Use of Mobile Photothermic Installation on Application of Drip Irrigation Technology in Orchards of Mountain and Foothill Areas of Uzbekistan

Abstract

Due to climate change, providing the population with clean drinking water, increasing the productivity of agricultural products in terms of quality and quantity, and the timely supply of necessary water to crops has become one of the main problems in the world. The water shortage in the Republic of Uzbekistan is increasing year by year. With the increase in the population of the republic, the need for water and energy resources has increased significantly. The main goal of this scientific research is to use water and energy-saving technologies in fruit orchards growing in the mountain and foothill areas of the Republic of Uzbekistan (Republic of Karakalpakstan and the Bukhara, Kashkadarya, Namangan, Surkhandarya, and Khorezm regions), where water resources and electricity are scarce. The methodology used for the research is comprehensive in nature, using both analytical and experimental research methods. In evaluating and comparing the efficiency of the proposed technical solution, comparison with traditional methods and methods of absolute and comparative economic efficiency of capital investments are used. The obtained results showed drip irrigation of fruit orchards 8–10 times alongside pumping units with a capacity of N = 4.0 kW (8 PTBs of 500 W each) provided enough water for cultivation; the power utilization ratio increased by 30–40% compared to stationary systems; the water savings in fruit orchards compared to traditional irrigation was 67.4 percent (Republic of Karakalpakstan)—76.1 percent (Bukhara region) (for the whole republic—60–70 percent). The use of such combined devices based on drip irrigation systems, mobile solar energy installation and automation system saves significant amounts of water and energy resources and increases the reliability of irrigation.

1. Introduction

Modern agriculture relies heavily on energy, creating a vulnerability to fluctuating fossil fuel prices. As fuel costs rise, so too does the expense of crop production. Harnessing renewable energy sources, such as solar power for irrigation systems, offers a solution. This approach mitigates the influence of fuel price volatility on food production while minimizing the environmental footprint of irrigation practices. Solar-powered drip irrigation holds promise for enhancing crop yields with minimal water consumption. However, the initial cost of these systems presents a significant barrier for small-scale farmers. Reducing the life cycle costs associated with solar-powered drip irrigation would increase its accessibility, empowering smallholders to boost their incomes and contribute to global food security on a larger scale [1]. The increasing global population presents a significant challenge in ensuring access to organic food. As a result, nations worldwide, along with the United Nations, have implemented food security programs. Food security has emerged as a critical priority for countries at all levels of economic development, with agriculture playing a pivotal role in enhancing food accessibility [2]. In 2018, a presidential decree established the “Measures to Further Ensure National Food Security” program in Uzbekistan [3].

Agriculture plays a pivotal role in ensuring food security, but it also places a significant demand on water resources. Currently, agricultural activities account for approximately 90% to 91% of the total water allocated to our nation, which amounts to 51 to 53 billion cubic meters annually [4]. Access to clean water for drinking and household purposes is a top priority in our republic. The legal framework enshrines this principle: Article 25 of the “Law of the Republic of Uzbekistan on Water and Water Use” explicitly states that the primary use of water resources should be to satisfy the population’s essential needs for drinking and domestic consumption [5]. When a region faces water scarcity, allocations intended for agricultural use are often reduced to meet the essential needs of the population. This situation is exacerbated by several factors: global climate change, population growth, and expanding economic sectors all contribute to an increasing demand for water resources, leading to a widening gap between supply and demand each year [6]. Given these circumstances, experience demonstrates that the most effective strategy for addressing water scarcity is through conservation and responsible water consumption [7]. Currently, two primary methods of irrigation are employed globally for agricultural purposes: surface irrigation by flooding; surface irrigation by furrows; surface-drip irrigation; sprinkling; aerosol moistening (fine-dispersed sprinkling); in-soil; in-soil-drip; and sub irrigation (raising the groundwater level) [8].

Innovative irrigation techniques, distinct from traditional surface and furrow methods, offer a sustainable and cost-effective approach to water management. These non-traditional methods have demonstrated significant benefits, including a 30–45% increase in crop yield and a 25–30% improvement in labor productivity. Furthermore, they contribute to substantial water conservation, reducing consumption by 45–60% [9]. These advancements also lessen the dependency on extensive internal irrigation networks, optimize land utilization and enhance environmental sustainability within irrigation systems. Examples of such water-saving technologies currently implemented include short-furrow irrigation [10,11,12,13], hydrogel granule application [14,15], laser-guided land leveling [16,17,18], sub-surface irrigation [19], portable pipe and tray systems [20,21,22], film-covered furrow irrigation [23], and drip irrigation [24,25,26].

The main disadvantages of currently used photovoltaic units are effective cooling designs; mobility; lack of adaptability to the sun; and high cost; the optimal operation of the photothermal device occurs at 20–25 degrees. To solve these problems, a project was created to develop and implement a mobile photothermal installation [26,27,28]. Stationary photovoltaic systems are only operated at a specific location, which sometimes makes it impossible to operate them throughout the year.

