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It’s the first question many homeowners ask once the panels are up, usually half-jokingly: “If the light goes, will my solar keep the fans running?” On 24 October 2026, Thermosun completed a 4kW rooftop solar installation in Yadav Nagar, Samaypur, and the honest answer for this system — and for most solar systems in Delhi — surprises people. It’s worth understanding before you buy, not after the first power cut.
Project Overview & Highlights
This Samaypur installation sits on a raised steel frame on a terrace in a closely built North-West Delhi lane, with a water tank and neighbouring rooftops all around. Here’s exactly what was delivered:
Not Sure Which Type of Solar System Suits Your Home?
On-grid, hybrid or off-grid — the right answer depends on your outages, budget and goals. A free site survey from a solar installation company Delhi families rely on walks you through all three.
📞 Call Now 📄 Free Site SurveyWill Your Solar System Work During a Power Cut?
⚡ Short Answer
With a standard on-grid (grid-tied) system like this 4kW installation, no. When the grid goes down, the inverter switches itself off automatically — even in bright midday sun. That’s by design, not a fault.
The reason is a safety feature called anti-islanding protection. If your solar system kept feeding power into the local line during an outage, it could energise wires that DISCOM staff believe are dead while they’re repairing them. So every grid-tied inverter shuts down the moment grid supply is lost and restarts automatically once it returns. It’s a requirement, and it protects the people working on the network.
If backup during outages matters to you, there are three kinds of solar system to choose between:
| Type | Works in a power cut? | Net metering? | Best for |
|---|---|---|---|
| On-grid (grid-tied) | No — shuts down with the grid | Yes | Cutting the bill at the lowest cost; most Delhi homes |
| Hybrid (grid + battery) | Yes — powers selected loads from battery and solar | Yes | Homes with frequent or long outages who still want bill savings |
| Off-grid | Yes — fully independent, battery-based | No | Places with no reliable grid connection |
A few honest points to weigh. Batteries add noticeable cost and need replacing during the life of the system, so a hybrid system is a bigger investment than an on-grid one. The PM Surya Ghar subsidy is designed around grid-connected rooftop systems, and battery backup is typically an extra cost on top — your installer should confirm exactly what’s covered before you commit. And if you already run an inverter-battery unit for backup at home, it can usually continue to serve your essential loads; the installer just needs to plan how the two coexist.
For this Samaypur home, the on-grid route made sense: it gives the best return on a solar system, qualifies for net metering and subsidy, and the household’s priority was a lower electricity bill rather than outage backup. Thermosun designs all three types — on-grid, hybrid and off-grid — so the recommendation depends on your situation, not on what’s easiest to sell.
KSolare Inverter — DC/AC Setup Explained
This 4kW system runs on a KSolare grid-tied string inverter, mounted on a sheltered interior wall with a DC panel box on one side (panel side) and an AC panel box with protection devices on the other (grid side), joined by tidy conduit runs. Inverters give off heat while working, so wherever one is mounted it needs clear space around it for airflow rather than being boxed in.
Net Metering With TPDDL Explained
Samaypur falls under Tata Power Delhi Distribution Limited (TPDDL), the DISCOM covering most of North and North-West Delhi. After commissioning, Thermosun filed the net metering application through TPDDL’s system, coordinated the inspection, and had the bi-directional meter installed. That meter records the units you draw from the grid and the surplus your system exports separately, and TPDDL nets the two off at each billing cycle — the mechanism behind the monthly savings below. It’s also why net metering requires a grid-tied connection in the first place.
Real Savings — What This Home Now Earns
With the array generating power and net metering active through TPDDL, here’s the estimated monthly financial picture for this 4kW system. Actual figures depend on consumption, season and panel cleanliness:
| Benefit | Monthly Value | Annual Value |
|---|---|---|
| Bill Reduction via Net Metering | ₹2,800 – ₹4,000 | ₹33,600 – ₹48,000 |
| Delhi GBI (₹2/unit generated, 3–10kW slab) | ₹900 – ₹1,050 | ₹10,800 – ₹12,600 |
| Total Monthly Financial Benefit | ₹3,700 – ₹5,050 | ₹44,400 – ₹60,600 |
📊 Solar Subsidy for This 4kW System
Under the currently documented structure, a residential system of 3kW or above receives the ₹78,000 PM Surya Ghar central subsidy plus up to ₹30,000 in Delhi state capital subsidy (₹10,000/kW, capped at 3kW) — a combined ₹1.08 lakh. A 4kW system doesn’t raise either cap; the extra return comes from higher generation, plus the Delhi GBI on top. Delhi has also announced a revised scheme for eligible low-consumption households, but it isn’t live on the official portal yet — see our Delhi Solar Subsidy 2026 guide for what’s confirmed and what isn’t.
