- Email: [email protected]
Experience with stand-alone centralized and individual house PV systems in Syria
~
Pergamon
0960-1481(95)00060-7
Renewable Enerqy, Vol. 6, No. 5 6, pp. 545 548, 1995 Copyright (C 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 096{~ 1481/95 $9.50 + 0.00
E X P E R I E N C E WITH S T A N D - A L O N E C E N T R A L I Z E D A N D I N D I V I D U A L H O U S E PV SYSTEMS IN SYRIA ALI HAMZEH Damascus University, Faculty of Mechanical and Electrical Engineering, Department of Electrical Engineering, P.O. Box 5115, Damascus, Syria
Abstract--The paper focuses on the following items : climatological data in Syria ; design approaches for village PV systems ; the installed Abu Sorra PV systems ; the installed El Mucherfeh PV systems ; evaluation of the installed PV systems; experience gained; social acceptance of the PV systems by users; and comparison between centralized and decentralized PV systems. The main conclusions are : (1) the acceptance by users of a.c. solar electricity (centralized system users) is much more than those of d.c. current (decentralized system users), because of the advantage of using conventional a.c. appliances; (2) the overall efficiency of the centralized PV system is 20% less than the efficiency of the individual unit, because of the inverter losses and greater wiring losses ; (3) the centralized system is about 24% more expensive than the individual PV systems.
INTRODUCTION Syria lies between the latitudes 32 and 37 degrees North of the equator. The climate varies from Mediterranean weather along the coast to a desert environment further into the interior. The land area measures some 180,000 km 2 and the population is about 14 million. The Syrian Arab Republic currently relies on petroleum, gas and electricity for its energy requirements. Most of Syria's electricity is presently (1994) produced through steam based on the following average figures : steam turbines 68.3%, gas turbines 15.9%, hydro turbines 13.3% and diesel 2.5%. Rural electrification has been regarded as a development priority for social and economic reasons. The electricity authority has, over the years, connected most of the population to the electric network. But for very small villages and newly established Bedouine settlements, the cost of grid connection would be prohibitively high. However, new and renewable energy sources would be preferred for rural electrification, if the systems were available at acceptable costs and with proven reliability. An encouraging factor for this approach is the huge solar energy potential in Syria.
CLIMATOLOGICAL DATA IN SYRIA With the exception of the experiences an average of sunshine. The country has a yearly average of 5.6 kW
narrow coastal strip, Syria 3100-3400 h per year of high solar insolation with h/mZ/day.
In Southern Syria (the Damascus area) the average duration of sunshine in winter is of 6.7 h which is 63% of the possible duration. In the summer this figure goes up to 11.8 h, which corresponds to 90% of the possible duration. Overall, the average sunshine duration is relatively high at 9.2 h/day or 77% of the possible duration. Solar insolation varies markedly with the time of the year. During January, the average solar insolation is 2.775 kW h/m2/day (Damascus area). Summer insolation rises significantly and reaches a peak level of 7.458 kW h/mZ/day during June. The variation in seasonal value of insolation is due, in most part, to Syria's latitudinal location. Rainstorms, cloudiness and sand storms are the main causes of scattering or diffusion of direct solar radiation. These occur during the O c t o b e r - M a y period with more than six days per month during December, January and February. The yearly temperature values for Damascus area are as follows : Mean temperature Mean max. temp. Mean min. temp. Absolute max. temp. Absolute min. temp.
15-20°C 22 28"C 8 1 l r'C 40M5'~C -8C
Like most interior regions Damascus experiences occasional temperatures below freezing for some months of the year. According to the available wind data, a moderately 545
A. HAMZEH
546
important wind regime covers the whole country with average speeds ranging from 3 to 5 m/s. The wind regime is steady and distributed around the mean wind speed. Wind speeds of c%13 m/s are prevalent in some locations (Homs, Nabk and Qunaitra areas) for a significant portion of the year. The potential for using solar energy technologies in Syria has been studied over a number of years. In December 1989 a project document was signed by UNDP, the Syrian Government, and UNDTCD. One of the activities to be undertaken was a demonstration of small stand-alone PV systems for village electrification.
