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This paper navigates the critical role of hydrogen in catalyzing a sustainable energy transformation. This review delves into hydrogen production methodologies, spotlighting green and blue hydrogen as pivotal for future energy systems because of their potential to significantly reduce greenhouse gas emissions. Through a comprehensive literature review and a bibliometric analysis, this study underscores the importance of technological advancements, policy support, and market incentives in promoting hydrogen as a key energy vector. It also explores the necessity of expanding renewable energy sources and international cooperation to secure a sustainable, low-carbon future. The analysis highlights the importance of scalable and cost-effective hydrogen production methods, such as solar-thermochemical and photo-electrochemical processes, and addresses the challenges posed by resource availability and geopolitical factors in establishing a hydrogen economy. This paper serves as a guide for policy and innovation toward achieving global sustainability goals, illustrating the essential role of hydrogen in the energy transition.

Jordan faces pressing energy challenges, characterized by a substantial dependence on imported resources. This paper addresses these challenges by examining the potential integration of solar thermal energy systems into poultry slaughterhouses, using a representative case study. The study starts by providing a brief background on Jordan's energy challenges and the rationale for exploring solar thermal applications in the poultry industry. The methodology involves a meticulous analysis of existing processes in the slaughterhouse, followed by the necessary calculations for integrating a solar thermal flat plate collector. Validation is performed through T*SOL and Polysun simulations, accompanied by a comprehensive economic analysis. The proposed flat plate collector-based system demonstrates the capacity to cover approximately 72% of the facility's annual energy requirements, resulting in substantial savings of 1,926,396 kWh per year, equivalent to 330,318 L of diesel. Simulation results indicate a concise payback period of 3.8 years and net profits approximately 6.6 times the initial investment over a 25-year span. Beyond economic benefits, the adoption of solar technology leads to an 84% reduction in annual CO2 emissions, underscoring its environmental advantages. The study also sheds light on a notable lack of awareness about solar thermal technology, emphasizing the need for knowledge dissemination to foster global renewable energy adoption.

The application of a fair tariff for electricity pricing is aimed at controlling demand and promoting sustainability by motivating homeowners to use household appliances as well as heating and cooling systems that offer increased energy efficiency. It is possible to structure the price levels such that customers (typically those who have increased demands for electricity) are encouraged to lower their overall demand. The reorganisation of electrical subsidies within the residential sector has considerable importance for the country’s economy as well as for more effective management of the consumption of electricity and the resulting effects on the environment, which lays the foundation for more sustainable development. In the current research, data from 260,000 regular customers paying standard electricity tariffs were gathered and the energy usage of in excess of 1,000 energy-subsidised District Electricity Distribution Company (IDECO) members of staff was recorded over a period of two years (2017 and 2018). A comparison was made between the two aforementioned groups to investigate the outcomes of energy subsidies on energy usage as well as consumption patterns within the residential sector. The results of the analysis indicated that on average, normal homeowners used approximately 297 kWh/month, whereas customers whose electricity was subsidised consumed approximately 615 kWh/month. In both winter and summer, there was an increase in the amount of energy consumed, particularly among those receiving subsidies, as the demand for heating and cooling was raised. The application of electricity tariffs (with no subsidisation) provides a means of controlling the demand profile that is particularly effective. The structure of tariffs can motivate customers (typically those electricity consumption levels are high) to lower their overall consumption in addition to peak demand (which has the consequence of limiting the strain on the grid and power stations) by requiring them to pay for electricity at maximum prices.

