Solar panel and inverter types for Indian roofs: mono PERC, TOPCon, bifacial and more

For most Indian homes, the choice of panel technology matters less than buying DCR modules from a reliable manufacturer, placing them where they are not shaded, and pairing them with a good inverter. Among current module types, mono PERC has been the mainstream workhorse, TOPCon modules offer somewhat higher efficiency and often better performance in heat, and bifacial modules can gain a little extra output on raised structures over light-coloured roofs. For inverters, a single string inverter suits most unshaded roofs; microinverters or optimisers help on roofs with unavoidable partial shade. This guide explains the terms that appear on quotations and which specifications to compare.

Module technologies

Type	How it differs	Points for Indian roofs
Mono PERC	Monocrystalline cells with a rear passivation layer; long the mainstream type	Proven, widely available in DCR versions
TOPCon (n-type)	Newer n-type cell structure with higher efficiency	Often lower temperature losses and degradation; check DCR availability and price
HJT (heterojunction)	High-efficiency n-type design	Less common in DCR supply; compare price per watt
Bifacial	Generates from both front and back	Gains depend on height and roof reflectivity; little gain flush on a dark roof
Half-cut cells	Cells cut in two to reduce losses	Common feature; can reduce the effect of partial shading
Polycrystalline	Older, lower-efficiency type	Largely replaced by mono types

Specifications to compare on the datasheet

Rated power (Wp) and efficiency (%): higher efficiency means more watts per square metre, useful on small roofs.
Temperature coefficient of Pmax (%/°C): how much output falls as the module heats up. Indian rooftops get very hot, so a smaller negative number is better.
Degradation: first-year and annual degradation in the performance warranty.
Product warranty (defects) and performance warranty (output over 25 years or more).
Dimensions and weight: matters for the structure and roof layout.

Inverter types

Type	How it works	Good for	Watch out for
String inverter (grid-tie)	Modules wired in strings to one central inverter	Unshaded roofs; most home systems	Shade on one module affects the string
Multi-MPPT string inverter	Two or more independent inputs	Roofs with two orientations or partial shade on one area	Design must use the MPPTs properly
Microinverters	One small inverter per module or pair	Complex roofs, partial shade	Higher cost; check local service support
Power optimisers	Module-level electronics feeding a string inverter	Partial shade with a central inverter	Extra components to maintain
Hybrid inverter	Manages panels, battery and grid	Backup with net metering	Needs DISCOM acceptance; battery compatibility

Inverter specifications to compare

Rated AC output (kW) matched to the array (often the array kWp is a little higher than the inverter kW).
Maximum efficiency and European/weighted efficiency.
Number of MPPTs and input voltage range.
Operating temperature range and IP rating (dust and water protection).
Monitoring: app or web portal to see daily generation.
Warranty: typically shorter than modules; ask for the term and the replacement process.
BIS registration and acceptance by your DISCOM.

Matching panels and inverter (illustrative)

A 3 kW design might use six 545 Wp modules (3.27 kWp) in one string on a 3 kW inverter. On a roof where three modules face east and three face west, a two-MPPT inverter with one string per orientation avoids the mismatch loss of mixing them. A vendor should explain the stringing on the single-line diagram.

Mounting structures

The structure holds the modules for 25 years through monsoon winds and coastal salt air.

Hot-dip galvanised steel or anodised aluminium resists corrosion; ask for the coating thickness for coastal areas.
Raised (elevated) structures keep the terrace usable and reduce heat behind the modules but cost more and need stronger anchoring.
Tilt: often close to the local latitude, facing south. Flat-mounted panels collect more dust.
Anchoring: chemical anchors or ballast blocks; avoid drilling that damages waterproofing without sealing.

Which choice is worth paying for?

Situation	Worth considering
Small roof, high consumption	Higher-efficiency modules (TOPCon or higher-wattage mono)
Very hot region	Modules with better temperature coefficient
Two roof orientations	Multi-MPPT inverter
Unavoidable partial shade	Optimisers or microinverters, or move the array
Raised structure over a white roof	Bifacial modules may add some output
Coastal area	Corrosion-resistant structure and higher IP-rated inverter

Mistakes to avoid

Paying extra for a premium technology on a roof where shade is the real problem.
Accepting a quote that lists module wattage but not the make and model.
Choosing an inverter brand with no service centre in your region.
Ignoring the structure, the part most likely to fail in a storm.

Back to the pillar guide: how many kW of solar you need. Related: solar quotation and vendor checklist, on-grid vs hybrid vs off-grid, DCR modules, ALMM and BIS.

Frequently asked questions

Are TOPCon modules available as DCR?

Availability depends on domestic cell production. Check the ALMM list and ask the vendor for the DCR certificate for the exact model.

Do higher-wattage modules give more units per kW?

Not by themselves. Units per kW depend on sunlight, heat, shade and losses. Higher wattage per module means fewer modules for the same kW.

Is a "Tier-1" label meaningful?

It is a financial-bankability classification used by some analysts, not a quality standard or a government certification. Rely on BIS registration, ALMM, DCR and warranty terms.

Should the inverter be on the roof?

Preferably in a shaded, ventilated place close to the array and the distribution board, protected from rain and direct sun.

Official sources

Ministry of New and Renewable Energy — ALMM lists and technical specifications
Bureau of Indian Standards — registration of modules and inverters
PM Surya Ghar national portal — scheme technical requirements