Economic and Environmental Outlook on Agrivoltaics: Review and Perspectives

Abstract

The growing world population has continued to drive up the demand for food and energy resources, putting substantial strain on the finite land, water, and fossil resources of the earth. Given the current climate crisis, the necessity of implementing renewable energy-generation strategies has become clear. Although solar energy is one of the most abundant and consistent forms of renewable energy available, conventional ground-mounted solar arrays require large amounts of land area, and solar energy generation may come into competition with agriculture with increasing installation capacity. Agrivoltaics has been presented as a solution to integrate agricultural activities with solar energy generation to enhance the land efficiency of both activities. Through this method, agriculture and solar energy become synergistic, generating multiple profit streams from the same land with additional potential environmental benefits. The review presented herein studies the literature pertaining to the triple bottom line for agrivoltaics systems: people, planet, and profit. Despite the early-stage nature of many available studies, researchers have reported that certain agrivoltaics systems could be up to 270% more profitable than standalone cropping systems and reduce the greenhouse gas potential of traditional agriculture and energy generation by up to 99%. By synthesizing the information from multiple techno-economic analyses, life-cycle assessments, and policy recommendations, we hope to provide some insight into the key parameters driving the long-term sustainability of agrivoltaics systems.

1. Introduction

Meeting the unprecedented demands of the growing world population for food and energy will require joint action to intensify agriculture and energy production simultaneously. While some level of demand increase is expected to result from population growth and rapid industrialization in many parts of the world, the projected increase in energy demand has grown more exponentially in recent years due to the rising prevalence of Artificial Intelligence tools, with experts predicting AI to account for up to 21% of the global energy demand by 2030 [1]. Given the current climate crisis, actions to meet these rising demands must also aim to reduce the greenhouse gas (GHG) footprints within both sectors [2]. Similarly, the increasingly scarce land and water resources must be considered as part a sustainable long-term solution [2,3,4,5].

Currently, agriculture claims 43% of the land area within the contiguous United States and an estimated 37% of the global land area, more specifically up to 50% of the world’s habitable land [6,7,8]. Moreover, the agriculture sector accounts for 70% of the global freshwater use and 26% of the global greenhouse gas emissions [2,9]. These demands and effects are disproportionately attributed to animal-based protein production. However, current global trends indicate that the demand for animal-derived protein sources will continue to outpace the demand for plant-based protein sources despite the negative environmental externalities [10]. Thus, any efforts to improve the long-term sustainability of food production must be multifaceted such that they address the emissions, land, and water intensity of both animal and plant production.

Many agree that the path toward net-zero emissions requires that some, if not most, of the global energy generation must transition from fossil fuels to renewable energy sources [2,3,5,7]. Although the ultimate solution will undoubtedly require a diverse mix of renewable energy-generation techniques, solar power (PV) has emerged as one of the most abundant and consistent sources of renewable energy global with the capacity to supply up to 50% of the global energy demands by 2050 [2,4]. Moreover, the production capacity of solar panels has grown substantially, accompanied by continual cost reduction, improving the economic outlook of large-scale PV projects [4]. However, the poor land efficiency of solar energy generation, approximately 0.3 MW/ha, would cause such PV projects to compete with agriculture for land resources [2,3,4,5]. In fact, USDA has begun restricting public funds for solar projects in an effort to protect “prime farmland” [11].

Agrivoltaics (AV) has been proposed as a solution to allow both agricultural activity and energy generation on the same land to maximize efficiency. These systems, illustrated in Figure 1, utilize ground-mounted solar panels that are installed at a height that accommodates continued use of the land for agricultural purposes, reducing the competition for land resources [2,3,7]. Specifically, the land can be jointly utilized for crop cultivation, animal husbandry, or habitat/ecosystem restoration efforts [3,5,7]. These systems most commonly incorporate one of the following configurations: solar panels in the traditional fixed-tilt or sun-tracking orientation raised on 5 m support frames to accommodate agricultural equipment, ground-mounted fixed-tilt or sun-tracking panels coupled with small grazing animals that require no additional ground clearance, or vertically mounted panels between crop rows [2,3,7].

