Payback · Santarém District · Portugal
Commercial solar payback in Cartaxo: 4.1 years
A self-consuming 100 kWp array on a commercial roof in Cartaxo typically pays back in about 4.1 years. That figure uses Cartaxo's specific yield of 1,575 kWh per kWp per year and a commercial tariff near €0.20/kWh, with 70% of generation used on site.
At that yield the array produces about 157,500 kWh a year and saves roughly €22,050 annually against an installed cost near €90,000. Over 25 years the net saving is around €461,250, while avoiding about 55.1 tonnes of CO₂ each year.
Cartaxo is in Santarém District, alongside Santarém, Tomar and Torres Novas. Those towns share the same irradiance zone, so payback is similar — the difference is which warehouses and factories still have empty roof. SolarScout lists them with a pre-computed business case rather than a generic "solar is cheap" pitch.
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Scan this area free →How the Cartaxo payback number is calculated
Start with 100 kWp × 1,575 kWh/kWp = 157,500 kWh of annual production on a representative warehouse or factory roof in Cartaxo. Apply 70% self-consumption against €0.20 per kWh and you get about €22,050 a year. Divide the €900/kWp installed cost (€90,000 for 100 kWp) by that saving and payback lands at 4.1 years.
This is a worked example, not a quote. Real payback moves with self-consumption, shading, export tariff and installed cost. It is still the right first filter: if a roof in Cartaxo cannot beat roughly 4.1 years on these inputs, it is probably not a priority lead.
Cartaxo versus the rest of Portugal
Relative to Portugal as a whole, payback in Cartaxo is about 0.2 years faster than the Portugal average of 4.3 years. Portugal enjoys very high sunshine hours along the Atlantic coast and interior. Warehouses, factories and cold-storage sites achieve rapid payback from on-site solar self-consumption.
That is why outreach in Cartaxo should open with the local number — 4.1 years and €22,050 a year on 100 kWp — not a national average that under- or over-sells the roof.
What actually changes payback on a Cartaxo roof
Yield is already baked into the 1,575 kWh/kWp zone for Santarém District. The bigger swings are usable roof area, daytime load (factories and cold stores self-consume more than empty warehouses) and whether the site pays the full €0.20/kWh commercial rate.
SolarScout estimates roof footprint from satellite and map data and, where Google Solar coverage exists, modelled annual output — so you can rank Cartaxo sites by savings instead of guessing from a map pin.
Frequently asked questions
What is the commercial solar payback in Cartaxo?
About 4.1 years for a self-consuming 100 kWp rooftop in Cartaxo. That uses 1,575 kWh/kWp of local yield and a tariff near €0.20/kWh, saving around €22,050 a year.
How much electricity does 100 kWp produce in Cartaxo?
Around 157,500 kWh a year. Multiply the 1,575 kWh/kWp specific yield for Santarém District by 100 kWp; shading and orientation can move that figure, which is why SolarScout models each roof rather than stopping at the city average.
Is payback in Cartaxo better than nearby towns?
Payback is in the same band as Santarém, Tomar and Torres Novas because they share the Santarém District irradiance zone. The practical difference is the stock of large, unshaded commercial roofs — SolarScout lists those in Cartaxo with a pre-computed saving so you can compare sites, not just towns.