DESIGN A P P R O A C H E S FOR THE VILLAGE PV
SYSTEMS The design approaches and options for the PV systems to be adopted have been recommended by a consultant on PV systems (B. McNelis, U.K.), who undertook a mission to Syria in October/November 1990. The design algorithm consists of the following steps. Step 1 : Village options. The main requirements for a PV demonstration are a village which: is not connected to the grid; has reasonable solar insolation; has people wanting electricity and helping with the project; and is easily accessible for monitoring and demonstration purposes (i.e. is close to Damascus). Based on these criteria two villages have been identified, Abu Sorra and El Mucherfeh, which are sited about 55 km South of Damascus on the way to Souida. Abu Sorra comprises 12 houses with three more houses expected to be constructed later. The population is approximately 275. The houses are relatively far apart, and the village is expanding. Each house has a 4 m 3 water storage tank which is filled every 4 or 5 days when the sheep (3000) are at the village, or every 15 days when water for only human consumption is required. The houses use bottled gas for lighting and cooking. Sheep dung is burned for bread making. E1 Mucherfeh is smaller than Abu Sorra comprising six houses. The houses are generally larger than in Abu Sorra, and they are closer to each other. The population is 110. Cooking, lighting and water requirements are similar to Abu Sorra. Step 2 : P V requirements. According to the Syrian Authority of Electricity, the consumption of a single household in small villages connected to the electric grid is 1370 kW h/year, equivalent to 3.75 kW h/day. An estimate of the electricity requirements of a house-
holder in the villages under consideration is given in Table 1. Obviously the load will vary from day to day and seasonally. For example, in winter fans would not be used but lights must be used for longer. For a professional PV system it would be normal to analyse the load and the insolation through the year and optimise the PV system design. This demand could be met using PV either through a centralized village power system or through individual house systems. Individual systems The daily design load, determined above as 1.5 kW h is used as the basis of the calculation of the size of the PV system. The rating of the PV array must be sufficient to meet the design load plus losses due to temperature effects (5%), efficiency of the charge controller and the battery (20%), wiring (5%), etc. Assuming a d.c. system the typical efficiency of the whole system is : 0.95 x 0.80 x 0.95 = 0.72. As the daily insolation, the value of 4 kW h/m 2 on a tilted surface is considered. This corresponds to the February data for Damascus. November, December and January have lower values, but not much less. The PV array size can be determined using the nomogram in Fig. 1. This gives an array rating of 500 Wp. The battery capacity required would, in the case of a professional system, be optimised using yearly load and insolation data. To guarantee 100% availability of electricity up to the design daily demand, a very large battery at an equally large cost would be required. In the simple approach used here it is reasonable to specify a minimum capacity of 3 days load, i.e. 4.5 kW h, with a controller being used to ensure that the battery is not discharged more than 60%. This gives a battery capacity of 7.5 kW h. A system voltage of 12 V is appropriate. Thus the battery would be rated at 625 A h. The estimated cost of the system is approximately $5000 per house.
Table 1. Typical design electrical load for village household Load
Power (W)
Duration (h/clay)
Energy (W h/day)
Lights 3 × 20 W Fans 2 x 60 W TV Miscellaneous Total
60 120 60 60 300
5 6 4 4
300 720 240 240 1500
PV systems in Syria
2500
~ ~
Daily solar__.~ / 2000_ irradiation ~'~ 2/ (kWh/m2) ~ 3 J 1500
"~:>, tO00 <
500 ~
~"
0
"0
2
t
r
i
e
a
l
energy (kW h)
3
"~
4
I da!}yenergy . . . . . L_ efficiency
~ -15
547
Centralised and individual systems Another approach worthy of consideration would be to install both a centralised system and several individual PV systems, for the purposes of comparison. The village Abu Sorra would be suitable for this purpose. The consultant has recommended a central system to feed 8 houses in A b u Sorra with rating of 3.5 kW, and individual systems for the other 7 houses rated each at 350 Wp. This recommendation assumed, because of the limited budget, a lower daily load of 1 k W h per house.
The installed Abu Sorra P V systems Based on the options mentioned earlier, the decision was to install both a centralized PV system and several individual PV systems in A b u Sorra. Some months ago the installation was finished and the systems put in operation. The centralized system consists of the following sub-systems.
Fig. 1. Nomogram for PV array sizing.