At present, AV is estimated to increase land productivity by approximately 60% [2,4,5]. Moreover, AV systems that couple PV with crop cultivation may reduce the “heat island effect” of many large-scale PV installations as shade cast by the panels will mitigate temperature stressors to certain plants while the water given off by the plants works to cool the panels from below [2,3,7]. Similarly, AV is estimated to increase water use efficiency by more than 60% for many crop varieties due to reduced levels of direct sunlight [2,3,4]. Although the potential benefits for animal husbandry may not be as clear, studies have indicated that AV has no negative effects on yield efficiency compared to open pastureland [5].

These promising indicators are not without caveats, and many uncertainties remain about the large-scale outlook for AV systems given the complex environmental relationships in agricultural systems. While some plants and ecosystems may benefit from reduced temperature and levels of direct sunlight, others may show depleted yields because of increased soil moisture or shading [3]. Similarly, only certain animals may be suitable for integration with PV given spatial limitations [5]. In general, more research is needed to understand the impact AV may have on these complex systems prior to global implementation [2].

While ample literature reviews have thoroughly defined the technological concepts, outlook, and challenges of agrivoltaics, they have generally neglected an in-depth and quantitative commentary on practical issues, namely monetary and environmental costs. Given that the goal of agrivoltaics is to reduce the land, water, and emissions impacts of both food and energy production while offering additional income streams to land owners, it is important to highlight and quantify these opportunities and costs. Although this is an emerging field, researchers have begun quantifying the economic and environmental factors of agrivoltaics projects in multiple settings. Thus, the goal of this review was to summarize a small number of studies and reflect on the overall economic and environmental outlook of agrivoltaics as an approach to enhance food and energy production while mitigating negative environmental effects. The selected works focus on economic analysis and life-cycle assessments, specifically comparing agrivoltaics systems with standalone photovoltaics and/or agriculture. These works were selected to represent insights from many regions of the globe and diverse agrivoltaics configurations, specifically highlighting on works with well-defined key performance indicators, goals and scope, and modeling or field trials. Although we recognize that the following discussion is not a comprehensive review of this ever-growing body of literature, we hope to offer a concise perspective on the current state of economic and life-cycle research in the field of agrivoltaics and identify gaps and shortcomings in available research that, if resolved, could encourage more rapid implementation of agrivoltaics systems and supporting policies.

2. Techno-Economic Analysis

Although the cost of purchasing and installing solar panels has fallen significantly since they were first commercially available, the capital costs may still present a barrier to entry for many large-scale applications. Moreover, the instillation costs for AV solar panels are greater than standard ground-mounted PV system because they must be installed on taller skids to accommodate crops, farming equipment, or grazing animals below the panels [12]. Given these high initial costs accompanied by the potential reduced productivity of some crops due to changes in shading, temperature, or moisture levels, the economic outlook for AV systems was not clear cut upon initial investigation. In fact, the biological complexity of agricultural systems may give a different result for each proposed AV system, dependent upon chosen agricultural activity, specific environment, and system design, as described in the following discussion of published case studies.

Moreda et al. [13] studied two 25-year AV projects that coupled fixed-tilt solar panels raised 5 m from the ground with either an early potato or processing tomato 4-year crop rotation scheme in southwestern Spain. The crop rotation system included four 6-ha plots for a total case study land area of 24 ha [13]. The PV structure installed on each plot consisted of 528 solar panels capable of generating approximately 3200 kW of power [13]. The techno-economic analysis (TEA) included considerations for water savings and yield reductions for each crop both attributed to partial shading from the PV structure [13]. The capital expenditures for the project, which primarily consisted of purchase and installation of the PV structures, was calculated as approximately €13 MM with total income from sale of energy ranging from €770,000 to €930,000 depending on the age and deterioration of the solar panels [13]. The internal rate of return (IRR) was quantified to compare the different scenarios, and results showed the IRR for these case studies ranged from 3.8% to 5.6% [13]. Citing a minimum acceptable IRR of 4.8%, the authors concluded that the profitability outlook for these projects was mixed [13].

Schindele et al. [14] compared the levelized cost of electricity (LCOE) for ground-mounted PV and AV systems and quantified the price performance ratio (ppr) for both potato and winter wheat in Germany. The AV and ground-mounded systems covered 2 ha of land [14]. Given the spacing requirements for AV, the installed capacity was reduced by 25% compared to the ground-mounted system [14]. Moreover, the higher capital costs of the AV system due to the 5 m instillation height requirement resulted in a 38% higher LCOE for the AV system [14]. Despite the higher capital costs, the ppr calculated for installing and AV system coupled with potato was 0.85, a value less than 1, which indicated a favorable profitability outlook [14]. Alternatively, the ppr for coupling AV with winter wheat production was 4.62, indicating that the profitability of AV may not be universal to all crop scenarios [14]. However, the authors concluded that the additional revenue generated in some cropping scenarios would justify the additional capital costs and favor AV over ground-mounted PV [14].

