Kuma Science services
Satellite-to-ground calibration and solar resource assessment
Reduce the uncertainty on the solar resource of a site or a country
Contact usA solar resource that is measured, not only estimated
Satellite products cover all of West Africa, but they are off by a few percent, and more during the harmattan. On a solar project, that gap weighs directly on energy yield and returns. We correct satellite series with ground measurements and state the uncertainty that remains.
Our calibration helps your teams:
- Work on a solar resource corrected for known satellite biases
- Know the remaining uncertainty on global and direct irradiance
- Find out whether their site is covered by a reference station
- Give funders a solar resource assessment they can rely on
The method has been validated on 31 stations in 13 West African countries. In Guinea, calibrated values for the 340 sub-prefectures are released as open data.
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Global horizontal (GHI) and direct normal (DNI) irradiance
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From a project site to a whole country
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Quantified uncertainty for every site
Correct satellite biases
Against the Kankan ground station, satellite series overestimate irradiance by close to 3% on average, and up to 4% during the harmattan. Calibration corrects these gaps season by season, using reference stations.
Calibration gives you:
- Corrected irradiance series, over the full depth of the satellite archives
- A seasonal correction, including the dry season
- Values ready for energy yield and sizing work
Know whether your site is covered
The correction transfers from a station to nearby sites, with an uncertainty that grows with distance. For each site, we give the nearest reference station, the expected gap on irradiance and a coverage verdict.
For each site, you get:
- The selected reference station
- The expected gap on global and direct irradiance, as median and P80
- A clear verdict: site covered or ground measurement recommended
A method validated across West Africa
Our work shows that satellite bias follows a regular latitude gradient. The method therefore transfers from one country to another in the region, with an uncertainty known in advance.
For countries and projects without a station, we offer:
- A resource assessment based on stations in the region
- The design of a ground measurement campaign
- Calibration of your own measurements, as soon as they are available
Our clients
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Solar plant developers
Reduce resource risk before financing a plant.
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Engineering firms
Base energy yield studies on a corrected, documented resource.
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Funders and banks
Get an independent, verifiable solar resource assessment.
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Energy agencies and ministries
Give the country a calibrated solar atlas, released as open data.
What we deliver
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Coverage diagnosis
Reference station, expected gap and coverage verdict for your sites.
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Calibrated series
Corrected global and direct irradiance, at monthly, daily or hourly steps.
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Resource assessment
Averages, year-to-year variability and P50 and P90 irradiance values.
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National solar atlas
Calibrated values across the country, released under an open licence.
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Methodology note
Sources, stations, correction law and uncertainty, for your auditors and funders.
How an assignment unfolds
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Diagnosis
We give each site its reference station and expected gap.
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Collection
We gather satellite series and available ground measurements.
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Calibration
We correct the series and quantify the remaining uncertainty.
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Delivery
We deliver the calibrated series and the methodology note.
Frequently asked questions
Why not use satellite data directly?
It is useful and covers the whole territory, but it carries region-specific biases. In West Africa, harmattan dust in particular is poorly represented. Calibration corrects these biases.
Do I need to install a measurement station on my site?
Not always. If a reference station is close enough, calibration transfers its correction to your site. Otherwise, we recommend a measurement campaign, often of one to two years.
Which countries are covered?
The method is validated in 13 West African countries. In Guinea, the Kankan and Tarambaly stations serve as references and calibrated values are published.
Are calibrated values public?
In Guinea, calibrated values by sub-prefecture are released as open data on the national reference system. Studies carried out for a client remain confidential.
What uncertainty can we expect?
It depends on the distance to the reference station and on the variable. We quantify it for each site, as median and P80, before any commitment.
Related services
A solar resource to assess?
Tell us about your sites. We get back to you within two working days with a first coverage diagnosis.