Rooftop Solar Savings Calculator

Find the right solar size for your home, the subsidy and when it pays back.

Private by design

Your inputs stay on your device and are not sent to our servers. Optional usage analytics does not receive your files or tool inputs.

Preparing rooftop solar savings calculator

Preparing tool

How to use Rooftop Solar Savings Calculator

Enter your monthly electricity bill and the price you pay per unit.
Add the cost per kW from your installer's quote, and your roof area if it is small.
Read the system size, subsidy, net cost, yearly savings and payback year.

Read the detailed guide →

What are the limits of Rooftop Solar Savings Calculator?

An estimate, not a quote. Real generation depends on your city, shade and roof angle; net-metering rules, fixed charges and the subsidy amount can change, so check pmsuryaghar.gov.in. Loan interest, inverter replacement and taxes are not included. Nothing you enter leaves your device.

Rooftop Solar Savings Calculator

System size, PM Surya Ghar subsidy and payback

Your electricity

Monthly electricity bill

₹

Price per unit

₹

Rupees per kWh from your bill, including charges.

Monthly units (optional)

If you know it. Leave 0 to work it out from the bill.

Share of your use to cover

Your system

Shadow-free roof area (optional)

sq m

About 10 sq m is needed per kW.

System size (optional)

Leave 0 to use the suggested size.

Installed cost per kW

₹

From your installer's quote.

Units made per kW a year

Sunny days give 4–5.5 units a day per kW; yearly averages are lower.

Subsidy

Claim PM Surya Ghar subsidy

Subsidy per kW, first 2 kW

₹

30,000 (33,000 in special-category states). Check pmsuryaghar.gov.in for the current amount.

Subsidy for the third kW

₹

18,000 (19,800 in special-category states). Nothing beyond 3 kW.

Over time

Yearly rise in electricity price

Yearly drop in panel output

Suggested system3.5 kWneeds about 35 sq m of roof

Net cost after subsidy₹1.32 Lcost ₹2.10 L, subsidy ₹78,000

First-year saving₹34,1254,550 units made a year

Pays back in3.7 years

Net gain over 25 years₹10.31 L

Money back over time (cumulative ₹, negative until payback)

Year by year (25 rows)

Year	Solar units used	Saving (₹)	Cumulative (₹)
1	4,550	34,125	-97,875
2	4,527	34,973	-62,902
3	4,505	35,842	-27,060
4	4,482	36,733	9,673
5	4,460	37,646	47,318
6	4,437	38,581	85,899
7	4,415	39,540	1,25,439
8	4,393	40,522	1,65,962
9	4,371	41,529	2,07,491
10	4,349	42,561	2,50,052
11	4,328	43,619	2,93,671
12	4,306	44,703	3,38,374
13	4,284	45,814	3,84,188
14	4,263	46,952	4,31,140
15	4,242	48,119	4,79,259
16	4,220	49,315	5,28,574
17	4,199	50,540	5,79,114
18	4,178	51,796	6,30,911
19	4,157	53,083	6,83,994
20	4,137	54,402	7,38,396
21	4,116	55,754	7,94,151
22	4,095	57,140	8,51,291
23	4,075	58,560	9,09,850
24	4,055	60,015	9,69,865
25	4,034	61,506	10,31,372

How it works

Rooftop solar cuts your bill by making units on your roof that you would otherwise buy from the grid. This calculator suggests a size from your bill, adds the PM Surya Ghar central subsidy, and shows how long the savings take to repay the cost.

Subsidy stops at 3 kW
Systems above 3 kW get the same central subsidy as 3 kW, so each extra kW is unsubsidised.
The July 2026 PIB note
The Ministry says the central assistance for the first 2 kW has been made higher but did not give the new amount. Type the current figure into the subsidy boxes if it differs.

Your use = 400 units a month × 12 = 4,800 units a year.
Size needed = yearly use × share covered ÷ units per kW = 3.32 kW; suggested 3.5 kW (rounded up to the next half kW).
Cost = 3.5 kW × cost per kW = ₹2,10,000; subsidy ₹78,000; net ₹1,32,000.
Yearly saving = units you use from solar × price per unit; payback is when the running total of savings reaches the net cost.

