A typical Indian 3-bedroom home with three air conditioners (ACs) sits in a very specific energy band — 600 to 900 kWh per month in summer, 350 to 500 kWh through winter. That profile changes the PM Suryaghar sizing math in ways most online calculators miss. The ₹78,000 central subsidy caps at 3 kW, but a 3-AC household almost always needs 5 kW or 6 kW to actually cover summer load. The decision is not whether to apply for PM Suryaghar — it is how to layer the subsidised 3 kW with the additional kilowatts you fund yourself, and whether a battery belongs in the design at all.
This guide walks through the kilowatt-hour (kWh) math for a 3-AC home, the five inputs that decide your system size, the cost-and-subsidy ledger at 3 kW, 5 kW, and 6 kW, and the day-versus-night consumption split that determines whether you should add storage.
Direct answer. A typical 3-AC Indian home consumes 25–32 kWh/day in summer and needs a 5 kW rooftop solar system to cover 80–90% of annual usage. The PM Suryaghar subsidy of ₹78,000 covers the first 3 kW; the additional 2 kW costs roughly ₹1.1 lakh out-of-pocket. All-in cost lands near ₹3.5 lakh, payback is 3.5–4 years, and most homes skip batteries because grid export at APPC still beats the storage premium.
If your bill has been crossing ₹4,000 a month through April–September, you are almost certainly in this band. Read on — the sizing decision you make now sets your electricity bill for the next 25 years.
What a 3-AC Home Typically Consumes (kWh Math)
A 3-AC home is not one number — it is a seasonal curve. Air conditioners dominate summer load, vanish through winter, and the rest of the household (refrigerator, lighting, fans, geyser, kitchen, entertainment) holds a roughly flat baseline of 8–12 kWh/day across the year. Layer the AC kWh on top of that baseline and you get the seasonal profile that decides your solar sizing.
Start with the air conditioner physics. A 1.5-ton split AC is the most common Indian residential size. Its electrical draw depends on three things: the tonnage, the Bureau of Energy Efficiency (BEE) star rating, and whether it is a fixed-speed or inverter unit. An inverter AC modulates compressor speed and saves 20–30% compared to a fixed-speed unit of the same star rating. The BEE star labelling programme revises the Indian Seasonal Energy Efficiency Ratio (ISEER) bands every couple of years, so a 5-star AC sold in 2018 may rate as a 3-star under 2024 norms.
| AC type | Tonnage | Rated draw | Typical kWh/hour | Annual kWh @ 1,500 hr |
|---|---|---|---|---|
| 1.5-ton fixed-speed 3-star | 1.5 T | 1.55 kW | 1.20 kWh | 1,800 kWh |
| 1.5-ton inverter 3-star | 1.5 T | 1.45 kW | 0.90 kWh | 1,350 kWh |
| 1.5-ton inverter 5-star | 1.5 T | 1.25 kW | 0.70 kWh | 1,050 kWh |
| 1-ton inverter 5-star | 1.0 T | 0.95 kW | 0.55 kWh | 825 kWh |
| 2-ton inverter 3-star | 2.0 T | 1.85 kW | 1.20 kWh | 1,800 kWh |
For the math that follows, assume the middle-of-the-road case: three 1.5-ton inverter 3-star ACs, each drawing 0.9 kWh/hour while running. In peak summer (April–June across most of north and central India), each AC runs 6–10 hours/day. Take 8 hours as the household-weighted average — bedrooms cool overnight, the living-room AC runs 4–6 hours in the evening.
That gives 3 ACs × 8 hours × 0.9 kWh = 21.6 kWh/day from ACs alone in summer. Add 10 kWh/day baseline and the household lands near 31–32 kWh/day in May–June, or 950 kWh in a month. Winter strips the AC load entirely — January consumption falls to 350–450 kWh because only fans, geysers, and the kitchen run. Across a full year, expect 7,500–9,500 kWh of total consumption for a 3-AC home with moderate use. That number is the input every sizing decision hinges on.
The 3-AC Home Sizing Calculator — 5 Inputs That Decide Your Solar
Most online solar calculators ask one question: your monthly bill. That is too crude for a 3-AC household. A ₹5,000 summer bill in Jaipur with 6.0 peak sun hours (PSH) needs a different system than a ₹5,000 summer bill in Bengaluru with 4.8 PSH. The framework below — The 3-AC Home Sizing Calculator — 5 Inputs That Decide Your Solar — captures the five variables that actually move the answer.