Garrod et al. [12] compared standalone cropping, ground-mounted PV, and AV systems in the UK. Multiple solar panel configurations were considered for AV including ground-mounted panels spaced to accommodate crop rows, panels installed 5 m above the ground, and vertical mounted solar panels spaced to accommodate crop rows [12]. The study quantified the land equivalence ratio (LER), corresponding to the sum of ratios between agricultural and energy yield in the AV versus standalone systems (cropping and PV), respectively [12]. The LER results indicated that AV systems outperformed standalone cropping or PV in all studied areas of the UK [12]. Moreover, the AV systems were found to be between 104% and 274% more profitable than standalone cropping, despite reductions in crop yields [12]. Finally, despite the high capital costs of panel instillation, the net present value assessment of AV systems indicated that AV systems are equally or more favorable to standalone cropping in terms of lifetime profits [12].

Zhang et al. [15] studied an AV system that utilized concentrator solar panels in place of standard solar panels. These solar panels support photosynthetic efficiency by transmitting red and blue wavelengths through the panels to the ground below while other wavelengths of light are reflected or converted to power [15]. Although these panels have been shown to have poorer conversion efficiency than standard solar panels, the authors reported achieving a conversion efficiency of 11.6% by optimizing the panel design and using a dual tracking system to capture the maximum amount of solar energy [15]. Moreover, results showed that the chosen crops, including ginger, peanuts, sweet potato, bok choy, and lettuce, increased in yield efficiency compared to standalone cropping due to the improved temperature and humidity conditions accompanied by the concentrated wavelengths of light [15]. These findings resulted in a LER between 1.5 and 1.9, indicating improved land efficiency across all scenarios [15]. Moreover, the cost comparison showed an 18% reduction for this particular AV scheme compared to a standalone ground-mounted PV system, resulting from the increased profits from the sale of agricultural goods [15].

Alam et al. [16] compared the profitability of several AV systems with ground-mounted PV, studying multiple solar panel configurations, high- and low-value crops, and the effect of land cost and size. The goal of this work was to present a standardized framework for economic analysis of AV systems, stating that AV is only economically attractive when the profits of AV and crop production are greater than the profits for standalone cropping or ground-mounted solar [16]. Two cases were studied, assuming that either high value or low value crops were grown on an AV farm in Pakistan [16]. Each case study considered north/south-facing fixed-tilt or east/west-facing vertical solar panel configurations [16]. The results showed that low-density AV systems were most preferable for high-value crops and low land cost, whereas high-density systems were preferable for low-value crops regardless of land cost [16]. However, they concluded that AV systems were only economically competitive with ground-mounted PV for high-value crops [16].

Rabasoma et al. [17] studied low- and high-density AV systems for tomato farming, comparing standalone crop production to an AV system in Botswana. Although tomatoes are shade-tolerant, the authors predicted a minimum reduction in yield by 16% resulting from partial shade [17]. However, the operating costs for both AV systems were greatly reduced because a solar-powered water pump was assumed for irrigation to replace the costly diesel-powered pump necessary in the standalone case [17]. The profitability assessment showed a payback period of 17 years for the standalone cropping system compared to a payback period of 3 to 4 years for both AV systems [17]. Moreover, the net present value for both AV systems was positive compared to a negative value for the standalone system [17]. Although the annual revenue for the systems included income from power generation, the authors failed to clearly cite the assumed selling price for the excess solar energy, somewhat convoluting their results.

Trommsdorff et al. [18] studied AV systems that produced cotton, soybean, tomato, and banana in India integrated with either vertical or raised fixed-tilt solar panels. Like other analyses, they found that the LER is between 1.6 and 2.4, and AV improved the land-use efficiency compared to either standalone cropping or PV generation [18]. However, the profitability assessment indicated the importance of government subsidies to overcome financial barriers: the scenario that considered no government subsidies, such as higher electricity sale price or lower discount rates, had a negative net present value at the end of 25 years, indicating an unprofitable investment [18]. However, the additional scenarios that included some level of government assistance resulted in a positive net present value, even for the high-cost scenario [18].