This research aimed to evaluate the thermal performance of rooftop PV as a shading element on uninsulated roof-related HVAC energy consumption of buildings in a moderate dry–warm climate zone. A transient-state 3D distributed thermal model was developed of the PV-added rooftop components. Photovoltaic (PV) solar rooftops as shading devices were constructed using Integrated Environmental Solution-Virtual Environment Software to predict the reduction and increase in heating and cooling loads connected with the roof floor each month. The impact of rooftop PV systems on a building’s roof-related energy burden was quantified about a low-rise residential building in a moderate dry–warm climate zone represented by the city of Amman in Jordan. The results indicated that PV roof structure reduced heat gain by 10.87% during the summer and increased heat loss by 3.8% during the winter. In the summer season, the electricity demand for indoor cooling declined, but the demand for indoor heating increased slightly. The investigation focused on a middle-income home in Jordan’s capital, Amman. The limitations imposed by building rooftops on the use of PV were also investigated in this research and the findings validate the importance of providing environmental authorities, the construction industry, and ordinary individuals with important guidelines on the use of renewable energy to heat and cool buildings. Consequently, this analysis enhances awareness of a building’s overall energy needs, which are crucial for the future design of sustainable buildings.

During the COVID-19 pandemic, the energy consumption profile has been changed in several facilities as a response to the lockdown and other precautionary measures. Lockdown has reduced the electrical load consumption in commercial buildings. Accordingly, the energy cost savings have been reflected in the energy bills. However, such savings were not due to improvement of energy performance and equipment efficiency, but because of changes that occurred in the operating conditions and parameters. As a result, it was complicated to identify the real energy savings in the energy retrofit projects during this period. For the energy conservation and refurbishment projects, a challenge was faced to calculate an accurate energy savings amount and to track the energy pattern and performance during these lockdown months.This study discusses the energy behavior of retrofitted buildings that follows the energy performance contracting. It shows the improvement of energy consumption for one year for 30 studied buildings. It discusses the strategy to follow in the calculation of the energy savings during a full lockdown period. This article addresses the approach to be taken into consideration and its consequences to monitor the energy profile as per the International Performance Measurement and Verification Protocol.

The traditional energy sector in Palestine suffers from many problems, shortages, and high prices. As a result, alternative energy sources have become the ideal solution to save energy, reduce costs, and self-reliance, albeit in part, and one of the alternative energy sources is wind energy, despite the low wind speed in Palestine. However, it can be used to a large extent in many fields. Where electrical energy plays an important role in the life of the individual and society, and indeed in all aspects of life in the country. Without electric energy, the economy and industries cannot be developed, and therefore this prompts to search for alternative renewable energy sources than traditional energy sources. This study aims to solve the problem of electrical energy in Palestine, especially in the city of Hebron. This study was conducted in the city of Hebron because it contains suitable wind capabilities to build these turbines and to obtain the necessary energy through renewable energy sources available in Palestine due to the availability of the appropriate climate and weather. Two different types of turbines will be studied and the type most suitable for Palestine's weather and wind speed available, and which of these types will be the most efficient, will be studied. This research has been studied and implemented based on a SolidWorks program. Initially, a three-dimension design was made in SolidWorks for two types of wind turbines, namely: the horizontal axis wind turbine and the vertical axis wind turbine of the Savonius type. Simulations were performed on each of the above types with different wind speeds (0.5-4.5) m/s. After simulation, it was found that Savonius turbines have the greatest ability to generate power at low wind speeds commensurate with the wind speed in the city of Hebron.

The negative consequences of toxic emissions from internal combustion engines, energy security, climate change, and energy costs have led to a growing demand for clean power sources in the automotive industry. The development of eco-friendly vehicle technologies, such as electric and hydrogen vehicles, has increased. This article investigates whether hydrogen vehicles will replace electric vehicles in the future. The results showed that fuel-cell cars are unlikely to compete with electric cars. This is due to the advancements in electric vehicles and charging infrastructure, which are becoming more cost-effective and efficient. Additionally, the technical progress in battery electric vehicles (BEVs) is expected to reduce the market share of fuel-cell electric vehicles (FCEVs) in passenger vehicles. However, significant investments have been made in hydrogen cars. Many ongoing investments seem to follow the sunk cost fallacy, where decision-makers continue to invest in an unprofitable project due to their already invested resources. Furthermore, even with megawatt charging, fuel-cell trucks cost more than battery-powered electric trucks. The use cases for fuel-cell electric trucks are also much more limited, as their running expenses are higher compared to electric cars. Hydrogen vehicles may be beneficial for heavy transport in remote areas. However, it remains to be seen if niche markets are large enough to support fuel-cell electric truck commercialization and economies of scale. In summary, we believe that hydrogen vehicles will not replace electric cars and trucks, at least before 2050.