Renewable resource utilization offers significant benefits over fossil fuels, including environmental sustainability, energy independence and reduced pollution. These advantages are particularly pronounced in rural and agricultural regions [29,30]. However, expanding electrical grids to these areas is not always economically feasible or logistically practical. Consequently, diesel generators remain a common power source in rural communities due to their ease of use and affordability [31]. Drip irrigation systems, which require pressurized water delivery, often rely on generators (gensets) due to limited access to electricity grids. These systems frequently involve pumping groundwater, either directly or from storage ponds. Solar energy offers a significant and sustainable alternative to fossil fuels, effectively reducing carbon dioxide emissions and mitigating the threat of global warming. India currently generates over 100 GW of solar power, with the potential to reach 750 GW through photovoltaic cells if cost-effective technologies become available in the near future. Parabolic trough (PFT) and linear Fresnel (LFT) collectors are highly effective solar concentrators for harnessing solar energy. The development of hybrid concentrators further enhances the efficiency of this process [32]. This scientific research aims to implement water- and energy-efficient technologies in fruit orchards located within the mountainous and foothill regions of the Republic of Uzbekistan. These regions, encompassing Karakalpakstan and the Bukhara, Kashkadarya, Namangan, Surkhandarya, and Khorezm Provinces, face significant challenges due to limited water resources and electricity availability. In the future, the project will be implemented in all horticultural farms of the Republic of Uzbekistan and in the countries of Central Asia.

2. Materials and Methods

The novelty of this technical solution lies in an unconventional approach to the choice of a mobile solar plant as a drive for pumps in a drip irrigation system, which will allow for more efficient use of the plant (due to the possibility of additional use in the non-growing season) and the use of an automation system that takes into account local characteristics (primarily, the hydrological, climatic, and soil conditions of the area and the presence of suspended solids in the water source). With this in mind, the methodology used in the research was of a comprehensive nature. Both analytical and experimental research methods were applied. When assessing the effectiveness of the proposed technical solution and comparing it with traditional methods, methods of absolute and comparative economic efficiency of capital investments were applied. In testing the installations, generally accepted methods of parametric (energy) testing of power installations were used, and in investigating the particle size distribution of sediment in the water in the water source, generally accepted hydrometric methods of research were used. The research was carried out between August 2022 and August 2024.

Scientific research was carried out in orchards growing in mountainous and sub-mountainous areas of the Republic of Uzbekistan (the Republic of Karakalpakstan and the Bukhara, Kashkadarya, Namangan, Surkhandarya, and Khorezm regions) (Figure 1).

Drip irrigation is widely recognized as the most efficient technique for conserving water resources [24,25,26]. Drip irrigation is a targeted watering method that delivers both water and mineral nutrients directly to the root zone of individual plants. This localized approach offers several advantages, making it particularly suitable in areas with small water resources and difficult access to their supply; on land with high gradients (mountainous and foothill areas); for soils with high permeability; for clean water sources; for crops with long row spacing (orchards and vineyards).

Uzbekistan possesses a significant amount of fallow arable land, approximately 750,000 hectares, situated in mountainous and foothill regions. This land holds potential for the cultivation of various agricultural products, including vegetables, melons, fruits, and grapes. Developing this underutilized resource could substantially increase the production of high-quality goods, benefiting both domestic consumption and international trade.

The primary obstacle to successful cultivation in these regions lies in the scarcity of both water and energy resources. A viable economic solution to this challenge involves implementing drip irrigation systems powered by renewable energy sources [8,24,25,26]. Crop yield is significantly influenced by the timely delivery of irrigation water according to the plant’s physiological requirements. In conventional irrigation practices, human intervention introduces variability and potential delays. To address this issue, the implementation of an automated drip irrigation system is suggested as a solution.

General Scheme of the Complex Drip Irrigation System

To realize the objective, a comprehensive drip irrigation system is recommended. This system comprises three interconnected components: 1. a drip irrigation system; 2. a solar energy system with pumping units; 3. an irrigation automation system (Figure 2).

3. Results and Discussion

3.1. Drip Irrigation System

Extensive field research on drip irrigation conducted over two years in the Surkhandarya region demonstrated significant water conservation benefits. The study found that soybean and sunflower irrigation using drip systems resulted in water savings of 39.4% to 41.7%. Furthermore, orchards and vineyards utilizing this method exhibited even greater efficiency, saving between 58.3% and 62.0% of water resources compared to traditional methods [8]. These findings strongly suggest that drip irrigation is a highly effective technique for maximizing water use efficiency in agriculture.

