program” started in the late 1990s [
6]. At the end of the 20th century, the EU began to continuously improve its renewable energy utilization target [
7,
8,
9,
10]. The solar energy utilization of Germany, Italy, Spain, France, and other major EU countries increased rapidly [
11]. In 2020, the gross electricity consumption of the EU accounted for 14% of the global consumption [
12]. China’s solar energy consumption has increased significantly since 2007 [
13]. In 2018, total solar energy consumption reached 40.16 Mtoe [
14], accounting for 24% of the world’s solar energy consumption and becoming the country with the highest solar energy consumption. Generally, Peng et al. [
15] stated that the demand for green energy is inversely proportional to the density of the population and directly proportional to GDP.
Currently, Hungary is a country of energy saving and renewable energy utilization, which is of great significance for its economic development [
16]. According to the Hungarian National Bank’s (MNB) Green Program, the MNB examined utility-scale renewable energy production within the support opportunities and development to strengthen environmental sustainability in the national financial system [
17]. Investment in the Hungarian renewable energy industry, mainly photovoltaic solar power plants, will reach investment needs of HUF 2253B (EUR 6324 M), HUF 1577B (EUR 3889 M) of debt financing, and 12 GW solar PV power capacities are planned by the end of 2040. These are initiated by the new National Energy Strategy and the National Energy and Climate Plan (2030, with an outlook up to 2040) [
18]; therefore, the proportion of renewable energy in the total energy consumption will reach at least 45%. From the report released by the National Climate Change Strategy, we know that Hungary plans to increase the share of solar energy as a primary energy from about 5% at present to 21% in 2030 [
19]. If the expected target is successfully achieved, Hungary can reduce greenhouse gas (GHG) emissions by nearly 52–85% compared to 1990 levels [
20]. The number of large-scale solar power plants in Hungary has continued to increase, so their total installed capacity is already close to 1800 MW, and if household-sized solar power plants are also included, the domestic photovoltaic capacity Is already around 2800 MW. Although this growth may have slowed in the second half of the year, Hungary will reach the 3000 MW limit this year (2022) at the latest, completing half of the planned goal set for 2030 in the energy strategy [
21]. The largest solar farm in the country operates in Kapuvár with a capacity of 25 MW. The park is in the hands of an Israeli stock exchange group, which owns a total of three solar power plants in Hungary: Kapuvár, Tuzsér, and Nádasd. Production is continuous in all three areas and the solar collectors operate with a total capacity of 57 MW [
22]. The largest solar power plants currently operating in Hungary are represented in
Figure 2.
Agrivoltaics refers to the radiant energy of sunlight combined with agricultural production, water savings, and the efficiency of electricity production [
23]; therefore, this technology can present positive impacts in the food—energy—water nexus [
24]. Radiation reduction provides many benefits, for example, it contributes to higher and more stable yields and increased plant resilience [
25]. Furthermore, the technology operates in a clean and self-cleaning manner, and no waste is generated during the operation. One of its major advantages is the higher land economy compared either to standalone PV systems or agricultural production [
26], and fossil energy and harmful emissions are also reduced. However, because of the late start of the Hungarian photovoltaic industry grid connection, the core technology of solar photovoltaic is still far behind developed countries such as those in Western Europe and North America.
Due to the unstable political situation and current energy crisis in EU countries, the EU strongly emphasizes the huge dependence of the EU on fossil fuel imports and has made the transition to renewable energy resources (RES) since the beginning of 2022 [
27,
28]. The excessive reliance of the agricultural development process in the EU on traditional fossil energy and large consumption have also caused many problems, such as a high cost of agricultural production, large environmental pollution in rural areas, and low agricultural economic efficiency [
29,
30]. Agricultural development needs to be transformed. As Tumiwa et al. [
31] presented, it is essential to pay attention to the sustainable management of natural resources to continuously increase agricultural productivity and gain a sustainable competitive advantage. Thus, the challenge of agricultural development with the implementation of Industry 4.0 is to maintain harmony between economic, social, and environmental aspects. All sustainability aspects in Industry 4.0 technology should be focused on dealing with many challenges and problems [
32]. The development of agrivoltaics plays a very positive role in solving the problems of backward technology, energy shortage, and environmental pollution that agricultural development faces. Foreign scholars have studied agrivoltaics in terms of economic benefits, energy benefits, social benefits, and other aspects, and they affirmed the positive role of developing solar farming [
33,
34,
35,
36]. The growth of solar farms would cause a conflict of land use with agricultural production. This problem can be solved by the concept of “agrivoltaic”, which is the joint development of solar photovoltaic and agricultural land. The economic benefits are outstanding, and it has many incomparable advantages over traditional agriculture. The results show that the economic value of grape farms adopting agrivoltaic systems may increase more than 15 times compared with traditional agriculture, while maintaining the same grape yield [
33]. In addition, grape-based agricultural production can be implemented in rural areas to electrify them. The role of agrivoltaics (solar farms) in agricultural and socio-economic development emphasizes that agriculture has a large demand for energy and the advantages of photovoltaic agriculture in energy saving, land saving, and other aspects. Kumpanalaisatit [
36] also pointed out that the application scope of photovoltaic technology in agriculture is not wide enough, and the low output–input ratio of agrivoltaics and the high price of photovoltaic-related products are the problems and difficulties in photovoltaic agriculture. Thompson et al. [
37] estimated that income from selling agricultural products (basil and spinach) and selling electricity increased the production values by 18% and 113%, respectively. Additionally, the APV systems would produce USD 2.04T in revenue with a simple payback time of 17 years and at the average 2018 electricity price of 0.1053 USD/kWh, the net present value (NPV) is estimated at a 6% (USD 35.72B), 3% (USD 332.93B), and 1% discount rate (USD 678.03B). With similar operating and maintenance costs, the net difference between APV systems and traditional PV systems is estimated to be USD 338.8B over the 35-year project life [
38]. Roy and Ghosh [
39] compared this to the small capacity of the ms-Si PV plants and larger counterparts, demonstrating that electricity production and crop production minimized the payback period by up to 30–35%. The results showed that the agricultural yields of a-Si and CdTe plants are better than mc-Si plants. The average simple payback period for the agrivoltaic system was 5 and 8 years [
40,
41,
42]. Agrivoltaics can reduce the variable behavior of apple trees, demonstrating the importance of conducting years of research [
43].