Alternative energy sources -such as solar energy- is potentially needed, as the energy sector in Palestine is completely controlled by Israeli authorities. Solar energy has the potential to be a useful alternative in Palestine because it has almost 228 sunny days each year. Among the several solar energy techniques, the photovoltaic system has the potential to make a significant contribution to the development of a more sustainable energy system. The amount of irradiance that enters the solar cells has a significant impact on the photovoltaic panel's output. As a result, dust and dirt on the panel will reduce the system's effectiveness by reducing incoming solar radiation and raising the panel's temperature. So, cleaning the Photovoltaic module on a regular basis will result in decreased energy loss and more economic benefits. The primary goal of this study is to detect the impact of dust on Photovoltaic efficiency. A 170.28 kW solar system in Nablus city, Palestine that is connected to an automated cleaning system was tested between January and July of 2021. The panels in the system were left un-cleaned for different time spans (ex. Weekly, Monthly, 2 Months, And 7 Months). The impact of dust accumulation on Photovoltaic performance was then investigated by comparing the power production between the un-cleaned panels to the automated cleaned panels. However, the cleaning method employed in this study was an automated cleaning system that is programmed to clean the plant every two days. Moreover, all the Photovoltaic panels employed in this study were of the Trina solar 330 types, which had similar attributes and performance. According to the study, the worst-case scenario was leaving the Photovoltaic panels un-cleaned for seven months in a row, which resulted in a power drop of 9.99 % and an average power reduction of 2.93 % per month. As a result of climate change, energy, water, and food security are major concerns in Palestine.

Many developing countries subsidise energy (petroleum fuel products, natural gas and electricity), which was reflected in an extra pressure on the national budget, and this will support inefficient use of energy. In this study, the effects of electrical energy subsidies on the total electrical energy consumption in the residential sector were examined. Data on more than 260,000 Jordanian ordinary customers were collected, and the energy consumption of more than 1000 energy-extra subsidised Irbid District Electricity Distribution Company (IDECO) staff members was recorded over a 2-year period (2017 and 2018). These two groups were compared to examine the consequences of subsidising energy on the energy consumption and the consumption behaviour in the residential sector. The analysis revealed that ordinary householders consume around 296 kWh/month, while for the subsidised group 615 kWh/month was noted. Energy consumption increased during the summer and winter months, especially in the subsidised group, due to the heavy reliance on mechanical systems for cooling and heating. Electricity full price (without any subsidies) can be a very effective way to control the demand profile. It can be structured to encourage customers (generally those that have significant electricity demand) to reduce their total usage as well as peak demand (thus reducing the pressure on the grid and the power plant) by charging them full electricity prices.

