Every day, the sun delivers more energy to India in one hour than the entire country consumes in a year. Rooftop solar panels capture a small fraction of that energy and convert it into electricity you can use directly in your home — and sell back to the grid when you produce more than you need.
But how exactly does that process work? From sunlight hitting a silicon cell to a rupee credit on your DISCOM bill — there are five distinct steps, each involving specific components. Understanding these steps helps you make better decisions when buying, installing, and maintaining a solar system.
Key takeaway. Rooftop solar in India works by converting sunlight into DC electricity via solar panels (using the photovoltaic effect), inverting it to AC via a string inverter, powering your home first, and feeding surplus power to the DISCOM grid via a bi-directional net meter. Heaven Green Energy handles every step from PM Suryaghar subsidy application to net meter commissioning — a typical 3 kW system in Gujarat reduces monthly bills by 70–90%.
Step 1: Sunlight Hits the Solar Panel (The Photovoltaic Effect)
A solar panel is made of dozens of individual solar cells — thin wafers of silicon, the same material used in computer chips. When photons from sunlight hit a silicon cell, they knock electrons loose from their atoms. These free electrons create an electric current — specifically, a Direct Current (DC).
This is called the photovoltaic (PV) effect, first discovered by Edmond Becquerel in 1839 and formally confirmed by Albert Einstein’s 1905 paper on the photoelectric effect (for which he won the Nobel Prize in 1921).
Types of solar cells used in India in 2026:
| Cell Type | Efficiency Range | Typical Use | Key Feature |
|---|---|---|---|
| Monocrystalline PERC | 20–22% | Residential, commercial | Best efficiency, compact size |
| TOPCon (n-type) | 22–24% | Premium residential | Lower temperature loss |
| HJT (Heterojunction) | 23–25% | High-efficiency niche | Lowest degradation |
| Bifacial | 20–24% + rear gain | Commercial, ground-mount | Captures reflected light |
| Polycrystalline | 17–19% | Budget installations | Lower cost, lower efficiency |
Most residential installations in India today use monocrystalline PERC or TOPCon panels. BIS IS 14286 certification is mandatory for panels used under the PM Suryaghar scheme. The solar modules selection guide covers panel technology in detail.
A standard 400 Wp panel produces 400 watts of electrical power at Standard Test Conditions (STC) — 1000 W/m² irradiance, 25°C cell temperature. Real-world output varies based on actual irradiance and temperature.
💡 Fast tip
A solar panel rated at 400 Wp is not producing 400 watts all day. It produces that output only at peak irradiance (around solar noon on a clear day). Average output across a full day in Gujarat is roughly 55–65 Wh per rated Wp — so a 400 Wp panel generates 220–260 Wh on an average day.
Step 2: DC Power Flows Through the Wiring System
The DC electricity generated by your solar panels flows through cables to a combiner box (the DC Distribution Box, or DCDB) where multiple strings of panels are combined. From the DCDB, the power flows to the solar inverter.
The wiring system includes several critical components:
- MC4 connectors: Waterproof connectors joining individual panels in a string.
- String cables: 4–6 mm² cross-section copper cables carrying panel DC voltage (typically 300–600V for residential systems).
- DCDB (DC Distribution Box): Houses string fuses, DC isolators, surge protection devices (SPDs), and monitoring connections. Mandatory under IS 16046.
- Earthing system: Every metal part of the structure and panel frame is earthed to IS 3043 standards to prevent shock and lightning damage.
The DC voltage in a typical residential string of 8 × 400W panels in series is approximately 320–420V — enough to be potentially fatal if touched without safety precautions. This is why the DC wiring should always be installed by qualified solar technicians, not DIY.
Step 3: The Inverter Converts DC to AC Power
Your home runs on Alternating Current (AC) at 230V / 50 Hz (Indian standard). Solar panels produce DC. The solar inverter is the device that bridges these two worlds — it converts the variable DC from your panels into grid-synchronized AC that your appliances can use.
Modern solar inverters do several things simultaneously:
- MPPT (Maximum Power Point Tracking): The inverter continuously adjusts its input voltage to extract the maximum possible power from the panels at any given irradiance and temperature. This is one of the most critical functions — a good MPPT can improve energy yield by 5–15% over a simple fixed-voltage converter.
- Grid synchronisation: The inverter matches its AC output frequency (50 Hz) and voltage (230V) exactly to the DISCOM grid. This is mandatory — a mismatch would damage appliances and could create a shock hazard for DISCOM linemen.
