Hyderabad Solar Calculator (TGSPDCL)

Rooftop solar payback for Hyderabad on TGSPDCL, where crossing 200 units a month moves every unit to a dearer table.

Your home

Average monthly electricity bill

₹

₹100₹50K

About 412 units a month on the TGSPDCL tariff. Use a year's average if your bill swings with the seasons.

Roof type

RCC flat roof

RCC, elevated structure

Metal sheet roof

Fine-tune

System size

Sized to cover a year of your consumption, at 5.5 peak sun hours a day in Telangana.

Usable shadow-free roof area (optional)

sq ft

About 100 sq ft per kW. Leave at 0 for no limit.

Installed cost per kW, GST included

₹

Typical for an on-grid system from an empanelled vendor. Replace it with your quote.

Yearly rise in electricity prices

0%15%

Indian residential tariffs have historically risen 4-7% a year.

Panel output lost each year

0%2%

Monocrystalline panels typically lose about 0.5% a year.

How you pay

Upfront

Solar loan

Pays for itself in2.8 yearsthen ₹14.43 L ahead after 25 years

A 3 kW system makes about 386 units a month, 94% of your use. Your bill drops from ₹3,000 to about ₹121 in year one.

Installed cost: ₹1,80,000
PM Surya Ghar subsidy: − ₹78,000
Net cost to you: ₹1,02,000
Saving in year one: ₹34,529
Return (IRR): 38.2% a year; over 25 years, before tax
CO₂ avoided: 79 tonnes; over 25 years

Subsidy43%

You pay57%
Central subsidy43%

Your money over 25 yearsStill to recoverAhead

Year-by-year cash flowShow

Year	Units made	Bills without solar	Bills with solar	Upkeep and EMIs	Running total
1	4,637	₹35,985	₹1,456	₹0	-₹67,472
2	4,614	₹37,784	₹1,578	₹0	-₹31,266
3	4,591	₹39,673	₹1,708	₹0	₹6,699
4	4,568	₹41,657	₹1,847	₹0	₹46,508
5	4,545	₹43,740	₹1,995	₹0	₹88,253
6	4,523	₹45,927	₹2,153	₹1,800	₹1,30,226
7	4,500	₹48,223	₹2,322	₹1,800	₹1,74,327
8	4,477	₹50,634	₹2,502	₹1,800	₹2,20,660
9	4,455	₹53,166	₹2,693	₹1,800	₹2,69,332
10	4,433	₹55,824	₹2,897	₹1,800	₹3,20,459
11	4,411	₹58,615	₹3,115	₹1,800	₹3,74,160
12	4,389	₹61,546	₹3,346	₹22,800	₹4,09,559
13	4,367	₹64,623	₹3,593	₹1,800	₹4,68,790
14	4,345	₹67,854	₹3,855	₹1,800	₹5,30,989
15	4,323	₹71,247	₹4,895	₹1,800	₹5,95,541
16	4,301	₹74,809	₹5,282	₹1,800	₹6,63,269
17	4,280	₹78,550	₹5,694	₹1,800	₹7,34,325
18	4,259	₹82,477	₹6,134	₹1,800	₹8,08,869
19	4,237	₹86,601	₹6,602	₹1,800	₹8,87,068
20	4,216	₹90,931	₹7,101	₹1,800	₹9,69,098
21	4,195	₹95,478	₹7,633	₹1,800	₹10,55,143
22	4,174	₹1,00,252	₹8,200	₹1,800	₹11,45,395
23	4,153	₹1,05,264	₹8,802	₹1,800	₹12,40,057
24	4,132	₹1,10,528	₹9,444	₹1,800	₹13,39,341
25	4,112	₹1,16,054	₹10,127	₹1,800	₹14,43,468

How it works

The bill you enter is worked backwards through your DISCOM's slabs, fixed charges, surcharges and duty to the units you use. The panels' yearly output is set against that use under net metering, and each month is re-billed on what is left. Because the units solar removes come off your most expensive slab first, the saving per unit is often well above the average rate on your bill. Tariffs rise by the escalation rate each year while the panels slowly lose output; maintenance, an inverter replacement in year 12 and any loan repayments are taken off, and the running total gives the payback year.

Saving₍y₎ = [Bill(U) − Bill(U − G₍y₎/12)] × 12 × (1 + e)^(y−1),  G₍y₎ = kW × H × 365 × PR × (1 − d)^(y−1)

U: Units you use a month, worked out from your bill
G₍y₎: Units the panels make in year y
H: Peak sun hours a day in your state
PR: Performance ratio: the share of rated output that reaches the meter, 0.77 here
e: Yearly rise in electricity prices
d: Yearly loss in panel output

Worked example

A Hyderabad home on TGSPDCL with a ₹3,000 monthly bill and a flat RCC roof, assuming prices rise 5% a year.

1Working the bill back through the TGSPDCL slabs, charges and duty gives about 412 units a month
2At 5.5 peak sun hours, 3 kW makes about 386 units a month, 94% of that use
33 kW at ₹60,000 per kW costs ₹1,80,000; PM Surya Ghar pays ₹78,000, leaving ₹1,02,000
4The first year saves ₹34,529, and the saving grows as tariffs rise

The system pays for itself in about 2.8 years and leaves the household about ₹14,43,468 ahead over 25 years.

Frequently asked questions

Why does the 200-unit line matter so much in Telangana?

Telangana's domestic tariff is not purely telescopic. Up to 200 units a month the rates are ₹3.40 and ₹4.80; above 200, the whole consumption moves to a table starting at ₹5.10 and reaching ₹10 a unit. Solar that brings net use under 200 cuts the bill by more than the units it replaces.

Does Gruha Jyothi make solar pointless?

Only for eligible homes that already stay within 200 units a month, whose bill is already free. Most homes that are interested in solar use well above that and pay the full tariff, and the free allowance does not apply once a month goes over it.

How does net metering settle on TGSPDCL?

Net metering with surplus settled yearly at the TGERC-approved rate.

How much is the PM Surya Ghar subsidy?

₹30,000 per kW for the first 2 kW and ₹18,000 for the third, so ₹30,000 for 1 kW, ₹60,000 for 2 kW and ₹78,000 for 3 kW or more. It is paid into your bank account after the DISCOM inspects and commissions the system, and only for installations by an empanelled vendor using ALMM-listed panels, applied for through pmsuryaghar.gov.in.

Why is my saving per unit higher than my average rate?

Residential tariffs are telescopic: the first units are cheap and each slab above costs more. Solar takes units off the top of your bill, so it removes the dearest ones first. A home in a ₹10-plus slab saves that rate on every unit the panels cover, even if the bill averages out lower.

Why not simply fit the biggest system my roof will hold?

The central subsidy stops rising at 3 kW, and under net metering surplus units are usually bought back at the regulator's average power purchase cost, often ₹2-3 a unit, far below what you pay for grid power. Sizing to your own consumption earns the full retail rate on every unit. The calculator suggests that size; override it to see what a bigger system does to the return.