Input 1: Average Monthly Bill (Summer Peak vs Annual Mean)
Pull out twelve months of electricity bills and look at two numbers: the May–June peak and the twelve-month average. A 3-AC home with a summer peak of ₹6,500 and an annual mean of ₹3,800 has very different sizing math from a household where both numbers sit near ₹4,200. The peak tells you the system must handle a higher summer load even at the cost of winter export. The mean tells you the payback math you can actually expect across the year.
Convert each bill to units by dividing the energy charge by the applicable slab tariff. A ₹6,500 bill in north India usually sits in the 600–800 kWh band — that is the input that decides whether 5 kW is enough or 6 kW is required.
Input 2: AC Running Hours per Day (Realistic, Not Aspirational)
Households consistently overestimate AC hours when they describe usage and underestimate when they read meter data. The honest answer for a 3-AC home with two bedrooms and one living-room AC sits between 6 and 10 hours/day across May–September. Bedrooms cool overnight, living-room AC runs from 7 p.m. to midnight, and the third bedroom runs only when the room is occupied.
For sizing, use a household-weighted hours number — typically 8 hours/day across all three ACs in peak summer, dropping to zero between November and February. Multiply by 0.7–0.9 kWh/hour depending on star rating to get daily AC kWh.
Input 3: Day vs Night Load Split
This is the input that decides whether a battery makes financial sense. Solar generates from sunrise to sunset — roughly 7 a.m. to 6 p.m. AC load in a 3-AC home runs heavily 9 p.m. to 7 a.m. (bedroom ACs overnight). The two curves barely overlap.
Estimate what fraction of your daily kWh runs during sunlight hours. For a 3-AC household where bedroom ACs dominate, the daytime share is usually 35–45% of total consumption. The rest exports to the grid at the Average Power Purchase Cost (APPC) — typically ₹2.50–₹3.50/kWh — instead of saving you the retail tariff of ₹7–₹8/kWh. That gap is the financial case for either load-shifting or storage.
Input 4: Available Shadow-Free Roof Area
A 5 kW rooftop system using 540 W tier-1 mono PERC modules needs roughly 500 sqft of shadow-free roof. A 6 kW system needs 600 sqft. If your roof shape is rectangular and obstruction-free, the calculation is straightforward. If you have water tanks, parapet shadows, or staircase blocks intruding, you may need to step down from 6 kW to 5 kW even when the bill math supports the larger size.
Measure the usable roof bay (length × breadth, less shadow setbacks). Divide by 100 to get approximate kilowatts peak (kWp). Aluminium mounting structure adds 4 inches of clearance, panels tilt 15–25° on flat roofs, and inter-row shading sets a minimum spacing equal to 60% of panel height when tilted.
Input 5: Sanctioned Load on the DISCOM Bill
The Distribution Company (DISCOM) sanctioned load printed on your bill is the legal ceiling for your solar system. A home with 5 kW sanctioned load can install up to 5 kW without a load enhancement application. If you want 6 kW solar but your bill shows 4 kW sanctioned load, you must file a load enhancement first — typical processing 15–25 days, fee ₹2,500–₹4,500 depending on state.
Most 3-AC homes already carry 5 kW or higher sanctioned load because the air conditioners themselves consume that much during simultaneous startup. Confirm the number on your bill before you finalise system size — feasibility rejection from a sanctioned-load mismatch is one of the more common failures we see in our PM Suryaghar complete guide tracking.
Recommended System Sizes for 3-AC Homes (3 kW vs 5 kW vs 6 kW)
The sizing decision for a 3-AC home is rarely about whether to install solar — it is about whether to limit yourself to the subsidy-capped 3 kW or step up to the larger system that actually fits your consumption. Below is the comparison we walk customers through. Generation figures assume 5.0 PSH (a national-average benchmark; Rajasthan, Gujarat, and Andhra Pradesh sites generate 10–20% more).
