Energy Environment and Economy

1. Introduction

Water and energy scarcity rarely arrive separately, and in Iraq they have arrived together, compounding each other in ways that are becoming difficult to ignore. Upstream dam construction on the Tigris and Euphrates has reduced the volume of surface water reaching downstream governorates, a trend documented in regional assessments of Iraq’s renewable and water-resource landscape (Al-Khatib & Al-Sari, 2021), while longer dry seasons and reduced rainfall have accelerated the salinization of arable land in several provinces (Mahmoud, 2022). The two pressures feed into one another: less surface water means greater reliance on groundwater, and pumping that groundwater requires energy that, in rural areas, is often unavailable from the national grid or too unreliable to depend on. It is a somewhat uncomfortable position for a country whose agricultural sector still supports a considerable share of rural livelihoods.

Babylon Governorate illustrates this dynamic with unusual clarity. In the Al-Shomali district specifically, farmers face what might be called a double deficit — surface irrigation canals no longer deliver consistent flow, and grid electricity, where it exists at all, is intermittent enough that most groundwater extraction depends on diesel generators (Al-Saffar, 2020). This arrangement works, more or less, but it is neither cheap nor stable. Fuel prices fluctuate, generators require frequent maintenance in the region’s dusty, high-temperature climate, and the greenhouse gas emissions involved sit uneasily alongside the country’s broader environmental commitments. There is, in short, a fairly strong practical case for looking elsewhere.

Solar photovoltaic technology is an obvious candidate, and not a new one — the underlying physics of converting incident radiation into usable electrical or mechanical energy has been well understood for decades (Duffie & Beckman, 2013; Goetzberger & Hoffmann, 2005). What has changed more recently is the sophistication with which these systems can be sized and matched to a specific hydraulic load. Early work by Glasnovic and Margeta (2007) argued that solar pumping schemes perform best when the irradiance profile is deliberately matched to the irrigation demand curve rather than treated as a generic power source, and subsequent studies have largely supported that view. Chandel and Nagaraju (2015), for instance, found that decentralized PV pumping installations achieve meaningfully lower losses when component sizing is approached carefully rather than approximated. Kumar and Rosen (2017), in a fairly comprehensive review, went further and suggested that oversizing — a common instinct among designers wary of underperformance — is itself one of the main barriers to wider adoption, since it inflates upfront cost without a proportional gain in reliability.

Controlling how that power is drawn from the array turns out to matter almost as much as sizing it correctly. Hamidat et al. (2003) showed that under partial shading or low irradiance, dynamic load matching becomes essential if the pump is to keep operating rather than stall, and maximum power point tracking (MPPT) has since become close to standard practice in serious PV pumping designs. Simulation tools such as PVsyst and MATLAB have made it considerably easier to anticipate how these nonlinear PV-pump interactions will behave before any hardware is purchased (Khatib & Elmenreich, 2016; Ibrahim & El-Mahdy, 2018), which is useful, though simulation alone cannot fully substitute for what happens once dust, heat, and real hydraulic variability enter the picture.

Iraq-specific literature on renewable energy is growing, if still somewhat thin. Al-Saffar (2020) catalogued the country’s considerable solar resource potential, and Al-Khatib and Al-Sari (2021) reached similar conclusions regarding the broader renewable capacity available to offset national grid deficits. Mahmoud (2022) looked specifically at solar-powered irrigation and reported clear advantages over diesel alternatives, at least in aggregate terms. What remains comparatively rare, however, is site-specific work that carries a design all the way from theoretical sizing through simulation and into an actual field installation with measured performance data — most regional studies stop at the simulation stage, or rely on generalized climatic averages rather than data drawn from the installation site itself.

This study attempts to close at least part of that gap. It presents the hydraulic and electrical design of a standalone 1500 W PVWPS tailored to the specific conditions of Al-Shomali district, follows that design through a PVsyst simulation built on local meteorological inputs, and — perhaps most usefully — compares the simulated predictions against measurements taken from the system once it was actually built and put to work. The aim is not simply to add another case study to the literature, but to offer a reasonably transparent, reproducible account of how such a system performs when theory meets an Iraqi summer.

2. Methodology

2.1 Study Design and Site Description

This study followed a sequential design–simulate–validate approach, moving from analytical hydraulic and electrical sizing calculations, through software-based performance simulation, to physical field deployment and empirical measurement. The site was a working agricultural plot in the Al-Shomali district, Babylon Governorate, southern Iraq [site coordinates and elevation to be inserted by the author, e.g., approximate latitude/longitude and ground elevation above sea level]. The region is characterized by an arid to semi-arid climate, high summer ambient temperatures, elevated solar irradiance, and a reliance on artesian groundwater wells for agricultural water supply, since surface irrigation canals in the area no longer provide a reliable source.

2.2 Water Demand and Hydraulic Load Determination

Daily agricultural water demand (V) was established at 25 m³/day, derived from local crop water requirements, estimated soil evaporation rates for the governorate, and the cultivated area served by the well [author to specify the crop type(s), cultivated area in hectares, and the reference evapotranspiration method used, e.g., FAO Penman–Monteith, to allow independent recalculation]. A submersible centrifugal pump was selected to draw water from an artesian well with a working depth of approximately 25–30 m and a borehole diameter of 15 cm.