Simple lightin # systems The alternative to providing PV electricity to meet a particular load is to provide a simple PV lighting system. All the major PV companies supply basic lighting kits which comprise one or two PV modules, and one to four fluorescent lamps with ballast, battery, controller and wiring. The cost of a 50 Wp kit is about $500. The consultant expects that introduction of small systems like this into villages such as Abu Sorra and E1 Mucherfeh could lead to a commercial demand. Centralised system The centralized system considered differs from the individual house systems in that an inverter is included so that local distribution is by alternating current (240 V, 50 Hz). The typical system efficiency is :
• PV array : 3.5 kWp at 25°C, A M 1.5, comprises 3 panels, each having 24 modules (type BP 255) and each module has 36 single crystalline rectangular cells. The array output voltage is 48 V. The array is facing the South with a tilt angle of 35 °. • Support structure, ground mounted. • Controller. • Batteries: type 2P1101, lead acid, depth of discharge = 20%, 24 x 2 V, capacity = 1100 A h, self discharge = 1 3% per month, dependent upon storage temperature. • Inverter : type 2248, input voltage = 48 V, output voltage = 220-240 V, 50 Hz, rated current = 46 A, provided with integral protection against overload. • Distribution wiring : cables N Y R Y 3 × 25 mm 2, 400 m for 6 houses. • 6 k W h meters, 240 V, 500 revolutions/kW h. • Measuring instruments for voltage and current of array output, battery output and inverter output.
0.95(array) × 0.85(inverter) x 0.80(battery) × 0.90(wiring) = 0.58. F o r Abu Sorra, the design daily load is 15 houses × 1.5 = 22.5 k W h . Using Fig. 1 (and scaling the y-axis by 10) the PV array size required is 9.7 kW. The battery capacity is 113 k W h . The total cost of the system would then be $107,700. For El Mucherfeh the same computation gives a total daily load of 9 kW h requiring an array rated at 4.0 kW and a battery of 45 kW h. The cost is about $45,000.
The decentralized PV system for Abu Sorra consists of 7 household PV power supplies each comprising the following. • 2 panels, with 4 and 3 modules, 350 Wp at 2Y~C, A M 1.5. • Support structure to m o u n t on flat roof. • Controller. • Batteries: 12 V, 600 A h, lead acid, D.O.D. 20%. • 4 d.c. fluorescent lamps and ballasts, 13 W.
A. HAMZEH
548
The installed El Mucherfeh P V systems For this village PV lighting kits were adopted, each comprising the following.
• • • •
PV module : 50 Wp at 25°C, AM 1.5. Support structure to mount on fiat roof. Battery: 12V, 50 A h lead acid, 20% D.O.D. 4 d.c. lamps and ballasts.
EVALUATION OF INSTALLED PV SYSTEMS AND
P O T E N T I A L FOR PV IN SYRIA
A preliminary study of the market for PV systems in Syria shows that there could be a total market of 10-13 MW for applications such as lighting, telecommunications (including microwave repeaters, U H F and VHF repeaters, TV translators, radio receivers and rural telephones), water pumping and cathodic protection. However, the potential market will be investigated in more detail along with the study of the existing PV systems.
GAINED EXPERIENCE
The systems in both villages have operated normally since installation. The monitoring of system performance, as an important element of the demonstration project, will be undertaken by Damascus University and the research centre as soon as the required instruments are supplied and connected. The purpose is to collect information not only to update similar systems for future use in Syria, but also to provide useful input for deploying such systems in different parts of the country. The performance will be digitally simulated as stand-alone systems; the predicted and actual performance will be compared, and the results extrapolated, through simulation, to various Syrian locations showing potential for utilizing PV systems. Concerning the acceptance by the users, they are very happy. However after installation of the centralized system, the d.c. current users are not now so pleased because they do not have the advantage of using d.c.-operated appliances.
CONCLUSIONS • The acceptance by users of a.c. solar electricity (centralized system users) is much greater than those of d.c. current (decentralized system users), because of the advantage of using conventional a.c. appliances. • The overall efficiency of the centralized PV system is 20% less than the efficiency of the individual one, because of the inverter losses and greater wiring losses. • The centralized system is about 24% more expensive than the individual PV systems. REFERENCES
1. Solar ener#y in Syria, SERI report Nr. 412-576 (1980). 2. B. McNelis, Renewable Eneryy Development Consultant's Report, 90348 November (1990). 3. Syria: Issues and options in the energy sector, UNDP/World Bank Report No. 5822 SYR (1986).