In their AV review article, Gomez-Casanovas et al. [2] cited that the literature published to date on the economic outlook of AV systems was limited and did not consider the larger picture in terms of standard design practices and the necessity of policy action. Although the techno-economic analyses presented above tend to be highly specific and may not apply to all systems and scenarios, some general conclusions may be drawn (summarized in

Table 1. Comparison of technoeconomic analysis findings.

PV Description	Agricultural Description	Referenced Study Location	KPIs Assessed	KPI Results	Reference
South-facing, fixed tilt	Potato, canola, faba bean, forage maize, and onion	Spain	IRR (%)	4.8–5.1	Moreda et al. [13]
South-facing, fixed tilt	Tomato, melon, onion, carrot, and dry pea	Spain	IRR (%)	5.2–5.6	Moreda et al. [13]
Southwest-facing, fixed tilt	Potato, canola, faba bean forage maize, and onion	Spain	IRR (%)	3.8–4.1	Moreda et al. [13]
Southwest-facing, fixed tilt	Tomato, melon, onion, carrot, and dry pea	Spain	IRR (%)	4.2–4.7	Moreda et al. [13]
Fixed tilt	Potato and winter wheat	Germany	PPR	Potato: 0.85	Schindele et at. [14]
				Winter wheat: 4.62
			LCOE	€0.0828/kWh
Fixed tilt	Cabbage	United Kingdom	LER	1.00–1.45	Garrod et al. [12]
			Revenue	₤31,400/ha–₤40,600/ha
Vertical mount	Cabbage	United Kingdom	LER	0.92–1.52	Garrod et al. [12]
			Revenue	₤27,200/ha–₤37,500/ha
Sun-tracking spectrally separated	Ginger, peanuts, sweet potato, bok choy, and lettuce	China	LER	1.50–1.91	Zhang et al. [15]
Fixed tilt	Tomato, cauliflower, and garlic	Pakistan	Feed in tariff requirement $∆FIT$ (%)	5.14–11.60	Alam et al. [16]
Fixed tilt	Cotton and wheat	Pakistan	Feed in tariff requirement $∆FIT$ (%)	15.22–23.03	Alam et al. [16]
Vertical mount	Tomato, cauliflower, and garlic	Pakistan	Feed in tariff requirement $∆FIT$ (%)	4.87–11.95	Alam et al. [16]
Vertical mount	Cotton and wheat	Pakistan	Feed in tariff requirement $∆FIT$ (%)	16.15–25.88	Alam et al. [16]
High-density fixed tilt	Tomato	Botswana	Revenue	₤290,000/ha	Rabasoma et al. [17]
			Payback Period	3.6 years
Low-density fixed tilt	Tomato	Botswana	Revenue	₤252,300/ha	Rabasoma et al. [17]
			Payback period	3 years
Fixed tilt	Cotton, soybean, tomato, and banana	India	IRR (%)	9.0–14.6	Trommsdorff et al. [18]
			LCOE	2.83 INR/kWh–3.65 INR/kWh
			LER	1.6–2.4

):

• The technology readiness level of these AV systems was still relatively low, and most installed systems were of the demonstration scale, necessitating highly specific economic analyses to indicate which experimental designs may be optimal for commercial deployment.
• Although AV had higher capital costs than either standalone cropping or ground-mounted PV, the additional revenue generated by sale of energy or agricultural products, respectively, resulted in more favorable LER across most of the presented case studies.
• In general, high-value crops that are shade tolerant presented a better economic outlook for integration with AV systems.
• Although the LCOE for AV was higher than for ground-mounted PV, the overall profitability of AV systems may be more favorable.
• Government assistance may be necessary to overcome the financial barriers of AV system installation.

3. Life-Cycle Assessment

In addition to the economic outlook for AV, it was important to quantify the potential environmental benefits. As cited previously, the agriculture industry utilizes large amounts of land and water as well as producing substantial greenhouse gas emissions. Although the TEAs presented in the previous section conclude that the land efficiency of AV is favorable over standalone cropping systems, there is little commentary about AV’s other performance with respect to other sustainability metrics. Thus, the following discussion will summarize the findings of the few published life-cycle assessments (LCAs) around different AV systems.