Green hydrogen is becoming an increasingly important energy supply source worldwide. The great potential for the use of hydrogen as a sustainable energy source makes it an attractive energy carrier. In this paper, we discuss the potential of producing green hydrogen in Jordan. Aqaba, located in the south of Jordan, was selected to study the potential for producing green hydrogen, due to its proximity to a water source (i.e., the Red Sea). Two models were created for two electrolyzer types using MATLAB. The investigated electrolyzers were alkaline water (ALK) and polymeric electrolyte membrane (PEM) electrolyzers. The first model was used to compare the required capacity of the PV solar system using ALK and PEM from 2022 to 2025, depending on the learning curves for the development of these technologies. In addition, this model was used to predict the total investment costs for the investigated electrolyzers. Then, a techno-economic model was constructed to predict the feasibility of using this technology, by comparing the use of a PV system and grid electricity as sources for the production of hydrogen. The net present value (NPV) and levelized cost of hydrogen (LCOH) were used as indicators for both models. The environmental effect, according to the reduction of CO2 emissions, was also taken into account. The annual production of hydrogen was 70.956 million kg. The rate of hydrogen production was 19.3 kg/s and 1783 kg/s for ALK and PEM electrolyzers, respectively. The LCOH was 4.42 USD/kg and 3.13 USD/kg when applying electricity from the grid and generated by the PV system, respectively. The payback period to cover the capital cost of the PV system was 11 years of the project life, with a NPV of USD 441.95 million. Moreover, CO2 emissions can be reduced by 3042 tons/year by using the PV as a generation source, instead of fossil fuels to generate electricity. The annual savings, with respect to the reduction of CO2 emissions, was USD 120,135.

The journal retracts the article “A Critical Review on Recycling Composite Waste Using Pyrolysis for Sustainable Development” Energies 2021, 14(18), 5748 [...]

The performance of photovoltaic (PV) solar panels is dependent on certain factors, such as dust effects. Even though Palestine’s energy issues are well-known, no research has been undertaken on the soiling effect on solar energy generation in Palestine’s climatic circumstances. The study’s findings can aid Palestine’s efforts to achieve long-term energy sustainability and solar energy use. Outdoor research was conducted in Tulkarm, Palestine, to explore the impact of dust on PV systems. The current study examined the impact of dust accumulation based on the Mediterranean climate. To accomplish this, a one-year experiment was conducted from 1 January to 31 December 2021. An 85-kW PV power plant at Tulkarm was utilized in the study. Knowing the efficiency reduction over time will aid in minimizing cleaning expenses by selecting the most appropriate cleaning interval. The results concluded that in January, February, November, and December, there will be a two-month cleaning period, monthly cleaning in March and October, as well as two weeks of cleaning in April and May. It may also be concluded that the plant should be cleaned weekly throughout the months of June, July, August, and September. This recommendation is necessary to maintain the PV panel plant operating at peak efficiency.

Countries with limited natural resources and high energy prices, such as Jordan, face significant challenges concerning energy consumption and energy efficiency, particularly in the context of climate change. Residential buildings are the most energy-consuming sector in Jordan. Photovoltaic (PV) systems on the rooftops of residential buildings can solve the problem of increasing electricity demands and address the need for more sustainable energy systems. This study calculated the potential electricity production from PV systems installed on the available rooftops of residential buildings and compared this production with current and future electricity consumption for residential households. A simulation tool using PV*SOL 2021 was used to estimate electricity production and a comparative method was used to compare electricity production and consumption. The results indicated that electricity production from PV systems installed on single houses and villas can cover, depending on the tilt angle and location of the properties, three to eight times their estimated future and current electricity use. PV installation on apartment buildings can cover 0.65 to 1.3 times their future and current electricity use. The surplus electricity produced can be used to mitigate urban energy demands and achieve energy sustainability.