Pergamon
0960-1481(95)00060-7
Renewable Enerqy, Vol. 6, No. 5 6, pp. 545 548, 1995 Copyright (C 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 096{~ 1481/95 $9.50 + 0.00
E X P E R I E N C E WITH S T A N D - A L O N E C E N T R A L I Z E D A N D I N D I V I D U A L H O U S E PV SYSTEMS IN SYRIA ALI HAMZEH Damascus University, Faculty of Mechanical and Electrical Engineering, Department of Electrical Engineering, P.O. Box 5115, Damascus, Syria
Abstract--The paper focuses on the following items : climatological data in Syria ; design approaches for village PV systems ; the installed Abu Sorra PV systems ; the installed El Mucherfeh PV systems ; evaluation of the installed PV systems; experience gained; social acceptance of the PV systems by users; and comparison between centralized and decentralized PV systems. The main conclusions are : (1) the acceptance by users of a.c. solar electricity (centralized system users) is much more than those of d.c. current (decentralized system users), because of the advantage of using conventional a.c. appliances; (2) the overall efficiency of the centralized PV system is 20% less than the efficiency of the individual unit, because of the inverter losses and greater wiring losses ; (3) the centralized system is about 24% more expensive than the individual PV systems.
INTRODUCTION Syria lies between the latitudes 32 and 37 degrees North of the equator. The climate varies from Mediterranean weather along the coast to a desert environment further into the interior. The land area measures some 180,000 km 2 and the population is about 14 million. The Syrian Arab Republic currently relies on petroleum, gas and electricity for its energy requirements. Most of Syria's electricity is presently (1994) produced through steam based on the following average figures : steam turbines 68.3%, gas turbines 15.9%, hydro turbines 13.3% and diesel 2.5%. Rural electrification has been regarded as a development priority for social and economic reasons. The electricity authority has, over the years, connected most of the population to the electric network. But for very small villages and newly established Bedouine settlements, the cost of grid connection would be prohibitively high. However, new and renewable energy sources would be preferred for rural electrification, if the systems were available at acceptable costs and with proven reliability. An encouraging factor for this approach is the huge solar energy potential in Syria.
CLIMATOLOGICAL DATA IN SYRIA With the exception of the experiences an average of sunshine. The country has a yearly average of 5.6 kW
narrow coastal strip, Syria 3100-3400 h per year of high solar insolation with h/mZ/day.
In Southern Syria (the Damascus area) the average duration of sunshine in winter is of 6.7 h which is 63% of the possible duration. In the summer this figure goes up to 11.8 h, which corresponds to 90% of the possible duration. Overall, the average sunshine duration is relatively high at 9.2 h/day or 77% of the possible duration. Solar insolation varies markedly with the time of the year. During January, the average solar insolation is 2.775 kW h/m2/day (Damascus area). Summer insolation rises significantly and reaches a peak level of 7.458 kW h/mZ/day during June. The variation in seasonal value of insolation is due, in most part, to Syria's latitudinal location. Rainstorms, cloudiness and sand storms are the main causes of scattering or diffusion of direct solar radiation. These occur during the O c t o b e r - M a y period with more than six days per month during December, January and February. The yearly temperature values for Damascus area are as follows : Mean temperature Mean max. temp. Mean min. temp. Absolute max. temp. Absolute min. temp.
15-20°C 22 28"C 8 1 l r'C 40M5'~C -8C
Like most interior regions Damascus experiences occasional temperatures below freezing for some months of the year. According to the available wind data, a moderately 545
A. HAMZEH
546
important wind regime covers the whole country with average speeds ranging from 3 to 5 m/s. The wind regime is steady and distributed around the mean wind speed. Wind speeds of c%13 m/s are prevalent in some locations (Homs, Nabk and Qunaitra areas) for a significant portion of the year. The potential for using solar energy technologies in Syria has been studied over a number of years. In December 1989 a project document was signed by UNDP, the Syrian Government, and UNDTCD. One of the activities to be undertaken was a demonstration of small stand-alone PV systems for village electrification.