- Anti-islanding protection: When the DISCOM grid goes down, the inverter automatically shuts off (within 100ms) to prevent back-feeding the dead grid. This is a safety regulation — IEC 62116 and IS 16169 both mandate it.
- Monitoring data logging: Stores real-time generation data and sends it to the manufacturer’s cloud platform for monitoring.
For residential 3BHK installations in India, a single-phase string inverter is the standard choice — efficient, reliable, and BIS IS 16221 / IEC 62109 certified. Three-phase inverters are used for larger homes and commercial installations.
The solar inverter complete guide covers inverter types, efficiency ratings, and warranty considerations for Indian buyers.
Step 4: Your Home Uses Solar Power First
When your solar system is generating, your home appliances draw from solar first — before the grid. This happens automatically through physics: the inverter’s output is slightly higher priority than the grid in the circuit.
The energy management sequence looks like this:
- Solar system generates 2.5 kW at noon.
- Your running appliances (fridge, fans, TV) are consuming 0.8 kW.
- The remaining 1.7 kW of solar surplus flows out through your meter to the grid.
- Your net meter’s export register counts these 1.7 kW-hours per hour.
At night: 5. Solar generation stops (no sun). 6. Your appliances draw 0.8 kW from the grid. 7. Your net meter’s import register counts this grid consumption.
At billing time, your DISCOM calculates: imports − exports = net consumption. You pay only on the net. This is net metering — the mechanism that makes grid-tied solar financially viable.
The connecting solar to the grid guide explains the net metering connection process step by step for Indian homeowners.
Step 5: Net Metering Gives You Credit for Surplus Power
Net metering (also called bi-directional metering) is the regulatory framework that allows you to sell surplus solar power back to the grid. Without net metering, your solar system would be unable to export power — and any surplus generation would simply be wasted.
How net metering works in India (as per CERC/SERC regulations):
- Your DISCOM replaces your standard single-direction meter with a bi-directional net meter.
- During the day, surplus solar power flows to the grid — your export register counts these units.
- At night and during cloudy periods, you draw from the grid — your import register counts these units.
- Your monthly bill is calculated on net units consumed (imports minus exports).
- If you export more than you import in a month, the surplus credit rolls over to the next month.
In Gujarat (UGVCL/DGVCL/MGVCL/PGVCL), export units are valued at ₹2.25–₹2.75/unit and import units cost ₹5.50–₹7.00/unit. This differential means it’s more valuable to self-consume solar (avoid ₹6–₹7/unit import cost) than to export (earn ₹2.50/unit credit).
For a full explanation of net metering benefits, billing, and state-wise rules, see the net metering in India complete guide.
Curious how much you’d save? Use our free solar calculator to see generation estimates, bill savings, and net metering credits for your home.
The Heaven Green Solar System Process: End to End
Understanding how the process flows from your first enquiry to a working system helps set expectations. The Heaven Green 7-Stage Solar Journey covers:
- Free site survey — roof assessment, load calculation, shading analysis, DISCOM compliance check. Written proposal in 48 hours.
- PM Suryaghar application — Heaven Green files your application on the national portal with your DISCOM consumer number, Aadhaar, and supporting documents.
- DISCOM feasibility approval — DISCOM inspects and approves within 7–15 working days.
- Installation day — panels mounted, inverter installed, DCDB/ACDB wired, earthing completed, all per IS 16046 and IS 732 standards.
- DISCOM net meter inspection — DISCOM engineer inspects for compliance and installs bi-directional net meter (typically 7–15 days after installation).
- System commissioning — inverter powered on, monitoring app configured, generation verified against design baseline.
- Subsidy DBT — commissioning certificate submitted to PM Suryaghar portal; ₹78,000 direct bank transfer within 30 days per MNRE SLA.
The full step-by-step installation and commissioning process is documented in the solar commissioning guide for Gujarat.
On-Grid vs. Off-Grid vs. Hybrid: Which Works for Your Home?
Most rooftop solar in India uses the on-grid (grid-tied) configuration. But two other options exist, each with different tradeoffs.
- PM Suryaghar eligible — ₹78,000 subsidy
- No battery cost — fastest payback
- Net metering earns credit for surplus generation
- Simple, low-maintenance system
- Shuts down during grid outages (anti-islanding)
- No backup power — pure bill reduction system
Hybrid systems add a battery bank (typically 5–15 kWh lithium LFP or VRLA) that stores surplus solar for use during outages or evenings. They cost ₹60,000–₹1,50,000 more but provide backup. They are PM Suryaghar eligible for the panel and inverter portion.
