What is on-grid solar?
On-grid solar is the most common solar system architecture in India: a rooftop or ground-mounted array connected to the local DISCOM's distribution network. The system feeds the building's loads during the day, exports surplus generation to the grid for credit, and draws from the grid whenever solar output is below demand. Net metering or gross metering is the billing mechanism that prices the exchange.
The hardware list is short. Solar modules, a grid-tie inverter with anti-islanding protection, a mounting structure, AC and DC disconnects, cables, a combiner box, and the DISCOM's bi-directional energy meter. No batteries. The grid effectively plays the role of a free battery, absorbing surplus and supplying deficit.
The economic case for on-grid solar in India rests on two pillars. First, the avoided retail tariff, which is the largest line item on most commercial bills. Second, the value of exported surplus, which under net metering nets against next-month consumption at retail tariff. Together they make the payback period 3 to 6 years for most projects in states with intact net metering.
Why on-grid solar matters
On-grid is the architecture that scales. Off-grid and hybrid systems serve specific niches (remote sites, backup-critical loads), but the mainstream residential and commercial solar market in India is on-grid because the economics work without the cost overhead of batteries.
For EPCs, on-grid is the default sale. PM Surya Ghar is essentially a national push for on-grid residential. The proposal, the equipment supply chain, the DISCOM workflow, and the installer empanelment are all built around on-grid. An EPC selling residential rooftop in 2026 sells on-grid 90 percent of the time.
For homeowners and businesses, on-grid is the cheapest way to lock in long-term electricity cost savings. The avoided retail tariff is the single biggest financial benefit of solar, and on-grid captures it without battery cost. The trade-off: no protection during a grid outage. For consumers where outages are rare and short, that trade-off is easy.
For the grid, distributed on-grid solar reduces peak-noon demand on commercial feeders, which is exactly where India's grid is most stressed in summer. Properly designed and net-metered, on-grid solar is a grid asset, not a burden.
How on-grid solar works
- Solar modules generate DC. Sunlight produces direct current at the modules.
- Inverter converts to AC. The grid-tie inverter performs Maximum Power Point Tracking, converts DC to AC at 230 V (single phase) or 415 V (three phase), and synchronises with the DISCOM's 50 Hz grid frequency.
- Loads consume first. The AC output flows into the building's distribution board and is consumed by whatever loads are running. The system does not "decide" to export; surplus simply flows backward.
- Surplus exports. Whenever generation exceeds load, the surplus flows out through the bi-directional meter to the DISCOM grid.
- Grid imports when needed. Whenever load exceeds generation (or solar is zero at night), the grid supplies the deficit, and the meter records imports.
- Net metering billing. Monthly net consumption is billed at retail tariff. Year-end true-up settles any surplus at APPC.
- Anti-islanding protection. If the grid drops (blackout), the inverter detects loss of grid voltage and immediately disconnects to protect line workers. The whole system goes offline.
Real example: a Coimbatore residential on-grid installation
Customer. Suresh Kumar, retired schoolteacher in Coimbatore, served by TANGEDCO. Family of four, two ACs used during summer, annual consumption around 4,200 kWh.
System. 3 kWp on-grid system using six 530 Wp monocrystalline modules and a 3 kW single-phase string inverter with anti-islanding protection. Cost before subsidy: ₹1.92 lakh.
PM Surya Ghar subsidy. ₹78,000 credited to bank account after DISCOM commissioning (about 60 days after application). Effective project cost: ₹1.14 lakh.
Annual generation. 3 kWp × 1,540 kWh/kWp/year × 0.79 Performance Ratio ≈ 3,650 kWh/year.
Net energy billed. Annual import minus export. Consumption 4,200 kWh, generation 3,650 kWh, net imports billed about 550 kWh at the residential slab tariff of around ₹5 per kWh = ₹2,750 a year of energy charges (down from about ₹19,000 before solar).
Payback. Effective payback against the ₹1.14 lakh post-subsidy outlay: about 7 years on energy savings alone, faster with the concessional loan structure.
Benefits of on-grid solar
- Lowest cost-per-kWh. No battery means lowest upfront cost and shortest payback among solar architectures.
- Best ROI. Avoided retail tariff is captured directly under net metering.
- Stackable with subsidies. PM Surya Ghar, state top-ups, and concessional loans all assume on-grid.