Traditional drip irrigation systems rely on pressurized water delivery. However, the presence of sediment in our nation’s water sources poses a significant challenge. The tiny orifices within drip lines are highly susceptible to clogging from even minor amounts of turbidity. Consequently, it is imperative to purify the water before it reaches the drippers. This purification process involves pumping water from its source into sedimentation tanks and subsequently through filtration systems. A pump maintains a pressure range of 35–40 m throughout this process, ensuring efficient water delivery to the irrigation system (Figure 3).

The specific design of the drip irrigation system will be tailored to the unique characteristics of each region, considering factors such as terrain and water source (surface or underground). Following these individualized designs, the contracted company will manufacture all necessary components for the drip irrigation system. The company will then deliver these components to the project site and oversee their installation.

Efficiency of Drip Irrigation System

The scientific literature [3,5,6,7,8] shows that drip irrigation is the most effective among water-saving technologies. For example, drip irrigation of fruit trees saves up to 66–80% of water compared to furrow irrigation [8].

We compare furrow irrigation and drip irrigation methods, i.e., how many times per vegetation period fruit orchards are watered and how much water is consumed [33,34,35,36]. The number of irrigations and the volume of water supplied during the growing season under furrow irrigation for orchards was developed under the guidance of [37,38,39,40]. However, an irrigation regime for drip irrigation has not been developed so far in our republic. One of the main objectives of the realized project is to determine an irrigation regime for drip irrigation of fruit orchards in 6 regions of our country. Taking into account that the experiments on the determination of irrigation regime start in spring, the calculated values of drip irrigation regime are given in the article (

Table 1. List of irrigation regimes for orchards and vineyards by hydromodule districts of the Republic of Karakalpakstan and Kashkadarya, Surkhandarya, Khorezm, Bukhara, Namangan regions of the Republic of Uzbekistan.

No	The Organization Where the Project Is Being Implemented	Information About the Orchard				Types of Irrigation						Water Saved, %
		Mechanical, Structure of the Soil, %	Groundwater Level, m	Type of Tree	Age of Tree	Furrow Irrigation			Drip Irrigation
						Irrigation Period/Day	Irrigation Norm, m3/ga	Age of Tree	Irrigation Period/Day	Irrigation Norm, m3/ga	Number of Irrigation
1	Republic Karakalpakstan, Beruni district “Ozod intensive bog” farm (N-I-A-b-V)	-heavy sand and clay—12.1%; -medium sandy—32.5%; -light sandy—38.0%; -sandy—17.4%.	3.5	apricot	2	11.05–31.08/ 113	3600	4	11.05–31.08/ 113	1102	18	69.4
2	Khorezm region, Gurlan district “Mevazor gardens” LLC (N-I-A-b-V)	-heavy sand and clay—30%; -medium sandy—47%; -light sandy—19.4%; -sandy—3.6%.	2.5	apple	3	10.05–31.08/ 114	3600	4	10.05–31.08/ 114	1026	18	71.5
3	Bukhara region, Kogon district, Bukhara Institute of Natural Managament “Educational and scientific center” (C-I-A-b-V)	-heavy sand and clay—18.3%; -medium sandy—30.9%; -light sandy—49.7%; -sandy—5.7%.	2.5	apricot, peach	1	21.04–15.09/ 148	5300	6	21.04–15.09/ 148	1265	27	76.1
4	Kashkadarya region, Koson district, “Agrosuvtexmontaj” LLC, Department of Exploitation of Karshi Main Canals (C-I-A-b-V)	-heavy sand and clay—14.3%; -medium sandy—32.5%; -light sandy—38.0%; -sandy—17.4%.	3.0	apricot, almond	1	11.04–26.09/ 168	4800	6	11.04–26.09/ 168	1566	30	67.4
5	Surkhandarya region, Sariosia district, “Mindal-agro” farm (C-I-A-b-V)	-heavy sand and clay—21.7%; -medium sandy—50.0%;	5.5	apple	7	16.04–15.09/ 153	4900	7	16.04–15.09/ 153	1350	27	72.5
6	Namangan region, New Namangan district, “Samarkand oltin tolasi” farm (C-II-A-c-IV)	-heavy sand and clay—39.0%; -medium sandy—39.7%; -light sandy—17.4%; -sandy—3.9%.	3.5	plum	1	11.04–10.09/ 152	4300	7	11.04–10.09/ 152	1120	28	74.0

).

It is known that the distance between fruit trees in our country is mainly 4 m and the distance between rows is 5 m. About 500 seedlings are placed on 1 ha. The volume of water per 3–15-year-old tree is 60–200 L [41,42] (for trees within an area of 1 ha 30,000–100,000 L (30–100 m³, see column 9 in Table 1). Table 1 shows the irrigation regime, the beginning and end of irrigation, as well as the duration of irrigation in days per 1 ha of orchard under furrow irrigation (during the growing season) and drip irrigation.

