Archives of Sustainable Energy Systems

Assessing the impact of solar PV on vegetation growth through ground sunlight distribution at a solar farm in Aotearoa New Zealand

2025-08-12T03:18:36+00:00

The global shift toward renewable energy has positioned solar photovoltaics (PV) as central to sustainable development. However, the land demands of ground-mounted PV systems raise concerns about competition with agriculture, particularly in regions with limited or productive farmland. Agrivoltaics, which integrates solar energy generation with agricultural use, offers a potential solution. While agrivoltaics has been extensively studied in arid and semi-arid climates, little is known about its feasibility and impacts in temperate environments such as Aotearoa New Zealand, particularly the effects of PV-induced shading on ground-level light availability and vegetation. This study modelled the spatial and seasonal distribution of ground-level irradiation and Photosynthetic Photon Flux Density (PPFD) beneath fixed-tilt PV arrays at Tauhei Solar Farm in the Waikato region. Using 2018 hourly SolarGIS data and a Python-based simulation, the research accounts for solar geometry, panel shading, and irradiance decomposition. It quantifies and maps PPFD to evaluate light conditions and its implications for vegetation growth. Results reveal significant spatial and temporal variation in PPFD. In summer, midday inter-row areas exceeded 450 μmol/m²/s, while winter under-panel zones often fell below 100 μmol/m²/s—near the light compensation point for many shade-sensitive plants. This variation supports a precision agrivoltaic strategy that zones land based on irradiance levels. By aligning crop types and planting schedules with seasonal light profiles, land productivity and ecological value can be improved. Spring and summer favour high-light crops, while winter is more suitable for shade-tolerant species or grazing. These findings are highly applicable in Aotearoa New Zealand’s pasture-based systems and show that effective light management is critical for agrivoltaic success in temperate climates.

An investigation into low-inertia grid stability with high injection of variable renewable energy sources

2025-08-29T02:37:32+00:00

As the world moves towards decarbonising the energy sector, variable renewable energy sources (VRES) are seen as an integral part of the transition. Much has been researched about the different forms of VRES, which are also known as inverter-based resources (IBR), and of the challenges of integrating them into pre-existing grid infrastructure. Nevertheless, the complex dynamics and impacts on grid stability, particularly within low-inertia grids, are case-specific and so warrant continued attention. This research analyses the specific response of one such grid, on Rakiura Stewart Island of Aotearoa New Zealand, to increasing solar photovoltaic capacity. Issues such as generator motoring and voltage rise are encountered, which suggest that the grid would also see frequency rises. As the capacity of VRES penetration increases, the effects are enhanced. Comparing the results show that negative effects are overall better mitigated by using a decentralised approach, as this offers more even distribution of the generation burden, lower line voltage drops, decreased line losses, and greater line loading reductions. Decentralised systems also have the advantage when it comes to decreasing loading on diesel generators in the grid, reducing fuel use and lengthening the lifespan of the generators. In exchange for these benefits, however, decentralised installations introduce higher node voltages and increase coordination complexity for seamless operation. Subsequent investigations should focus on the strategic integration of energy storage and power electronics, including flexible alternating current transmission system (FACTS) devices and static synchronous compensators (STATCOMs).

Techno-economic analysis of hybrid wave energy and floating photovoltaic systems in remote islands: A case study in Indonesia

2025-08-12T03:46:19+00:00

Remote islands in Indonesia continue to face significant challenges in achieving reliable and sustainable electricity access, with diesel-based systems dominating energy supply despite high operational costs, limited availability, and environmental drawbacks. This research investigated the techno-economic feasibility of two renewable energy configurations for achieving 24-hour electrification on remote islands, using Pulau Enggano as a representative case. Scenario 1 combines a floating photovoltaic (FPV) system, a wave energy converter (WEC), and battery storage, while Scenario 2 relies solely on FPV and battery systems. Using the System Advisor Model (SAM) of NREL for performance simulation and an annuitizing method for Levelized Cost of Electricity (LCOE) analysis, both systems were designed to meet hourly and annual energy demands. Scenario 1 achieved an LCOE of USD 306/MWh, offering a more stable supply profile with reduced battery cycling. Scenario 2, though technically sufficient, resulted in a higher LCOE of USD 382/MWh due to larger storage requirements. Both scenarios were compared against the adjusted diesel generation cost of USD 246/MWh. Sensitivity analysis revealed that WACC and CAPEX are the most influential factors on economic performance, particularly for Scenario 2. Battery cost uncertainty also significantly impacted the LCOE of the battery-dependent system. This study concludes that hybrid renewable energy systems leveraging both solar and marine resources can deliver continuous power more economically and reliably than solar-only alternatives, especially when supported by appropriate financing mechanisms. The research highlights the need for targeted policy support—such as subsidy reforms and capital incentives—to enhance the competitiveness of clean energy in Indonesia's remote regions. Future research is recommended to assess the role of bioenergy alternatives like palm oil biodiesel and to expand real-world resource validation using long-term time series data.