DESIGN A P P R O A C H E S FOR THE VILLAGE PV
SYSTEMS The design approaches and options for the PV systems to be adopted have been recommended by a consultant on PV systems (B. McNelis, U.K.), who undertook a mission to Syria in October/November 1990. The design algorithm consists of the following steps. Step 1 : Village options. The main requirements for a PV demonstration are a village which: is not connected to the grid; has reasonable solar insolation; has people wanting electricity and helping with the project; and is easily accessible for monitoring and demonstration purposes (i.e. is close to Damascus). Based on these criteria two villages have been identified, Abu Sorra and El Mucherfeh, which are sited about 55 km South of Damascus on the way to Souida. Abu Sorra comprises 12 houses with three more houses expected to be constructed later. The population is approximately 275. The houses are relatively far apart, and the village is expanding. Each house has a 4 m 3 water storage tank which is filled every 4 or 5 days when the sheep (3000) are at the village, or every 15 days when water for only human consumption is required. The houses use bottled gas for lighting and cooking. Sheep dung is burned for bread making. E1 Mucherfeh is smaller than Abu Sorra comprising six houses. The houses are generally larger than in Abu Sorra, and they are closer to each other. The population is 110. Cooking, lighting and water requirements are similar to Abu Sorra. Step 2 : P V requirements. According to the Syrian Authority of Electricity, the consumption of a single household in small villages connected to the electric grid is 1370 kW h/year, equivalent to 3.75 kW h/day. An estimate of the electricity requirements of a house-
holder in the villages under consideration is given in Table 1. Obviously the load will vary from day to day and seasonally. For example, in winter fans would not be used but lights must be used for longer. For a professional PV system it would be normal to analyse the load and the insolation through the year and optimise the PV system design. This demand could be met using PV either through a centralized village power system or through individual house systems. Individual systems The daily design load, determined above as 1.5 kW h is used as the basis of the calculation of the size of the PV system. The rating of the PV array must be sufficient to meet the design load plus losses due to temperature effects (5%), efficiency of the charge controller and the battery (20%), wiring (5%), etc. Assuming a d.c. system the typical efficiency of the whole system is : 0.95 x 0.80 x 0.95 = 0.72. As the daily insolation, the value of 4 kW h/m 2 on a tilted surface is considered. This corresponds to the February data for Damascus. November, December and January have lower values, but not much less. The PV array size can be determined using the nomogram in Fig. 1. This gives an array rating of 500 Wp. The battery capacity required would, in the case of a professional system, be optimised using yearly load and insolation data. To guarantee 100% availability of electricity up to the design daily demand, a very large battery at an equally large cost would be required. In the simple approach used here it is reasonable to specify a minimum capacity of 3 days load, i.e. 4.5 kW h, with a controller being used to ensure that the battery is not discharged more than 60%. This gives a battery capacity of 7.5 kW h. A system voltage of 12 V is appropriate. Thus the battery would be rated at 625 A h. The estimated cost of the system is approximately $5000 per house.
Table 1. Typical design electrical load for village household Load
Power (W)
Duration (h/clay)
Energy (W h/day)
Lights 3 × 20 W Fans 2 x 60 W TV Miscellaneous Total
60 120 60 60 300
5 6 4 4
300 720 240 240 1500
PV systems in Syria
2500
~ ~
Daily solar__.~ / 2000_ irradiation ~'~ 2/ (kWh/m2) ~ 3 J 1500
"~:>, tO00 <
500 ~
~"
0
"0
2
t
r
i
e
a
l
energy (kW h)
3
"~
4
I da!}yenergy . . . . . L_ efficiency
~ -15
547
Centralised and individual systems Another approach worthy of consideration would be to install both a centralised system and several individual PV systems, for the purposes of comparison. The village Abu Sorra would be suitable for this purpose. The consultant has recommended a central system to feed 8 houses in A b u Sorra with rating of 3.5 kW, and individual systems for the other 7 houses rated each at 350 Wp. This recommendation assumed, because of the limited budget, a lower daily load of 1 k W h per house.
The installed Abu Sorra P V systems Based on the options mentioned earlier, the decision was to install both a centralized PV system and several individual PV systems in A b u Sorra. Some months ago the installation was finished and the systems put in operation. The centralized system consists of the following sub-systems.
Fig. 1. Nomogram for PV array sizing.