The experiment examined the efficacy of drip irrigation compared to furrow irrigation for fruit trees. Two drip lines per tree, delivering 8 L of water per hour, were installed in experimental plots (

Table 2. Amount of water supplied to fruit trees per 1 ha during the vegetation period.

The Location Where the Project Is Being Implemented	Planting Scheme	Number of Trees, pcs.	Water Supply			Water for Irrigation, м3:					Water Saving, %
			Time, Hour	Number, Times		For Each Tree	Ones		During the Growing Season
				Furrow	Drip		Furrow	Drip	Furrow	Drip
Karakalpakstan	4 × 3	1310	7.5	4	18	0.060	900.0	61.2	3600	1102	69.4
Khorezm	5 × 3; 5 × 2.5	1020	7.5	4	18	0.060	900.0	57.0	3600	1026	71.5
Bukhara	6 × 5; 5 × 3	650	9.0	6	27	0.072	883.3	46.8	5300	1265	76.1
Surkhandarya	5 × 4	625	8.0	7	27	0.080	700.0	40.0	4900	1350	72.5
Kashkadarya	6 × 5; 5 × 3	725	9.0	6	27	0.072	800.0	52.5	4800	1566	67.4
Namangan	5 × 5	500	10.0	7	28	0.080	614.3	40.0	4300	1120	74.0

). Data collected included tree density per hectare, irrigation duration, number of furrows and drip lines, total irrigation events per tree, water usage per tree per irrigation event, and water consumption for a single furrow or drip irrigation. The percentage of water saved using drip irrigation versus furrow irrigation throughout the growing season was then calculated.

The results of calculations (Figure 4) indicate that water losses are within 3–40% and water saving (97–60%), respectively. Actual results for each object will be established on the basis of field experiments.

The main parameters of drip irrigation are the parameters of the pipe and the soil. These parameters are taken into account in our experiments. When determining the optimal parameters of the pipe in the drip irrigation system, it was necessary to determine the moisture distribution function. In this case, the function was considered dependent on time and coordinates.

What determines the principle of diffusion of moisture through the soil is the distribution of moisture through the soil from the drops of the pipe.

Diffusion of moisture through the earth—the moisture diffusion equation for spherical coordinates has the following form:

$${\displaystyle \frac{1}{r^2}}[{\displaystyle \frac{\partial }{\partial r}}\left(r^{2}D\left(\theta \right){\displaystyle \frac{\partial \theta }{\partial r}}\right)]={\displaystyle \frac{\partial \theta }{\partial t}}$$

(1)

Here, r—droplet radius, θ—volumetric moisture (the main parameter of the moisture diffusion function), D(θ)—the diffusion coefficient, and t—the time taken for moisture diffusion.

Equation (1) is a parabolic second-order differential equation. Equation (1) can be converted into an ordinary differential equation by considering Boltzmann transformations. It is linearized by averaging the diffusion coefficient.

$$D_{or}={\displaystyle \frac{1}{{\theta }_m-{\theta }_0}}{\int }_{{\theta }_0}^{{\theta }_m}D\left(\theta \right)d\theta$$

(2)

Here, ${\theta }_m$—maximum moisture retention; ${\theta }_0—$initial humidity storage. Then the equation becomes:

$$L{\displaystyle \frac{\partial \theta }{\partial t}}={\displaystyle \frac{1}{r^2}}{\displaystyle \frac{\partial }{\partial t}}\left(r^2{\displaystyle \frac{\partial \theta }{\partial t}}\right)$$

(3)

Here, L = 1/$D_{or};$ $D\left(\theta \right)=k\left(\theta \right)/c\left(\theta \right)$- diffusion coefficient.

$$\mathrm{k}={\mathrm{k}}_0\left(\right(\theta -{\theta }_0)/({\theta }_m-{\theta }_0){)}^{3.5}$$

(4)

(k₀—filtration coefficient at full saturation);

$$\mathrm{c}=-{\displaystyle \frac{d\theta }{d\psi }}$$

(5)

$\theta =f\left(\psi \right)$ dependence can be obtained in a number of ways.

Equation (3) is solved based on the following initial and boundary conditions.

T = 0 → $\theta ={\theta }_0;$

R = a₀ → $\theta =f\left(t\right);$

r$\to \infty$ → $\theta$—limited

We use the Laplace method to solve the problem. As a result, based on Equation (3) and the boundary conditions, the following result was obtained:

$${\displaystyle \frac{1}{r^2}}{\displaystyle \frac{d}{dr}}\left(r^2{\displaystyle \frac{\overline{d\theta }}{dr}}\right)=L\lambda \theta -L{\theta }_0$$

(6)

Solving them, we created an expression for the moisture diffusion function:

$$\overline{\theta }={\displaystyle \frac{a_0}{r}}\overline{f}\left(\lambda \right)e^{-\alpha \surd }\lambda -{\displaystyle \frac{a_0}{r}}{\displaystyle \frac{{\theta }_0}{\lambda }}{e}^{-\alpha \surd }\lambda +{\displaystyle \frac{{\theta }_0}{\lambda }}$$

(7)

Here, $\alpha =\left(r-a_0\right)\sqrt{L}.$

Based on the experimental results in [43], it is possible to choose ps by approximating the time dependence of humidity with an exponential function.

