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Your system on a roof
Choose a size and the way your roof faces. You see how many panels that is, how much roof it covers and what it produces a year in your municipality, from PVGIS, next to the same system facing each other way.
Production per year, Lisboa, south
6,360 kWh
- Panels of 450 W
- 9
- Panel area
- 18 m²
- Per kWp
- 1,590 kWh
- Against a south facing roof
- same
The same system facing each way
- South6,360 kWh
- South east5,950 kWh
- South west6,080 kWh
- East5,040 kWh
- West5,210 kWh
How it works
Panels are counted at 450 W each. Roof area uses the ADENE and DGEG figure of about 22% panel efficiency, so each kWp needs about 4.5 m² of panel surface, before gaps and edges.
Production is the PVGIS yield for your municipality at 35° tilt and 14% system losses, for each of the five directions. Shade from trees, chimneys or neighbouring buildings is not included; an installer's site visit should measure it.
Sources
- PVGIS, European Commission Joint Research Centre (yields per municipality, 1 kWp, 35° tilt, 14% losses, SARAH2 data for 2005 to 2020)
- ADENE and DGEG, practical guide to individual self consumption, chapter I (panel efficiency about 22%, power warranty 97% in year one and 80% at 25 years, inverters, registration)
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