What’s in this article
Does your on-grid system actually work during a power cut?
Most people who install rooftop solar in Tamil Nadu or Kerala answer that question the same way: “Of course — I have solar panels, why would a power cut affect me?”
Here’s the uncomfortable answer: if you have a standard on-grid (grid-tied) system — which is what the vast majority of subsidized residential installations under PM Surya Ghar actually are — your panels stop feeding your home the moment the grid goes down. Not eventually. Almost instantly — well-built inverters commonly trip in a fraction of a second.
This isn’t a defect. It’s the law.
Why your inverter is designed to shut itself off
When TANGEDCO or KSEB power fails, utility linemen have to assume every wire on that line is dead before they touch it to fix the fault. If your solar inverter kept pushing electricity into the grid during an outage, it could re-energize a line a lineman believes is safe — a real electrocution risk.
To prevent exactly that, every legally connected on-grid inverter sold in India is required to carry anti-islanding protection — a safety circuit that detects the moment grid voltage disappears and disconnects the inverter. This is governed by the CEA (Technical Standards for Connectivity of Distributed Generation Resources) Regulations, 2013, with the actual anti-islanding test procedure specified under IS 16221 Part 1 (India’s version of the international IEC 62116 standard). The regulation doesn’t fix one universal disconnection speed in milliseconds — well-built modern inverters commonly trip in well under a second in practice — but it does fix the reconnection side clearly: inverters must not reconnect until grid stability holds for a minimum of 60 seconds after power returns.
There’s no bypass for this. It’s not a setting you can switch off, and no installer can legally disable it for you, whatever they may promise on a sales call. It exists to protect people working on the lines, not as a limitation someone forgot to engineer around.
So what happens to the electricity your panels are still generating?
Nothing — it simply isn’t used. Even at 1 PM on a cloudless day, with your panels producing at full output, an on-grid system with no battery goes completely dark the second the grid trips, because there’s no way for it to safely island itself off the grid and power your home independently.
For a lot of homeowners, this fact only becomes visible the first time it matters — mid-outage, expecting the lights to stay on because “I have solar,” and finding out they don’t.
The alternative: what a hybrid system does differently
A hybrid inverter paired with battery storage is built to legally do the thing an on-grid system can’t: disconnect from the utility grid and continue operating as an isolated “island,” powering your home from stored battery charge and live solar generation. Because it’s fully separated from the grid rather than still connected to it, none of the lineman-safety concern applies. The switchover is fast enough — commonly cited in the 10–20 millisecond range by inverter manufacturers — that most appliances don’t even register the transition; a running fan or fridge compressor generally doesn’t stutter.
This is exactly why, when we build backup into a Kondaas installation, we build it around Aurvo’s own LiFePO4 battery packs rather than treating battery backup as a bolt-on afterthought — the battery chemistry and the inverter’s switchover behavior have to be matched, not just bundled.
The tradeoff, and it’s a real one: a hybrid system costs meaningfully more than a plain on-grid setup, because you’re paying for battery capacity and a more capable inverter, not just the panels. Published market figures for a battery-plus-hybrid-inverter retrofit (adding backup to an existing on-grid system, no new panels) commonly range from roughly ₹1.7–2.5 lakh for a modest 5kWh lithium setup, while a full new hybrid system with 5kWh of storage typically runs ₹4–5.5 lakh before subsidy. The gap between those two numbers is almost entirely about whether you’re retrofitting or starting fresh — treat any number you hear before a proper load assessment of your own home as illustrative, not a quote.
What to actually check before you decide
- Ask any installer directly: “Is this on-grid, off-grid, or hybrid?” — don’t assume based on the word “solar” alone.
- If backup during outages matters to you, ask specifically what happens to your inverter the moment grid power fails — the honest answer for a plain on-grid system is “it shuts off.”
- If you already have an on-grid system and outages genuinely bother you, ask about retrofitting hybrid capability rather than assuming you need to start over — depending on your existing inverter, it’s sometimes possible to add battery backup rather than replace the whole system.
- Size the battery to your actual essential loads (lights, fans, fridge, WiFi router) rather than trying to back up the whole house — it’s the difference between an affordable retrofit and an oversized, overpriced one.
If you haven’t yet checked whether you even qualify for the current MNRE subsidy before any of this, start there — the subsidy math changes the order in which on-grid vs. hybrid makes financial sense. And if you’re crossing the TN–Kerala border and comparing TNEB against KSEB rules, this net metering breakdown covers what actually changes.
The real question to ask yourself
On-Grid System Power Cuts: Quick Answers
Why does an on-grid system shut down when the grid fails?
Every on-grid system is legally required to shut down the moment utility power disappears. This is not a defect — it is an anti-islanding protection mechanism mandated by India’s grid safety standards (CEA 2022 Grid Connectivity Regulations). If your on-grid system kept running during a blackout, it would push live electricity into lines that linesmen treat as dead. The protection exists for their safety and for yours.
Can I add a battery to my existing on-grid system to get backup power?
Yes, but it requires the right inverter. A basic string inverter in an on-grid system cannot accept a battery — it was designed for export-only operation. You need either a hybrid inverter (which replaces the string inverter) or a separate battery inverter sitting between the existing system and your critical loads. Kondaas designs both configurations; which route is cheaper depends on the age and brand of your existing inverter.
Does an on-grid system still earn net metering credits during the day even if there are evening power cuts?
Yes. Net metering credits accumulate whenever your on-grid system is exporting to the grid — which only happens when the grid is live and the sun is up. Evening power cuts don’t affect daytime credits already banked. However, if the power cut happens during peak solar hours, your on-grid system shuts down and loses that generation window entirely.
How is an on-grid system different from a hybrid system?
An on-grid system has no local storage. It generates, exports, and earns credits — but goes dark the moment the grid does. A hybrid system adds a battery bank, so when the grid fails, critical circuits switch to battery within milliseconds. The on-grid system’s advantage is lower upfront cost; the hybrid system’s advantage is uninterrupted power. In Tamil Nadu, where power cuts still run 1–4 hours in summer, the hybrid configuration is increasingly the practical choice for homes and MSMEs.
On-Grid System Owner Checklist: Are You Protected?
If you own or are planning an on-grid system, run through this list before the next summer cuts begin:
- Know your inverter brand and model — check whether it is hybrid-upgradable or needs full replacement if you want battery backup later.
- Check your net metering agreement — confirm whether your on-grid system is on net metering or net billing; the payout rate differs.
- Identify your critical circuits — if adding backup to your on-grid system, decide in advance which circuits (refrigerator, fans, router, lights) go on the protected leg.
- Verify ALMM compliance — your on-grid system’s panels must appear on the ALMM List-II if you want subsidy. Ask your installer for the module certificate.
- Log your power cut hours — one month of data tells you whether a battery addition to your on-grid system will pay back within a reasonable cycle.
It isn’t “should I go solar.” Almost everyone in Tamil Nadu and Kerala should, at this point — the economics are solid. The real question is whether you’re buying a system that lowers your bill, or a system that also keeps your lights on when the grid can’t. Those are two different products with two different price tags, and no one should find out which one they bought during the next outage.
If you’re not sure which one is sitting on your roof right now, that’s a five-minute question worth asking — before the next power cut answers it for you.
Not sure whether your current system (or the one you’re being quoted) is on-grid or hybrid? Get a straight answer — talk to the Kondaas team about what backup actually costs for your home’s real essential-load size.