| System size | Daily generation | Monthly generation | Annual generation | Roof area | % summer load covered | % winter load covered |
|---|---|---|---|---|---|---|
| 3 kW | 12–14 kWh | 360–420 kWh | 4,500 kWh | 300 sqft | 45–55% | 100% (surplus exported) |
| 5 kW | 20–24 kWh | 600–720 kWh | 7,500 kWh | 500 sqft | 75–85% | 100% (large surplus) |
| 6 kW | 24–28 kWh | 720–840 kWh | 9,000 kWh | 600 sqft | 90–100% | 100% (largest surplus) |
Three observations from the numbers above. First, a 3 kW system covers less than half of summer load for a 3-AC home — fine if you only care about claiming maximum subsidy but you continue paying ₹2,500–₹3,500 monthly across summer months. Second, the 5 kW system hits the sweet spot — high summer coverage, manageable out-of-pocket investment after subsidy, comfortable winter surplus that earns export credits. Third, 6 kW makes sense only if you have the roof area, sanctioned load, and consumption pattern to justify the extra ₹1.1 lakh investment for the additional kWh.
The 5 kW system is the default recommendation for a typical 3-AC household. It uses the full ₹78,000 subsidy headroom, fits on most 30×40 ft plot roofs, stays within standard 5 kW sanctioned loads, and pays back in 3.5–4 years. The 6 kW recommendation kicks in when summer bills consistently cross ₹6,500 or when the household runs ACs 10+ hours/day.
For broader sizing logic across other load profiles, see our home solar system size guide.
Get a custom sizing review for your 3-AC home. Our team analyses your last 12 months of bills, your roof geometry, and your sanctioned load — and gives you the exact kW recommendation before you commit. Talk to a sizing engineer →
Cost, Subsidy, and Payback Math (City-by-City)
Cost is national; payback is local. Tier-1 panel and BIS-certified inverter pricing barely varies between Jaipur and Bengaluru — the same module costs the same. What changes is the kilowatt-hour your roof produces (PSH variance) and the retail tariff you offset (state-level DISCOM tariffs).
| System size | All-in cost (pre-subsidy) | PM Suryaghar subsidy | Net out-of-pocket |
|---|---|---|---|
| 3 kW | ₹1.85–₹2.05 lakh | ₹78,000 | ₹1.07–₹1.27 lakh |
| 5 kW | ₹2.95–₹3.20 lakh | ₹78,000 | ₹2.17–₹2.42 lakh |
| 6 kW | ₹3.45–₹3.70 lakh | ₹78,000 | ₹2.67–₹2.92 lakh |
The subsidy is fixed at ₹78,000 — extra kilowatts above 3 kW come at roughly ₹55,000 per kW at full retail cost. Heaven Green’s installed pricing is competitive with the all-in numbers above because we source ALMM-listed tier-1 panels (Adani, Waaree, Tata) at volume and pass the rate through.
Payback now layers the city math. Below is the 5 kW system payback across the cities we install in most frequently. Calculations assume 75% self-consumption (typical for a 3-AC home without load shifting), with the balance exported at APPC.
| City | PSH | Annual kWh @ 5 kW | Retail tariff (blended) | Annual savings | Payback (5 kW) |
|---|---|---|---|---|---|
| Jaipur (JVVNL) | 5.7 | 8,400 | ₹7.10 | ₹56,800 | 3.8 yrs |
| Jodhpur (JdVVNL) | 6.0 | 8,800 | ₹6.95 | ₹58,200 | 3.7 yrs |
| Ahmedabad (Torrent) | 5.8 | 8,500 | ₹6.65 | ₹52,800 | 4.1 yrs |
| Lucknow (UPPCL) | 5.0 | 7,500 | ₹6.85 | ₹47,800 | 4.5 yrs |
| Bengaluru (BESCOM) | 4.8 | 7,200 | ₹7.40 | ₹49,600 | 4.4 yrs |
| Hyderabad (TGSPDCL) | 5.4 | 8,000 | ₹7.20 | ₹54,000 | 4.0 yrs |
Sources: MNRE Solar Atlas for PSH, state regulator tariff orders for retail rates. Detailed payback derivations live in our how to calculate solar ROI guide and the solar payback period breakdown.
A 25-year cumulative savings for a 5 kW system in Jaipur, accounting for 0.5%/year panel degradation and assumed 3% annual retail tariff escalation, lands near ₹19–₹22 lakh. Net of the ₹2.2 lakh out-of-pocket investment, that is a 9–10× return on capital over the system life.
