Tariff Studio
From a client’s consumption to the right solar, wind and storage capacities — with the bill to prove it.
Tariff Studio sizes open-access projects against state tariff orders and open-access rules, and gives you a client-ready report.
Built for 9 states and 3 commercial structures.
Sample case — recommended mix
- Capacity mix
- 2 MW solar + 2 MW wind + 2 MW / 2h battery
- Year-1 saving
- ₹92.99 lakh
- Effective tariff
- ₹10.7414 /kWh
- Grid-only
- ₹12.2912 /kWh
- Renewable share
- 86.8%
The problem
Rules of thumb don’t survive a real bill.
Sizing open-access projects with rules of thumb or generic spreadsheets gives numbers that fall apart when they meet an actual DISCOM bill. Tariff Studio starts from the tariff and works outwards, so the capacity you recommend is built on the bill your client will actually receive.
Same plant, same load, three states
₹227
lakh a year, Maharashtra
₹116
lakh a year, Karnataka
₹7–92
lakh a year, Tamil Nadu, depending on the additional surcharge
How it works
Four steps, one engine
The same annual billing simulation prices every point it tests, so the capacity it recommends and the bill it reports are computed the same way.
- 01
Upload
Consumption and generation, 15-minute interval — from the client’s meter export or their own files. Data quality is reported, not assumed.
- Interval data
- 15 min
- Consumption
- 60.00 lakh kWh
- Generation
- solar and wind profiles
- Contract demand
- 1,500 kVA
- Months covered
- 12
Example day — 96 blocks
- 02
Pick state and structure
Choose the state and the commercial structure. The state’s own tariff orders and open-access rules do the rest.
MHKATNGJTSAPRJUPDLThird partyGroup captiveCaptiveSample case: Maharashtra, third party open access
- 03
Size
Solar and wind are sized independently; storage is then tested on top of the mix that would feed it.
Mix Year-1 bill 25-yr NPV Solar only ₹658.85 L ₹11.15 Cr Solar + wind ₹644.91 L ₹13.65 Cr 2 MW solar + 2 MW wind + 2 MW / 2h ₹644.45 L ₹15.52 Cr - 04
Solve for the PPA rate and report
Solve for a solar, wind, blended or storage-backed rate — then download the brief and detailed reports.
2 MW solar + 2 MW wind + 2 MW / 2h
Year-1 Bill Year-1 Savings 25-Year NPV ₹644.45 L ₹92.99 L ₹15.52 Cr Effective Tariff ₹10.7414 /kWh IRR 12.7%
Proof
Your bill, line by line, matched to the rupee.
Tariff Studio does not estimate a bill — it reconstructs one, charge line by charge line, from the state’s own orders, and then sizes the plant against it. So the capacity you recommend can be put next to the invoice your client actually receives.
How we validate
We took real open-access invoices and reproduced them charge by charge: demand charge, operating charge and the consumption rebates, with every other line within 1%. The demand-netting floor and the time-of-day windows were read out of the invoices themselves — those are the parts a generic model gets wrong.
The same load, priced from the grid only to the recommended mix
| Configuration | Year-1 bill | 25-year NPV |
|---|---|---|
| Grid only — no open access | ₹737.44 L | — |
| Solar only — 4 MW | ₹658.85 L | ₹11.15 Cr |
| Solar + wind — 2 MW wind | ₹644.91 L | ₹13.65 Cr |
| Solar + wind + 2 MW / 2h battery | ₹644.45 L | ₹15.52 Cr |
Coverage
Nine states. Three commercial structures.
Each state is built from its own tariff orders, regulations and open-access rules — not a national average with a state label on it.
MH
Maharashtra
KA
Karnataka
TN
Tamil Nadu
GJ
Gujarat
TS
Telangana
AP
Andhra Pradesh
RJ
Rajasthan
UP
Uttar Pradesh
DL
Delhi
Third party
Power bought from a generator through open access.
No plant to build and no capital of your own: you buy the output, and your bill falls from the first unit.
Group captive
A plant owned jointly by a group of consumers who use its power.
Several consumers hold the plant together and take its power in proportion to their shareholding.