Off-grid systems are completely independent of the DISCOM grid. They use larger battery banks and are designed for remote areas with no grid access. They are not PM Suryaghar eligible and have the highest cost per unit of electricity.
The on-grid vs off-grid vs hybrid systems guide covers the full comparison with cost and use-case analysis.
Key Components and Their Functions: Quick Reference
| Component | Function | IS/IEC Standard | Typical Lifespan |
|---|---|---|---|
| Solar panels | Convert sunlight to DC electricity | IS 14286 / IEC 61215 | 25–30 years |
| String inverter | Convert DC to grid-sync AC | IS 16221 / IEC 62109 | 10–15 years |
| DCDB | DC protection, string fusing, SPD | IS 16046 | 20+ years |
| ACDB | AC protection, isolator, energy meter prep | IS 13032 | 20+ years |
| Net meter | Bi-directional metering | IS 15884 | 10–15 years |
| Mounting structure | Panel support at optimal tilt | IS 875 (wind load) | 25+ years |
| DC cables | String wiring | IS 17100 (TUV 2PfG) | 25+ years |
| Earthing system | Fault protection | IS 3043 | 25+ years |
Standards referenced from Bureau of Indian Standards and IEC technical committees.
How Heaven Green Energy Explains All This to First-Time Solar Buyers
Heaven Green Energy believes every customer should understand their solar system before the installation day — not after. Our site survey process includes a 30-minute walkthroughing of exactly how your system will work, which components we’re installing, what each monitoring metric means, and how to read your first post-solar DISCOM bill.
We are MNRE-empanelled and install only BIS IS 14286 certified panels and IEC 62109 certified inverters — ensuring your system meets every standard required for the PM Suryaghar subsidy.
- Residential Solar — complete rooftop solar systems with end-to-end commissioning.
- Solar Calculator — see your system size, generation, and savings estimate.
- Products: Solar Modules — BIS-certified panels for residential systems.
- Products: Solar Inverters — IEC-certified string and hybrid inverters.
- Contact our team — free consultation, site survey within 24 hours.
Frequently Asked Questions
How does a solar panel actually produce electricity?
Solar panels use the photovoltaic effect. When photons from sunlight hit silicon atoms in the panel’s cells, they knock electrons free, creating a flow of electrons — an electric current. This current is Direct Current (DC). A silicon cell produces roughly 0.5–0.6 volts; cells are wired in series to build panels that produce 30–50V, and panels are wired in strings to produce the 300–600V needed by the inverter.
Does rooftop solar work on cloudy days?
Yes, but at reduced output. Solar panels generate electricity from diffuse light, not just direct sunlight. On a lightly overcast day in India, output is typically 40–60% of a clear-sky day. On heavily overcast monsoon days, output may be 20–35%. Annual generation calculations already account for monsoon months, so the payback period calculations are not based on perfect-weather assumptions.
What happens to my solar system when the power goes out?
With a standard on-grid (grid-tied) system, your solar inverter automatically shuts off within milliseconds of detecting a grid outage. This is called anti-islanding protection — it’s mandated by IS 16169 and IEC 62116 to protect DISCOM linemen working on outage repairs. Your system restarts automatically when the grid is restored. For backup power during outages, you need a hybrid system with a battery.
How much electricity does a 3 kW solar system produce per day in India?
A 3 kW system in Gujarat with 5.5 peak sun hours/day produces approximately 12–16.5 kWh per day in good conditions. Over a month, that’s 360–495 kWh. The actual daily output varies from about 6–8 kWh on a heavily overcast monsoon day to 16–17 kWh on a clear winter day. Annual average is 12–14 kWh/day.
Can I run my home entirely on solar power?
For most urban Indian homes, rooftop solar with net metering covers 70–100% of the annual electricity bill — not by powering the home entirely from solar at all times, but by combining direct solar use during the day with net metering credits that offset grid use at night. True 100% solar independence requires a large battery bank sized for 2–3 days of autonomy, which is expensive and usually not the right financial choice for grid-connected homes.
What is the role of the DISCOM in rooftop solar?
Your DISCOM (Distribution Company — UGVCL, DGVCL in Gujarat; MSEDCL in Maharashtra; BESCOM in Bangalore; etc.) plays three key roles: (1) approving your solar installation via the feasibility certificate, (2) installing the bi-directional net meter that tracks your generation and import/export, and (3) crediting your net metering surplus on your monthly bill. DISCOM approval is mandatory — you cannot legally connect solar to the grid without it.