Day vs Night Consumption — Why 3-AC Homes May Want a Battery
The single biggest reason 3-AC homes consider batteries is the load-curve mismatch. Solar peaks at noon; AC load peaks at midnight. Without a battery, two-thirds of your summer-evening AC consumption is bought from the grid at retail tariff (₹7–₹8/kWh) while two-thirds of your noon generation is sold back at APPC (₹2.50–₹3.50/kWh). The arbitrage gap is real money.
| Time block | Typical household kWh | Solar generation (5 kW) | Direction |
|---|---|---|---|
| 6 a.m.–9 a.m. | 2.5 kWh | 1.5 kWh | Self-consume |
| 9 a.m.–12 p.m. | 3.0 kWh | 7.5 kWh | Export surplus |
| 12 p.m.–3 p.m. | 3.5 kWh | 8.0 kWh | Export surplus |
| 3 p.m.–6 p.m. | 4.0 kWh | 4.0 kWh | Self-consume |
| 6 p.m.–10 p.m. | 7.5 kWh | 0.5 kWh | Import from grid |
| 10 p.m.–6 a.m. | 9.5 kWh | 0 kWh | Import from grid |
A 10 kWh lithium battery shifts roughly 8 kWh of midday surplus into evening/overnight consumption. At a ₹4.50/kWh arbitrage gap, that saves about ₹13,000/year. But a 10 kWh battery installation in India in 2026 costs ₹1.6–₹2.0 lakh, and the PM Suryaghar central subsidy does not cover storage. Payback for the battery alone runs 12–15 years against a 10-year warranty — the math does not work for most households.
The alternative is smart load-shifting — running dishwashers, washing machines, water pumps, and even pre-cooling bedrooms with the AC at 4 p.m. to ride the solar curve. A 3-AC home that load-shifts aggressively can push self-consumption from 35% to 55%, capturing most of the battery economic gain with zero capital outlay. This is the strategy we recommend in 80% of 3-AC home designs. The deeper financial breakdown sits in our solar and air conditioner cost analysis.
Verdict — battery for 3-AC home
Skip the battery on the first install. Build a 5 kW grid-tied system, adopt load-shifting habits, and revisit storage in 2029–2030 when lithium prices are expected to fall another 25–30% and the central scheme may add a storage subsidy component. The arbitrage you give up today is smaller than the capital you avoid locking into expensive cells.
Common Sizing Mistakes for 3-AC Homes
We have audited hundreds of 3-AC home installations across north and central India. The same five mistakes show up repeatedly — each one costs the household either money or roof real estate.
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1
Sizing only for the subsidy cap. Stopping at 3 kW because that maximises subsidy leaves 50% of summer load uncovered. The subsidy headroom should set a floor, not a ceiling — 5 kW remains the right answer for most 3-AC homes.
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2
Oversizing past sanctioned load without a load enhancement. Installing 6 kW on a 4 kW sanctioned-load connection causes feasibility rejection. File the load enhancement first; it adds 20 days but saves the entire application.
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3
Sizing on annual-average usage instead of summer peak. A household that averages 500 kWh/month but peaks at 850 kWh/month in May should size for the peak. Undersizing to the average leaves you buying expensive summer units.
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4
Forcing a battery into the first install. Most 3-AC homes do not earn back the battery cost in its warranty life. Build grid-tied first; revisit storage when lithium drops further or when grid outages become a daily disruption.
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5
Picking the cheapest panel quote without checking the ALMM list. Non-ALMM panels (often Chinese-origin modules sold at 15–20% discount) fail the DISCOM net-meter inspection. You lose the entire ₹78,000 subsidy. Verify every quoted panel model on the current MNRE ALMM register.
The deeper rejection-pattern analysis sits in the PM Suryaghar complete guide. The single most decisive check before signing any quote is opening the MNRE ALMM register and verifying the panel model number is current. A second sanity check worth doing — ask the installer for the inverter’s BIS certificate number and confirm it on the BIS portal. Non-certified inverters cause the same inspection failure as off-list panels.
AC Tonnage and Star Rating Impact on Solar Sizing
The same household with three 1.5-ton 3-star ACs and three 1.5-ton 5-star ACs has wildly different solar needs. The 5-star upgrade saves 600–800 kWh/year per AC — across three units, that is 1,800–2,400 kWh/year, or roughly 1.2–1.5 kW of solar capacity you no longer need to install.
