Dated, weather-based
Tomorrow's forecast
Tomorrow's value is a weather-based estimate for Tuesday, September 1, 2026: 55.9 kWh from the 10 kWp reference system, with a likely range of 47.0 kWh–60.3 kWh. It changes with the next weather forecast.
Portugal · 10 kWp reference system
Porto solar forecast and PV yield
Photo: Diego Delso,CC BY-SA 3.0. Cropped, resized and converted to WebP by GridPassport.
Forecast target: . Any “tomorrow” label on this page refers to this dated target.
- Tomorrow's forecast
- 55.9 kWh 10 kWp reference system
- Typical annual output
- 15,089 kWh 10 kWp reference system
- Typical specific yield
- 1,509 kWh/kWp Per year
Tuesday, September 1, 2026
About 55.9 kWh tomorrow
For a standard 10 kWp south-facing system in Porto, GridPassport estimates 55.9 kWh on Tuesday, September 1, 2026, with a likely range of 47.0-60.3 kWh. The strongest production window is expected at 13:00-17:00 local time.
Updated Aug 31, 2026, 12:01 AM GMT+1 · fresh snapshot- Likely range
- 47.0-60.3 kWh
- Strongest window
- 13:00-17:00
- Confidence
- medium
How to read and use the data
Porto solar forecast: daily weather versus long-term PV yield
The daily and annual figures answer different questions. Use the dated forecast to plan tomorrow, and the PVGIS specific yield to compare locations or estimate a typical year.
Multi-year climate baseline
PVGIS specific yield
Porto's PVGIS specific yield is about 1,509 kWh/kWp per year. It is a multi-year climate benchmark, not a prediction for tomorrow or for this calendar year. In the PVGIS profile, July is typically the strongest month and December the weakest.
3, 5 and 10 kWp reference systems
Scale the same assumptions to your system size
SystemTomorrow estimate (likely range)PVGIS typical year
3 kWpTomorrow estimate (likely range)16.8 kWh14.1 kWh–18.1 kWhPVGIS typical year4,527 kWh/year
5 kWpTomorrow estimate (likely range)27.9 kWh23.5 kWh–30.1 kWhPVGIS typical year7,544 kWh/year
10 kWpTomorrow estimate (likely range)55.9 kWh47.0 kWh–60.3 kWhPVGIS typical year15,089 kWh/year
Linear reference scaling only: south-facing, 35° tilt and 14% system losses. It does not resize inverter clipping, shade or local roof constraints.
From forecast to a household plan
Battery, EV, heat pump and flexible loads
Treat the forecast as a gross solar-energy budget before household base load and conversion losses. The numbers support scheduling; they do not guarantee surplus.
Battery
Keep room for the solar window
Use 13:00-17:00 as the first candidate charging window. Battery state of charge, reserve settings and inverter limits still decide how much can be stored.
EV
Compare the charge with the 5 kWp budget
The scaled 5 kWp estimate is 27.9 kWh before household use. Compare the remainder after base load with the planned EV charge and stagger charging if needed.
Heat pump
Shift only flexible thermal demand
If comfort controls allow it, place discretionary hot-water heating or pre-heating inside 13:00-17:00. Never override frost protection, hygiene cycles or manufacturer limits.
Large loads
Avoid stacking appliances
A 3 kWp system scales to about 16.8 kWh for the day before household use. Run flexible loads sequentially during the strongest hours rather than assuming all forecast energy is simultaneous power.
Local questions
Solar forecast FAQ
How much could a 5 kWp solar system produce tomorrow in Porto?
Using the same south-facing, 35-degree and 14% loss assumptions, the 5 kWp estimate is 27.9 kWh for Tuesday, September 1, 2026, with a scaled likely range of 23.5 kWh–30.1 kWh. This is a linear reference-system estimate, not a site survey.
What does 1,509 kWh/kWp mean for Porto?
It means the PVGIS multi-year profile produces about 1,509 kWh in a typical year for each installed kWp under the reference assumptions. A 5 kWp system therefore scales to about 7,544 kWh in a typical year before site-specific adjustments.
Is the Porto forecast the same as the PVGIS annual estimate?
No. Tomorrow's forecast uses dated weather and an uncertainty band for one day. The PVGIS figure is a multi-year climate-based specific yield used for typical monthly and annual comparisons.
When should a battery, EV or heat pump use solar in Porto?
Start with 13:00-17:00, then check household base load, battery headroom, EV energy required and heat-pump safety or comfort constraints. The forecast estimates daily energy, not guaranteed instantaneous surplus.
Typical year
Solar production month by month in Porto
A standard 10 kWp system produces about 15,089 kWh in a typical year at this location. Monthly averages show seasonality; they are not a forecast for a specific year.
905Jan
1037Feb
1255Mar
1377Apr
1528May
1489Jun
1627Jul
1591Aug
1423Sep
1133Oct
878Nov
848Dec
Values are kWh per month. Source: European Commission JRC PVGIS.
What makes Porto's solar profile different?The typical annual yield is about 1,509 kWh per installed kWp, ranking Porto #3 of 6 modelled locations in Portugal. That is close to the median of the 6 Portugal locations in this dataset. July is typically the strongest month and December the weakest; the stronger month produces about 1.9 times as much.
See the 12-month data
MonthMonthly outputDaily averageYear-to-year variation
MonthJanuaryMonthly output905 kWhDaily average29.2 kWh/dayYear-to-year variation±193 kWh
MonthFebruaryMonthly output1,037 kWhDaily average37.0 kWh/dayYear-to-year variation±194 kWh
MonthMarchMonthly output1,255 kWhDaily average40.5 kWh/dayYear-to-year variation±188 kWh
MonthAprilMonthly output1,377 kWhDaily average45.9 kWh/dayYear-to-year variation±135 kWh
MonthMayMonthly output1,528 kWhDaily average49.3 kWh/dayYear-to-year variation±138 kWh
MonthJuneMonthly output1,489 kWhDaily average49.6 kWh/dayYear-to-year variation±95 kWh
MonthJulyMonthly output1,627 kWhDaily average52.5 kWh/dayYear-to-year variation±90 kWh
MonthAugustMonthly output1,591 kWhDaily average51.3 kWh/dayYear-to-year variation±76 kWh
MonthSeptemberMonthly output1,423 kWhDaily average47.4 kWh/dayYear-to-year variation±104 kWh
MonthOctoberMonthly output1,133 kWhDaily average36.5 kWh/dayYear-to-year variation±160 kWh
MonthNovemberMonthly output878 kWhDaily average29.3 kWh/dayYear-to-year variation±193 kWh
MonthDecemberMonthly output848 kWhDaily average27.3 kWh/dayYear-to-year variation±130 kWh
Nearby solar forecasts
Compare Porto with nearby cities
Tomorrow, in one email
Get Porto's solar forecast by email
Tomorrow's expected production, likely range and strongest hours. One useful email each day.
Method and data
Every city uses a 10 kWp system facing south at 35 degrees with 14% system losses. Tomorrow's figure combines hourly weather with GridPassport's PV production and uncertainty model. The monthly profile uses the European Commission JRC PVGIS multi-year climate series. Roof direction, shade, snow, dirt, inverter clipping and local weather can change real output.
CSV and JSON snapshots are published under CC BY 4.0 with source attribution.