Based on recent developments and the predicted future advancement of lighting technologies, researchers are now questioning the extent to which daylight is effective in lowering the overall energy consumption of buildings. As light-emitting diode (LED) luminaires are highly energy efficient, the amount of power consumed for lighting purposes can be reduced, even in situations where the lighting system is at its full power. It has already been demonstrated that LED-lighting technologies can facilitate significant energy savings through minimizing window size (the main source of heat loss in buildings), and there is considerable potential for developing the LEDs’ source efficacy and lighting-product efficiency to ultimately achieve levels of efficacy of approximately 350 lumens per Watt (lm/W). For building designs to be sustainable in the future, it is critical that the windows-to-wall ratio (WWR) is optimized to minimize both heating and cooling loads, as well as the total energy consumed by the building for lighting, according to the efficiency of the LED, while still maintaining a suitable lighting level for occupants. This research examines the influence of the WWR on the total amount of energy consumed by standard buildings in Jordan using various LED luminaires (existing and projected efficiencies). DesignBuilder software was utilized to analyze the effect of LED-technology development on optimizing the WWR for a typical residential structure in Jordan. The research presents beneficial recommendations with respect to optimizing the WWR for primary decision-makers in the design of residential buildings with enhanced energy efficiency, considering the losses and gains associated with solar heat and light to capitalize on solar energy with no adverse impacts by windows size. The outcomes suggest a WWR of 17% could be achieved by typical residential buildings in Jordan that have extremely efficient LED lighting systems (350 lm/W), which is more than 50% less than the existing level of 40% recommended by multiple standards. Additionally, this study highlighted that when the efficiency of LED technologies increases, the energy demand of the building will be reduced because of lower energy usage combined with heat gain resulting from the LED efficiency.

The rising usage of carbon and glass fibers has raised awareness of scrap management options. Every year, tons of composite scrap containing precious carbon and glass fibers accumulate from numerous sectors. It is necessary to recycle them efficiently, without harming the environment. Pyrolysis seems to be a realistic and promising approach, not only for efficient recovery, but also for high-quality fiber production. In this paper, the essential characteristics of the pyrolysis process, their influence on fiber characteristics, and the use of recovered fibers in the creation of a new composite are highlighted. Pyrolysis, like any other recycling process, has several drawbacks, the most problematic of which is the probability of char development on the resultant fiber surface. Due to the char, the mechanical characteristics of the recovered fibers may decrease substantially. Chemically treating and post-heating the fibers both help to reduce char formation, but only to a limited degree. Thus, it was important to identify the material cost reductions that may be achieved using recovered carbon fibers as structural reinforcement, as well as the manufacture of high-value products using recycled carbon fibers on a large scale. Recycled fibers are cheaper than virgin fibers, but they inherently vary from them as well. This has hampered the entry of recycled fiber into the virgin fiber industry. Based on cost and performance, the task of the current study was to modify the material in such a way that virgin fiber was replaced with recycled fiber. In order to successfully modify the recycling process, a regulated optimum temperature and residence duration in post-pyrolysis were advantageous.

Energy savings gained through natural lighting could be offset by the loss of energy through windows; therefore, the target of this study is to examine the effects of enhancing the efficiency of lighting systems on the optimum window-to-wall ratio (WWR) of Jordanian residential structures. This research proposes the hypothesis that the WWR of residential structures that contain artificial lighting systems with increased efficiency will be lower than buildings in which solar lighting is provided. The energy simulation tool, DesignBuilder (DesignBuilder Software Ltd, Stroud, UK) was used to simulate an intricate model showing a standard Jordanian residential building with a size of 130 m2. The study offers useful guidance regarding the optimum WWR for key decisionmakers when designing energy-efficient residential structures in the context of Jordan. By considering the balance between gains and losses in solar heat and light gain to exploit energy from solar sources with no reverse effects, while making comparisons between different WWR situations, the findings indicate that the typical WWR for residential structures in Jordan that have efficient Light Emitting Diode (LED) systems of lighting installed could be between 25% and 30%, which is lower than the highest WWR stipulated by the ASHRAE standards.

Since buildings are one of the major contributors to global warming, efforts should be intensified to make them more energy-efficient, particularly existing buildings. This research intends to analyze the energy savings from a suggested retrofitting program using energy simulation for typical existing residential buildings. For the assessment of the energy retrofitting program using computer simulation, the most commonly utilized residential building types were selected. The energy consumption of those selected residential buildings was assessed, and a baseline for evaluating energy retrofitting was established. Three levels of retrofitting programs were implemented. These levels were ordered by cost, with the first level being the least costly and the third level is the most expensive. The simulation models were created for two different types of buildings in three different climatic zones in Palestine. The findings suggest that water heating, space heating, space cooling, and electric lighting are the highest energy consumers in ordinary houses. Level one measures resulted in a 19–24 percent decrease in energy consumption due to reduced heating and cooling loads. The use of a combination of levels one and two resulted in a decrease of energy consumption for heating, cooling, and lighting by 50–57%. The use of the three levels resulted in a decrease of 71–80% in total energy usage for heating, cooling, lighting, water heating, and air conditioning.

