System size · India
Under PM Surya Ghar, eligible 3 kW and 5 kW residential plants typically share the same ₹78,000 central CFA cap. Upsizing only makes sense when your units and roof justify the extra unsubsidised kilowatts.
The trap
CFA commonly stops climbing after 3 kW. Vendors who imply “5 kW gets more government money” are usually wrong on central CFA — confirm on pmsuryaghar.gov.in.
| Size | Typical central CFA | What changes |
|---|---|---|
| 3 kW | Up to ₹78,000 | Often best CFA efficiency for mid-consumption homes |
| 5 kW | Still up to ₹78,000 | ~2 kW extra at full cost; more generation if you need it |
Last reviewed
Tariff slabs differ by DISCOM, so two homes with the same ₹ bill can have different unit counts. Rough India thumb-rules (conservative, weather-dependent):
Targeting 80–90% of annual units is usually safer than “zero bill forever” claims — fixed charges and export settlement rules still leave a residual bill. The figure this all rests on is how many units one kW actually generates where you live, which varies more across India than most quotes admit.
Oversizing so surplus banks at a low year-end rate can destroy returns — especially if you export what you never self-consume at high slab tariffs.
The subsidy ceiling does something to the arithmetic that a quotation's headline never shows. Assistance rises to 3 kW and then stops, so the capacity you add beyond the third kilowatt is bought at full price with no support at all.
Work it through with round numbers. Suppose a 3 kW system is quoted around ₹1,90,000 gross. After the ₹78,000 ceiling, your net cost is about ₹1,12,000 — roughly ₹37,000 per kilowatt. Now take a 5 kW system at around ₹3,17,000 gross. The assistance is still ₹78,000, so your net cost is about ₹2,39,000 — roughly ₹48,000 per kilowatt.
The average cost per kilowatt has risen by about a third, and the two extra kilowatts themselves cost you around ₹1,27,000, or roughly ₹63,000 each. That is the number to judge, not the average. The marginal kilowatt is nearly twice the price of a subsidised one, and it has to earn its keep on savings alone.
Those figures are indicative and your quotes will differ — the point is the shape, not the exact rupees. Whenever you compare sizes, divide the difference in net cost by the difference in capacity. That single calculation prevents most oversizing.
Before comparing economics, check whether the larger system is even available to you. Both of these are physical or contractual limits, not preferences.
Usable roof area. Roughly 8–10 m² per kilowatt of genuinely shadow-free space, plus room to walk around the array for cleaning. A 5 kW system therefore needs a substantially clear terrace, and on a typical small urban plot the water tank, stair room, parapet shadow and setbacks often mean the honest answer is 3 kW regardless of budget. Measure the shadow-free area, not the total roof.
Sanctioned load. This is printed on your bill and is the one most people miss. If the PV capacity you apply for exceeds it, many distribution companies require a load enhancement, bringing charges and a separate queue outside your installer's quotation. That cost belongs in the comparison, and it can quietly erase the case for the larger plant. Check the figure before choosing a size, and confirm whether your connection is single or three-phase.
This is the part that decides it, and it has nothing to do with the roof. A unit you consume while the panels are generating avoids your full retail tariff, including the expensive upper slabs. A surplus unit exported is settled at whatever your state's rules allow, which is generally less.
So the extra two kilowatts only pay well if you actually use what they produce, at the time they produce it. Consider two households with identical bills. One has someone home during the day, a borewell pump, weekday cooling and a car charging at midday: much of the extra output is self-consumed at full tariff, and the upsize can be justified. The other is empty from morning to evening: nearly all the extra output is exported at the lower rate, so the marginal kilowatts that cost around ₹63,000 each are earning the weakest possible return.
Before upsizing, ask yourself honestly when your consumption happens. If the answer is mostly evenings and nights, a bigger array is the wrong purchase — and load-shifting into daylight on a 3 kW system will do more for your return than adding capacity. The mechanics are in net metering in India.
For most Indian households the answer is 3 kW, and not through timidity — it is where public money stops subsidising you, where a normal urban roof stops being comfortable, and where sanctioned load typically stops being a problem. Going larger is a defensible decision on evidence of sustained high daytime consumption across twelve months of bills. It is not defensible on available roof space, on a round number, or on a hope that a bigger plant means a zero bill. Fixed charges and export settlement leave a residual bill in any case — see costs, savings and payback and how the amount is built up in solar subsidy explained.
If your consumption sits well outside this 3–5 kW band, the arithmetic shifts rather than simply scaling. Below it, fixed costs are spread over fewer panels and the per-watt price rises — see 1 kW pricing. Above it, central assistance has already stopped and three-phase supply usually enters the picture — see 10 kW pricing.
Run the Sealix home check from your bill, then read PM Surya Ghar and costs & savings. City context: Pune, Chennai, Bengaluru, Mumbai.
No. Central residential CFA commonly caps at ₹78,000 for eligible 3 kW and larger systems. A 5 kW plant usually receives the same CFA ceiling; the extra 2 kW is at full cost.
Size from average monthly units you want to offset, roof area, and sanctioned load — not from a fixed bill rupee alone. Many homes with roughly 300–400 units/month fit near 3 kW; higher sustained consumption can justify 5 kW despite no extra CFA.
Close to full retail price, because assistance stops rising at 3 kW. On indicative numbers, a 3 kW system might net around ₹1,12,000 after the ceiling, or roughly ₹37,000 per kilowatt, while a 5 kW system nets around ₹2,39,000, or roughly ₹48,000 per kilowatt. The two additional kilowatts themselves cost around ₹63,000 each. Always divide the difference in net cost by the difference in capacity rather than comparing averages.
Roughly 8 to 10 square metres of genuinely shadow-free roof per kilowatt, so about 40 to 50 square metres for 5 kW, plus room to walk around the array for cleaning. On a typical small urban plot the water tank, stair room and parapet shadows often mean the honest answer is 3 kW regardless of budget. Measure the shadow-free area rather than the total roof.
It may, and this is the constraint most people miss. The sanctioned load is printed on your bill, and if the PV capacity you apply for exceeds it many distribution companies require a load enhancement with its own charges and processing queue outside the installer's quotation. That cost belongs in your comparison and can remove the case for the larger plant entirely.
When you genuinely consume the extra output at the time it is produced, since a self-consumed unit avoids your full tariff while an exported unit settles for less. A household with daytime presence, pumping, weekday cooling or midday vehicle charging can justify it. A household empty from morning to evening exports most of the additional output at the lower rate, which is the weakest possible return on kilowatts bought at full price.