Captive
A plant owned by the consumer for its own use.
You own the plant and consume all of it — the most capital, and the most control.
Capabilities
What you can do with it
Solar sizing
Test solar capacities against the load and the state’s charges.
Wind sizing
Size wind independently of solar and compare the two.
Storage sizing
Test storage on top of the solar and wind you have sized.
Solve-for-PPA-rate modes
Set a target saving and get the PPA rate that reaches it.
Storage-rate ceiling
The highest storage rate at which you still save. Below it the battery works for both sides; above it the developer earns and you pay, and the tool tells you which side of that line your quote is on.
Bill calculator
See every charge the state applies, block by block through the year.
Client-ready reports
Brief and detailed reports you can hand to a client or a board.
Sample reports
See the deliverable.
What a client receives. The detailed report runs to eight pages; the brief version is one. Both are generated from the same run, so they never disagree.
- ₹92.99 L
- Year-1 saving, sample case
- 2 + 2 + 2
- MW solar + wind + 2h battery
- ₹10.74
- Effective ₹/kWh vs ₹12.29 grid-only
The recommended mix bills lower than grid-only supply in 11 of 12 months of the sample year. It bills higher in July — worth knowing before any monthly figure is quoted as a saving, because the annual result nets those months against the rest.
Both reports show what the result rests on, and the data-quality notes behind it, so a figure can be followed rather than taken on trust.
View the sample report (PDF, 8 pages)Who it’s for
Three people, one number to defend
Developers
Switch between third party and group captive in one session and answer the off-taker in the room.
Request free trialConsultants
One engine across states, so each client no longer needs a rebuilt model.
Request free trialCorporate buyers
See your bill block by block, with every state charge applied. Contract the right capacity, not the biggest.
Request free trialAccess
Get access
Start with a 7-day free trial on preloaded sample plants. We approve each request by hand and send your sign-in link within one working day.
Free trial, 7 days
- Preloaded sample plants across states. No data to prepare.
- Run the full sweep, the bill calculator, the tariff solver and scenario comparison.
- Read the brief and detailed reports on screen.
Your own plant
- Upload your own consumption and generation data and run your own projects.
- Download the brief and detailed reports and put them in front of a client.
- Terms for your own plant we discuss with you directly — write to sales@terrastrom.com.
Request access
Tell us who you are and where you are looking — we set up each account ourselves and reply to every request.
Questions
Questions we get asked
Is my data secure?
Your data stays on our servers and is never used to price anyone else’s project. Consumption and generation files are encrypted at rest; the encryption key sits outside the application directory. Access is by named account, with roles, and every account can be disabled immediately. Backups run daily and are held for fourteen days. Files you upload are yours to delete, and deleting a project removes it from the working system.
Which tariffs and which year are loaded?
Nine states are loaded: Maharashtra, Tamil Nadu, Gujarat, Karnataka, Telangana, Andhra Pradesh, Rajasthan, Uttar Pradesh and Delhi. Rates are for FY2026-27, and the pack is dated 20 August 2026. Every rate carries a confidence letter: H where the source order states the number explicitly; M where it states a range or a qualitative rule and we use a defensible default; and L where the order does not state it at all and the value must be replaced from the operative order before it is relied on.
How often are tariff rules updated?
Each state’s tariff order is read when it is issued and the pack is re-issued with a new date and revision. Every rate keeps its source and its confidence letter, so a change is visible as a change rather than a silent edit. Rates that a state has not yet notified stay marked as unconfirmed.
What do I need from my client to get started?
For the free trial, nothing: sample plants are preloaded. For your own plant, bring the client’s 15-minute consumption and generation profiles, the state and the commercial structure you prefer. Meter exports as CSV or Excel are fine; the engine reports what the data quality will support rather than filling gaps silently.
Can Tariff Studio be used for deviation settlement?
No. Tariff Studio is a planning and sizing tool for open-access projects and tariff-based bill modelling. It is not a tool for deviation settlement.
Ready to size your next project against the real bill?
7-day free trial on sample plants. Sign-in link within one working day.
Request free trial