Developing an improved global solar radiation map for Zimbabwe through correlating long-term ground- and satellite-based monthly clearness index values

Hove, Tawanda; Manyumbu, E.; Rukweza, G.

doi:10.1016/j.renene.2013.10.032

Cited by 9 publications

(4 citation statements)

References 11 publications

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“…The computations are done on hourly time-steps for the average day of each month. Starting with only the monthly-average daily global horizontal irradiation (GHI), obtained in this case from the Zimbabwe database developed in [13], the hourly-average GHI for each month was obtained by the model of Collares-Pereira and Rabl [14]. The monthly average diffuse radiation on a horizontal surface was obtained from global radiation by using a diffuse-ratio versus clearness index correlation function suitable for Zimbabwe [15].…”

Section: Methodsmentioning

confidence: 99%

“…In Zimbabwe, the price of electricity is $0.11/kWh for domestic customers consuming 50-300 kWh/month and from $0.04/kWh (off-peak) to $0.13/kWh (peak period), for time-of-use customers [2]. Solar radiation is abundant (an annual average of 5.6-7 kWh/day) and ubiquitously distributed over the country [3]. Electricity, which is the conventional energy for heating water, is in short supply, with frequent load-shedding [4] events and reliance on importation of the commodity.…”

Section: Introductionmentioning

confidence: 99%

“…The optimal size of this collector model to deploy in the solar water heating system at the case-study location is 18 m 2 per m 3 of daily hot water demand; with a hot water storage volume of 900 l/m 3 ; at an optimal solar fraction of 91%. Although the method of this paper was applied only for a solar water heating application of specified operating temperature, at a specified location, it can be applied equally well for any other solar water heating application and at any other location.…”

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confidence: 99%

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A Thermo-Economic Model for Aiding Solar Collector Choice and Optimal Sizing for a Solar Water Heating System

Hove

2018

Springer Proceedings in Energy

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The choice of solar collector type to employ and the number of chosen collectors to subsequently deploy, are important planning decisions, which can greatly influence the economic attractiveness of solar water heating systems. In this paper, a thermo-economic model is developed for the computation of a suitable metric that can aid in choosing the most cost-effective collector to use in a solar water heating system and to determine the optimal sizing of the solar water heater components once the choice collector has been picked. The energy-per-dollar comparison metric, calculated as the annual heat energy output of the collector in an average year, at the so-called "sweet-spot" size of the collector array, divided by the annualized life-cycle cost, based on warranty life and collector initial cost, was recommended as instructive for comparing cost-effectiveness of different solar collectors. For the determination of the sweet-spot size of collector to use in a particular solar water heating system, at which the energy-per-dollar is calculated, the Net Present Value of Solar Savings was used as the objective function to maximize. Ten (10) different models of liquid solar thermal collectors (5 flat plate and 5 evacuated tube type), which are rated by the Solar Ratings & Certification Corporation (SRCC), were ranked according to the energy-per-dollar criterion through the thermo-economic model described in this study. At the sweet-spot collector area for the solar water heating system, the corresponding volume of hot water storage tank and the optimal solar fraction are also simultaneously determined. The required hot water storage volume decreases as the deployed collector area increases while the solar fraction increases, with diminishing marginal increase, until it saturates at a value of unity. For the present case study where the required load temperature is 50°C and the solar water heating system is located in central Zimbabwe (latitude 19°S and longitude 30°E), the selected collector model happened to be a flat-plate type, which achieved the highest energy-per-dollar score

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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A Thermo-Economic Model for Aiding Solar Collector Choice and Optimal Sizing for a Solar Water Heating System

Hove

2018

Springer Proceedings in Energy

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“…The evaluation of satellite data performance has been found to possess significant biases, which can be attributable to potential errors in the satellite data measurements of ground parameters due to changes in tropospheric features and surface environmental conditions as well as measuring methods [69] to [72]. Hence, applying a correction factor to satellitederived data in order to obtain corresponding ground based measurements results in a comprehensive solar radiation database [73] to [75].…”

Section: Satellite Data Correctionmentioning

confidence: 99%

Angstrom-Prescott Type Models for Predicting Solar Irradiation for Different Locations in Zimbabwe

Iradukunda¹,

Chiteka²

2023

sv-jme

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Adequate assessment of solar radiation data is crucial for planning and designing solar energy systems. However, a major challenge facing solar energy technologies is the availability of solar radiation data at the specific area of interest. In this paper solar radiation and sunshine duration data from 29 stations in Zimbabwe were used to generate both monthly and annual Angstrom-Prescott (A-P) type coefficients, a and b, that are location based. The coefficients were developed using linear correlation between the clearness index and sunshine duration. The adaptation relationship between satellite and ground-measured irradiation had an R2 of 0.6738. The correlation between the clearness index and the sunshine duration in most of the stations was fairly high with the highest coefficient of determination, R2, of 0.9030. The A-Pregression coefficient, a, generated using the data from each station ranged between 0.2252 and 0.3976, whereas the regression coefficient, b, ranged between 0.3218 and 0.6265. The estimated and measured values of global solar radiation, He, and Hm, respectively from each station were compared using the mean absolute percentage error (MAPE), the root mean square error (RMSE), the mean absolute error (MAE) and the relative standard error (RSE). The MAE values for the models ranged from 0.5438 MJ/m2 to 2.2845 MJ/m2. The MAPE indicated a range between 2.5642 % and 10.334 %. The RSE ranged between 0.0346 % and 0.1537% while the RMSE for the models ranged from 0.7360 MJ/m2 to 2.9454 MJ/m2. The statistical indicators showed results that were within the recommended range for solar radiation predicting models from similar studies.

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Design for manufacture and assembly of an intelligent single axis solar tracking system

et al. 2020

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Developing an improved global solar radiation map for Zimbabwe through correlating long-term ground- and satellite-based monthly clearness index values

Cited by 9 publications

References 11 publications

A Thermo-Economic Model for Aiding Solar Collector Choice and Optimal Sizing for a Solar Water Heating System

A Thermo-Economic Model for Aiding Solar Collector Choice and Optimal Sizing for a Solar Water Heating System

Angstrom-Prescott Type Models for Predicting Solar Irradiation for Different Locations in Zimbabwe

Design for manufacture and assembly of an intelligent single axis solar tracking system

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