| Term | Definition |
|---|---|
| Voltage | The electrical potential difference between two points in a circuit, which drives the flow of electric current. Measured in Volts (V). |
| Current | The flow of electric charge in a circuit. It is the rate at which charge flows, measured in Amperes (A). |
| Power | The rate at which electrical energy is consumed or generated in a circuit. Measured in Watts (W). Power = Voltage × Current. |
| Energy | The total work done or the total electrical energy consumed over a period of time. Measured in Watt-hours (Wh) or Kilowatt-hours (kWh). |
| AC Cable | Electrical cables designed to carry alternating current (AC) electricity. These cables are used to transmit power over long distances in the grid. |
| DC Cable | Cables specifically designed for transmitting direct current (DC) electricity, commonly used in solar energy systems to carry power from panels to inverters. |
| Energy Meter | A device used to measure the amount of electrical energy consumed or generated by a system, often used for billing purposes. Energy meters can measure both AC and DC energy usage. |
| Earthing | The process of connecting an electrical system to the ground (earth) for safety. It provides a path for fault current to flow into the earth, preventing electrical shocks and fires. |
| MCB (Miniature Circuit Breaker) | A small circuit breaker used for protection against overcurrent and short circuits in low-voltage electrical circuits. Common in residential setups. |
| MCCB (Molded Case Circuit Breaker) | A higher-capacity circuit breaker that provides protection against overloads and short circuits, typically used in industrial and commercial installations. |
| SPD (Surge Protection Device) | A device that protects electrical circuits from voltage spikes or surges, typically caused by lightning or power fluctuations. |
| Transformer | A device used to change the voltage level of alternating current (AC). It can step up or step down voltage for transmission or distribution purposes. |
| AC Distribution Box | A panel or box used to distribute AC electrical power to various circuits in a building or facility. It typically includes circuit breakers or fuses to protect the circuits. |
| DC Distribution Box | A panel designed to distribute DC power to various components of a solar power system. It often includes fuses or breakers for protection of each string of panels. |
| String Combiner Box | A junction box used to combine the output from multiple solar panels or strings of panels into a single DC output before sending it to the inverter. This box typically includes protection devices like fuses or circuit breakers. |
| Array Junction Box | A box used in solar arrays to connect multiple strings of solar panels, providing a central location for protection devices (fuses/circuit breakers) and monitoring equipment. |
| String Monitoring Box | A monitoring device that tracks the performance of individual strings of solar panels, ensuring each string operates efficiently and optimally. |
| Wheeling | The transmission of electricity through a network owned by a third party, with the electricity typically generated at one location and sent to another. The owner of the transmission network charges a fee for this service. |
| SCADA (Supervisory Control and Data Acquisition) | A system used for real-time monitoring, control, and management of large-scale solar power plants. SCADA systems help operators monitor energy production, detect faults, and optimise performance. |
| Substation | A facility that transforms electrical voltage levels (usually from high voltage to low voltage) for transmission and distribution. It is equipped with transformers, circuit breakers, and other components. |
| Overhead Transmission Line | Power lines that are suspended above the ground on towers or poles, used to transmit electricity over long distances from power plants to substations or directly to consumers. |
| Grid | The interconnected network of electrical transmission and distribution lines that deliver electricity from power plants to homes, businesses, and industrial consumers. |
| HT Panel (High Tension Panel) | A distribution panel used for high voltage systems, typically above 33kV, often found in power substations and industrial settings for managing high-voltage electricity. |
| MV Panel (Medium Voltage Panel) | A distribution panel used for medium voltage systems, typically between 1kV and 33kV. MV panels are used in commercial, industrial, and grid-tied applications for controlling power distribution. |
| LT Panel (Low Tension Panel) | A distribution panel that operates at low voltage (up to 1kV), typically used in residential and small commercial applications for circuit protection and control. |