According to Eurostat [
44], the dependency on energy import of the 27 European countries in 2020 was met by net imports of 57.49% on average, with some examples such as Greece, (81.41%), Ireland (71.30%), Belgium (78.05%), and Germany (63.71%). The highest country-level dependence on energy imports was found in Cyprus (93.07%) and Malta (97.56%), while the lowest share of total energy needs was found in Iceland (11.96%) and Sweden (33.51%), respectively. In this case, a transition to renewable energy systems (RES) is certainly necessary. The technological progress with energy-saving effects and the investment subsidies of output and capital in the energy market to the general equilibrium model set that energy and capital can be complementary in the production process, and new machinery and equipment can reduce the consumption and waste of energy [
45]. According to the life-cycle theory, the results show that agrivoltaic systems have a similar environmental performance in comparison to traditional PV installations, the role of capital investment subsidies depends largely on the structure of the energy market [
46,
47], and the increase in capital is affected by capital investment subsidies and energy consumption prices in the energy market. The social market consumption potential of photovoltaics is based on green electricity savings in Europe and proposed that the use of social marketing methods for solar energy can increase electricity consumption [
48,
49]. However, there are common barriers to the adoption of agrivoltaics such as limited information on technology, economic aspects, legal issues, financial concerns, and sociodemographic factors [
34,
50].
The electricity network is inaccessible for more than one billion people around the world [
51], and the number of starving people is estimated between 720 and 811 million; the prevalence of undernourishment increased to 9.9% in 2020 [
52], slowing down the spread of diseases [
53], climate change, and related environmental issues that affect all people globally [
54] and should be solved simultaneously and within a short time [
55]. Food, energy, and environment can be considered the most important global challenges [
56]. All the aforementioned challenges can be influenced to a large extent with more effective agricultural systems. A dichotomy of ‘food versus fuel’ has misled thinking and hindered the necessary action to build agricultural systems in sustainable ways [
57]. We need to produce green energy without endangering food production.
Agrivoltaic systems are promising technologies for combining all three (food, energy, and environmentally friendly) types of land use. Agriculture and solar power generation, at the same time, have the potential to contribute to the sustainable utilization of rural areas. Moreover, farmers have the opportunity to develop new ways to grow their income without losing the productivity of their land. The importance of APV systems is rapidly growing: the worldwide installed capacity was estimated at 5 MWp in 2012 and achieved 2.8 GWp in 2019; however, their technical potential is significantly higher (Germany reaches 1700 GWp year
−1) [
58].
Compared to ground-mounted configuration, the rooftop PV systems resulted in a 2.9% increase in capacity utilization factor, and up to a 23.7% decrease in the levelized cost of electricity (LCOE) because of mutual shading impact. It showed that a roof PV system installation has many advantages over ground-mounted PV systems, including avoiding land use [
59]. Consequently, large-scale ground-mounted PV systems can especially be considered an available option for APV systems. For future spread, APV systems should be economically viable compared to both ground-mounted PV systems and conventional agricultural systems (without PV systems).
The research aimed to show the expected economic impacts of APV systems based on the real data of an operating Hungarian PV project located in the Kaposvár area with the highest capacity in Hungary, the economic data of Schindele et al. [
34] about PV and APV systems, and the typical economic data of Hungarian apple production. Based on the baseline scenario, we provide a sensitivity analysis to explain which factors could have the greatest importance for the future spread of APV systems.