The BEE star rating measures the Indian Seasonal Energy Efficiency Ratio (ISEER), which captures performance across realistic indoor and outdoor temperature ranges rather than a single peak condition. ISEER 4.5+ qualifies as 5-star under the 2024 BEE norms; ISEER 3.5–4.0 is 3-star. The BEE star labelling programme revises these bands periodically, so a 5-star AC from 2018 may sit at 3-star equivalence today.
| Star rating | ISEER band (2024) | 1.5-ton kWh/hour | Annual kWh (1,500 hr) |
|---|---|---|---|
| 3-star inverter | 3.50–4.00 | 0.90 | 1,350 |
| 4-star inverter | 4.00–4.50 | 0.80 | 1,200 |
| 5-star inverter | 4.50+ | 0.70 | 1,050 |
If you are buying solar and new ACs in the same financial window, the order matters. Buy 5-star inverter ACs first, run them for a billing cycle to capture the new consumption baseline, then size solar against the lower number. This sequence typically saves ₹70,000–₹1,00,000 of solar capital that would otherwise be wasted offsetting inefficient AC load. Old fixed-speed ACs from before 2017 are the most egregious — replacing them often pays back faster than installing extra solar.
For households where AC replacement is not in the budget, size solar against the current AC profile and plan the AC upgrade as a separate 5-year capital cycle. The solar system will continue to pay back even as your AC consumption falls over time — the excess generation simply exports as surplus credit at APPC. There is no penalty for over-generating once your AC efficiency improves, so the worst case for a forward-looking sizing decision is harmless surplus rather than a stranded asset.
One related point on tonnage. A 3-AC home where one of the units is a 2-ton living-room AC (common in homes with 250+ sqft halls) draws roughly 1.2 kWh/hour instead of 0.9 kWh/hour. Across 8 hours/day in peak summer, that single AC adds 2.4 kWh/day to the household load — equivalent to roughly 0.5 kW of additional solar capacity. Factor the largest AC in the house separately rather than assuming three identical 1.5-ton units; the sizing answer can shift from 5 kW to 6 kW just from one oversized living-room unit.
How Heaven Green Energy Helps Design 3-AC Home Solar
A 3-AC home solar design is not a catalogue order. It needs a billing-history audit, a roof site survey, a sanctioned-load check, and a city-specific generation forecast before the kW number can be locked. Heaven Green Energy handles all four as part of every residential proposal.
Our process for 3-AC home customers:
- 12-month bill audit — we extract month-wise kWh consumption, identify your summer peak, and map AC running hours from the load curve.
- Roof site survey — physical visit (urban) or drone/photo audit (smaller towns) confirming usable shadow-free area at the proposed installation angle.
- Sanctioned-load and DISCOM feasibility pre-check — we verify your bill against the system size and flag any load enhancement need before portal submission.
- City-specific generation modelling — using MNRE Solar Atlas PSH data plus local shading and orientation, we forecast monthly generation with ±5% accuracy.
- ALMM-listed tier-1 panels only — Adani, Waaree, or Tata modules with full MNRE-compliant documentation.
- BIS-certified inverters — Polycab, Sungrow, or Growatt with 5–10 year manufacturer warranties handled through us.
- PM Suryaghar end-to-end handling — application, document upload, DISCOM coordination, net meter inspection, and subsidy DBT tracking until credit hits your account.
- 25-year performance support through our O&M (Operation and Maintenance) contracts.
Explore the services and tools that match your stage:
- Residential Solar — 3 to 10 kW rooftop systems with PM Suryaghar subsidy handled end-to-end.
- Solar Calculator — enter your bill and city to see kW recommendation, subsidy, and payback in 60 seconds.
- Contact our sizing team — free consultation with one of our design engineers, no obligation.
Want the broader subsidy stacking math? Our PM Suryaghar complete guide lays out how the ₹78,000 central subsidy combines with state components in Rajasthan, Gujarat, and other top solar states. For households comparing solar against an AC-replacement plan or a combined upgrade, our sizing engineers will model both scenarios side by side and recommend the sequence that gives the better five-year cash position. No two 3-AC homes have the same usage curve, and the right answer for your house may not be the same as your neighbour’s — that is exactly what the custom design process exists to settle.