For example:

$$f\left(t\right)=\left({\theta }_0-{\theta }_m\right)\exp \left(-t\right)+{\theta }_m$$

(8)

In that case:

$$\overline{f}\left(t\right)=\left({\theta }_m-{\theta }_0\right){\displaystyle \frac{a_0}{r}}{\displaystyle \frac{1}{1+\lambda }}+{\theta }_m{\displaystyle \frac{1}{\lambda }}$$

(9)

Substituting Equation (8) into Equation (6), we obtained the following for the moisture diffusion function:

$$\overline{\theta }=\left({\theta }_m-{\theta }_0\right){\displaystyle \frac{a_0}{r}}\left[{\displaystyle \frac{\exp \left(-\alpha \sqrt{\lambda }\right)}{1+\lambda }}+{\displaystyle \frac{\exp \left(-\alpha \sqrt{\lambda }\right)}{\lambda }}\right]+{\theta }_0{\displaystyle \frac{1}{\lambda }}$$

(10)

Using the theorem of A.M. Efros, the following formula was created:

$$\theta =({\theta }_m-{\theta }_0)({\displaystyle \frac{a_0}{r}})(erfc ({\displaystyle \frac{\alpha }{2\sqrt{t}}})+{\displaystyle \frac{1}{\surd \pi t}}{\int }_0^{\infty }cos(\tau -\alpha )\exp \left(-{\displaystyle \frac{\tau }{4t}}\right)d\tau )+{\theta }_0$$

(11)

The calculations were carried out using the above formulas and the program “Mathcad”. For this, we accepted the following initial values:

$${\theta }_m=0.5; {\theta }_0=0.08; a_0=-{\theta }_0; k_0=0.041{\displaystyle \frac{cм}{min}}$$

$D_{or}$ Based on [5], we adopted the following expression for the definition:

$$\theta =\exp (-\psi \beta )$$

(12)

Here, β is determined by experiment.

The obtained results almost coincided with the experimental results. As can be seen from the graph, θ grows rapidly in the initial period and then remains stable and approaches θ_m. Figure 5 shows the dependence of θ on the radius corresponding to its value at t = 600. It can be seen that moisture retention initially decreases rapidly at the initial values of the radius and then asymptotically tends to θ₀. The results obtained using “Mathcad” are shown below:

θ₀ = 0.08 θ_m = 0.5 a₀ = 0.1 k₀ = 0.041 β = 0.05 r = 12 α = 0.4

$$D_{10}=\left[{\displaystyle \frac{k_0}{\beta {({\theta }_m-{\theta }_0)}^{4.5}}}\right]D_{11}={\int }_{{\theta }_0}^{{\theta }_m}({{\theta }_m-{\theta }_0)}^{3.5}\ast {\theta }^{-1}d\theta$$

D₁= D₁₀ × D₁₁D₁ = 35.779

$$B1(t)={\int }_0^{\infty }cos(\tau -\alpha )\mathit{exp}\left(-{\displaystyle \frac{\tau }{4t}}\right)d\tau )$$

$$\theta (t)=({\theta }_m-{\theta }_0)({\displaystyle \frac{a_0}{r}})\left(erfc ({\displaystyle \frac{\alpha }{2\sqrt{t}}})+{\displaystyle \frac{1}{\sqrt{\pi t}}}B1(t)\right)+{\theta }_0$$

3.2. Solar Energy Installation System with Pumping Units

In regions facing scarcity of both water and energy resources, photovoltaic systems offer a viable solution for powering the pumping units and control equipment essential to the efficient functioning of intelligent drip irrigation systems. This innovative approach leverages advanced photovoltaic battery technology [19,44]. The proposed system is distinguished by its integration of these modernized batteries (Figure 6). Photovoltaic battery (PVB) technology is recognized for its relatively low efficiency. The efficacy of PVBs is significantly impacted when deployed without considering regional climatic factors. High atmospheric temperatures, in particular, lead to a decrease in PVB efficiency and consequently reduced power generation. This diminished performance negatively affects the energy output and economic viability of PVB-based systems. In contrast, photothermal batteries (PTBs) integrated into autonomous mobile photothermal water-lifting units (AMPWLUs) demonstrate enhanced efficiency, even in arid climates [29,30]. Typically, various configurations of photovoltaic systems are employed for extracting water from wells:

1. Direct water-lifting systems. These offer ease of maintenance and cost-effectiveness compared to other systems. However, their operational efficiency hinges upon sufficient solar irradiance to generate the electricity required for the pump. The absence of energy storage capacity means they are inoperable during periods of cloud cover or at night. Moreover, connecting these systems to additional external power consumers is not recommended.

