Solar Energy

Is it worth investing in solar PV with batteries at home?

Published

3 years ago

March 21, 2021

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Is it worth investing in solar PV with batteries at home?

Solar energy is a clean, renewable source of electricity that could potentially play a significant part in fulfilling the world’s energy requirements, but there are still some challenges to fully capitalizing on this potential. Researchers looked into some of the issues that hamper the uptake of solar energy and proposed different policies to encourage the use of this technology.

Installing solar panels to offset energy costs and reduce the environmental impact of their homes has been gaining popularity with homeowners in recent years. On a global scale, an increasing number of countries are similarly encouraging the installation of solar photovoltaics (PV) at residential buildings to increase the share of renewable energy in their energy mix and enhance energy security. Despite the promising advantages this mode of electricity generation offers there are still a number of challenges that need to be overcome.

Batteries to store excess electricity

Solar PV electricity generation peaks during the day when electricity demand is low, resulting in overproduction – especially on weekdays when people are usually not at home. Currently, this excess electricity supply is typically exported to the central electricity grid, but ideally, homes that have solar panels should be able to store overproduction of solar electricity, for example, using batteries, and consume it in the evening when demand is high and there is no solar electricity generation.

The problem is that the investment cost for batteries is currently quite high, which makes it economically unprofitable for consumers to pair their solar PV with a battery. In their new study published in the journal Applied Energy, researchers from IIASA, University College London, UK, and Aalto University, Finland, looked into this challenge and proposed different policies to encourage residential electricity consumers to pair solar PV with battery energy storage.

“We wanted to determine whether investing in residential solar PV combined with battery energy storage could be profitable under current market conditions for residential consumers and what kind of support policies can be used to enhance the profitability of stand-alone batteries or PV-battery systems.

On top if this, we also wanted to compare the system (or regulatory) cost of each PV-battery policy to the benefit of that particular policy for residential consumers who invest in these technologies,” explains lead author Behnam Zakeri, a researcher with the IIASA Energy, Climate, and Environment Program.

Benefits of using battery storage

The study shows that without a battery, homeowners only use 30-40% of the electricity from their solar PV panels, while the rest of the electricity is exported to the grid with very little to no benefit for the owner. With a home battery, the self-consumption of solar PV in the building almost doubles, allowing the residents to reduce electricity imports from the grid by up to 84%, which can in turn help the owner to become less dependent on the grid and electricity prices.

In addition, the researchers found that while PV-batteries are presently not really profitable for residential consumers, they can become so with the implementation of slightly different policies and regulations, even in high-latitude countries where solar irradiation is relatively low.

Energy policies for a decentralized energy system

The authors propose some novel energy storage polices that offer a positive return on investment between 40% and 70% for residential PV-battery storage, depending on the policy. These include, among others that national renewable energy policies adopt more innovative incentives to enhance the economic profitability of decentralized green energy solutions based on the contribution of these systems to the grid.

The results indicate that this can be easily achieved by, for example, rewarding consumers for using their solar PV generation onsite, instead of encouraging them to export the excess solar energy they produce to the grid.

The researchers further posit that the way utility companies and electricity distribution firms generate income today may itself be a hindrance to promoting the self-consumption of renewable energy in buildings, as these companies generally charge consumers for each unit of electricity imported from the grid.

If consumers therefore become independent from the grid, grid operators and utility companies would lose a significant part of their income. Such a scenario calls for new business models and operating modes to guarantee that central utilities do not see decentralized solutions as a threat to their revenues.

In today’s renewable electricity generation environment, capital subsidies are one option to partly pay for investment in batteries. The study points out that these policies are costly for the system, and may not automatically result in system-level benefits as they do not reward the optimal use of batteries. In this regard, Zakeri and his colleagues propose a “storage policy” that rewards residential battery owners to store and discharge electricity whenever the system needs it.

The profitability of PV-battery systems of course also depends on the type of retail pricing mechanism in the system. The findings indicate that dynamic electricity pricing at the consumer side, such as hourly electricity prices with an enhanced gap between off-peak and peak prices, will encourage consumers to use home batteries to benefit from charging at low price hours and discharging the battery when the electricity price is high. This way of operating a home battery could help reduce the pressure on the electricity grid at peak times, which has significant benefits for the system.

“Traditional, central energy structures are transitioning to new systems based on decentralized, renewable energy solutions. This requires more flexible, modern, and effective policies that can guarantee the social and economic benefits of the energy transition. We hope our analysis contributes to a better understanding of the role of some energy policies that can promote decentralized energy solutions,” Zakeri concludes.

Research Report: “Policy options for enhancing economic profitability of residential solar photovoltaic with battery energy storage”

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Solar Energy

Project receives funding for advanced solar-thermal research

Published

6 days ago

April 12, 2024

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Project receives funding for advanced solar-thermal research

by Sophie Jenkins

London, UK (SPX) Apr 12, 2024

The University of Surrey, leading a collaboration with the University of Bristol and Northumbria University, has received a GBP 1.1 million grant from the Engineering and Physical Sciences Research Council (EPSRC) to develop solar-thermal devices. These devices aim to revolutionize the way we heat homes and generate power, differing from traditional solar cells by converting sunlight into heat for energy production.

The research focuses on creating surfaces that selectively absorb sunlight and emit heat through near-infrared radiation. This project leverages the combined expertise of the institutions in photonics, advanced materials, applied electromagnetics, and nanofabrication to address a global need for efficient solar energy utilization.