- Long warranty horizon. 25-year module warranty, 5 to 10 years on the inverter.
- Minimal maintenance. Cleaning, visual inspection, occasional inverter firmware updates. No battery replacement cycle.
- Lower BOS complexity. Fewer components, less wiring, less to fail.
- Easy to expand. Adding capacity later is straightforward (subject to DISCOM cap).
- Grid services. Surplus generation supports the local grid at peak-noon hours.
Limitations of on-grid solar
No power during outages. Anti-islanding requires the inverter to shut down when the grid is dead. For homes and businesses with frequent or long outages, this is the deal-breaker.
Dependent on net-metering policy. If the state moves the customer to net billing or gross metering, the export value drops.
DISCOM bottleneck. Feasibility approval, meter installation, and commissioning timelines vary widely by state.
Capacity caps. Most state regulations cap net-metered systems at the sanctioned load or a state-defined ceiling.
No self-sufficiency. The system is permanently tied to the DISCOM relationship. Disconnection or extended outages stop generation.
Fixed charges remain. Even with 100 percent kWh offset, demand charges, fixed charges, and electricity duty are still payable.
Future tariff risk. A 25-year payback assumes a 25-year tariff structure. Net-metering rules can and do change with each SERC order.
On-grid solar in India
| Aspect | Status |
|---|---|
| Dominant architecture in 2026 | On-grid for residential and commercial rooftop in metro and Tier-2 cities |
| Central scheme alignment | PM Surya Ghar built around on-grid + net metering |
| Typical residential system | 3 to 5 kWp, on-grid, net-metered |
| Typical commercial system | 10 kWp to 999 kWp, on-grid, mix of net and gross metering depending on state |
| State leaders by deployment | Gujarat, Maharashtra, Tamil Nadu, Karnataka, Rajasthan, Uttar Pradesh |
| Typical residential cost | ₹55,000 to ₹75,000 per kWp (3 to 5 kWp range, before subsidy) |
| Typical commercial cost | ₹45,000 to ₹60,000 per kWp (50+ kWp range) |
| Typical payback | 3 to 6 years residential after subsidy; 3 to 5 years commercial |
Quick facts
| Term | On-Grid Solar (Grid-Tie Solar) |
|---|---|
| Architecture | Solar plant connected to DISCOM grid, no battery by default |
| Billing | Net metering, gross metering, or net billing depending on state and capacity |
| Required hardware | Modules, grid-tie inverter (with anti-islanding), mounting, BOS, bi-directional meter |
| Standards | CEA Connectivity Regulations, IEEE 1547, IS 16221, IS/IEC 61727 |
| Behaviour during outage | System trips offline (anti-islanding) |
| Subsidy alignment | PM Surya Ghar mandates on-grid + net metering |
| Typical residential cost | ₹1.8 to ₹2.5 lakh for 3 kWp (pre-subsidy) |
| Typical payback | 3 to 6 years (residential with subsidy); 3 to 5 years (commercial) |
Common mistakes about on-grid solar
- Expecting power during a blackout. On-grid systems shut down when the grid drops. This is by design and required by safety codes.
- Oversizing past annual consumption. Year-end surplus is paid at APPC, far below retail. Sizing past 100 percent of annual usage destroys economic value.
- Skipping DISCOM feasibility before quoting. If the local feeder is saturated, the system cannot be net-metered.
- Confusing on-grid with off-grid. On-grid relies on the grid. Off-grid uses batteries instead. They are fundamentally different architectures.
- Adding a generator without isolation design. Most grid-tie inverters cannot operate in parallel with a small genset.
- Ignoring the demand-charge component. Solar offsets kWh, not demand. Commercial customers still pay demand charges even with full kWh offset.
- Treating quoted payback as guaranteed. Payback depends on irradiance, tariff structure, and DISCOM execution speed.
- Adding an inverter with weak anti-islanding spec. Some imported imports cut corners on anti-islanding. Always use IS 16221 compliant inverters.
- Sizing to peak load not to consumption. A house with 8 kW peak demand at noon does not need 8 kWp of solar. Size to annual kWh.
- Promising "Muft Bijli" to customers without sizing for it. 300 free units a month under PM Surya Ghar only works if system size matches consumption profile.