| ACB (Air Circuit Breaker) | A type of circuit breaker used in high-voltage applications to protect electrical circuits. ACBs are designed to open and close under air pressure and are used in industrial settings. |
| VCB (Vacuum Circuit Breaker) | A type of circuit breaker that uses a vacuum to extinguish the arc that forms when the circuit is broken, typically used in medium-voltage systems (11kV-33kV). |
| Equipment | Description |
|---|---|
| Solar Panels (PV Modules) | The primary component that captures sunlight and converts it into direct current (DC) electricity. |
| Module Mounting Structure | Racks or frames that support solar panels, usually installed on rooftops or open fields. These are usually made of aluminium or galvanized steel. |
| Solar Tracking System | A mechanism that moves the solar panels to follow the sun’s path, optimising energy production. |
| Solar Cells | The individual units inside solar panels that convert sunlight into electricity. |
| Inverter (Central/String/Inverter System) | Converts the DC electricity produced by solar panels into alternating current (AC) for grid compatibility. |
| DC Disconnect Switch | A switch to safely disconnect the DC output of the solar array from the inverter. |
| AC Disconnect Switch | A switch that disconnects the AC output from the inverter to the grid or load for maintenance. |
| Transformer | Steps up or steps down the voltage from the inverter to match the grid voltage (for grid-connected systems). |
| Surge Protection Device (SPD) | Protects electrical equipment from voltage spikes caused by lightning or grid fluctuations. |
| Fuse and Circuit Breaker | Protection devices that prevent overcurrent or short-circuit conditions from damaging equipment. |
| String Combiner Box | Combines the DC output from multiple strings of solar panels into a single output. |
| Array Junction Box (AJB) | A box that connects solar panel strings to the combiner box or inverter. |
| Energy Meter | Measures the amount of electrical energy generated by the solar plant or consumed from the grid. |
| SCADA System (Supervisory Control and Data Acquisition) | A system for monitoring and controlling the performance of the solar plant in real-time. |
| AC Distribution Panel | Distributes AC power from the inverter to various circuits or loads within the facility. |
| Grid Connection Box (Grid Tie Equipment) | Interfaces the solar plant with the local electrical grid, allowing for power export or import. |
| Interconnection Switch | A manual or automatic switch that connects or disconnects the solar plant from the grid. |
| Battery Storage System | Stores excess energy generated by the solar panels for use when sunlight is not available. |
| Battery Management System (BMS) | Manages the operation, charging, and discharging of the battery storage system. |
| Earthing System | Provides a safe path for fault currents to flow to the ground, protecting both equipment and people. |
| Overcurrent Protection Device | Protects against electrical overloads, preventing potential damage to solar plant equipment. |
| Fire Safety System | Detects and prevents fires that could occur due to electrical faults in the system. |
| Racking and Mounting System | Provides the structural support for the solar panels, ensuring they are safely installed and oriented. |
| Cables and Connectors | Electrical cables and connectors used to connect the panels, inverters, and other system components. |
| Cleaning Equipment | Tools or automated systems used for cleaning solar panels to maintain efficiency (e.g., robotic cleaners). |
| MC4 | MC4 is a type of electrical connector specifically designed for solar photovoltaic (PV) systems. |
| Technology | Description | Efficiency | Key Advantages | Applications |
|---|---|---|---|---|
| Monocrystalline Silicon | Made from a single continuous crystal structure, offering high efficiency. The silicon is sliced into wafers. | 15% to 22% (varies by manufacturer) | High efficiency / Space-efficient (requires less area) / Long lifespan / High power output | Residential, commercial rooftops, ground-mounted systems |
| Polycrystalline Silicon | Made from silicon crystals that are melted together. Less efficient than monocrystalline but more affordable. | 13% to 17% | Lower cost than monocrystalline / Easy to manufacture / Good long-term durability | Residential, commercial systems (large-scale or budget-friendly installations) |
| Thin-Film Solar Panels | Made by depositing layers of photovoltaic material on a substrate. Can be flexible and lightweight. | 10% to 12% | Lightweight and flexible; can be integrated into surfaces such as windows or rooftops / Lower cost per watt | Large-scale ground-mounted installations, building-integrated photovoltaics (BIPV) |
| PERC (Passivated Emitter Rear Cell) | A variation of monocrystalline silicon, featuring a passivated rear surface to reduce recombination and improve efficiency. | 18% to 23% | Higher efficiency than traditional monocrystalline / Better performance in low light and high temperatures | Residential, commercial, utility-scale installations |