Towards a viable roadmap for solar and wind waste recycling in Aotearoa New Zealand

2025-08-13T01:59:40+00:00

Aotearoa New Zealand’s ambition for 100 percent renewable electricity by 2030 and full decarbonisation by 2050 has driven a rapid expansion of solar photovoltaic and wind power generation infrastructure. However, this growth presents a parallel sustainability challenge in the effective management of end-of-life waste management. This study therefore estimates future volumes of renewable energy waste through to 2080 and evaluates the economic potential of material recovery alongside an assessment of relevant policy and infrastructure conditions. Using a mixed-methods approach, quantitative projections based on installation lifespans and material intensity were developed for solar and wind waste streams, and a qualitative analysis of European Union and Australian best practices were undertaken to inform policy recommendations. The results indicate that cumulative waste from utility-scale systems will reach approximately 1.68 million tonnes by 2080, with high-value materials such as aluminium, copper, and steel offering a recoverable economic value of up to NZ$ 11.8 billion. Moreover, the analysis reveals that technical complexity, regulatory gaps, and limited economies of scale currently hinder the development of a local recycling industry. Additionally, our findings suggest that a viable recycling roadmap is achievable through extended producer responsibility schemes, targeted regional infrastructure investment, and integration of circular economy policies. Finally, proactive planning will enable Aotearoa New Zealand to align environmental sustainability with renewable energy deployment and position itself as a leader in the responsible management of clean energy transitions.

Impact of climate change on solar and wind electricity generation in Aotearoa New Zealand

2025-07-24T07:53:16+00:00

Climate change is driving the energy sector with significant impacts on renewable electricity generation systems. The purpose of this study is to analyse the impact of climate change on solar and wind electricity generation in Aotearoa New Zealand projected to 2050. To have realistic and tangible results and reduce the uncertainties, climate change is modelled with three climate and economic scenarios. The annual electricity generation projected for 2050 is estimated through simulations conducted with SAM (System Advisor Model), using data provided by NIWA. The projected energy output in 2050 is compared with the electricity production of two solar farms and five wind farms in 2024. The results show that solar electricity generation will be similar to the data that the Electricity Authority captured for 2024, with some slight seasonal variations. Wind-generated electricity is likely to be more affectedby climate change, with a substantial increase in average wind speed in winter and spring, especially on the southern island. A decrease in wind in summer and autumn reduces wind-generated electricity. The risks to the reliability and stability of solar and wind power generation systems are particularly amplified by the increase in extreme weather events, such as intensified storms, atmospheric rivers, and floods. This study highlights the vulnerability of Aotearoa New Zealand’s energy sector to climate change, and the need for adaptation strategies. The recommendations include flexibility of power grid management with alternative sustainable electricity generation solutions and storage strategies and strengthening solar and wind farm infrastructure to make them more resilient and durable against extreme weather events.

Underwater solar panels in Aotearoa New Zealand: An economic analysis

2025-08-13T01:41:21+00:00

The global shift toward renewable energy sources has intensified research into innovative solar energy solutions. One promising avenue is submerged photovoltaic solar panels (SP2), which leverage water cooling to enhance efficiency while addressing land use constraints. This study conducted an economic analysis of SP2 technology in the Aotearoa New Zealand context, comparing its viability to conventional land-based photovoltaic (LPV) and floating photovoltaic (FPV) systems. Using a cost-benefit analysis (CBA) framework, capital expenditures (CAPEX), operational costs, efficiency gains, and potential financial returns of SP2 farms were assessed. The findings indicate that while SP2 panels offer improved cooling and potential efficiency gains, these advantages are largely offset by higher installation and maintenance costs, biofouling risks, and structural challenges. Sensitivity analyses suggest that material advancements—particularly in GaInP and CdTe solar cells—could improve SP2 feasibility in the long term if manufacturing costs decrease. Additionally, the study highlights niche applications where SP2 could complement agricultural activities by preserving farmable land while providing renewable energy. Despite current economic limitations, SP2 technology remains a promising research direction, with potential improvements in cost efficiency, durability, and deployment strategies. Future work should focus on large-scale pilot projects, material innovation, and environmental impact assessments to refine the feasibility of underwater solar farms as a viable component of the renewable energy landscape.

Quantifying the green hydrogen demand across key sectors in Aotearoa New Zealand: Implications for electricity generation

2025-08-12T04:20:19+00:00

The transition to green hydrogen presents a great opportunity for Aotearoa New Zealand to meet its long-term climate targets while decarbonising energy intensive sectors. With over 80% of electricity already generated from renewable sources, the country is well-positioned to produce green hydrogen through water electrolysis. However, the extent to which hydrogen demand may impact electricity generation capacity remains underexplored. This study quantifies projected hydrogen demand across four key sectors: steel, heavy-duty transport (trucks and coaches), methanol production, and fertilizer manufacturing, from 2025 to 2050. Historical production and activity data were collected from national and international sources and used to project future sectoral activity. Hydrogen demand was estimated under both ideal stoichiometric and real-world adjusted efficiency scenarios. These values were then converted into electricity requirements using efficiency benchmarks for Proton Exchange Membrane (PEM) and Solid Oxide Electrolyser Cell (SOEC) technologies. The results show that the transport and methanol sectors exhibit the highest hydrogen demand, followed by fertilizers and steel. Under real-world assumptions, electricity demand to produce hydrogen could reach between 30 and 55 terawatt-hours annually by 2050, potentially exceeding Aotearoa New Zealand’s current generation capacity. The findings highlight the importance of aligning hydrogen development with renewable electricity expansion and infrastructure planning. The study provides a replicable modelling approach for emerging hydrogen economies, particularly in the Global South. It contributes to the evolving body of knowledge by offering a sector-specific assessment of hydrogen demand, integrating technological parameters with national energy system planning, and informing future hydrogen strategy development in Aotearoa New Zealand and beyond.