The data behind the calculator
The calculator replays every quarter-hour of 2025-10 – 2026-09: the real Nord Pool Estonia prices, ERA5 weather for ten Estonian regions, the Elektrilevi standard load profile and Baltic balancing-market prices. The dataset was built on 15 October 2026 and is refreshed weekly; the window rolls forward with every refresh, so the result always rests on the last 12 months.
Datasets
| Dataset | Source | Step | What it holds |
|---|---|---|---|
| Nord Pool EE day-ahead price | Elering dashboard API | 15 min (hourly before Oct 2025) | Exchange price in €/MWh for every interval; the basis of buy and sell prices and of arbitrage. |
| Weather | Open-Meteo ERA5 archive | 1 hour | Global, direct and diffuse irradiance, air temperature and snow depth for ten regions: Tallinn, Tartu, Pärnu, Narva, Viljandi, Kuressaare, Rakvere, Võru, Haapsalu, Paide. |
| Standard load profile | Elektrilevi | 1 hour / 15 min | Household and small-business hourly coefficients 2024–2026: how a month’s consumption spreads over its hours. |
| Balancing energy prices | Baltic Transparency Dashboard | 15 min | Estonian mFRR and aFRR satisfied-demand prices up and down, and balancing energy reference prices. |
| Balancing profile | One home park’s aggregator reports | 15 min | kWh moved per kW of inverter and € per kWh for every interval, anonymised; the capacity-fee estimate. |
| Tariffs | Elektrilevi price list 1 June 2026, Elering, EMTA | – | Network package rates, monthly fees, state fees, VAT, default seller margins. |
Time window
The main window is 2025-10 – 2026-09: the last 12 full months. For comparison the calculator can also show the year before (2024-10 – 2025-09), where solar and price data exist but balancing activations do not yet.
Every series is laid on one 15-minute UTC grid; hourly sources are repeated four times. Local time, summer and winter time and public holidays follow Estonian time.
Regions
Pick the nearest in the calculator. Weather differs less between regions than roof direction and tilt do, but snow and cloud differ between the coast and inland.
| Region | Latitude | Longitude |
|---|---|---|
| Tallinn | 59.437 | 24.754 |
| Tartu | 58.378 | 26.729 |
| Pärnu | 58.386 | 24.497 |
| Narva | 59.377 | 28.190 |
| Viljandi | 58.364 | 25.590 |
| Kuressaare | 58.253 | 22.485 |
| Rakvere | 59.347 | 26.356 |
| Võru | 57.834 | 27.019 |
| Haapsalu | 58.943 | 23.541 |
| Paide | 58.886 | 25.557 |
Where the calculation runs
The datasets and the calculation engine run on the server. The browser sends only the values you enter and receives the monthly and yearly results; the time series and the model cannot be downloaded. An uploaded consumption file is sent for the calculation only and is not stored.
Requests with identical inputs are cached for an hour, which is why most slider moves answer instantly.
Attribution and licences
Nord Pool prices come from Elering’s public interface. Weather: Open-Meteo (CC BY 4.0), based on the Copernicus/ECMWF ERA5 reanalysis. The standard load profile is published by Elektrilevi and approved by the Competition Authority. Balancing-market data: the joint transparency platform of the Baltic TSOs (Elering, AST, Litgrid).
The balancing profile is derived from one house’s aggregator reports and anonymised; no personal or location data is published.
Sources
- Prices: Elering – Nord Pool EE day-ahead API
- Weather: Open-Meteo ERA5 archive
- Load profile: Elektrilevi tüüpkoormusgraafik
- Balancing market: Baltic Transparency Dashboard
- Tariffs: Elektrilevi võrguteenuse hinnakiri (1.6.2026), Elering – tasakaalustamisvõimsuse tasu, Enefit väiketootja