| Bifacial Solar Panels | These panels capture sunlight on both the front and rear sides, allowing them to generate power from reflected light. | 16% to 25% (depends on installation) | Can increase energy yield by up to 30% in certain conditions / More efficient in high-reflective environments | Commercial, utility-scale (especially in reflective or snowy areas) |
| Heterojunction (HJT) Solar Cells | A hybrid technology combining thin-film and crystalline silicon, designed to maximise efficiency. | 20% to 26% | High efficiency / Good performance in high temperatures / Better light absorption | High-end residential, commercial, and utility-scale projects |
| Perovskite Solar Panels | A new generation of solar technology using perovskite materials to absorb light and generate electricity. | 15% to 25% (still evolving) | Low manufacturing cost / Lightweight / High efficiency potential / Flexible | Residential, experimental research, and building-integrated applications |
| Amorphous Silicon | A non-crystalline form of silicon, often used in thin-film solar panels. | 6% to 8% | Very flexible / Low cost / Lightweight / Can be used on a variety of surfaces | Small devices, portable solar products, flexible solar applications |
| Copper Indium Gallium Selenide (CIGS) | Thin-film technology made from copper, indium, gallium, and selenium, with high light absorption properties. | 10% to 15% | High efficiency compared to other thin-film technologies / Flexible / Lightweight | Large-scale installations, building-integrated PV (BIPV), portable solar devices |
| Organic Photovoltaic (OPV) | Uses organic materials (carbon-based) to convert sunlight into electricity. Still under research for efficiency. | 5% to 10% | Low-cost manufacturing potential / Flexible and lightweight / Can be integrated into building materials | Research and development, potential for future large-scale deployment |
| TOPCon (Tunnel Oxide Passivated Contact) | A next-generation technology that improves monocrystalline silicon cells with a passivated contact layer to reduce recombination. | 21% to 26% | High efficiency / Improved performance and stability / Low degradation rate / Potential for cost reduction in the long term | High-end commercial, utility-scale applications, emerging in residential use |
| Inverter Type | Sub-Type | Description | Efficiency | Applications | Advantages |
|---|---|---|---|---|---|
| Off-Grid Inverters | – Standalone Inverters | Used in isolated systems, where no connection to the electrical grid is available. Converts DC to AC. | 85% to 95% | Remote areas, rural areas, islands, backup power systems. | No dependency on grid / Ideal for remote areas / Can integrate with batteries |
| Grid-Tie (On-Grid) Inverters | – String Inverters | Converts DC from solar panels to AC for use in the grid. Each inverter connects to a series of panels. | 95% to 98% | Residential and commercial solar systems connected to the grid. | High efficiency / Easy installation / Lower cost compared to central inverters |
| – Micro Inverters | Small inverters attached to individual solar panels. Converts DC to AC at panel level. | 95% to 98% | Small to medium residential systems, systems with shading issues. | Optimised panel performance / Monitoring at the panel level / Avoids shading issues | |
| – Central Inverters | Large inverters that handle the output from multiple strings of panels, typically used for large-scale solar plants. | 97% to 99% | Utility-scale solar power plants, commercial rooftop installations. | High power capacity / Suitable for large installations / Cost-effective at scale | |
| Hybrid Inverters | – Grid-Connected Hybrid Inverters | Combines off-grid and grid-tied features, includes battery storage integration for energy management. | 95% to 98% | Residential and commercial installations with battery storage, smart grids. | Energy storage integration / Can work both with grid and off-grid / Ideal for load management |
| Other Specialised Inverters | – Battery Inverters | Specifically designed for managing the charging and discharging of battery banks in solar+storage systems. | 95% to 98% | Systems with high focus on energy storage, off-grid or backup power. | Efficient energy storage management / Provides backup power capabilities |
| – Power Optimisers | Typically paired with string inverters to optimise the output from each solar panel, especially useful in partial shading situations. | 95% to 98% | Residential, commercial systems with shading issues. | Panel-level optimisation / Reduces energy loss from shading and mismatched panels |
| Financial Terms | Explanation |
|---|---|