Pascaris et al. [19] studied AV systems coupled with pasture-fed rabbit production, comparing the integrated scenario to a case study including separated rabbit production and solar energy generation and a case study including separated rabbit production and conventional energy generation with the energy mix of Texas. The LCA took a cradle-to-gate approach, assuming that all downstream processing and consumption of resources was equivalent for all scenarios [19]. Each of the case studies was designed to produce approximately 413,000 MWh of energy and 7200 rabbits, and a multi-component functional unit of cumulative MWh output and kg rabbit meat was defined to facilitate the comparison of two distinct services produced without necessitating allocation complications [19]. The key performance indicators (KPIs) considered in this investigation were greenhouse gas (GHG) potential and fossil energy demand [19]. The integrated system results indicated 69% fewer GHG emission and 83% less fossil energy use compared to the separated rabbit–PV scenario, with reductions largely attributed to the nonuse of animal feed and its packaging/transport [19]. Moreover, the integrated system results showed 99% fewer emissions and 99% less fossil energy use compared to the separated rabbit–conventional energy scenario [19].

Busch and Wydra [20] conducted an LCA to evaluate AV integrated with potato production, comparing the integrated system with separated PV and potato production and separated conventional energy and potato production, utilizing the energy mix of Germany. The LCA used a cradle-to-gate approach, and each case was sized to produce 14 million kWh of electricity and 9200 dt of potatoes [20]. This study quantified many midpoint indicators to compare the systems with key differences between scenarios arising for mineral/metals use, fossil fuel use, water use, eutrophication, climate change, ozone depletion, and ionizing radiation [20]. In general, the AV and separated PV–potato scenarios displayed similar environmental results, and the environmental effects resultant from potato production was almost identical across all three scenarios [20]. Notably, the AV and PV–potato scenarios performed better than the conventional energy–potato scenario in all aforementioned key midpoint indicators, save mineral/metals use [20]. However, the authors noted that the PV–potato system did narrowly outperform the AV system as a result of increased material consumption for the construction of mounting structures [20].

Krexner et al. [21] compared 5 case studies to evaluate the performance of AV to mono-production scenarios. The case studies include a raised fixed-tilt AV system, vertical panel AV system, standalone cropping utilizing the standard Australia energy mix, standalone cropping using green energy, and standalone ground-mounted PV [21]. Like previously introduced studies, this analysis utilized a joint-functional unit framework to avoid complications from allocation, independently quantifying the environmental effects of agricultural activities and energy utilization to quantify the overall effects of each scenario [21]. A 4-year crop rotation scheme was utilized to quantify agriculture activities including sugar beet, wheat, and soybean production. In all analyzed midpoint indicators, the vertical panel AV system showed reduced environmental impacts compared to the raised fixed-tilt AV system [21]. Notably, both AV systems performed worse than all mono-production scenarios with regard to carcinogenic toxicity, non-carcinogenic toxicity, terrestrial acidification, and mineral resource recovery due to the materials necessary for construction of these systems [21]. Finally, the standalone cropping scenario utilizing green energy was shown to perform best among alternatives across all analyzed midpoint indicators [21].

Wagner et al. [22] performed an LCA to evaluate the environmental impact of integrating 1 ha of existing agricultural land with a raised fixed-tilt solar array for an integrated AV system. The crops produced included wheat, celery, potato, and a clover-grass fodder mix in a 4-year rotation scheme [22]. By summing the net impact of installing the solar array and the net benefit of conventional energy use avoided, the authors generated an overall change in emissions for several midpoint indicators [22]. The clearest benefits of the analysis were avoided climate change, eutrophication, and fossil fuel use, with a total reduction of 91%, 95%, and 91%, respectively [22]. However, more mineral resources were necessary in the integrated system for construction of the solar array, resulting in the only negative net impact to the environment for the studied system [22]. Combining all of the evaluated midpoint indicators into a single score, the authors found that the integrated system reduced environmental effects by 79% compared to the standalone cropping scenario [22].

These LCAs, while not comprehensive, offered some valuable insights into the environmental effects of AV systems. Like the previously presented TEAs, the investigated case studies were highly specialized with limited discussion of broader implications to other animal grazing or cropping scenarios. However, there are recognizable trends within these published results (summarized in

Table 2. Comparison of life cycle assessment findings.

