Center approves scheme worth 5070 crore rupees for developing floating solar power plants

Amid ongoing heat and high humidity, people prefer to stay indoors using air conditioners, fans, and refrigerators, which raises concerns about rising electricity bills. However, millions of people who have connected to the PM Surya Ghar Muft Bijli Yojna scheme and installed solar panels on their home roofs are enjoying coolness without worrying about bills, as this government program provides 300 units of free electricity.

The Essence of the PM Surya Ghar Program

PM Surya Ghar Yojna is an initiative by the central government launched by Prime Minister Narendra Modi in 2024. The program not only provides 300 units of free energy but also offers financial support to citizens for installing solar panels on their home roofs. The government assists by providing subsidies for the costs associated with installing panels of various capacities depending on consumption.

Goals and Current Reach of the Project

Currently, approximately 27 million homes have been covered by this program. The government's goal is to provide solar energy to 100 million households.

Subsidies for 3 kW Panels

The government sets different subsidy amounts for solar panels of varying capacities. Under this government scheme, one can install a solar panel ranging from 1 kW to 3 kW or more. For the installation of a 3-kilowatt solar panel, the estimated cost can range from 1.5 to 2 million rupees. In this case, the government provides a subsidy of 78,000 rupees, which is transferred directly to the bank account or credited against the loan. This reduces citizens' expenses and allows them to benefit from the free electricity allowance.

Additional Support and Usage Options

Various states also offer additional subsidies under the Solar Mission. For instance, in Uttar Pradesh, the government provides an extra assistance of 30,000 rupees for panels of 3 kW and above, increasing the total subsidy from 78 thousand to 108 thousand rupees. If consumption is between 0 and 150 units, one can install a 1-2 kW solar panel and receive a subsidy ranging from 30,000 to 60,000 rupees. To apply for a loan for solar panel installation, one can contact the toll-free number 15555.

Online Application Procedure

Applying for the PM Surya Ghar Free Bijli Scheme is very simple: it only takes 5 minutes to apply through https://pmsuryaghar.gov.in. After this, solar panels can be installed by an accredited vendor registered with your DISCOM. After installation, an application must be submitted for a net meter with installation details. After the meter installation and verification by the DISCOM, a commissioning certificate will be issued. Upon receiving this certificate, the applicant provides bank account details and a cancelled cheque through the portal to receive the subsidy.

Scientists from China have developed a three-layer solar cell combining perovskite and silicon, which demonstrated a record voltage of 3.15 volts. The main breakthrough was the successful stabilization of the most vulnerable top perovskite layer using an organic salt.

Principle of Tandem Cell Operation

Tandem (two-layer) solar cells provide higher efficiency compared to standard silicon cells due to more effective utilization of sunlight. However, the design is not limited to two layers; it is possible to add a third, fourth, or even fifth photoactive layer. To achieve maximum overall efficiency, the bandgap of the upper layers must be wider, as photons must be distributed among the layers in decreasing order of energy.

Problems with Perovskite Analogues

Unlike three-layer cells based on gallium arsenide and III-V semiconductors, which are already used in space with efficiencies exceeding 40 percent, analogues based on perovskites and silicon face difficulties. The bottom layer is usually silicon with a bandgap of 1.12 electron volts, while the second and third layers are perovskite. The greatest challenge lies in obtaining and maintaining the stability of the third layer, which requires a bandgap of 1.8 electron volts or higher.

Mechanism of Instability

To widen the perovskite bandgap, some iodine ions in the crystal lattice are replaced by bromine. Excessive bromine content triggers phase segregation: ions begin to migrate, leading to the formation of heterogeneous regions with different compositions—where bromine predominates and where iodine predominates.

Solution to Stabilization Problem

Chinese material scientists led by Haijian Tan from Nanjing University managed to create an effective and stable three-layer perovskite cell. The design utilized a textured silicon heterostructure cell as the bottom layer. Above it is a perovskite with a bandgap of 1.52 electron volts, and the top layer is an ultra-wide bandgap perovskite Cs0.25FA0.6MA0.15Pb(I0.43Br0.57)3 with a bandgap of 1.93 electron volts, which was the main source of stability problems.

Role of Organic Additives

To prevent phase segregation in the perovskite, Tan and his team introduced the organic salt 1,4-phenylenediamine dihydroiodide (PEDAI). This additive forms strong bonds with the crystal structure, increasing the ion migration barrier and promoting greater layer uniformity. Additionally, PEDAI molecules occupy voids and bind with lead ions, reducing the number of defects within the perovskite. The surface of the layer was also treated with another organic salt—3MTPAI, which helped reduce the number of grain boundary defects and improved electron transport.

Results and Prospects

Ultimately, a device with an efficiency of 26.18 percent was obtained, confirmed by independent examination, and a record voltage of 3.15 volts. Although this efficiency is currently lower than that of two-layer tandems reaching 35.5 percent this month, the authors expect rapid growth in efficiency in the coming years. Regarding stability, the devices showed respectable results, retaining 96 percent of initial efficiency after 1500 hours of continuous operation. There is a hypothesis that the salt additives proposed by Tan could also be applied to improve the stability of standard two-layer tandems.