| CAPEX (Capital Expenditure) | In solar projects, CAPEX refers to the initial investment required to set up a solar power plant. It is a one-time cost. |
| OPEX (Operational Expenditure) | OPEX refers to the annual or recurring expenses for operating the solar power plant after it is installed. |
| PPA (Power Purchase Agreement) | The PPA typically specifies the terms, conditions, pricing, and duration of the agreement, which can range from 10 to 25 years. |
| LCOE (Levelized Cost of Energy) | LCOE is used to evaluate the cost-effectiveness of energy production, and it’s important for determining profitability. |
| IRR (Internal Rate of Return) | A higher IRR is generally considered favorable for investors as it indicates a more profitable investment. |
| ROI (Return on Investment) | ROI is a measure of the financial performance of a solar project and indicates the return an investor can expect. |
| DSCR (Debt Service Coverage Ratio) | DSCR is critical for lenders as it ensures the project generates enough revenue to meet debt obligations. |
| Bankability | Bankable projects have secure PPAs, strong creditworthiness, and a low-risk profile, making them more likely to secure financing. |
| Subsidy | In India, subsidies may be available for residential, commercial, or community solar projects, helping reduce upfront costs. |
| Debt Financing | Debt financing is common in solar projects, where loans are repaid over time with interest, and it can help fund CAPEX. |
| Equity Financing | Equity investors take on more risk but have the potential for higher returns, as they are shareholders in the project. |
| Green Bonds | Green bonds can provide lower-cost financing for solar projects that promote sustainability. |
| Term | Explanation |
|---|---|
| DISCOM (Distribution Company) | DISCOMs play a crucial role in the sale and distribution of solar-generated electricity in India. |
| ALMM (Approved List of Model and Manufacturers) | The ALMM ensures that only certified and compliant manufacturers supply panels for government-supported solar projects. |
| MNRE (Ministry of New and Renewable Energy) | MNRE oversees the promotion and regulation of solar energy projects, including setting policies and incentives. |
| Solar Park | Solar parks can host hundreds of megawatts of solar capacity and are an efficient way to develop solar energy at scale. |
| SECI (Solar Energy Corporation of India) | SECI is the key facilitator for auctioning solar projects, facilitating financing, and managing policy implementation. |
| SCADA (Supervisory Control and Data Acquisition) | SCADA systems provide real-time data on solar plant performance, ensuring efficient operation and maintenance. |
| Net Metering | Net metering enables residential and commercial users to offset their electricity bills by feeding surplus solar energy into the grid. |
| Gross Metering | Under gross metering, all solar power produced is fed into the grid, and the system owner is paid at a pre-determined rate. This system is common in large-scale solar installations. |
| PPAs (Power Purchase Agreements) | PPAs are long-term contracts, typically lasting 20-25 years, that guarantee a fixed price for solar-generated electricity. |
| Subsidy Schemes | Subsidy schemes help reduce the high upfront cost of solar installations, making them more affordable for end users. |
| RPO (Renewable Purchase Obligation) | RPOs are designed to drive the growth of solar energy by ensuring that utilities and large consumers source a minimum share of energy from renewables. |
| RECs (Renewable Energy Certificates) | RECs are a financial mechanism to promote the use of renewable energy and enable market-based incentives for solar projects. |
| Tariff | In India, solar tariffs have come down significantly due to competitive bidding, driving the affordability of solar power. |
| FIT (Feed-in Tariff) | FITs were historically used to incentivize solar generation, but are largely replaced by competitive bidding in India. |
| KPI (Key Performance Indicators) | KPIs help monitor the ongoing performance of solar power plants and ensure optimal operation over their lifespan. |
| O&M (Operation & Maintenance) | O&M is crucial for maintaining the long-term performance and financial returns of solar power plants. |
| Term | Description |
|---|---|
| Ampere (A) | Unit of electric current, measuring the flow of electric charge in a circuit. |
| Area (m²) | Total surface area of solar panels or the land used for the solar power plant, measured in square meters. |
| Balance of System (BOS) | All components of a solar power system excluding the solar panels, like inverters, wiring, and mountings. |
| Cell Efficiency (%) | Percentage of sunlight energy converted into electricity by a solar cell. |
| Central Inverter | Large inverter used in utility-scale solar plants, typically connected to multiple solar arrays. |