Get two or three installer quotes: the cost per kW is the number that moves payback most.
Check for shade on the roof between 10 am and 3 pm.
Net metering rules and fixed charges differ by state, so confirm with your electricity company.

Subsidy follows the MNRE table for PM Surya Ghar: Muft Bijli Yojana (residential): ₹30,000 per kWp for the first 2 kWp, ₹18,000 for the third kWp, nothing beyond 3 kWp (₹33,000 and ₹19,800 in special-category states), so up to ₹78,000 (Annexure I, MNRE, published on pib.gov.in; PIB press release, 28 July 2026, notes higher assistance for the first two kWp without stating amounts, so both rates are editable). The official FAQ says 1 kW needs about 10 sq m of shadow-free area and can make 4 to 5.5 units on a clear day; the default of 1,300 units per kW a year is a cautious average. Size = yearly use × share ÷ units per kW. Savings are capped at your own use, valued at your price per unit rising by your yearly rate, with panel output falling by your yearly percentage.

Preparing rooftop solar savings calculator

Rooftop Solar Savings Calculator

System size, PM Surya Ghar subsidy and payback

Your electricity

Monthly electricity bill

₹

Price per unit

₹

Rupees per kWh from your bill, including charges.

Monthly units (optional)

If you know it. Leave 0 to work it out from the bill.

Share of your use to cover

Your system

Shadow-free roof area (optional)

sq m

About 10 sq m is needed per kW.

System size (optional)

Leave 0 to use the suggested size.

Installed cost per kW

₹

From your installer's quote.

Units made per kW a year

Sunny days give 4–5.5 units a day per kW; yearly averages are lower.

Subsidy

Claim PM Surya Ghar subsidy

Subsidy per kW, first 2 kW

₹

30,000 (33,000 in special-category states). Check pmsuryaghar.gov.in for the current amount.

Subsidy for the third kW

₹

18,000 (19,800 in special-category states). Nothing beyond 3 kW.

Over time

Yearly rise in electricity price

Yearly drop in panel output

Suggested system3.5 kWneeds about 35 sq m of roof

Net cost after subsidy₹1.32 Lcost ₹2.10 L, subsidy ₹78,000

First-year saving₹34,1254,550 units made a year

Pays back in3.7 years

Net gain over 25 years₹10.31 L

Money back over time (cumulative ₹, negative until payback)

Year by year (25 rows)

Year	Solar units used	Saving (₹)	Cumulative (₹)
1	4,550	34,125	-97,875
2	4,527	34,973	-62,902
3	4,505	35,842	-27,060
4	4,482	36,733	9,673
5	4,460	37,646	47,318
6	4,437	38,581	85,899
7	4,415	39,540	1,25,439
8	4,393	40,522	1,65,962
9	4,371	41,529	2,07,491
10	4,349	42,561	2,50,052
11	4,328	43,619	2,93,671
12	4,306	44,703	3,38,374
13	4,284	45,814	3,84,188
14	4,263	46,952	4,31,140
15	4,242	48,119	4,79,259
16	4,220	49,315	5,28,574
17	4,199	50,540	5,79,114
18	4,178	51,796	6,30,911
19	4,157	53,083	6,83,994
20	4,137	54,402	7,38,396
21	4,116	55,754	7,94,151
22	4,095	57,140	8,51,291
23	4,075	58,560	9,09,850
24	4,055	60,015	9,69,865
25	4,034	61,506	10,31,372

How it works

Subsidy stops at 3 kW
Systems above 3 kW get the same central subsidy as 3 kW, so each extra kW is unsubsidised.
The July 2026 PIB note
The Ministry says the central assistance for the first 2 kW has been made higher but did not give the new amount. Type the current figure into the subsidy boxes if it differs.

Your use = 400 units a month × 12 = 4,800 units a year.
Size needed = yearly use × share covered ÷ units per kW = 3.32 kW; suggested 3.5 kW (rounded up to the next half kW).
Cost = 3.5 kW × cost per kW = ₹2,10,000; subsidy ₹78,000; net ₹1,32,000.
Yearly saving = units you use from solar × price per unit; payback is when the running total of savings reaches the net cost.

Get two or three installer quotes: the cost per kW is the number that moves payback most.
Check for shade on the roof between 10 am and 3 pm.
Net metering rules and fixed charges differ by state, so confirm with your electricity company.