Understanding what goes into a solar system helps you evaluate quotes, ask the right questions, and avoid being sold inferior components at premium prices. Here is what each major component does and what the specifications actually mean.
Solar Panels: The Power Source
Solar panels (photovoltaic modules) convert sunlight into DC electricity. In 2025, virtually all residential installations use either PERC (Passivated Emitter and Rear Cell) or the newer TOPCon (Tunnel Oxide Passivated Contact) monocrystalline cells — both offering efficiency above 20%.
Key specifications to understand
| Spec | What it Means | Good Value (2025) |
|---|---|---|
| Watt peak (Wp) | Power output under standard test conditions (25°C, 1000W/m²) | 400–550 Wp per panel |
| Efficiency (%) | % of sunlight converted to electricity | 20–23% (PERC/TOPCon) |
| Temperature coefficient | Power loss per °C above 25°C | Below -0.35%/°C |
| Degradation rate | Annual power decline over system life | Below 0.55%/year |
| Product warranty | Manufacturer guarantee against defects | 12 years minimum |
| Performance warranty | Guaranteed output at end of 25 years | 80–84% of rated output |
Panels are rated at 25°C, but rooftop temperatures in Bangalore regularly reach 55–65°C in summer. A panel with a temperature coefficient of -0.40%/°C loses 12% of its power at 55°C. TOPCon panels have better high-temperature performance than older PERC technology.
Tier-1 vs Tier-2 Panels
Bloomberg NEF's "Tier-1" classification identifies manufacturers with strong financial backing and consistent quality control. Tier-1 brands for India include: Jinko Solar, LONGi Green Energy, REC Group, Waaree Energies, Adani Solar, and Vikram Solar. Tier-2 panels can be 15–20% cheaper but carry higher risk of early degradation and warranty claim difficulties.
Inverters: The Brain of the System
The inverter converts DC electricity from your panels into AC electricity your home can use. It is the most technically complex component and — importantly — the component most likely to fail over a 25-year system life. Choosing a quality inverter with strong Indian service support is critical.
Types of inverters
- String inverters: One central inverter for all panels. Most cost-effective for simple rooftops. Performance is limited by the weakest panel in the string. Best brands: Sungrow, SMA, Fronius, Delta.
- Microinverters: One inverter per panel. Each panel operates independently — shading one panel doesn't affect others. Higher cost but better for complex or partially-shaded roofs. Best brands: Enphase, APSystems.
- Hybrid inverters: String inverter with battery management capability. Allows battery integration now or in the future. Best for homes wanting backup. Best brands: Sungrow SH series, Growatt, Sofar.
Inverter specifications
| Spec | What it Means | Good Value |
|---|---|---|
| Efficiency (%) | % of DC input converted to AC output | Above 97% |
| MPPT trackers | Circuits that maximise panel output | 2+ for complex roofs |
| IP rating | Weather/dust protection | IP65 minimum for outdoor |
| Warranty | Manufacturer guarantee | 5–10 years |
| Monitoring | App/portal for real-time data | Built-in Wi-Fi monitoring |
Batteries: When to Add Storage
Battery storage allows you to store surplus solar generation for use at night or during power cuts. In 2025, lithium iron phosphate (LFP) batteries are the standard choice for residential solar — safer, longer-lasting, and more stable than older lithium-ion chemistries.
Battery specifications
- Usable capacity (kWh): The energy you can actually draw. A 10 kWh battery with 90% depth of discharge gives you 9 kWh usable.
- Cycle life: How many charge-discharge cycles before capacity degrades to 80%. LFP: 4,000–6,000 cycles (10–15 years). Lead-acid: 300–1,000 cycles (3–5 years).
- Round-trip efficiency: Energy out ÷ energy in. LFP achieves 92–96%. Lead-acid: 70–80%.
- C-rate: How fast the battery can charge or discharge relative to its capacity. A 1C rate means full charge/discharge in 1 hour.
To power critical loads (lights, fans, Wi-Fi, some appliances) through a 4-hour power cut, most homes need 5–8 kWh of usable battery storage. For whole-home backup, plan for 10–15 kWh per 4 hours of full autonomy.
Mounting Structures: Often Overlooked, Always Important
The mounting structure holds your panels on the roof for 25 years through heat, monsoon, and the occasional storm. Hot-dip galvanised steel or anodised aluminium are the only acceptable materials. Cheap unpainted iron structures rust within 3–5 years and can damage your roof. Always ask for the structure material and specification in your proposal.