2. AMPWLUs with varying storage capacities. These ensure continuous operation of water pumps regardless of the time of day. While more expensive than direct photovoltaic water-lifting systems, AMPWLUs’ accumulator systems offers significantly higher power generation efficiency. These solar-powered water pumps play a crucial role in reducing reliance on electricity generated from fossil fuels. The effectiveness of these pumps is directly tied to the power output of PVBs. This power output can be calculated using a specific equation, which is not provided in the passage (13).

$$P_{ch}=U_M{I}_M$$

(13)

where I_M and U_M represent, respectively, the maximum current and voltage of the PVB array.

In order to ascertain the system’s electrical efficiency, one must first establish its input power. This input power can be mathematically defined as follows:

$${ P}_k=ES$$

(14)

where

E—intensity of solar radiation (W/m²);

S—surface of the PVB (m²)

The efficiency of the system is determined by the ratio of the power generated by the PVB to the radiation power incident on the PVB surface.

$$\eta ={\displaystyle \frac{P_{ch}}{P_k}}={\displaystyle \frac{P_{ch}}{ES}}$$

(15)

This project aims to utilize an AMPWLU powered by a PVB with a capacity of 4000 W. This system is used to power 8 PTBs, each with a capacity of 500 W, along with a 3000 W water-lifting pump. To assess the effectiveness of these devices in real-world conditions, test experiments have been conducted at implementation sites. Recognizing the challenges posed by dry climates in certain regions, a specialized heat collector made from honeycomb polycarbonate has been developed. The design features wider and taller parallel channels (1.5 times larger than standard collectors) to enhance cooling efficiency for the rear surface of the PTB units. The project seeks to optimize water flow rate and volume from the thermal collector, thereby reducing the temperature of the PTBs to meet the certification standards (AM 1) specified by the PVB manufacturer under defined operating conditions.

This project repurposes the platform of a commonly used waste transport cart in urban environments for the generation of AMPWLUs (presumably, a type of renewable energy). Future design modifications to the cart platform hold the potential to amplify the photovoltaic system’s power output to 6–7 kW.

Table 3. Physical–technical characteristics of PTB parts with power of 4000 W.

Maximum Power PVB, Pmax	500 W	8 PVB
Coefficient of efficiency PVB, η	20.3 %	20.3%
Open circuit voltage PVB, Uoc	22.8 B	22.8
Short-circuit current PVB, Isc	8.9 A	8.9 A
Fill factor VACh, ff	0.71–0.73	0.71–0.73
Thermal collector capacity (CC) made of cellular polycarbonate, V	17 L	17·8 = 136 L
Thermal conductivity of cellular polycarbonate, r	0.2–3.9 W/m °C	0.2–3.9 W/m °C

details the physical and technical specifications of the PTB components, which currently boast a power capacity of 4000 W.

This study was investigated the relationship between changes in solar radiation flux density, daytime air temperature, and the temperature of water extracted from a depth of 30–40 m. A specialized distribution mechanism divides the ascending water flow, diverting one-third to a water-lifting unit. This portion then circulates through a heat collector situated on the rear surface of a photovoltaic thermal (PTB) system before rejoining the primary water stream and entering the storage basin.

AMPWLU systems demonstrate high water-lifting efficiency throughout the day because of their integrated electric energy storage system. This system utilizes advanced helium accumulators boasting an efficiency of up to 80% and a lifespan of 8 to 10 years. Furthermore, the system incorporates pure sine wave inverters, ensuring compatibility with contemporary water pumps capable of lifting water from depths of 80 to 100 m.

AMPWLUs’ mobile design utilizes a two-coordinate system for precise solar disk orientation. This dynamic positioning significantly reduces solar radiation loss on photovoltaic panels compared to stationary installations, achieving up to an 80% reduction. Consequently, AMPWLUs demonstrate a substantially higher installed capacity utilization factor (3–4 times) than traditional fixed power plants. Furthermore, the advanced control electronics incorporated into AMPWLU controllers, featuring load point tracking on the volt–ampere characteristic curve and “pure sine” inverter technology, ensure high efficiency and minimal electrical losses.

3.3. Irrigation Automation System

Optimizing crop yield necessitates mitigating biological stressors during irrigation. Human intervention in traditional irrigation practices can introduce variability and inefficiency. To address this, the project incorporates an automated drip irrigation system. This system utilizes programmed controls that adjust water delivery based on the specific water requirements of the plants [31,32]. By employing intelligent automation, the system promotes more economical water usage for agricultural irrigation, leading to a more sustainable and efficient allocation of water resources.

