# Data Upload

You can upload your **measured** PV power as a time series — separately for each
string of a site. This data is stored permanently and is the basis for
[Calibration & Monitoring](/en/v2/api/calibration): geometry detection, performance
rating and shading analysis.

:::note
**Active beta.** Data upload, calibration and monitoring are in active beta and
available **only through the pvnode web app** — there is no public API for them yet, and
results may still be inconsistent. They require a plan that includes **calibration**.
:::

## Where to upload

Open a site in **the pvnode web app → your site → the _Monitoring_ tab**. Each string has its own
upload control: pick the CSV for that string and it is ingested immediately. You can
upload data for several strings one after another.

![Upload production data to pvnode](/v2/upload_data_english.webp)

## How much data to provide

The more recent history you upload, the better every downstream step works.

| Coverage        | What you get                                            |
|-----------------|---------------------------------------------------------|
| **< 3 months**  | Not enough to fully calibrate or rate a string.         |
| **3–6 months**  | Minimum for a usable result.                            |
| **6–12 months** | Better — seasonal angles and shading are captured.      |
| **Full year**   | Best — the sun covers its complete path across the sky. |

Further, we recommend data with a granularity of at least 15 minutes per time-step. Everything higher than this might
work, but does not deliver the best possible results.

## CSV format

A CSV with **two columns**: a **timestamp** and the measured **`pv_power`** in
**watts** (the same field name the forecast uses). Only the first two columns are read,
a header row is optional, and the delimiter (`;` or `,`) is detected automatically.

```csv title="string-measurements.csv"
timestamp;pv_power
2025-06-01T12:00:00+02:00;4200
2025-06-01T12:15:00+02:00;4350
2025-06-01T12:30:00+02:00;4100
```

### Timestamps & timezone

| Case                            | Interpretation                          |
|---------------------------------|-----------------------------------------|
| With UTC offset (`+02:00`, `Z`) | The offset is used directly.            |
| Naive (no offset)               | Interpreted in the **site's timezone**. |

All timestamps are stored internally in **UTC**, so they stay correct even if you later
change the site's timezone.

## How the data is processed

- **Per string.** Each upload belongs to exactly one string of the site.
- **Merged** into any data already stored — overlapping slots from a newer upload
  **overwrite** older values (newest wins). So you can backfill history and top up
  incrementally without creating duplicates.
- Stored **permanently** until you delete it (or delete the site).

After an upload, the string row shows how many data points are stored, the covered date
range, and a coverage rating. The _Data_ step also charts the **last 7 days** of
uploaded production so you can sanity-check the series.

## Limits

| Limit        | Behavior                                                      |
|--------------|---------------------------------------------------------------|
| File size    | Larger than **10 MB** is rejected.                            |
| Row count    | More than **600,000** input rows is rejected.                 |
| Invalid data | A file with no parsable timestamp + watts column is rejected. |

## Next step

Once at least one string has data, continue with
**[Calibration & Monitoring](/en/v2/api/calibration)** to detect each string's true
geometry, rate its performance, and map its shading.