Upload
shana-harper
View
220
Download
2
Embed Size (px)
Citation preview
Evaluation of solar irradiance in the Vhembe district of the Limpopo province of South Africa using different theoretical models.
BY T.S. MULAUDZI, E.N. MALUTA AND V.SANKARAN
Evaluation of solar irradiance in the Vhembe district of the Limpopo province of South Africa using different theoretical models.
BY T.S. MULAUDZI, E.N. MALUTA AND V.SANKARAN
UNIVERSITY OF VENDAUNIVERSITY OF VENDAEnergy Postgraduate Conference 2013
OUTLINE OF THE PRESENTATION
Introduction , Study Area, Methodology,Results and discussions & Conclusions
INTRODUCTION• Importance of solar energy• Availability of weather stations in Vhembe• Availability of the ground measured solar
irradiance• Challenges and Ways of addressing these
challengesSTUDY AREA : Limpopo Province; Vhembe district – Makhado,
Musina, , Mutale and Thulamela
VHEMBE DISTRICT
METHODOLOGY -1
• Selected models:– Angstrom (clearness index (CI) and relative
sunshine hours (RSSH))
– Hargreaves and Samani model (temperature based model) (maximum and minimum temperature data)
– Garcia model (CI, daylength (N) and temperature
* o
H na b
H N
max min* where ro
Hk T T T T
H
*
o
H Ta b
H N
METHODOLOGY - 2
• Measured data– Daily global solar radiation (H) in MJ/(m2 day) –
from Agricultural Research Council (ARC)– Actual sunshine hours (n) in hours - from South African Weather Services (SAWS)– Maximum and minimum temperature data in
degrees (ARC)• Computed data
– Extraterrestrial global solar radiation (Ho)
– Day lengths in hours(N)• Other parameters
- Regression constants (a, b & kr), where a = 0.186, b = 0.467 and kr = 0.16 for inland.
METHODOLOGY-3
• Estimate of H for the years 2007, 2008, 2009 and 2010.
• Compare some of these data with the measured data.
• Graphical representation of the estimated and measured data (2010).
• Tabulate the average annual data.• Accuracy tests of the estimated
data.
RESULTS-1
Results-2
Analysis
2010 Average global solar irradiance in MJ/m2
Station
Obser
Temp Angs Gar
Mut 15.273 18.081 21.130 20.746
Mhi14.695 19.361 21.088 19.917
Rab17.510 18.378 21.077 18.671
All17.014 19.129 21.104 19.298
Statistical analysis
DISCUSSIONS
• Comparison of the observed and the estimated H using different models :
Mutale & Rabali - Temperature based model and Angstrom model predictions are the best. Garcia model data shows some variations.Mhinga - Both the temperature and Garcia models overestimated the global solar irradiance in this area. The Angstrom model exhibits a good variationAlldays – Good variation for all the models.
• Average global solar irradiance– The difference between the observed and the estimated
data is less than 7.0 MJ/(m2 day) for all the models.• Statistical data
– RMSE for each model is very close to zero – the predictive data show good variation trends.
CONCLUSIONS
• The estimated global solar radiation for the stations studied are comparable with the observed data from ARC.
• The best suitable models for this area are the temperature based and Angstrom model.
THANK YOU