Professor Marian Florescu, Principal Investigator from Surrey, highlighted the importance of the project: “The sun provides an immense amount of energy daily, much more than we currently harness. By advancing these solar-absorbing surfaces, we aim to transform solar energy use into a sustainable powerhouse for our increasing energy needs.”

Goals of the project include developing high-temperature solar absorbers, enhancing the efficiency of solar-absorbing structures, and improving the management of heat generated from sunlight. Prototypes will be constructed to demonstrate these technologies.

Professor Marin Cryan, Co-Principal Investigator from the University of Bristol, explained their focus on thermionic solar cell technology, which uses concentrated sunlight to initiate electron emission for high-efficiency solar cells.

Dr. Daniel Ho, Co-Principal Investigator from Northumbria University, added: “Our university leads in thermophotovoltaic research, utilizing advanced thermal analysis techniques. We’re excited to contribute to groundbreaking developments in renewable energy.”

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Solar Energy

Improving Solar and Wind Power Integration in the U.S. Grid

Published

7 days ago

April 11, 2024

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Improving Solar and Wind Power Integration in the U.S. Grid

by Clarence Oxford

Los Angeles CA (SPX) Apr 11, 2024

The Midcontinent Independent System Operator manages a high-voltage electricity network spanning from Manitoba to Louisiana, serving 45 million users. This vast operation requires maintaining a balance between the energy generated and the demand across its regions.

The traditional reliance on coal and natural gas power plants is changing. For example, wind farms in Iowa now generate over 64% of the state’s electricity, and recent initiatives like the Alliant Energy Solar Farm at Iowa State University represent the shift towards renewable energy sources. These sources, however, introduce variability and uncertainty into grid management.

Zhaoyu Wang, a Northrop Grumman associate professor of electrical and computer engineering at Iowa State, emphasized, The power system seeks certainty which is challenging with unpredictable natural resources like sun and wind.

Wang is leading the MODERNISE project, aimed at modernizing grid operations. The U.S. Department of Energy has earmarked a $3 million grant over three years for this initiative, with an additional $1.1 million coming from project collaborators including Argonne National Laboratory and Siemens Corp.

The project, titled Modernizing Operation and Decision-Making Tools Enabling Resource Management in Stochastic Environment, involves developing computational tools that allow for better integration and management of renewable energy sources into the grid.

Jennifer M. Granholm, U.S. Secretary of Energy, supported this initiative stating that effective integration of renewable resources is essential for deploying clean energy. The project is part of a larger $34 million investment by the DOE to develop technologies that enhance grid reliability and efficiency.

By aggregating smaller renewable energy resources into larger operational blocks, MODERNISE aims to improve grid stability and predictability. Bai Cui, project co-leader and assistant professor at Iowa State, explained that this approach allows operators to manage grid operations more effectively by understanding and handling the uncertainties of renewable supply sources.

This initiative promises to make grid operations more adaptable and efficient, critical for accommodating the increasing reliance on renewable energy.

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Solar Energy

Quantum Material Achieves Up to 190% Efficiency in Solar Cells

Published

7 days ago

April 11, 2024

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Quantum Material Achieves Up to 190% Efficiency in Solar Cells

by Clarence Oxford

Los Angeles CA (SPX) Apr 11, 2024

Researchers from Lehigh University have developed a material that significantly enhances the efficiency of solar panels.

A prototype incorporating this material as the active layer in a solar cell displays an average photovoltaic absorption rate of 80%, a high rate of photoexcited carrier generation, and an external quantum efficiency (EQE) reaching up to 190%. This figure surpasses the theoretical Shockley-Queisser efficiency limit for silicon-based materials, advancing the field of quantum materials for photovoltaics.

This work signifies a major advance in sustainable energy solutions, according to Chinedu Ekuma, professor of physics at Lehigh. He and Lehigh doctoral student Srihari Kastuar recently published their findings in the journal Science Advances. Ekuma highlighted the innovative approaches that could soon redefine solar energy efficiency and accessibility.

The material’s significant efficiency improvement is largely due to its unique intermediate band states, which are energy levels within the material’s electronic structure that are ideally positioned for solar energy conversion.

These states have energy levels in the optimal subband gaps-energy ranges capable of efficiently absorbing sunlight and producing charge carriers-between 0.78 and 1.26 electron volts.

Moreover, the material excels in absorbing high levels in the infrared and visible regions of the electromagnetic spectrum.

In traditional solar cells, the maximum EQE is 100%, which corresponds to the generation and collection of one electron for each photon absorbed. However, newer materials and configurations can generate and collect more than one electron per high-energy photon, achieving an EQE over 100%.

Multiple Exciton Generation (MEG) materials, though not yet widely commercialized, show immense potential for enhancing solar power system efficiency. The Lehigh-developed material utilizes intermediate band states to capture photon energy typically lost in traditional cells, including energy lost through reflection and heat production.

The research team created this novel material using van der Waals gaps, atomically small spaces between layered two-dimensional materials, to confine molecules or ions. Specifically, they inserted zerovalent copper atoms between layers of germanium selenide (GeSe) and tin sulfide (SnS).

Ekuma developed the prototype based on extensive computer modeling that indicated the system’s theoretical potential. Its rapid response and enhanced efficiency strongly indicate the potential of Cu-intercalated GeSe/SnS as a quantum material for advanced photovoltaic applications, offering a path for efficiency improvements in solar energy conversion, he stated.

While the integration of this quantum material into existing solar energy systems requires further research, the techniques used to create these materials are already highly advanced, with scientists mastering precise methods for inserting atoms, ions, and molecules.

Research Report:Chemically Tuned Intermediate Band States in Atomically Thin CuxGeSe/SnS Quantum Material for Photovoltaic Applications