| Charge Controller | A device that regulates the voltage and current coming from the solar panels to the battery, preventing overcharging. |
| Direct Current (DC) | Electric current flowing in one direction only, generated by solar panels. |
| DC to AC Inverter | Device converting DC electricity (from solar panels) into AC electricity for general use. |
| Energy (kWh, MWh, GWh) | Total electricity generated or consumed over time, measured in kWh, MWh, or GWh. |
| Efficiency (%) | The percentage of sunlight energy converted into usable electricity by a solar panel/system. |
| Fossil Fuel Backup | Use of traditional energy sources (e.g., coal or natural gas) to support power generation when solar is insufficient. |
| Gigawatt (GW) | Unit of power equal to one billion watts, often used to describe large-scale solar plants. |
| Grid Connection | The process of linking a solar power plant to the electrical grid to transfer power to the utility system. |
| Hertz (Hz) | Unit of frequency, representing the number of cycles per second in an AC power supply. |
| Horizontal Axis Tracking | Solar tracker that moves panels horizontally to follow the sun’s movement. |
| Inverter (kW, MW) | Device converting DC electricity from solar panels to AC electricity. Rated in kilowatts (kW) or megawatts (MW). |
| Irradiance (W/m²) | Solar power received per unit area, measured in watts per square meter (W/m²). |
| Kilowatt (kW) | Unit of power equal to 1,000 watts, often used to rate solar power systems. |
| Kilowatt-hour (kWh) | Unit of energy equivalent to the amount of energy used by a 1 kW load for one hour. |
| Lifetime (Years) | Expected operational lifespan of a solar power system or component, typically around 25–30 years. |
| Maximum Power Point Tracking (MPPT) | MPPT is a technology used in solar inverters to maximise the energy harvested from solar panels. |
| Monocrystalline Silicon | Type of solar panel made from a single crystal of silicon, known for higher efficiency. |
| Nominal Operating Cell Temperature (NOCT) | Temperature a solar cell reaches under standard conditions to evaluate its performance. |
| Off-Grid Solar System | A solar power system not connected to the electrical grid, often used in remote areas with energy storage. |
| On-Grid Solar System | A solar power system connected to the electrical grid, where excess power is fed into the grid. |
| Photovoltaic (PV) | Technology that converts sunlight into electricity using semiconductor materials (solar cells). |
| Power (W, kW, MW) | Rate at which energy is generated or consumed, measured in watts (W), kilowatts (kW), or megawatts (MW). |
| Power Conversion Efficiency | The efficiency at which power is converted from one form (e.g., DC to AC) in a solar power system. |
| Rated Capacity (kW, MW) | Maximum power output a solar power system can generate under ideal conditions. |
| Return on Investment (ROI) | A financial metric that measures the profitability of a solar power investment. |
| Solar Cell | Basic unit of a solar panel that converts sunlight into electricity, typically made from silicon. |
| Solar Irradiance | The power per unit area received from the sun, usually in watts per square meter (W/m²). |
| Solar Panel | A collection of solar cells that generate electricity from sunlight. |
| Standard Test Conditions (STC) | Standard conditions for testing solar panels: 1000 W/m² irradiance, 25°C temperature, 1.5 air mass. |
| Solar Battery | A rechargeable battery used to store electricity generated by solar panels for later use. |
| Solar Battery Storage System | A system of batteries and associated components to store electricity for use during low-sunlight periods. |
| Solar Inverter | A device that converts DC electricity from solar panels into AC electricity for use in homes and businesses. |
| Solar Inverter Efficiency | The percentage of power output by the inverter relative to the input DC power from the solar array. |
| Solar Panel Efficiency | The percentage of sunlight converted into electricity by a solar panel under standard conditions. |
| String Inverter | An inverter designed to handle a series (or “string”) of solar panels, typically used in residential systems. |
| Sub-Panel | A smaller electrical panel connected to the main electrical system, typically used in off-grid applications. |
| Sine Wave Inverter | An inverter that produces a clean AC output waveform, similar to the power provided by the grid. |
| Square Wave Inverter | An inverter producing a less stable, simpler AC waveform, used for less sensitive loads. |
| Tilt Angle | Angle at which solar panels are mounted relative to the ground. The tilt affects energy production efficiency. |
| Tracker (Single-axis, Dual-axis) | Mechanism used to adjust the position of solar panels to maximise energy capture by following the sun. |