PV Functional Unit	Agricultural Functional Unit	Referenced Study Location	KPIs Assessed	KPI Results	Reference
412,600 MWh	19,440 kg rabbit meat	United States	GWP	388,000 kg CO2-eq	Pascaris et al. [19]
			Fossil Energy Demand	46,000,000 MJ
14,400,000 kWh	9200 dt potatoes	Germany	GWP	0.19 kg CO2-eq	Busch and Wydra [20]
			Ozone depletion	1.06 × 10−8 kg CFC-11 eq
			Ionizing radiation	6.75 × 10−3 kBq U-235 eq
			Photochemical Ozone formation	6.14 × 10−4 kg NMVOC eq
			Particulate matter	1.82 × 10−8 cases of illness
			Human toxicity (non-cancer)	1.86 × 10−8 CTUh
			Human toxicity (cancer)	4.86 × 10 CTUh
			Acidification	2.11 × 10−3 Mol H+ eq
			Eutrophication (freshwater)	8.75 × 10−5 kg P eq
			Eutrophication (marine)	1.93 × 10−3 kg N eq
			Eutrophication (terrestrial)	8.18 × 10−3 Mol N eq
			Ecotoxicity (freshwater)	1.38 × 102 CTUe
			Land use	1.55 × 10 Aggr. Index
			Water use	5.77 × 10−2 m3 depriv.
			Resource use (fossils)	1.88 × 10 MJ
			Resource use (minerals/metals)	1.08 × 10−5 kg Sb eq
1620 MWh/4yr fixed-tilt	4-yr crop rotation: 69.35 t sugar beet/ha, 5.41 t winter wheat/ha, 2.64 t soybean/ha, 5.41 t winter wheat/ha	Austria	GWP	114.09 g CO2-eq/FU	Krexner et al. [21]
			Human toxicity (non-cancer)	350 g 1,4-DCB/FU
			Human toxicity (cancer)	62 g 1,4-DCB/FU
			Acidification	0.65 g SO2 eq/FU
			Eutrophication (freshwater)	50 g P eq/FU
			Mineral resource scarcity	2.5 g CU eq/FU
1196 MWh/4yr vertical mount	4-yr crop rotation: 65.52 t sugar beet/ha, 5.12 t winter wheat/ha, 2.50 t soybean/ha, 5.12 t winter wheat/ha	Austria	GWP	61.41 g CO2-eq/FU	Krexner et al. [21]
			Human toxicity (non-cancer)	200 g 1,4-DCB/FU
			Human toxicity (cancer)	19 g 1,4-DCB/FU
			Acidification	0.49 g SO2 eq/FU
			Eutrophication (freshwater)	20 g P eq/FU
			Mineral resource scarcity	1.75 g CU eq/FU
713 MWh/yr	1.3 t wheat/yr, 2.7 t celery bulb/yr, 6.5 t potato/yr, 1.6 g clover grass/yr	Germany	Single score results	Impact/Benefit	Wagner et al. [22]
			GWP	1.43/16.34
			Ozone depletion	0.01/0.03
			Ionizing radiation	0.02/0.28
			Photochemical Ozone formation	0.28/0.99
			Particulate matter	0.46/0.50
			Human toxicity (non-cancer)	0.15/0.34
			Human toxicity (cancer)	0.17/0.10
			Acidification	0.26/1.51
			Eutrophication (freshwater)	0.47/9.60
			Eutrophication (marine)	0.10/0.59
			Eutrophication (terrestrial)	0.13/0.67
			Ecotoxicity (freshwater)	0.86/3.01
			Land use	0.02/0.03
			Water use	0.34/0.38
			Resource use (fossils)	0.86/9.49
			Resource use (minerals/metals)	3.87/0.38

):

• Analyzed systems containing any quantity of installed solar, including standalone PV and AV, resulted in higher impacts for mineral resource consumption that systems utilizing the standard energy mix of their location.
• AV systems reduced the emissions and fossil resource use compared to any scenario utilizing the standard energy mix.
• AV systems generally presented similar LCA results as scenarios considering standalone cropping and PV but require more mineral resources.
• AV systems offered additional environmental benefits, including reduction in eutrophication and ozone depletion but may result in higher levels of carcinogenic and non-carcinogenic human toxicity and terrestrial acidification due to the production of solar panels.
• Single score analysis showed that the net benefits of AV are greater than the costs due to the reduction in standard energy consumption.