Simple lightin # systems The alternative to providing PV electricity to meet a particular load is to provide a simple PV lighting system. All the major PV companies supply basic lighting kits which comprise one or two PV modules, and one to four fluorescent lamps with ballast, battery, controller and wiring. The cost of a 50 Wp kit is about $500. The consultant expects that introduction of small systems like this into villages such as Abu Sorra and E1 Mucherfeh could lead to a commercial demand. Centralised system The centralized system considered differs from the individual house systems in that an inverter is included so that local distribution is by alternating current (240 V, 50 Hz). The typical system efficiency is :
• PV array : 3.5 kWp at 25°C, A M 1.5, comprises 3 panels, each having 24 modules (type BP 255) and each module has 36 single crystalline rectangular cells. The array output voltage is 48 V. The array is facing the South with a tilt angle of 35 °. • Support structure, ground mounted. • Controller. • Batteries: type 2P1101, lead acid, depth of discharge = 20%, 24 x 2 V, capacity = 1100 A h, self discharge = 1 3% per month, dependent upon storage temperature. • Inverter : type 2248, input voltage = 48 V, output voltage = 220-240 V, 50 Hz, rated current = 46 A, provided with integral protection against overload. • Distribution wiring : cables N Y R Y 3 × 25 mm 2, 400 m for 6 houses. • 6 k W h meters, 240 V, 500 revolutions/kW h. • Measuring instruments for voltage and current of array output, battery output and inverter output.
0.95(array) × 0.85(inverter) x 0.80(battery) × 0.90(wiring) = 0.58. F o r Abu Sorra, the design daily load is 15 houses × 1.5 = 22.5 k W h . Using Fig. 1 (and scaling the y-axis by 10) the PV array size required is 9.7 kW. The battery capacity is 113 k W h . The total cost of the system would then be $107,700. For El Mucherfeh the same computation gives a total daily load of 9 kW h requiring an array rated at 4.0 kW and a battery of 45 kW h. The cost is about $45,000.
The decentralized PV system for Abu Sorra consists of 7 household PV power supplies each comprising the following. • 2 panels, with 4 and 3 modules, 350 Wp at 2Y~C, A M 1.5. • Support structure to m o u n t on flat roof. • Controller. • Batteries: 12 V, 600 A h, lead acid, D.O.D. 20%. • 4 d.c. fluorescent lamps and ballasts, 13 W.
A. HAMZEH
548
The installed El Mucherfeh P V systems For this village PV lighting kits were adopted, each comprising the following.
• • • •
PV module : 50 Wp at 25°C, AM 1.5. Support structure to mount on fiat roof. Battery: 12V, 50 A h lead acid, 20% D.O.D. 4 d.c. lamps and ballasts.
EVALUATION OF INSTALLED PV SYSTEMS AND
P O T E N T I A L FOR PV IN SYRIA
A preliminary study of the market for PV systems in Syria shows that there could be a total market of 10-13 MW for applications such as lighting, telecommunications (including microwave repeaters, U H F and VHF repeaters, TV translators, radio receivers and rural telephones), water pumping and cathodic protection. However, the potential market will be investigated in more detail along with the study of the existing PV systems.
GAINED EXPERIENCE
The systems in both villages have operated normally since installation. The monitoring of system performance, as an important element of the demonstration project, will be undertaken by Damascus University and the research centre as soon as the required instruments are supplied and connected. The purpose is to collect information not only to update similar systems for future use in Syria, but also to provide useful input for deploying such systems in different parts of the country. The performance will be digitally simulated as stand-alone systems; the predicted and actual performance will be compared, and the results extrapolated, through simulation, to various Syrian locations showing potential for utilizing PV systems. Concerning the acceptance by the users, they are very happy. However after installation of the centralized system, the d.c. current users are not now so pleased because they do not have the advantage of using d.c.-operated appliances.
CONCLUSIONS • The acceptance by users of a.c. solar electricity (centralized system users) is much greater than those of d.c. current (decentralized system users), because of the advantage of using conventional a.c. appliances. • The overall efficiency of the centralized PV system is 20% less than the efficiency of the individual one, because of the inverter losses and greater wiring losses. • The centralized system is about 24% more expensive than the individual PV systems. REFERENCES
1. Solar ener#y in Syria, SERI report Nr. 412-576 (1980). 2. B. McNelis, Renewable Eneryy Development Consultant's Report, 90348 November (1990). 3. Syria: Issues and options in the energy sector, UNDP/World Bank Report No. 5822 SYR (1986).