# Solar panel calculator by roof area

> Type the roof area and see how many panels fit, the installed power and how much energy they make in a year.

## Calculate. The result changes as you type.

- Roof area (m²): 100. The whole roof, or the part you want panels on.
- Usable share (%): 60. What is left after edges, chimneys and shade.
- Power of one panel (W): 450. A typical panel today.
- Area of one panel (m²): 2. The size of the same panel.
- Yield per kWp in a year (kWh): 1,200. PVGIS gives the value for your location.

The starting values are typical assumptions. The result is an estimate, not a quote: it does not account for shade, orientation or the roof’s structure. [PVGIS](https://re.jrc.ec.europa.eu/pvg_tools/en/) gives the monthly yield for your location, free.

## The same calculation, on the real roof. Without climbing up.

- **What is already on the roof.** A model reads a dated aerial photo of each roof and answers: detected, none seen or unclear, with the date of the photo.
- **Panels, power and yield.** Where the roof has been modelled: the maximum number of panels, the power in kWp, the yearly energy and the usable area, marked as estimates.
- **The largest roofs first.** Sort the buildings in your area by footprint, so the large roofs come first.
- **The company at the address.** For commercial buildings, the companies registered at exactly the building’s official address.

## From a roof to a quote. Three steps.

1. **Find the building.** By address or straight on the map.
2. **Read the roof.** The panels already there, with the date of the photo, and the yield, where the roof has been modelled.
3. **Check the site.** For a quote, [PVGIS](https://re.jrc.ec.europa.eu/pvg_tools/en/) gives the yield for the real orientation and tilt, and the installer measures the shade on site.

## Solar panel questions. What the record holds, and what it does not yet.

### How many panels fit on 100 m² of roof?

With the calculator’s starting assumptions (60% usable, 450 W panels of 2 m²), 30 panels, or 13.5 kWp. A real roof may take fewer, because of shade and obstacles.

### How much energy does 1 kWp make in a year?

It depends on the location, the orientation and the tilt. [PVGIS](https://re.jrc.ec.europa.eu/pvg_tools/en/) gives you the value for your location. The calculator starts from 1,200 kWh, an assumption you can change.

### Can I do the calculation by address?

Yes, in baseray: the building shows the panels already installed and, where the roof has been modelled, the number of panels, the power and the yearly yield.

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- [Check an address](https://baseray.ai/address-check)
- [Open the live map](https://app.baseray.ai)
- Links and facts checked on 8 Oct 2026
- https://baseray.ai/romania-solar-calculator
- Română: https://baseray.ai/ro/calculator-fotovoltaic
- Čeština: https://baseray.ai/cs/rumunsko-fotovoltaicka-kalkulacka
- Dansk: https://baseray.ai/da/rumaenien-solcelleberegner