4. Outlook for the Triple Bottom Line

For a solution to be sustainable, it must seek to maximize benefits to all elements of the triple bottom line: people, planet, and profit. Because it is difficult to quantify the impacts new systems may have on social issues, most analyses tend to focus on economic or environmental aspects as illustrated in the preceding sections. However, a few researchers have evaluated the potential effects that AV may have on society, focusing specifically on policy measures, public support for solar energy, and socio-economic outcomes as described below.

In addition to their findings regarding the economic viability of AV systems in India, Trommsdorff et al. [18] synthesized a framework to understand the potential social challenges of the system adoption, paying particular attention to the risks, benefits, and responsibilities of investors, financiers, and farmers. Three scenarios were considered to evaluate different levels of cooperation between the farmer and investor ranging from no interaction to a fully symbiotic relationship [18]. Further, they evaluated the financial, social, and political costs and benefits for each stakeholder [18]. In general, the lower levels of interaction between farmer and investor result in higher levels of social or political risk, but also lower financial investment on the part of the investor [18]. Based on these qualitative conclusions, the authors recommended that an integrated farming system that engaged with all stakeholders would result in the best operational and social outcomes and support the long-term sustainability of such AV projects [18].

Pascaris et al. [23] evaluated the ability of AV systems to improve the public support of solar installations. The authors developed a survey that studied the differences in public support between conventional ground-mounted solar and AV installations, surveying residents from both Lubbock County, TX and Houghton County, MI [23]. While the survey results indicated that 82% of respondents would be more in favor of solar installations that integrated agriculture activities, land use and land type were a particularly important factor for public support [23]. Specifically, respondents preferred that AV systems be cited on existing agricultural land and not on public property [23]. Given these particular concerns, the authors recommended that governments be particular to leverage energy siting and zoning policies in support of these preferences with care taken to require that agricultural activities continue on the land below the solar panels [23].

Schindele et al. [14] presented policy implications of AV systems in addition to the economic results reported in their study. The authors recommended that subsidies may be helpful to remove the barrier to installation for many AV projects but encouraged additional regulation that ensures the continuation of agricultural activities [14]. Further, they recommended that funding guidelines require that the AV systems are designed to maximize both crop and energy production to avoid the creation of pseudo-AV systems that aim to reap additional support through false claims [14]. The authors also suggested that AV installations may be optimally utilized for permanent plant cultures that produce higher value crops in place of a standard crop rotation scheme, improving the profitability of these systems [14]. It may also be necessary that policymakers enact price floors and ceilings as well as size requirements of AV installations [14]. These policy practices during the early stages of AV deployment could aid in the survival of the technology and improve the long-term outlook for additional projects [14].

These recommendations and reflections clearly indicated that policy frameworks will be very important to support the long-term success and public support of AV systems. These policies may include actions that establish clear requirements for location of AV projects or those that mandate the design and operation of the systems. Further, policies that influence and engage all stakeholders in support of a fully integrated system between energy and agriculture activities will support the most robust system despite potential additional costs.

5. Conclusions and Future Recommendations

As with many emerging technologies, the initial economic and environmental case studies for agrivoltaics have been highly specific with few generalizations made about the outlook for the industry as a whole. It is clear from the range of KPIs and functional units reported in Table 1 and Table 2 that there is little homogeneity across published studies, making comparison difficult. Further, many of the selected studies are short-term in nature, and there is a general lack of large-scale field trials to support the findings of the available pilot data. Because of these shortcomings in the research, policy initiatives have been slow to gain traction, and agrivoltaics has not yet been widely implemented, even in locations where early-stage research findings show promising economic and environmental outcomes. Thus, researchers that are contributing to this ever-growing body of literature should aim to improve the consistency of reported KPIs, especially with respect to economic indicators, grow the body of data available for both large-scale and late-stage AV systems, and offer more specific discussions with respect to policy recommendations to more rapidly deploy AV systems in locations where there are positive economic and environmental outcomes.

Despite the diverse nature of the presented literature, both in scope and results, common trends are recognizable. In general, AV systems are preferable in terms of land-use efficiency compared to standalone cropping or PV, and the higher capital investments for AV are typically balanced by additional revenues from agricultural activities. Moreover, AV systems have favorable environmental outcomes compared to standalone agriculture and conventional generation, but the installation of solar panels requires higher inputs of mineral resources, a negative environmental outcome of these systems. Finally, it is clear that policy measures will be necessary to ensure the long-term sustainability of AV projects, specifically policies regarding project location, funding, and stakeholder engagement.