5. Discussion and Conclusions
In order to solve the classical “food or energy” debate, agrivoltaic systems should deal with the competition and cooperation between photovoltaic power generation and agricultural production, and improve agrivoltaic benefits and land use efficiency based on Schindele et al.’s [
34] economic data and conclusion. In our results, many factors affect the output of agrivoltaic systems. These are explored and discussed, analyzed, and verified by the example of a photovoltaic power station (Kaposvár Solar Power Plant Project). By selecting the relevant data for the photovoltaic power station in the typical day type, the single influence factor and the historical data for the photovoltaic power output are plotted and analyzed to visually observe and compare with APV and PV systems, APV, and conventional apple production. Then, the principle of the sensitivity analysis is described in detail. Sensitivity analysis is a commonly used method in statistics to analyze multiple influence factors for predicting the outcome of a decision, and it is more scientific and reasonable than a simple correlation analysis. Finally, the sensitivity analysis method is used to identify the effects of the competitiveness of APV compared to PV and agricultural production. Through the analysis of the relevant factors that economically affect APV compared to PV and agricultural production, the foundation is laid for the selection of the main influencing factors as the prediction input of the photovoltaic power generation prediction model.
The result obtained for the over-10-year-old “Golden Delicious” apple orchard when the APV shed is oriented due to the south of France is in line with Juillion et al. [
43], which, for the organic APV canopy potato described by Schindele et al. [
34], obtained a total CAPEX for the installation and commissioning of APV. This amounts to EUR 1,343,850 and for PV-GM, EUR 1,031,035 and the internal rate of return is 1.6% lower than the weighted average cost of capital. In a broader sense, Robinson [
69] concluded that V-systems have very high apple yield efficiency to allow a good balance between cropping and vegetative growth; however, it depends on their economic performance. From the inception of our study, we conclude that both the APV system and the cost of establishment of an apple orchard also depend on financial concerns. It was envisaged that a negative factor for APV system profitability would be the high CAPEX compared to conventional PV-GM power plants. Malu et al. [
33] noted that the cost per unit of land (e.g., acre) is lower for the installation of an APV system than for a conventional PV system because the packing ratio of PV is lower for a solar farm (APV) than for PV-GM farms. According to the authors, the lack of profitability in some combinations of the examples analyzed here does not detract from the potential profitability of APV systems. The fruit orchard is protected from hail and sunburn damage [
71] allowed by APV shading and, most importantly, this increases the diversity of farmers.
Farmers also face even more problems and difficulties in the development of agrivoltaics in Hungary, because the development needs to comprehensively consider the investment costs and benefits compared with the government’s legislation towards it. Therefore, farmers should standardize their own behavior, constantly carry out scientific and technological innovation, and optimize their agricultural production structure, and PV developers may adjust the profit model for farmers, seek various forms of cooperation with farmers, and provide a more professional system guarantee for the development of APV systems. In the future, with society’s (including farmers) deepening understanding of agrivoltaics and the continuous development of modern agriculture in Hungary, the reduction in photovoltaic power generation costs and the energy-saving potential of agrivoltaic use are of great significance for the promotion and use of agrivoltaics with solar energy and agricultural production in rural areas. Different factors affecting the implementation of the APV system were shown in our calculation, such as the high investment cost, lower income for farmers, and the investment cost which cannot be returned to investors. However, government support is needed to build an APV system in Hungary because the production cost is too high.
Limitations
The scope of the research is large, the data are limited, the future trend of APV development is uncertain in Hungary, and the extraction of the research content in the paper is still insufficient, which needs to be continuously improved in the follow-up research work.
The paper only takes the Kaposvár Solar Park as an example to conduct research in Hungary, lacking comparison in different regions with different electricity and agricultural yields. The comparison of APV and PV systems with a conventional apple plantation in different rural regions and the actual utilization efficiency of APV and PV systems forms need to be further explored. Currently, the APV system is not competitive in Hungary without state subsidy, and our results may be used for determining the regulations for APV systems. Due to limited statistical data and incomplete survey data, it is difficult to obtain the same comprehensive data on rural household energy consumption on a large-scale PV system. In future work, we need to accurately track the preface of relevant research, strengthen data collection, conduct in-depth research, and make a more comprehensive assessment of rural PV energy with agricultural production. If an APV system is implemented in the future in Hungary with state and private support, then we will have the opportunity to consider and use the actual data of a farm-level APV system.
Hungary (like the EU) is in a critical period of energy transformation. There are great uncertainties in the future socio-economic development and APV utilization. Based on the absence of an exciting long-term national development plan, the article forecasts the future structure and investment of APVs for the implementation of APVs, but the prediction accuracy needs to be verified and improved. More timely data should be obtained, and different methods and models should be used to supplement and revise the prediction results of rural APV systems with electricity generation and agricultural production from the perspectives of electricity consumption influencing factors, PV to APV transformation in rural areas, and APV technological progress. When this paper studied the assessment of the development potential of APV systems, it only considered the power generation capacity and investment cost of the system and ignored many factors of the cost calculation of the cost benefit analysis, such as the uncertain price of electricity, transportation cost, the equipment of APV and PV installations, the considered agricultural species and their yields, and production functions in different regions. Additionally, the area where the plant will be installed, the hours of sunshine, and the quality of the PV panels should be considered to find the best location. It is hoped that this can be improved in future work.