Solar for hydroponics

Solar for hydroponics

An international research team has examined combining solar power generation with energy-intensive hydroponic horticulture and has found that this may be a viable solution depending on project size and available incentive policies. Their approach considered various factors impacting PV system efficiency, including environmental factors, the type of solar array, and the electricity demand from the hydroponic farm.


A Chinese-Qatari research group has assessed the potential of integrating PV power generation with hydroponic farms (SAHFs), which are a kind of horticultural crops that do not use soil and utilize mineral nutrient solutions in an aqueous solvent, usually in greenhouses or closed spaces.


“Hydroponic systems provide water-efficient food production but they are not an energy-efficient solution,” the scientists explained. “This is because they require electricity for heating and cooling, ventilation, irrigation, LED lighting, and other horticultural practices to maintain the hydroponic farm operations in controlled environments.”


The scientists investigated, in particular, how a multi-period, electricity-intensive hydroponic crop production system may be coupled to a PV system under different incentive policies such as feed-in tariff (FIT) programs, rebate schemes, net metering and improving electricity tariff (IET) mechanisms, which consist of simply raising electricity prices for consumers or reducing existing subsidies to the electricity price.


Their approach considered various factors impacting PV system efficiency, including environmental factors, the type of solar array, and the electricity demand from the SAHF. A series of experiments were conducted assuming SAHF operations in Qatar. This framework should provide SAHF developers with enough information to ascertain if a PV system should be installed and which type of solar modules should be used, as well as for identifying optimal sizing and capacity.


For the business case in Qatar, the scientists took into account a 1200 mhydroponic farm containing 60 growing trays with an area of 10 m2 each, and an overall 600 m2 are used for growing. The farm has an estimated cost of $4,984 per tray, with the interest rate being assumed to be 2.5%. Electricity and water tariffs were assumed to be $0.036/kWh and $0.0015/L, respectively. Four crops such as tomato, cucumber, lettuce and pepper, as well as six types of PV systems were considered. One-at-a-time (OATsensitivity analysis was used to identify the best project configuration under the four different incentive schemes.


The incentive threshold under the IET policy was found to be $0.0425/kWh, while for feed-in tariffs and net metering the threshold was $0.0063/kWh and $0.027/kWh, respectively. For the rebate scheme, a minimum rebate of 14.90% was considered necessary.


The scientists explained that the IET scheme is the most effective in pushing farmers to resort to solar, although it is the more expensive for them, while feed-in tariffs and rebates are indicated an ideal solution for solar hydroponics farms with limited size. “For the hydroponic farmers, once it is profitable to engage in solar energy generation and the right type of PV system is selected, the best strategy is to take full advantage of the available space to maximize the PV system capacity if the surplus electricity can be sold to the grid or other entities,” they emphasized. “The profit of the SAHF is more sensitive to the subsidy levels of the surplus FIT and IET than other policy parameters, while the outputs of the farm show insensitivity to all the subsidies.”


The proposed model was described in the paper “Decisions on design and planning of solar-assisted hydroponic farms under various subsidy schemes,” published in Renewable and Sustainable Energy Reviews. The research group comprises scientists from the Nanjing University of Aeronautics and Astronautics in China and the Hamad Bin Khalifa University in Qatar.

Google lends a hand in the search for new solar cell designs with open-source tool

Google lends a hand in the search for new solar cell designs with open-source tool

Scientists in the United States developed a computer simulator that can calculate the conversion efficiency of different solar cell materials and configurations – helping to guide research and optimization of new cell designs. The simulator is available to researchers as an open-source tool to save time and spot the best opportunities for optimization of any given approach.


The number of materials with the potential for use in each of the many layers in a solar cell is enormous. And even once they have chosen one to work with, scientists need to understand its interactions with the other materials present, and the effects of changing parameters such as layer thickness, dopant concentration and a wealth of others in order to get the best out of the cells they are working on.


With so many possibilities, this can be a time-consuming process. And scientists today are increasingly able to turn to artificial intelligence to guide them in the next steps to take in practical lab work. And developing a system to do just that for solar cell design was the focus of a group of researchers at the Massachusetts Institute of Technology (MIT), who worked with experts at Google Brain to develop a system to evaluate the potential of different solar cell designs, and also predict which changes would provide improved performance characteristics. “We developed a tool that will enable others to discover more quickly other higher performance devices,” explained MIT researcher Giuseppe Romano. “Our tool can identify a unique set of material parameters that has been hidden so far because it’s very complex to run those simulations.”


