Tariff Studio — User Guide
How to use the tool, what data it needs, and how to read what it tells you. For any site, in any supported state. Version 0.8.1, rev 0, 2026-09-23.
In one paragraph. Tariff Studio works out how much solar, wind and battery capacity an industrial or commercial electricity consumer should contract through open access, and what it would save against buying everything from the DISCOM. It does this from the consumer's real 15-minute consumption and real 15-minute generation data, priced on the chosen state's tariff and open-access rules. Every figure on screen and in a report comes from that calculation.
1. Before you start: the data you need
| What | Form | Where it comes from |
|---|
| Consumption (required) | One year at 15-minute intervals, as a CSV file. | The DISCOM meter (a download of the meter's load survey), or the factory's own energy meter. A monthly electricity bill is not enough on its own: the tool needs the pattern within each day. If the consumer cannot produce the 15-minute file, Terrastrom can prepare it from the meter data and the bills. |
| Solar generation (required) | One year at 15-minute intervals, CSV. | The plant's own generation data, or a reference profile for the location. If only hourly figures exist, Terrastrom converts them to 15-minute intervals. |
| Wind generation (required) | One year at 15-minute intervals, CSV. | As for solar. |
| Nameplate capacity of each generation file | kW | The capacity the generation file was recorded at. It must match the file — the tool scales the file from it. |
| Contract demand and power factor | kVA, and a number such as 0.98 | The consumer's electricity bill. |
| Calendar (optional) | JSON file of weekly offs, holidays and shutdowns | The factory. Without it, Sunday is taken as the only day off. |
| State and commercial structure | Chosen on screen | Where the factory is, and whether the project is third party, group captive, or captive. |
The CSV format is the same for all three files: a header row, then one row per 15-minute period.
date,block,kWh,tier
2026-01-01,0,212.5,measured
2026-01-01,1,208.0,measured
...
2026-01-01,95,221.3,measured
date is written YYYY-MM-DD.block is the number of the 15-minute period in the day, 0 to 95: block 0 is 00:00 to 00:15, block 95 is 23:45 to 24:00. It is a time slot, not a limit on kWh.kWh is the energy in that 15 minutes — not kW. (A reading in kW is four times the kWh for a quarter-hour.)tier says whether the row is measured or modelled.- Every day must have all 96 blocks. A file may be up to 25 MB and 40,000 rows; a full year is 35,040 rows.
2. Signing in, and what each account can do
You need an email address and password to use the tool; Terrastrom sets up your account. Without signing in nothing runs, and the Reports tab appears only once you are signed in on an account that includes reports.
Everything is done inside a project: a named, numbered set of your data files plus the details that belong with them. Until one is open the other tabs are greyed out, because there would be nothing for them to size. Preparing a project is free; it is sealing it, once you are satisfied with what it contains, that uses a credit.
| Account | Your own data | Full sizing sweep | Reports | Calculations a day |
|---|
| Free | No — demonstration data only | Yes | Yes | 100 |
| Registered | Yes | Yes | Yes | 50 |
| Paid | Yes | Yes | Yes | 2,000 |
The free account is the whole tool on the bundled sample, not a cut-down one: it runs the full
sweep, the solver and both report types. What separates it from a subscription is your own data, how
many calculations a day, and whether a report can leave the building — a free account reads a report
on screen, with a band across it saying it is a sample, and downloading it is part of a subscription.
A "calculation" is each run the tool makes — changing a setting starts one. If the day's allowance is used up, a notice at the top of the page says so and when the next calculation becomes available.
Is it signed in? A steady blue dot beside your email at the top right means you are signed in. A blinking amber dot beside the sign-in boxes means you are not.
How long it stays signed in. Up to 30 days on the same browser, including after closing it, as long as it is not left unused for more than 8 hours. If the internet connection drops, you stay signed in: a notice appears, and the tool carries on by itself when the connection returns, with everything you loaded and set still in place. When you come back another day, the data list offers "Your last upload", so you do not have to upload the files again.
3. Using it, step by step
Step 1
Open or create a project — Projects tab
The first tab lists your projects and the credits left on your account, with the date the next ones expire. New project starts one; preparing a project costs nothing and uses no credit. A project holds the four data files and the details that belong with them, and everything else in the tool works inside it — that is why the other tabs stay greyed out until a project is open. A draft you never seal is removed after seven days, so an abandoned upload does not sit on our disk. If your account is the free one, the only entry is Sample project, which opens the bundled demonstration at once; there are no upload controls.
Step 2
Enter the details and the files — stages A and B
Name the project, and choose the state and the commercial structure. The state is chosen here rather than at run time, because it is what stops one credit pricing the same consumption data in several states. Then load the three CSV files (and the calendar if you have one), both nameplates, the contract demand, the power factor and the site names. Every file can be replaced as many times as you like while the project is a draft. When it has worked, a line says what was loaded.