Any building’s design should sustain thermal comfort for occupants and promote less energy usage during its lifetime using accurate building retrofits to convert existing buildings into low-energy buildings so that the heating and cooling loads can be minimized. Regarding the methodology adopted in this research, an energy model of an educational building located at the German Jordanian University in Jordan was constructed utilizing DesignBuilder computer software. In addition, it was calibrated utilizing real energy consumption data for a 12-month simulation of energy performance. Subsequently, a computerized evaluation of the roles of building envelope retrofits or the adaptive thermal comfort limits in the reduction of the overall building energy consumption was analyzed. The results of the study show that the current building’s external wall insulation, roof insulation, glazing, windows, and external shading devices are relatively energy-efficient but with high cost, resulting in significant financial losses, even though they achieved noticeable energy savings. For instance, equipping the building’s ventilation system with an economizer culminated in the highest financial profit, contributing to an annual energy savings of 155 MWh. On the other hand, in an occupant-centered approach, applying the adaptive thermal comfort model in wider ranges by adding 1 °C, 2 °C, and 3 °C to the existing operating temperatures would save a significant amount of energy with the least cost (while maintaining indoor thermal comfort), taking over any retrofit option. Using different adaptive thermal comfort scenarios (1 °C, 2 °C, and 3 °C) led to significant savings of around 5%, 12%, and 21%, respectively. However, using different retrofits techniques proved to be costly, with minimum energy savings compared to the adaptive approach.

With the growing demand for clean and economically feasible renewable energy, solar photovoltaic (PV) system usage has increased. Among many factors, the tilt and azimuth angles are of great importance and influence in determining the photovoltaic panel’s efficiency to generate electricity. Although much research was conducted related to solar PV panels’ performance, this work critically determined the tilt and azimuth angles for PV panels in all countries worldwide. The optimum tilt and azimuth angles are estimated worldwide by the photovoltaic geographic information system (PVGIS). Also, annual and average daily solar irradiation incident on the tilted and oriented plate optimally (AR1 and DR1) are calculated. Besides, annual and average daily solar irradiation incident on plate tilt optimally and oriented because of the south in the northern hemisphere and because of the north in the southern hemisphere (AR2 and DR2) are estimated. PVGIS is also used to calculate the annual and average daily solar irradiation incident on the horizontal plate (AR3 and DR3). The data collected from PVGIS are used to develop an efficient and accurate artificial neural network model based on feed-forward neural network approach. This model is an essential subpart that can be used in an embedded system or an online system for further PV system analysis and optimization. The developed neural model reflected very high accuracy in predicting the PV panels’ optimal tilt and azimuth angles worldwide. The benefit of tilting is generally increased by increasing the latitude. As the latitude increases, the tilt factor (F) increases because of the increase in the optimum tilt angle by increasing the latitude. The optimal orientation is due to the north in the southern hemisphere and due to the south in the northern hemisphere for most cities worldwide. In sum, it can be concluded that the optimum tilt angle is equal to or greater than the latitude until the latitude 30°. The optimum tilt angle becomes less than the latitude, and the difference is increased until it reaches more than 20°. Hence in this study the aim is to develop a simple neural network model which can accurately predict the annual radiation and optimum tilt and azimuth angle in any region of the world and can be easily implemented in a low-cost microcontroller.