The model is described in the paper ∂PV: An end-to-end differentiable solar-cell simulator, published in Computer Physics Communications. With data on a solar cell configuration, it outputs a predicted efficiency, and shows which of the input parameters affects the prediction the most. It can evaluate multiple variables for each layer including doping concentration, dielectric constant and bandgap. And its researchers point to layer thickness as a particularly important variable. “…the thickness is critical,” said MIT scientist Sean Mann. “There is a strong interplay between light propagation and the thickness of each layer and the absorption of each layer.”


MIT is making the model available as an open-source tool that can be taken up by researchers and industry. According to the institute, it is ready to be combined with other algorithms and machine learning processes to quickly assess many possible changes to device design and pull out those with the most potential.


And since it is based on open-source code, future users will be able to optimize it further for more complex cell architecture, such as tandem and multijunction devices. The current version, “can cover the majority of cells that are currently under production, and there are ways to approximate a tandem solar cell by simulating each of the individual cells,” said Romano. “But once it’s up there, the community can contribute to it, and that’s why we are really excited.”

Photovoltaic rotary energy system for domestic applications, high-rise buildings

Photovoltaic rotary energy system for domestic applications, high-rise buildings

Scientists from the Adana Science and Technology University in Turkey have designed a prototype of a rotary energy system (RES) that they claim may become a solution that is particularly suitable for domestic applications and high-rise buildings in regions with high wind energy and solar energy potential.


“The system was manufactured using 3D print technology and consists of a single structure,” research author, Abdurrahman Yavuzdeger, told -”Its rotation movement produces air streams that are able to reduce the operating temperature of the solar panels and reduces dust accumulation considerably.”


The system has a decagonal shape and each of its sides hosts a polycrystalline photovoltaic panel with a size of 140×60×2.5 mm and a weight of just 33g. The modules are placed at a 30mm distance from one another and they have a power conversion efficiency of over 17%. Their rated voltage is 6V and the rated current is 100mA.


Air ducts measuring 95×150 mm are embedded between each of the system’s 10 sides to reduce the operating temperatures of the panels and, simultaneously, that of the whole system. A slip ring with an efficiency of around 96% has been used to solve the problem of entanglement of the cables in the solar modules.


stepper motor Nema 23 for low-speed applications is used to rotate the system. It measures 56.4×56.4×76 mm and weighs in at 1kg. Its operating voltage is 8.6 V and its operating current is 1 A on each phase. A stepper motor driver TB6600 is used for rotation speed adjustment and the speed is controlled by a controller interface. The system’s rotating speed ranges from 0 to 100 revolutions per minute (rpm). A measurement station records ambient temperature and solar radiation data.


The system was operated 0, 10, 50, and 100 rpm/h and with solar radiation of between 110 and 1210 W/m2. “Although the highest irradiance value is at 10 rpm, the highest power value produced from the RES has been measured at 100 rpm,” the scientists said. “The cooling of the PV panels has been realized with the increase of the rotation speed.”


The highest output power of the system was found to be 1.8067 W at operating 100 rpm and 756 W/m2 solar radiation, while the lowest was 0.5698 W at operating 10 rpm and 234 W/m2 solar radiation.

Micro-inverters vs. string/central inverters

Micro-inverters vs. string/central inverters

A group of researchers from the University of Limoges has compared the performance ratio (PR) of PV systems equipped with micro-inverters to that of installations relying on central or string inverters at several locations across France. Surprisingly, the study finds that micro-inverters do not perform better.


The PR is a parameter that defines the relationship between the actual and expected power production of a PV system, and is largely unrelated to an installation’s location or orientation. This value is used to understand how efficiently the PV system is operating.


The researchers initially analyzed all advantages and disadvantages of an installation with micro-inverters or central/string inverters, and said that micro-inverters should offer an advantage on many points, including price. “We must also consider the lifespans of this equipment, which is a little less than 10 years for a central inverter and can reach 30 years for a micro-inverter,” they further explained. “Micro-inverters also appear to be better suited to reducing the impact of losses that can occur in solar panels whether due to shading or panel malfunction.”


These assumptions were evaluated by analyzing 200 PV installations located in France. The work considered their actual production of solar energy, as well as the orientation, the inclination, the peak power, the geographical area, and other factors. “In order to carry out a statistical study on the PR, 200 data sets were recovered: 100 for installations with Enphase M210, M215, M250 and IQ7 microinverters and 100 with installations using SMA SunnyBoy 3000, SunnyBoy 5000 inverters and Sunny Tripower STP 8000,” the academics explained. “Of the 100 systems, 50 are SunnyBoy 3000 (input power 3.2 kW), 25 are SunnyBoy 5000 (input power 5.2 kW) and 25 are Sunny Tripower STP 8000 (input power 8, 2 kW).”