| Volt (V) | Unit of electrical potential or voltage, typically used to describe solar panel operating voltages. |
| Voltage (V) | The electrical potential difference driving current in a circuit. |
| Watt (W) | Unit of power, used to measure the output or consumption of electricity. |
| Watt-hour (Wh) | Unit of energy equivalent to the amount of energy used by a 1W device for one hour. |
| Zero Net Energy (ZNE) | A situation where a building generates as much energy as it consumes, often through solar power. |
| Energy Storage System (ESS) | A system used to store energy, typically in the form of batteries, to be used when solar power is not available. |
| Lithium-ion Battery | A type of rechargeable battery commonly used for solar energy storage due to its high energy density and efficiency. |
| Lead-Acid Battery | Traditional battery type, commonly used in off-grid solar systems but with lower efficiency and lifespan compared to lithium-ion. |
| Capital Expenditure (CAPEX) | The initial investment required to develop a solar power project, including the cost of equipment, installation, land, and labor. |
| Operating Expenditure (OPEX) | Ongoing costs of running and maintaining a solar power plant, including maintenance, insurance, and staff salaries. |
| Debt Financing | Raising capital for a solar project through loans, bonds, or other debt instruments. Debt financing typically needs to be repaid with interest. |
| Equity Financing | Raising capital for a solar project through investments in exchange for ownership or a share of profits. Equity investors assume more risk but can receive higher returns. |
| Project Finance | A financing method where the project’s cash flow, rather than the balance sheet of the sponsor, is used to repay loans. It is often used for large-scale solar projects. |
| Internal Rate of Return (IRR) | A metric used to evaluate the profitability of a solar project. It represents the annualized rate of return at which the net present value (NPV) of the project’s cash flows is zero. |
| Net Present Value (NPV) | The value of a solar project’s expected future cash flows, discounted to present value. It helps assess whether a project is financially viable. |
| Payback Period | The length of time required for a solar project to recover its initial investment from the generated cash flow. |
| Levelized Cost of Energy (LCOE) | A measure of the cost per unit of energy (e.g., kWh) produced by a solar power plant over its lifetime, including both CAPEX and OPEX. |
| Power Purchase Agreement (PPA) | A long-term contract between a solar developer and an off-taker (e.g., utility or corporation) to purchase electricity at a fixed price for a set period, typically 15 to 25 years |
| Renewable Energy Certificate (REC) | A tradable certificate proving that electricity has been generated from renewable sources, often used in financial models to generate additional revenue streams. |
| Tax Equity Financing | A form of financing where investors provide capital in exchange for tax benefits, such as the Federal Investment Tax Credit (ITC), which helps offset the costs of a solar project. |
| Project Sponsor | The organisation or individual responsible for the development, financing, and operation of a solar project. |
| Cash Flow | The amount of money coming in and going out of the solar project over time. Positive cash flow is critical for the success of the project. |
| Grid Parity | The point at which the cost of solar power becomes equal to or lower than the cost of power from the grid, making solar energy financially competitive without subsidies. |
| Asset-Backed Financing | A financing approach where the assets (e.g., solar panels, inverters, etc.) of a project are used as collateral for a loan. |
| Solar Investment Tax Credit (ITC) | A federal tax incentive in the United States that allows solar project developers and investors to deduct a percentage of the cost of installing a solar energy system from their federal taxes. |
| ALMM (Approved List of Models and Manufacturers) | A list of approved solar modules and manufacturers, mandated by the Indian government to ensure the use of quality equipment in solar projects. |
| DISCOM (Distribution Company) | A company responsible for the distribution of electricity in a particular region in India. Solar power projects often sell electricity to DISCOMs under power purchase agreements (PPAs). |
| MNRE (Ministry of New and Renewable Energy) | The Indian government body responsible for formulating policies and programs to promote renewable energy, including solar power. |
| GST (Goods and Services Tax) | Tax levied on the sale of solar products and services in India. The GST rate for solar modules, inverters, and other equipment is typically around 5%. |
| PM Surya Ghar | A government initiative providing incentives for the installation of solar rooftop systems for residential customers |