What Thermosun Handled — Start to Finish
- 1Site Survey & Needs Discussion Terrace, shading and the household’s priorities — bill savings versus outage backup — discussed before choosing the system type.
- 2Raised Frame Design Galvanized steel structure designed around the water tank and neighbouring rooftops.
- 3Procurement of ALMM-Approved Components Panels and KSolare inverter sourced from the MNRE-approved list for subsidy eligibility.
- 4Panel Installation Full 4kW array mounted and wired across the raised frame.
- 5Inverter & DC/AC Panel Box Setup KSolare inverter installed with protection devices, fully conduit-protected.
- 6Safety Compliance Earthing and protective wiring documented to IS standard.
- 7TPDDL Inspection & Net Meter Net metering application filed, inspection coordinated, bi-directional meter installed.
- 8PM Surya Ghar & Delhi GBI Filed Complete subsidy and GBI registration submitted, bank details confirmed for DBT processing.
Samaypur, Badli & Across North-West Delhi — We Cover Your Area
As a solar EPC company in Delhi handling design, installation, net metering and subsidy paperwork, Thermosun serves Samaypur, Jahangirpuri, Rohini and the wider TPDDL belt directly.
💬 WhatsApp Now 📄 Free Site SurveyWhy Choose Thermosun
The most useful thing an installer can tell you is what a system won’t do. Being upfront that an on-grid system switches off in a power cut, and laying out the hybrid alternative with its real cost, is how we approach every rooftop solar installation Delhi homeowners ask us about — no surprises after handover. With over 1,000 installations behind us across residential, commercial and institutional projects, that straight talk is a big part of why people call Thermosun the best solar company in Delhi for solar for home projects where trust matters as much as price.
More Real Installations Across Delhi
Frequently Asked Questions
Will my solar panels work during a power cut?
With a standard on-grid system, no. The inverter shuts down automatically when grid supply is lost, even in full sunshine. Only hybrid or off-grid systems with batteries can supply power during an outage.
What is anti-islanding protection?
It’s a safety feature in grid-tied inverters that stops them feeding power into the line during an outage, so DISCOM staff working on the network aren’t exposed to unexpected live wires. The inverter restarts automatically when grid supply returns.
Can I add battery backup to my solar system?
Yes, through a hybrid system designed with a battery and backup output for selected loads. It costs more than a standard on-grid system and batteries need replacing over the system’s life.
Does the PM Surya Ghar subsidy cover batteries?
The subsidy is designed around grid-connected rooftop solar, and battery backup is typically an additional cost. Confirm exactly what’s covered with your installer before deciding.
Which DISCOM handles net metering in Samaypur?
Samaypur falls under Tata Power Delhi Distribution Limited (TPDDL), which covers most of North and North-West Delhi. Net metering applications for this area go through TPDDL’s system.
How much solar subsidy does a 4kW system get in Delhi?
Under the currently documented structure, a 4kW residential system receives the ₹78,000 PM Surya Ghar central subsidy and up to ₹30,000 Delhi state capital subsidy — ₹1.08 lakh combined — plus the Delhi GBI. Confirm the latest figures on the official portal before applying.
How much can a Samaypur household save monthly with a 4kW system?
Based on this installation, combined bill reduction and Delhi GBI income comes to roughly ₹3,700–₹5,050 per month, depending on consumption, season and panel cleanliness.
Conclusion
This Samaypur installation is a good reminder that “solar” isn’t one product. An on-grid system gives the best bill savings and qualifies for net metering and subsidy, but it switches off in a power cut; a hybrid system keeps selected loads running but costs more. Choosing the right one starts with an honest conversation about what you actually want from your system — and the correct TPDDL paperwork finishes the job. For homeowners across Samaypur, North-West Delhi or anywhere in the city wondering which setup fits their home, a free site survey is the easiest place to get a straight answer.