The average capacity of the installations relying on micro-inverters was 3.8 kW and that of the second category was 5 kW.


The analysis showed that micro-inverters are more sensitive to environmental factors. Furthermore, the scientists found that the size of a PV system doesn’t have an influence on the performance of either micro-inverters or inverters.


“According to the production data, the performance ratio is ultimately almost identical for installations with inverters or micro-inverters,” the French group emphasized. “The PR is around 79% for both the average facility equipped with micro-inverters and the average for other facilities.” It also reported slight growth in the PR with lower irradiance for both micro-inverter and central/string devices, which could depend on the inclination and orientation of the panels or the geographical area.


“Finally, the results show a homogeneity of the performance ratio between the two technologies despite different operations,” the academics concluded. “However, even if the performance ratio is identical between inverters and micro-inverters, micro-inverters are still to be favored because of their lifespans and their prices.” They go on to explain that microinverters may not be replaced for an entire 25 year module lifetime, and that they allow stakeholders to better guarantee the safety of the installation even in the event of fire.

Pilot floating platform for offshore hybrid wind-solar-wave projects

Pilot floating platform for offshore hybrid wind-solar-wave projects

Developed by German company Sinn Power, the floating platform currently hosts solar modules totaling 80 kW and may also embed small wind turbines and wave energy converters.


German wave energy technology company Sinn Power GmbH has unveiled its first floating ocean ‘hybrid’ platform, that combines wave, wind and solar energy.


The floating structure is hosting 80 kW of solar modules and was deployed in Heraklion, on the Greek island of Crete. It is claimed to withstand 12m-high waves and wind speeds of up to 27m/s without suffering any damage.


“Sinn Power’s Ocean Hybrid Platform is a seaworthy solution suitable for near shore and offshore applications and ready for reliable and economical operation,” the company said in a statement, noting that the installation relies on solar modules with IP68 junction boxes and smart-grid forming power electronics for floating hybrid systems.


According to the manufacturer, the platform can be used in a modular approach to build floating solar facilities with a combined capacity of up to 10 MW.


The system can also be powered by wave energy converters, depending on the maritime conditions and power demand. Furthermore, each of the corner points of the platform can host small wind turbines of different sizes, in a modular configuration. The small scale wind turbines are provided by German specialist Luvside. 


The facility has a size of 6x12m and can be equipped with adjustable buoyancy for different load scenarios. The anchoring specifications depend on a project’s size and water body. The structure fences are made of maritime aluminum and each floating body consists of a polyethylene segment, a connection hub, and a belt. The support buoys are said to enable a corrective movement of the platform and reduce tension within the entire structure.


“Sinn Power has successfully carried out real-life tests in Heraklion and actively markets its innovative solution to project developers worldwide,” the company stated.

SunPower launches VPP offering for its energy storage customers

SunPower launches VPP offering for its energy storage customers

SunPower Corp. said it will launch a virtual power plant program that will let energy storage customers who use its SunVault system to be paid for allowing the local utility to use stored energy during peak demand.


SunPower said it will coordinate charging and discharging customers’ batteries, while keeping some electricity in reserve for backup power to the home. Participating customers will be told ahead of time that their battery will be discharged and can choose to bypass or pre-set their system so their reserve does not fall below a certain level. In return, customers are expected to be paid by the utility for the use of their stored energy.


SunPower’s first offering is called ConnectedSolutions and will be marketed to customers served by Eversource and National Grid in Massachusetts, Rhode Island, and Connecticut.

Russia launches major solar plant in Siberia

Russia launches major solar plant in Siberia

A $40 million solar field which will double the generation capacity of the Omsk region is planned to start generating in December as part of the national government’s clean air ambitions.


Russian PV manufacturer Hevel has almost completed construction of its 30 MW Russko-Polyanskaya solar plant in Western Siberia, the government of the Omsk region has announced.


The solar field is expected to generate 35.5 GWh, enough to power 3,000 rural houses, the local government estimated. The RUB2.8 billion ($40 million) plant is slated to become operational on December 10.


Russko-Polyanskaya, not far from the border with Kazakhstan, will become the third solar plant in the Omsk Oblast, a warm part of Siberia with around 300 sunny days per year. The area is sparsely populated and is lacking infrastructure and power generation facilities. Most of the electricity in that part of Russia is generated by thermal power plants.