Step 3
Read the review screen — stage C
Each file is checked as soon as it loads, and all three are judged together. Errors — a missing or repeated block, an unreadable row, the wrong columns — are listed with the line they are on, and the project cannot be sealed while any of them stands. Warnings are things that load but look wrong: less than a full year, a solar file with output at night, a nameplate that does not match the file's own peak, a peak far from the contract demand entered. The screen also shows each file's statistics — period covered, annual energy, peak, load factor or yield, and the share that is metered rather than modelled — and four pictures of the year: daily totals, a heat map whose blank stripes are the periods the file did not contain, monthly bars, and a typical day. Short gaps cannot be filled in the tool. They are shown and never interpolated, because an invented value is a difference of opinion waiting to happen; Terrastrom can take a gap up separately on a support basis. GO stays disabled until every error is fixed and you have ticked that you have read the warnings.
Step 4
Seal the project — stage D, GO
Sealing uses one credit. Afterwards the consumption, solar, wind and calendar files, the two nameplates and the state cannot be changed, and the credit is spent. Everything else — PPA prices, escalations, billing basis, sizes, sweep range, contract demand, power factor and the structure — can still be changed as often as you like. The project then stays open for three calendar months after the end of the month you sealed it in. There is no cooling-off period and no undo, so check the four files on the review screen before you press it. The credit can only be put right by Terrastrom, and only for a genuine mistake.
Step 5
Set the economics
PPA prices, billing basis, discount rate, DISCOM escalation, OA charges escalation and the battery cost. Each has a ? beside it that explains it; hover to read, click to keep it open, click elsewhere or press Esc to close.
Step 6
Size the project: Right-sizing tab
The quick preview updates as you change things; it is for direction only. Press Run full sweep for the real answer. Stage 1 shows solar alone; Stage 2 tests every solar and wind combination in the sweep range and outlines the best one; Stage 3 tests batteries on top. Set the sweep step to the smallest size that can really be added, such as one wind turbine. If the best size lands on the edge of the range, widen it and run again.
Step 7
Compare options: Compare projects tab
Several fixed sizes side by side, on the same data and assumptions.
Step 8
Fine-tune: Bill calculator tab
Start from Use Stage 2 recommended mix and change the sizes; the Stage 2 figures stay on screen beside yours. The cost lines show how each charge is calculated. Solve PPA rate for a target saving finds the PPA rate that gives a chosen saving at the size set; Undo puts the previous rates back. Compare structures prices the same size as third party and as captive.
Step 9
Issue a report: Reports tab
Enter the company name and site address once (they can be corrected later), then generate a brief or detailed report of the last full sweep. Issued reports can be downloaded again at any time, or hidden from the list — hiding does not delete them. A project may hold up to 10 reports: at the limit the Generate buttons say so and you must delete one you no longer need. Deleting is the only thing that frees a slot, and it is the only irreversible button on the tab. Reports for each project are grouped together, with a count of how many that project holds.
4. Which states are ready
| State | Status |
|---|
| Tamil Nadu (TN) | Modelled from regulations; bill check pending |
| Maharashtra (MH) | Checked against a real bill |
| Gujarat (GJ) | Illustrative only |
| Karnataka (KA) | Modelled from regulations; bill check pending |
| Telangana (TG) | Illustrative only |
| Andhra Pradesh (AP) | Illustrative only |
| Rajasthan (RJ) | Illustrative only |
| Uttar Pradesh (UP) | Illustrative only |
| Delhi (DL) | Illustrative only |
Only a state checked against a real electricity bill should be quoted to a client. The others show how the answer is likely to come out, and are labelled that way.
5. What a report looks like
For anyone whose account does not include reports, these are complete sample reports from the demonstration data, with the client's details replaced:
6. If something goes wrong
| You see | What it means, and what to do |
|---|
| "That file cannot be used" with a list | The file could not be read. Every problem is listed at once — fix them and load again. |
| Points listed under "worth checking" | The file loaded, but something looks wrong. Check each one. |
| "Connection to the server was lost" | Nothing is lost. Wait; the tool resumes by itself when the connection returns. |
| "Your session ended" | Sign in again at the top right. Your data and settings are still on the page. |
| "Daily limit reached" | The account's calculations for the last 24 hours are used up. The notice says when the next one is available; Terrastrom can change an account's allowance. |
| Charts do not change | Look at the top of the page for a notice, and at the status line under "Run full sweep". |
Generated by tools/build-user-guide.mjs from the tool's own settings. Not regulatory advice. Figures from states not checked against a real bill are illustrative.