The first industrial-scale pyrolysis plant for solid tire wastes has been installed in Jenin, northern of the West Bank in Palestine, to dispose of the enormous solid tire wastes in the north of West Bank. The disposable process is an environmentally friendly process and it converts tires into useful products, which could reduce the fuel crisis in Palestine. The gravimetric analysis of tire waste pyrolysis products from the pyrolysis plant working at the optimum conditions is: tire pyrolysis oil (TPO): 45%, pyrolysis carbon black (PCB): 35%, pyrolysis gas (Pyro-Gas): 10% and steel wire: 10%. These results are depending on the tire type and size. It has been found that the produced pyrolysis oil has a High Heating Value (HHV), with a range of 42 − 43 ( MJ / kg ) , which could make it useful as a replacement for conventional liquid fuels. The main disadvantage of using the TPO as fuel is its strong acrid smell and its low flash point, as compared with the other conventional liquid fuels. The produced pyrolysis carbon black also has a High Heating Value (HHV) of about 29 (MJ/kg), which could also encourage its usage as a solid fuel. Carbon black could also be used as activated carbon, printers’ ink, etc. The pyrolysis gas (Pyro-Gas) obtained from waste tires mainly consist of light hydrocarbons. The concentration of H2 has a range of 30% to 40% in volume and it has a high calorific value (approximately 31 MJ / m 3 ), which can meet the process requirement of energy. On the other hand, it is necessary to clean gas before the burning process to remove H2S from Pyro-Gas, and hence, reduce the acid rain problem. However, for the current plant, some recommendations should be followed for more comfortable operation and safer environment work conditions.

The optimum tilt angle of solar panels or collectors is crucial when determining parameters that affect the performance of those panels. A mathematical model is used for determining the optimum tilt angle and for calculating the solar radiation on a south-facing surface on a daily, monthly, seasonal, semi-annual, and annual basis. Photovoltaic Geographical Information System (PVGIS) and Photovoltaic Software (PVWatts) is developed by the NREL (US National Renewable Energy Laboratory) are also used to calculate the optimum monthly, seasonal, semi-annual, and annual tilt angles and to compare these results with the results obtained from the mathematical model. The results are very similar. PVGIS and PVWatts are used to estimate the solar radiation on south-facing surfaces with different tilt angles. A case study of a mono-crystalline module with 5 kWP of peak power is used to find out the amount of increased energy (gains) obtained by adjusting the Photovoltaic (PV) tilt angles based on yearly, semi-annual, seasonal, and monthly tilt angles. The results show that monthly adjustments of the solar panels in the main Palestinian cities can generate about 17% more solar energy than the case of solar panels fixed on a horizontal surface. Seasonal and semi-annual adjustments can generate about 15% more energy (i.e., it is worth changing the solar panels 12 times a year (monthly) or at least 2 times a year (semi-annually). The yearly optimum tilt angle for most Palestinian cities is about 29°, which yields an increase of about 10% energy gain compared to a solar panel fixed on a horizontal surface.

Concentrating solar power (CSP) technologies are foreseen to be a crucial actor in the future renewable energy mix. Soil accumulation on the optical surfaces of CSP plants involves significant expenses of the operation and maintenance activities because a high cleanliness level is required to achieve proper plant revenues. Normally, only the front side of the solar reflectors is cleaned to reflect the maximum possible amount of direct solar radiation towards the receiver. However, soil deposited on the backside of the reflector could provoke degradation and might need to be considered in the cleaning strategy. As this possible degradation has never been studied, this work is dedicated to assess if the backside of reflectors should be regularly cleaned. The influence of the sand in the possible paint degradation depends on its chemical composition and the weather conditions. Therefore, several climatic conditions of artificially soiled reflector samples with different types of sand were simulated in accelerated aging tests. Concerning the results obtained, the ambient conditions simulated by the damp heat and thermal cycling tests were the only ones that produced a significant degradation of the backside paints. Also, the sand from Ouarzazate was responsible for higher deterioration.