“The [solar] plant’s designed power generation capacity is equivalent to [the] burning of more than 1,800 tons of coal, and it would … avoid more than 5,000 tons of CO2 emissions into the atmosphere from the operation of coal-fired power plants,” said Oleg Shutkin, director of the engineering and generation department at Hevel.


In addition to avoiding emissions, the new solar plant will improve the Omsk region’s self-sufficiency in power generation, added regional energy minister Anton Gaak. “Thanks to the solar plant, the efficiency of the power grid economy is rising,” said the politician. “With new power generation, we can adjust this [system] and, ultimately, reduce the price for electricity for customers in [the] Omsk region.”


The Russko-Polyanskaya plant is set to almost double Omsk’s solar power generation capacity, to 61 MW. Solar plants will account for 3.8% of regional electricity output, Gaak said, adding that figure is projected to rise sharply in the coming years.


“We have achieved an agreement to launch new solar power plants with [a] combined production capacity close to 100 MW in the industrial zone of … Neftyanikov town and the southern districts of the Omsk region,” Gaak said, without elaborating further.


The Omsk government had already promised to build six solar plants in the region within the next three years.


In addition, the local authorities are mulling new incentives for investors willing to develop solar in the region. Proposals include a possible reduction of property tax for companies running renewable energy projects.


The development of solar generation is part of the national Clean Air program, under which the Omsk region wants to cut CO2 emissions by 20% by 2024. The investment cost of the program has been estimated at RUB116 billion ($1.66 billion).



Indian manufacturer unveils 375-410 W half-cut modules with 20.4% efficiency

Chinese PV Industry: Government announces deployment of 30 GW of renewables in northwestern China

Furthermore, TBEA has announced a plan to invest in four solar power plants and Flat Glass has agreed to acquire two quartz mines.


China’s National Development and Reform Commission (NDRC) confirmed this week that development began this month on a series of renewable energy projects with a total capacity of 30 GW. All the projects are located in China’s northern and northwestern provinces of Xinjiang, Inner Mongolia, Ningxia, Gansu, Qinghai and Shaanxi. Gansu is expected to host five projects totaling 12.85 GW and Qinghai 15 projects with a combined capacity of 10.9 GW. There will be around 2 GW of PV projects planned for the deserts of Inner Mongolia, and another 2 GW for Ningxia and Shaanxi, respectively. Most of these renewable energy projects will integrate wind power, solar PV, storage, and ultra-high voltage grid for connection and inter-provincial transmission. Some of the projects will include hydrogen generation and storage.


Module maker Risen Energy announced on Thursday that it will sell a solar park located in Australia, the Merredin Solar Farm, to Solar United Network Pte. Ltd. The total transaction value is around AUD186 million ($139.9 million). The solar farm is located between Perth and Kalgoorlie, and was connected to the grid in August. Risen said the deal would generate a net profit of RMB43 million ($6.7 million).


Chinese electronic engineer TBEA announced on Thursday that it wants to invest in four PV power plants with respective capacities of 102 MW, 50 MW, 80 MW and 20 MW. All the facilities will be located in northwestern China. The company will invest a total of RMB1.45 billion ($227 million) in the four projects — RMB770 million, RMB205 million, RMB363 million, and RMB114 million, respectively.


Glass maker Flat Glass Group announced on Wednesday that the company has purchased two quartz mines thanks to an investment of of RMB2.65 billion ($414 million). Located in Anhui province, the two quartz mines have estimated quartz assets of around 21 million metric tons and an annual supply capacity of 2.4 million metric tons of high-quality quartz.

Tesla orders 45 GWh of EV batteries from CATL

Tesla orders 45 GWh of EV batteries from CATL

Reports calculated that the single order would be enough to support production of 800,000 vehicles.


Chinese media reported that Tesla ordered 45 GWh of lithium iron phosphate (LFP) batteries from Chinese battery producer CATL. The batteries reportedly will be used for the automaker’s Model 3 and the Model Y.


The reports calculated that the 45 GWh would be enough to support production of 800,000 vehicles, which is more than Tesla’s sales through the first three quarters of 2021 (625,000 units). The news outlet pegged the battery capacity of the two models at 55 kWh and 60 kWh.


On October 28, CATL broke ground on a new lithium-ion battery production base in Yichun, east China’s Jiangxi Province. The first phase of the project involves an investment of around $2.1 billion to build a 50 GWh lithium-ion battery production base.