Key takeaways
- On-grid solar is the rooftop architecture connected to the DISCOM grid, with no batteries by default.
- The grid plays the role of "free battery" via net metering, soaking up surplus and supplying deficits.
- It is the cheapest solar architecture per kWp and the shortest-payback option.
- Anti-islanding requires the system to shut down during a grid outage. No power during blackouts.
- PM Surya Ghar, state subsidies, and concessional loans all assume on-grid + net metering.
- Dependent on net-metering policy. State changes can affect future returns.
- Most Indian residential and commercial solar in 2026 is on-grid.
Frequently Asked Questions
What is on-grid solar in simple words?
On-grid solar is a rooftop or ground-mounted solar system that is connected to the DISCOM's distribution grid. It uses the grid as a backup at night and sends surplus daytime generation to the grid for credit. It does not include batteries by default.
How is on-grid different from off-grid solar?
On-grid systems are connected to the DISCOM grid and rely on it for nighttime power. Off-grid systems are standalone, use batteries, and never touch the grid. Hybrid systems do both: grid-connected but with battery backup for blackouts.
Does on-grid solar work during a power cut?
No. A standard on-grid grid-tie inverter shuts down when the grid is dead, a safety requirement called anti-islanding. To keep power during a blackout, you need a battery and a hybrid inverter, or stay off-grid with battery.
What does on-grid solar need?
Solar modules, a grid-tie (string or central) inverter with anti-islanding protection, mounting structure, BOS (cables, AC/DC disconnects, combiner box), a bi-directional energy meter, and a net-metering or gross-metering agreement with the DISCOM.
Is on-grid solar cheaper than off-grid?
Yes. On-grid systems skip the battery, which can be 30 to 50 percent of an off-grid system cost. A 3 kWp on-grid residential system in India costs about ₹1.8 to ₹2.2 lakh. The equivalent off-grid system with battery storage costs ₹3 to ₹4.5 lakh.
Is on-grid solar eligible for PM Surya Ghar?
Yes. PM Surya Ghar is built around on-grid solar with net metering. The subsidy is released after the DISCOM installs the net meter and issues the commissioning certificate.
Can I use on-grid solar with a backup generator?
Yes, with care. Most on-grid inverters cannot operate in parallel with a small genset; they need either grid or no source. Switching arrangements need to be designed by the EPC so the genset and solar do not conflict.
What is the typical payback for on-grid solar in India?
Three to six years for commercial systems, four to six years for residential under PM Surya Ghar. Payback is shorter where net metering is intact, retail tariffs are high, and the DISCOM processes approvals quickly.
How long does it take to install an on-grid system?
Physical installation for a 3 to 5 kWp residential rooftop takes one to three days. The longer timeline (30 to 90 days) is dominated by DISCOM feasibility, paperwork, meter installation, and commissioning.
What size of on-grid system is right for my home?
Size to your average annual kWh consumption, divided by the local annual yield per kWp (typically 1,400 to 1,650 kWh per kWp in India). A 400 kWh-per-month household needs roughly 3 kWp. Avoid oversizing past annual consumption because surplus is paid at APPC, not retail.
What permissions do I need for an on-grid system?
DISCOM feasibility approval, net-metering agreement, building society or RWA approval where applicable, and (for systems above the central subsidy slab) state-specific paperwork. Empanelled installers handle most of this through the National Portal.
Can on-grid solar work in areas with frequent power cuts?
It works during the cuts in the sense that the modules continue generating, but the inverter trips offline for safety. Areas with frequent or long outages are better served by a hybrid system with battery backup. Pure on-grid is best where the grid is reliable.
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- Central Electricity Authority (CEA). Technical standards for connectivity of distributed generation. cea.nic.in
- IEEE 1547. Standard for interconnection and interoperability of distributed energy resources.
- IS 16221 / IS/IEC 61727. Inverter grid interconnection and safety standards.
- MNRE. Grid-connected rooftop solar guidelines and ALMM specifications.
- National Portal for Rooftop Solar. Workflow for on-grid residential installations under PM Surya Ghar.
- State DISCOM technical specifications. Grid-tie inverter requirements, anti-islanding protection.
- Forum of Regulators. Model regulations for net metering and grid-connected rooftop solar.
Written by QuickEstimate Editorial, QuickEstimate Editorial (Surat).
Last updated: 4 June 2026.