23rd International Conference on Concentrating Solar Power and Chemical Energy Systems

Reflected Solar Irradiance for CSP Plants Simulation: Impact and Importance for Solar Resource Assessment

Plan

2

Objectives Context Methods for soiling assessment Results and discussion

Objectives

2

Perform more accurate simulations of CSP plants expected output based on reflected DNI (on a soiled surface)

Find the most optimal method to assess soiling on operating power plants

Context

3

• Motivations and opportunities for RDNI based simulations

High soiling conditions in Benguerir;

High impact on plant output in Benguerir;

Need for Yield analysis with real site-soiling

measurements;

Availability of a +10000m2 linear

Fresnel solar field;

Manual Soiling/Reflectivity

measurement devices are tedious;

Availability of CSP plants output

simulation;

Possibility to access the output of future CSP

projects taking into account the soiling

factor

Solar field soiling mapping

5

• Solar field reflectance mapping one

week after cleaning (5th June)

• Average reflectance for the entire

solar field 83,7%

• Reflectance peak 95%

• Reflectance pit 68,1%

Solar field soiling mapping

6

• Solar field reflectance mapping five

weeks after cleaning (4th July)

• Average reflectance for the entire

solar field 66,8%

• Reflectance peak 91,5%

• Reflectance pit 48%

Reflected DNI measurements

4

orkneywind.co.uk

• Measurement of reflectance/RDNI done continuously with the traCS

• Cleanings performed on mirror sample every two weeks

Power plant simulations

7

• Short term simulations performed with EBSILON (single day simulation)

• Long term calculations done with Greenius and an internally developed code

Short terms simulation results

8

• Performance loss highly linked to weather conditions stiffness

• Higher performance drop with higher irradiance fluctuations

• Lower performance loss with stable weather

DNI

RDNI

Pout (RDNI)

Pout (DNI)

∆P≈20KWTh

The DNI and RDNI values over the experiment period

• The values of the 3 DNI inputs for simulation over the measurement period.

Higher performance drop with higher irradiance fluctuations

• Soiling affect’s the DNI value very much and it’s in accordance with the

Cleanliness values measured by TraCS.

• The power output has a similar behaviour with the DNI

• The difference is small with low DNI values.

The Power output simulation over the experiment period

Long term simulation results

9

• Over the period of Mai - July

• Average Cleanliness drop 15,8%

• Average performance loss 22%

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Ref

lect

ed D

NI/

Per

form

ance

dro

ps

(%)

Cu

mu

late

d ir

rad

ian

ce (

W/m

2 )

Irradiance (DNI) Cleanliness Production loss

Conclusions and perspectives

10

• Higher performance loss du to mirrors soiling may justify the need for

accurate soiling measurements before selecting CSP project sites

• Irradiance and performance losses for Benguerir are relatively high, hence

more frequent cleanings are necessary (once per week)

• Complete simulation for one year will provide a firm prevision of

performance loss for Benguerir

Thanks for your attention!

El Ghali Bennouna Thermal systems Research Institute on Solar Energy and New Energies (IRESEN) ................................................................. Green Energy Park, Km 2 Route Régionale R206, Benguerir ................................................................. Tél : + 212 (0)620 30 75 10 Fax : + 212 (0)537 68 88 52 E-mail : bennouna@iresen.org Skype : ben.elg ................................................................. www.iresen.org www.greenenergypark.ma www.energy-science.org www.pv-science.org www.csp-science.org www.wind-science.org

www.minwatercsp.com contact@minwatercsp.eu