The Hydrogen Stream: Saudi Arabia bets on blue hydrogen, Denmark wants to improve green alkaline electrolysis

The Hydrogen Stream: Saudi Arabia bets on blue hydrogen, Denmark wants to improve green alkaline electrolysis

Elsewhere, Snam and Toyota are pushing for more hydrogen-based mobility in Italy, and Woodside Petroleum wants to establish an export-oriented hydrogen and ammonia production facility in Australia.


Saudi Arabia’s energy minister, Abdulaziz bin Salman, has said most of the gas from the $110 billion (€94.7 billion) Jafurah development will be used to make blue hydrogen, as part of an attempt by the kingdom to become the biggest supplier of hydrogen in the world, according to reports by news agencies Bloomberg and Reuters. “We are the biggest adventurers, when it comes to blue hydrogen,” Bloomberg quoted Prince Abdulaziz as saying. “We’re putting our money where our mouth is … on hydrogen. We have a terrific gas base in Jafurah, we will use it to generate blue hydrogen.” According to Reuters, the country wants to export around 4 million tons of hydrogen by 2030.


Eleven companies have launched the GreenHyScale project in Denmark. The plan, which includes a 100 MW electrolysis plant, aims at accelerating pressurized alkaline electrolysis to enable the large scale production of green hydrogen. “Our focus is to create a replicable solution for stakeholders in both Denmark and the rest of Europe – replicability is key to the dissemination of green hydrogen,” said Anders Bøje Larsen, chief technology officer of Danish green industrial park GreenLab today. “That makes GreenHyScale an important project with the potential to contribute greatly to the positive development of a hydrogen infrastructure in and outside of the EU.” The partner companies also want to lower the leveled cost of hydrogen towards cost parity with fossil fuels. The project is backed by €30 million of EU funding.


Japanese automaker Toyota, Italian gas transmission system operator Snam and Portuguese bus and coach manufacturer CaetanoBus have signed a memorandum of understanding to promote hydrogen-based mobility. “With this agreement, we aim to build an alliance between operators in the energy and transport sectors to offer end users competitive sustainable hydrogen mobility solutions,” said Snam chief mobility officer Alessio Torelli. The agreement may lead to “end-to-end” hydrogen mobility projects in Italy and other European countries, including along the entire value chain. “The presence of an adequate hydrogen refueling infrastructure is a necessary condition for developing its full potential for mobility,” said Luigi Ksawery Lucà, CEO of Toyota Motor Italia.


Australian energy company Woodside Petroleum has unveiled plans to establish an export-oriented hydrogen and ammonia production facility in southern metropolitan Perth. “Local refuelling stations can be built independently of the export project timelines and could operate as early as 2023, subject to approvals and customer demand,” the company wrote yesterday. In collaboration with the government of Western Australia, the company wants to build the project on around 130 hectares of vacant industrial land, near gas, power, water and port infrastructure. “‘H2Perth’ will also facilitate substantial growth of renewables in Western Australia by providing to the grid a flexible and stabilizing load that benefits uptake of intermittent renewable electricity by households and local industry,” said Woodside CEO Meg O’Neill.


South Korea-based Doosan Fuel Cell has signed a memorandum of understanding Korea Western Power and Korea Electric Power Corporation (KEPCO) in Seoul. The companies will develop a project to directly inject pure biogas – removed from unused biogas – into hydrogen fuel cells. “Doosan Fuel Cell plans to develop hydrogen fuel cell technology exclusively for pure biogas and supply main equipment, while Korea Western Power and KEPCO E&C are in charge of overall business, and design and construction of pre-treatment facilities, respectively,” the partners wrote. Doosan Fuel Cell has hydrogen fuel cell models that use energy sources such as clean and by-product hydrogen, LNG, and LPG. The agreement signed by the companies was not the only recent hydrogen development in South Korea. According to several reports, steelmaker POSCO and Korean Southern Power have also announced significant investments in hydrogen.


Aberdeen City Council has announced U.K.-based energy major BP as its preferred bidder for a commercial partnership to accelerate the city’s ambitions to become a world-class hydrogen hub. “Phase 1, which involves the delivery of a green hydrogen facility, is targeting first operations from 2024,” said a statement released by the local authority yesterday. “As a result, options could include using power drawn from a new photovoltaic solar farm, green power purchase agreements, and a private-wire grid connection to generate hydrogen for buses, heavy goods vehicles and large vans.” BP vice president Louise Kingham OBE said: “These new business opportunities are underpinned by our 50-plus years of operations in the North Sea where, based out of Aberdeen, we have built up vast skills and experience that are directly transferable to emerging energy industries.”