Solar panel technology
A solar panel is a sealed group of cells that turns light into direct current. The name on the datasheet matters less than whether the module fits the roof, the inverter, and, if you want central assistance, the domestic-content rule.
How a photovoltaic panel works
Light frees electrons in the cell. Metal contacts collect that direct current. The module does not make alternating current by itself.
- 1Sunlight
- 2Solar cell
- 3Direct current
- 4Inverter
- 5Home supply
Solar cell basics
Most rooftop cells are crystalline silicon. A junction inside the cell separates charges when photons arrive. Cells are strung in series inside the module, so the module voltage is the sum of the cell voltages, and shade on one part of the string can pull the whole string down.
The glass, encapsulant, backsheet or rear glass, and frame are there to keep water and mechanical stress away from the cells for years. A cracked glass or a browned encapsulant is a reason to stop and ask, not to keep washing over it.
Module families you will see on a quotation
None of these is the best choice on every roof. The datasheet, the price, the warranty text, and the roof decide together.
Monocrystalline
Cells cut from a single crystal. They usually offer higher efficiency than older multicrystalline modules, so a given kilowatt needs a bit less area. They are not immune to shade or heat.
Mono PERC
PERC adds a rear layer that reflects unused light back into the cell. It improved efficiency over plain mono cells. Newer cell designs now sit beside it, not instead of a law that PERC must be used.
TOPCon
TOPCon uses a thin tunnel-oxide and polysilicon contact to reduce electrical losses. Datasheets often show a slightly better temperature behaviour than older PERC modules. That still has to be read for the exact model.
Bifacial
Both faces can convert light. The rear face helps when light reflects from a pale roof or from the ground. On a dark, closely mounted rooftop the rear gain can be small. Do not pay for a bifacial gain that the layout cannot see.
DCR and non-DCR
For central financial assistance under PM Surya Ghar, MNRE requires modules made in India from cells made in India. That is the domestic content requirement, called DCR. A non-DCR module, even if it is a good module, makes that installation ineligible for the central assistance. If a household chooses to forgo the assistance, the guideline allows a path without that cell rule. Confirm the module paperwork before you rely on the assistance.
Numbers on the datasheet
Module efficiency
Efficiency is how much of the sunlight on the glass becomes electricity under the standard test. A higher number means more watts from the same area. It is not the annual generation of your roof.
Temperature coefficient
Cells lose power as they heat up. The coefficient, often written per degree above 25°C, tells you how steep that loss is. A rooftop in Indore runs hot for much of the year, so this line is worth reading.
Degradation
Output falls slowly over the years. Datasheets describe that fall. Light-induced changes in the first days are separate from the long yearly drift. Ask which curve applies to the model in the quotation.
Warranties
Manufacturers usually split a product warranty from a performance warranty. The years and the remaining-power promise belong to that datasheet. This page does not state an Anvi Solar warranty term.
How to choose, without a universal winner
Match the module current and voltage to the inverter's operating window. Check the roof area, the shade, and the weight the structure can take. Prefer a datasheet you can keep, a serial number you can read, and a DCR document if the central assistance is part of the plan.
A practical comparison is two quotations for the same roof with the yearly energy estimate, the module model, and the warranty pages side by side. The lower price is not automatically the better module, and the newest cell name is not automatically the better roof.
Common mistakes
Chasing efficiency only
A slightly less efficient module can be the right one if it fits the string design and the budget. Efficiency does not remove shade.
Ignoring heat
The nameplate watt is measured at 25°C cell temperature. A hot roof produces less than that nameplate at the same sunlight.
Assuming any module gets the subsidy
Non-DCR modules do not qualify for the central assistance described in the MNRE guideline.
Safety
A module in sunlight produces voltage even when the inverter is off. Do not disconnect connectors under load, and do not cut a cable to 'see what happens'. Isolation is an electrician's job.
Where to read further
Panel questions
Is TOPCon always better than PERC?
No. TOPCon often shows better datasheet losses, but shade, price, warranty, and whether the module is DCR can matter more on a given roof.
Will a bifacial panel make much more energy on a house roof?
Only if the rear face actually receives reflected light. A low mount on a dark roof may show little extra. The layout has to be honest about that.
What efficiency should I insist on?
There is no single number on this page. Compare modules of the area you have, and read efficiency together with temperature behaviour and the warranty.
Related guides
- Solar inverter guideThe inverter turns panel current into household current and decides what happens when the grid fails.
- Solar structure and mountingThe structure holds the modules to the roof. Its size is an engineering result, not a catalogue guess.
- Solar wiring and protectionDirect current from the roof and alternating current in the house are protected differently.
Ready to Explore Solar Energy?
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