REFERENCE

Solar Glossary

Plain-language definitions for solar energy terms used in India — from ALMM to TOPCon.

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ALMM: Approved List of Models and Manufacturers — MNRE's registry of solar panels and inverters meeting quality standards for government-linked projects. Panels must be ALMM-listed for PM Surya Ghar subsidy eligibility.
Annual Maintenance Contract (AMC): A service agreement with a solar installer covering periodic inspections, cleaning, and minor repairs over a defined period. AMCs typically run 1–5 years and help ensure consistent system performance.

Battery Storage: An optional component that stores surplus solar electricity for use when the sun is not shining. Common in off-grid and hybrid systems. On-grid systems in India often operate without batteries, using net metering instead.

Capacity Utilisation Factor (CUF): The ratio of actual energy generated by a solar system to the theoretical maximum it could generate if operating at full capacity continuously. A CUF of 17–20% is typical for rooftop solar in India.
Channel Partner (MNRE): An installer empanelled by MNRE to carry out rooftop solar installations under government schemes. Using an empanelled channel partner is mandatory to claim PM Surya Ghar subsidy.

DBT (Direct Benefit Transfer): The mechanism by which PM Surya Ghar subsidies are disbursed directly to the homeowner's bank account after successful installation and inspection, bypassing intermediaries.
DISCOM: Distribution Company — the local electricity distribution utility that delivers power to your home. DISCOMs handle net metering applications, meter upgrades, and net metering account statements. Examples: UPPCL in Uttar Pradesh, TPDDL in Delhi.

Feed-in Tariff: A rate at which utilities pay for electricity exported from a solar system to the grid. India uses net metering rather than a fixed feed-in tariff for most residential solar; export credits offset import charges at the applicable tariff rate.

Grid-Tied / On-Grid System: A solar system connected to the utility grid. Surplus generation is exported to the grid (credited via net metering) and the grid supplies electricity when solar generation is insufficient. The most common type of residential solar in India.

Hybrid Solar System: A solar system that combines grid connection with battery storage. Allows homeowners to store surplus solar electricity and use it during power cuts, while still exporting excess to the grid.

Inverter: A device that converts DC electricity from solar panels into AC electricity usable in your home. Types include string inverters (one per array), microinverters (one per panel), and hybrid inverters (with battery compatibility). Inverter life is typically 10–15 years.

kWh (Kilowatt-Hour): The standard unit of electricity consumption and generation. One kWh = 1 unit on your electricity bill. A 3kW solar system in India generates approximately 3,900–4,500 kWh per year.
kWp (Kilowatt-Peak): The rated maximum power output of a solar panel or system under Standard Test Conditions (STC). A 3kWp system has panels with a combined peak output of 3,000 watts. Actual generation is lower due to real-world conditions.

MNRE: Ministry of New and Renewable Energy — India's central government ministry responsible for solar energy policy, subsidies, empanelment of installers, and the PM Surya Ghar scheme.
Monocrystalline Panel: A solar panel made from a single silicon crystal, offering higher efficiency (20–23%) and better performance in limited roof space. The dominant technology in new residential installations in India.

Net Metering: A billing arrangement where electricity exported to the grid is credited against electricity imported from the grid. Your DISCOM installs a bidirectional meter, and you pay only for net consumption. Essential for maximising rooftop solar value.

Off-Grid System: A solar system that operates independently of the utility grid. Requires battery storage for power at night or during low-generation periods. Suited for areas without reliable grid access; not eligible for PM Surya Ghar subsidy.

Payback Period: The time taken for cumulative electricity savings to equal the initial system cost (after subsidy). Typical payback for well-sized on-grid systems in India is 4–7 years; the system then continues generating for 20+ more years.
PERC (Passivated Emitter and Rear Cell): A monocrystalline panel technology that improves efficiency by adding a passivation layer to the rear of the cell. PERC panels dominate the residential solar market and offer a good balance of efficiency and cost.
PM Surya Ghar Muft Bijli Yojana: India's flagship central government scheme for residential rooftop solar, launched in 2024. Provides central subsidies (up to ₹94,500 for systems up to 10kW) and enables 300 free units of electricity per month for eligible households.
Polycrystalline Panel: A solar panel made from multiple silicon fragments, offering slightly lower efficiency than monocrystalline at a marginally lower cost. Less common in new residential installations, as the cost gap with monocrystalline has narrowed.

Rooftop Solar: A photovoltaic (PV) system installed on the roof of a building to generate electricity from sunlight. Includes panels, inverter, mounting structure, wiring, and (optionally) batteries. The focus of Solar AI Advisor's advisory services.

Solar Irradiance: The power of sunlight reaching a surface, measured in watts per square metre (W/m²). India receives excellent solar irradiance, averaging 4–6 kWh/m²/day across most regions — among the best in the world for solar generation.
String Inverter: An inverter connected to a series (string) of solar panels. The most common inverter type for residential systems; cost-effective but sensitive to shading — if one panel underperforms, it affects the whole string.

TOPCon (Tunnel Oxide Passivated Contact): A next-generation monocrystalline panel technology offering higher efficiency (22–24%) than standard PERC. Increasingly available in the Indian market; typically commands a small price premium over PERC.

Our AI advisor can answer solar questions specific to your home and electricity bill.