Frequently Asked Questions
What size solar system does a typical 3-AC Indian home need?
A 3-AC home running 1.5-ton inverter ACs about 8 hours/day in summer consumes 25–32 kWh/day or 750–950 kWh in peak summer months. A 5 kW rooftop solar system covers 75–85% of summer load and 100% of winter load — the recommended size for most 3-AC households. Stepping up to 6 kW makes sense only if summer bills consistently exceed ₹6,500 or AC running hours cross 10/day.
How much PM Suryaghar subsidy does a 3-AC home get for a 5 kW system?
The PM Suryaghar central subsidy is capped at ₹78,000 for any system 3 kW and above. A 5 kW system claims the full ₹78,000, with the additional 2 kW above 3 kW funded out-of-pocket at roughly ₹55,000 per kW. Net out-of-pocket cost for a 5 kW system lands near ₹2.2–₹2.4 lakh on an all-in installed cost of ₹3.0–₹3.2 lakh.
Should a 3-AC home add a battery to the solar system?
For most 3-AC households, no. A 10 kWh lithium battery costs ₹1.6–₹2.0 lakh and is not covered under PM Suryaghar. The annual arbitrage gain — shifting noon surplus into evening AC consumption — works out to roughly ₹13,000/year, against a battery warranty life of 8–10 years. Smart load-shifting (running dishwashers, washing machines, and pre-cooling at 4 p.m.) captures 60–70% of the same financial benefit at zero capital cost.
How long is the payback period for a 5 kW solar system in a 3-AC home?
Payback for a 5 kW grid-tied system in a 3-AC home is 3.5–4.5 years depending on city. Jaipur and Jodhpur hit 3.7–3.8 years thanks to 5.7–6.0 PSH and strong retail tariffs. Bengaluru and Lucknow land at 4.4–4.5 years due to lower PSH. The 25-year cumulative savings sit between ₹17 lakh and ₹22 lakh across most Indian cities.
Can I install a 6 kW solar system if my sanctioned load is only 4 kW?
No — your DISCOM will reject the feasibility application. You must first file a load enhancement request with your distribution company, increasing sanctioned load to at least 6 kW. The process adds 15–25 days and costs ₹2,500–₹4,500 depending on state. Most 3-AC homes already carry 5–6 kW sanctioned load because the AC compressors themselves draw that much during simultaneous startup.
Does running 5-star inverter ACs change the solar sizing math?
Yes — significantly. Replacing three 3-star fixed-speed 1.5-ton ACs with three 5-star inverter units cuts AC consumption by roughly 35–40%, or 1,800–2,400 kWh/year. That is the equivalent of 1.2–1.5 kW of solar capacity. If you are upgrading both solar and ACs, buy the 5-star ACs first, run one billing cycle to confirm the new baseline, then size solar against the lower number. Sequencing this correctly saves ₹70,000–₹1,00,000 of solar capital.
What is the difference in monthly bill before and after installing 5 kW solar?
A 3-AC home in north India with a pre-solar summer bill of ₹6,500 and a winter bill of ₹2,200 typically drops to a summer bill of ₹600–₹1,200 and a winter bill of ₹0–₹250 (just fixed charges and electricity duty after solar credit) after a 5 kW PM Suryaghar installation. The annual electricity-cost reduction averages ₹56,000–₹61,000, which is the basis for the 3.5–4 year payback math.
Will my solar system run my AC during a grid outage?
A standard PM Suryaghar grid-tied (without battery) system does not run during a grid outage — the inverter shuts off for safety as required by the Central Electricity Authority connectivity regulations. To run ACs during outages, you need either a hybrid inverter with battery backup or a separate diesel generator. In most Indian cities with reasonable grid stability, this is not required; in towns with frequent multi-hour outages, a 5 kVA hybrid inverter with a 5 kWh battery adds ₹1.2 lakh and provides 3–4 hours of single-AC backup.
Is rooftop solar worth it if I plan to sell the house in 5 years?
Yes — by year five, a 5 kW PM Suryaghar system has already paid back its out-of-pocket investment through bill savings. Beyond that, multiple property surveys in Indian metros now record a 4–6% premium on resale price for homes with documented operational solar systems and clean PM Suryaghar paperwork. The combination of recovered savings plus resale uplift makes the 5-year horizon a positive financial case in most cities.
