What each type does
An on-grid system works alongside the grid: daytime solar is used in the home first, surplus can be exported under the applicable rules, and the grid supplies the rest. An off-grid system runs only from panels and batteries, so the battery bank and your usage decide how long power lasts. A hybrid system keeps the grid connection and adds batteries through a hybrid or battery inverter, so selected circuits can keep running during an outage, depending on the design.
What happens in a power cut
A normal grid-tied inverter disconnects when grid power fails. This anti-islanding behaviour protects people repairing the lines, so on-grid solar alone will not keep your fans running during a cut, even on a sunny afternoon. If outages are frequent, ask the installer to size backup for the loads you actually need, such as lights, fans and a fridge, rather than the whole house, and to show in the quotation how the system switches over.
Subsidy and metering
The residential CFA under PM Surya Ghar is designed for grid-connected rooftop systems and is calculated on solar capacity within the capacity tiers; adding batteries does not raise it. MNRE has clarified, as reported in September 2024, that grid-connected residential systems with battery storage remain eligible, and hybrid inverters may be used under your state regulator's provisions. The subsidy is still worked out on solar capacity, not battery size. Ask the vendor and your DISCOM to confirm in writing how a hybrid installation will be registered, metered and inspected before you pay. Off-grid systems are outside this grid-connected route.
Which type fits which situation
| Check | What to clarify |
|---|---|
| Reliable grid, simplest setup | On-grid; confirm net metering with your DISCOM |
| Frequent power cuts | On-grid with separately sized backup, or a hybrid design for essential loads |
| No dependable grid connection | Off-grid; size batteries for the loads and hours without sun you need to cover |
| Applying for PM Surya Ghar | Grid-connected route; get in writing how any battery affects registration and metering |
A useful definition
- Anti-islanding
- A safety function that stops a grid-tied inverter from feeding power into the lines during an outage.
Quick answers
Can I add batteries later to an on-grid system?
Often, but it depends on the inverter. Some designs need a hybrid inverter or an additional battery inverter, and the change may need to be notified under your DISCOM's process. Ask the installer, before you sign, whether the proposed inverter supports adding batteries later and what would have to be replaced.
A common question
Will a battery lower my electricity bill further?
Not necessarily. A battery stores energy for later but adds cost, conversion losses and eventual replacement. Whether it lowers the bill depends on when you use power and on the applicable metering rules, so ask for the assumptions behind any claim.
Sources for this guide
MNRE
Residential CFA operational guidelines · §§5–6
Standard rates, household/GHS eligibility, DCR and payment process. PDF, 57 pages.
Checked: Rules can changeMNRE (as reported)
Battery storage eligible for CFA · September 2024
Trade-press report of an MNRE clarification: grid-connected residential rooftop systems with battery storage remain eligible for CFA, and hybrid inverters may be used under state regulator provisions.
Checked: Rules can changeUPNEDA / MNRE
Rooftop technical specifications
Module, inverter, structure, protection and metering scope to discuss with the installer.
Checked: Rules can change