Determining the optimal irrigation strategy for agricultural crops involves a thorough analysis of the site’s soil characteristics. This includes evaluating factors such as water permeability, capillarity, maximum water retention capacity, volume, bulk density, and porosity. These parameters are considered in relation to the specific growing season to accurately estimate soil moisture levels. These comprehensive data are then integrated into an intelligent drip irrigation program, which comprises three main components (Figure 7).

Moisture Sensor. The system utilizes moisture sensors deployed throughout the irrigation zone. These sensors continuously monitor soil moisture levels and transmit the data in real-time to a central processing unit. Powered by solar panels for sustainable operation, the sensors provide the central unit with crucial information about soil hydration. Based on this data analysis, the central unit then issues automated commands to the pump controller, initiating irrigation when required to maintain optimal soil moisture for crop growth.

Pump Controller. The pump controller manages the operation of the pump by activating and deactivating it as needed. It also continuously monitors the water level within the supply. Should the water level drop below a predetermined threshold, the controller will automatically cease pump operation to mitigate the risk of electrical shorts. This device operates under the authority of a central unit, faithfully executing commands to turn the pump on or off based on data received from the central unit.

Software and mobile application. The project team developed software and a mobile application for the automated irrigation system [30]. This technology facilitates communication and control between soil moisture sensors, pump activation/deactivation, and the regulation of drip irrigation components. The mobile application provides users with real-time operational data and enables them to remotely initiate or terminate the system.

3.4. Supply of Quality Water to the Drip Irrigation System

Drip irrigation systems face challenges due to sediment content in the water source. While groundwater is typically clear and suitable for direct use, surface water sources like the Amudarya, Syrdarya, and Zarafshan Rivers carry significant amounts of suspended and bedload sediments. These sediments, characterized by a specific size distribution (

Table 4. Size and amount of suspended sediment in water sources.

Diameters of Suspended Sediment Fractions (mm) and Their Quantity (%)									Daverage, мм
2.0−1.0	1–0.5	0.5–0.2	0.2–0.1	0.1–0.05	0.05–0.01	0.01–0.005	0.005–0.001	>0.001
Zarafshan River (Hydropost 124, Navaiy, 10 August 2015)
-	-	20.3	26.3	27.5	3.4	2.5	5.5	14.5	0.133
Sirdaryo River (Hydropost 1, Kal Village, 8 June 2017)
-	22.5	18.5	9.9	15.4	4.9	28.8	-	-	0.264
Amudaryo River (Hydropost 83, Tuyamuyun Gorge, 29 June 2017)
-	7.5	16.8	16.9	22.1	4.6	1.3	17.4	13.4	0.161

and Figure 8), can lead to operational issues within drip irrigation systems. The presence of sediment causes clogging of emitters, ultimately resulting in system malfunction. Furthermore, the abrasive nature of these sediments accelerates wear and tear on the pump components responsible for delivering water to the drip system [45].

The size of turbidity in water passing through droppers and pumps should not be more than d = 0.1 mm, and the amount should not be more than 0.3 g/L (

Table 5. Permissible values of concentration and size of suspended particles contained in irrigation water of drip irrigation systems.

Size of Through Holes, mm	Permissible Concentration of Suspended Particles in Water and Their Sizes
	Concentration, g/L	Particle Size, mm
<1	0.03–0.05	<0.05
1–2	0.05–0.1	<0.07
>2	0.1–0.3	<0.1

) [25,46]. The amount and size of suspended solids that can pass through the droppers are presented in Table 5.

The compositions of suspended sediment samples from the Amudarya, Syrdarya, and Zarafshan Rivers were analyzed (

Table 6. Analysis of turbidity boundary conditions in rivers.

Water Source and Sampling Point	Year, Day, Month of Sampling	Sediment Diameters (mm) and Their Quantity (%)
		(0.1–2.0) mm	(0.1–0.001) mm
Zarafshan River (Hydropost 124, Navaiy)	10 August 2015	46.6	53.4
Sirdarya River (Hydropost 1, Kal Village	8 June 2017	50.9	49.1
Amudarya River (Hydropost 83, Tuyamuyun Gorge	29 June 2017	41.2	58.8

), and compositions were identified that can and should not pass through droppers and pumps (Table 6). Analysis of Table 6 shows that the turbidity sizes in all water sources that should not pass through droppers and pumps (d > 0.1 mm, Table 6, column 3) are 400–500% greater than the sizes that can pass through them (d < 0.1 mm, Table 6, column 4).

With drip irrigation, in order to avoid clogging of droppers with dirt and abrasive wear on pump parts, muddy water is purified using coarse and fine filters and then fed into the drip irrigation system [46]. The fine filter captures undissolved heavy metal compounds, various organic compounds, and chemical elements, as well as relatively large microorganisms. The coarse filter captures large insoluble fractions present in turbid water—coarse and fine sand, rust particles, and other large objects [46].

