[GRASS-dev] Re: r.sun units
Marcel Suri
marcel.suri at jrc.it
Fri Dec 1 09:37:52 EST 2006
Hello,
I looked at the discussion related to the units used in r.sun and can
just summarize what were other have already said:
The mode 1 gives values of instantaneous solar power (irradiance)
impinging on a surface in "Watts per square meter" (W/m2) or in other
words in "joules per second per square meter" (J/m2/s)
The mode 2 integrates solar energy (irradiation) according to
user-defined steps that is received by square meter during the whole
day (actually from sunrise to sunset). The result is given in Watt-hours
per square meter (Wh/m2) -> if multiplied by 3600, the daily total
energy received by the surface would be expressed in joules per square
meter (J/m2).
We are aware of using Watt-hours (as non-SI unit), but this is because
we work in the field of photovoltaic applications (solar electricity),
where this unit is still preferred.
Best regards,
Marcel
--
Marcel Suri
European Commission - DG Joint Research Centre
Institute for Environment and Sustainability
Renewable Energies Unit
via E. Fermi 1, TP 450
I-21020 Ispra (VA), Italy
phone: +39 0332 786661, fax: +39 0332 789992
http://re.jrc.ec.europa.eu/pvgis/pv/
******
Interested in solar radiation data? Please help us to understand better
your needs, and fill in a questionnaire at:
http://re.jrc.ec.europa.eu/iea-shc-task36/quest1_en.htm
Jaro Hofierka wrote:
> Hamish wrote:
>
>> Hi Jaro, Marcel, Tomas,
>>
>> I was wondering if you could contribute some insight WRT this thread on
>> the GRASS users' list:
>>
>> http://thread.gmane.org/gmane.comp.gis.grass.devel/17118
>>
>>
>> I fear my advice so far is rather bad.
>>
>> thanks,
>> Hamish
More information about the grass-dev
mailing list