When feeding underground, spring, stream, and other clean water into a drip irrigation system, only soft filters can be used. In cloudy water, both types of filters are used. However, you can avoid the use of coarse filters by using the method of hydraulic water purification for large turbidities, which cannot pass through drippers and pumps.

Hydraulic calculation of the supply channel and drainage pond. Using hydraulic calculations, it is possible to retain suspended sediment with a particle size of—d > 0.1 mm in the supply channel. To do this, the average water speed in the supply channel must be less than or equal to the non-erosive sediment speed, the average size is less than 0.1 mm (d < 0.1 mm), i.e.,

$$V_{средн.}\le V_0^{0,1мм}$$

(16)

The sizes of the largest sediments in the sediment composition of the Syrdarya, Amudarya, and Zarafshan Rivers are 1.0–0.1 mm (

Table 7. Composition of suspended sediments of the Syrdarya, Amudarya, and Zarafshan Rivers and their hydraulic size, depth, and time of sedimentation.

No	Granulometric Composition	Hydraulic Size, mm/s	Settlement Time to a Depth of 1 m
1	Coarse sand (d = 1.0–0.50 mm)	100	10 s
2	Medium sand (d = 0.50–0.20 mm)	53	19 s
3	Fine sand (d = 0.20–0.10 mm)	6.9	2.4 min
4	Sandy loam (d = 0.10–0.05 mm)	1.7	9.8 min
5	Loam (d = 0.05–0.01 mm)	0.07	3.9 h
6	Clay (d = 0.01–0.005 mm)	0.08	2.3 days
7	Heavy clay (d = 0.005–0.00 1 mm)	0.0007	16.2 days
8	Colloidal particles (d > 0.001 mm)	Hydraulic size, mm/s	10 s

, Figure 9) [47,48]. Figure 10 shows the process of sedimentation of sediment particles from the source, along the length of the channel and in the drainage basin.

One of the main structures of an automated integrated drip irrigation system is a drainage basin. The main task of the pool is to maintain the water entering the drip irrigation system in the required volume, as well as to clarify the water entering the drip irrigation system. The depth of the basins at the sites where the drip irrigation system was determined depending on the geometric (d) and hydraulic value (W) of the turbidity in them, up to 3–4 m. Part of the sediment with a size d > 0.1 mm coming from the source settle in the supply channel. Sediments with hydraulic coarseness from 9.8 min (sandy loam − d = 0.10–0.05 mm) to 3.9 min (loam − d = 0.05–0.01 mm) [49], settle to the bottom of the drainage basin pool during the day (Figure 9). Table 5 shows data on the composition of sediments with a diameter d < 0.1 mm, depth, time (hydraulic size) of sedimentation and distance on the Syrdarya, Amudarya, and Zarafshan Rivers.

Water purified of large sediments (d = 1.0–0.1 mm) in the channel is not dangerous for drippers and pumps, since the sediment size (d = 0.10–0.001 mm) in the remaining water does not exceed the limit value. On the contrary, supplying fine fractions of suspended particles to irrigated fields will improve the quality of irrigation water, which contains mineral fertilizers (humus, etc.) that affect soil fertility [38,39].

4. Conclusions

The efficiency of applications of complex automated drip irrigation systems in foothill gardens of the Republic of Karakalpakstan and the Bukhara, Kashkadarya, Namangan, Khorezm, and Surkhandarya regions of the Republic of Uzbekistan was analyzed.

The conclusions of the study can be summarized as follows:

1.

The use of a mobile PTB system with capacity N = 4.0 kW (8 PTBs with a capacity of 500 W each) allows us to provide energy for pumping units with capacity up to N = 3.0 kW, supplying sufficient water for drip irrigation of 8-10 ha of orchards with fruit trees.

2.

During the summer months, the implementation of photothermal battery (PTB) technology is projected to yield nearly double the electricity generation compared to conventional photovoltaic (PV) systems. This enhanced performance is attributed to the cooling effect inherent in PTBs.

3.

The adaptability of the photothermal battery system enables its utilization across all seasons. The installed capacity utilization factor increases by 30–40% (depending on the location of the research object) compared to stationary systems.

4.

For reliable operation of the drip irrigation system, the supplied water must be purified of sediment up to 0.1 mm. Purification of water supplied to the drip irrigation system from sediment (d > 0.1 mm) by hydraulic method (by improving the design of supply channels and drainage) will allow to operate the system without coarse filters, the use of which leads to additional hydraulic (and, consequently, energy) losses in the system.

5.

Water saving in orchards under the use of complex drip irrigation system at facilities is 67.4% (Republic of Karakalpakstan)—76.1% (Bukhara region) in comparison with traditional irrigation (for the Republic as a whole—60–70%);

Thus, the use of such combined installations on the basis of a drip irrigation system, mobile solar energy installation, and automation system will allow us to save water and energy resources significantly and to increase the reliability of water irrigation.