Total Dynamic Head (TDH) — the total equivalent lift the pump must overcome — was determined from direct field measurement of its four constituent components, summed according to the standard hydraulic relation:

TDH = H_static + H_drawdown + H_discharge + H_friction (1)

where H_static is the static water level in the well (measured at 18 m using [instrument, e.g., an electric water-level dipmeter — to be specified]), H_drawdown is the additional depression of the water table under continuous pumping (estimated at 4 m from a step-drawdown or comparable well test — test protocol and duration to be specified by the author), H_discharge is the vertical rise from ground level to the tank inlet (3 m, measured directly), and H_friction is the head loss attributable to pipe roughness and fittings (calculated at 2.5 m using the Hazen–Williams or Darcy–Weisbach equation, with pipe diameter, length, material, and roughness coefficient to be reported). Substituting these values gives TDH = 18 + 4 + 3 + 2.5 = 27.5 m, which was then used as the design basis for pump selection and PV array sizing.

2.3 Electrical and Hydraulic Energy Sizing

The daily hydraulic energy requirement (E_h, kWh/day) needed to lift the design volume against the calculated TDH was obtained from the standard fluid-mechanics relation

E_h = (ρ · g · V · TDH) / (3.6 × 10⁶) (2)

which, for water (ρ = 1000 kg/m³) and standard gravitational acceleration (g = 9.81 m/s²), simplifies to the commonly used engineering approximation

E_h = (V · TDH) / 367 (3)

Applying Equation 3 to the design parameters (V = 25 m³/day, TDH = 27.5 m) yields a net hydraulic energy demand of approximately 1.87 kWh/day. Because this figure represents only the theoretical minimum, it does not account for real-world losses in the pump, motor, and any power-conditioning electronics. The required photovoltaic array energy (E_PV) was therefore derived by dividing the hydraulic energy by an assumed overall system efficiency (η_sys):

E_PV = E_h / η_sys (4)

A conservative η_sys of 45–50% was adopted, reflecting typical electromechanical losses under high-temperature field conditions, which supported the selection of a 1500 W array — a margin intended to accommodate soiling losses, thermal derating in summer, and day-to-day irradiance variability rather than to meet the bare theoretical minimum alone.

2.4 System Components and Configuration

The array consisted of five 300 W monocrystalline silicon modules connected in series, rated at 32.2 V and 9.3 A under Standard Test Conditions (STC) [manufacturer and model number to be specified], producing a combined array output of 1500 W and a voltage compatible with the input range of the MPPT controller. Modules were mounted on a fixed metal frame oriented at a tilt angle of 33° and an azimuth of 0° (true south), values chosen to approximate the optimal collection angle for the site latitude. A Perturb and Observe (P&O) MPPT algorithm, implemented via an EPEVER Tracer 4210AN controller using a perturbation step size of ΔV = 0.5 V and a sampling interval of Δt = 100 ms, was used to continuously adjust the operating voltage of the 1500 W, 24 V DC submersible pump so as to track the array’s maximum power point as irradiance varied, reducing the likelihood of pump stalling under partial shading or low-light conditions. Water-level sensors were installed in both the well and the storage tank, feeding back to the controller to prevent dry-running of the pump and to halt operation once the 25 m³ tank reached capacity. No electrochemical battery storage was included in the design; instead, the system relies on hydraulic (tank) storage to bridge non-sunlight hours, a choice discussed further as a limitation below.

2.5 Simulation Protocol

Performance simulation was carried out in PVsyst (PVsyst SA, 2024) using hourly meteorological input data specific to the Al-Shomali site [data source to be specified — e.g., Meteonorm database, satellite-derived irradiance, or an on-site pyranometer/weather station, including the record period and temporal resolution]. The array was modeled under an unshaded, free-horizon assumption, with component parameters (module electrical characteristics, MPPT behavior, and pump curve) drawn from the software’s internal device library and cross-checked against manufacturer datasheets where available. The simulation was run over a full meteorological year to capture seasonal variation in irradiance, ambient temperature, and resulting hydraulic output, and to generate the loss-diagram and Performance Ratio outputs reported in the Results section.

2.6 Field Deployment and Empirical Validation Protocol

Following simulation, a physical prototype matching the simulated specifications was constructed and commissioned at the study site. Volumetric flow validation was performed using a 1 m³ calibrated metering tank and digital chronometry, with flow rate measured at the design operating point (27.5 m TDH) [number of measurement trials, dates, and time-of-day conditions to be specified for reproducibility]. Field monitoring is understood here to have continued over [monitoring duration and start/end dates to be specified by the author] to allow comparison of simulated and measured Performance Ratio, daily pumped volume, and system efficiency across representative seasonal conditions. Where discrepancies between simulated and measured output were observed, panel soiling (dust accumulation) was assessed qualitatively as a likely contributing factor, consistent with conditions widely reported across the region; a quantified soiling-loss measurement (e.g., paired clean/soiled panel comparison) would strengthen this attribution in future work.

2.7 Environmental and Performance Metrics

System performance was evaluated using the Performance Ratio (PR — the ratio of actual to theoretically expected energy yield under STC), overall system efficiency (η_sys), specific energy yield (Y_f, kWh/kWp/day), and total annual pumped volume. Annual CO₂ emission savings were estimated by comparison against an equivalent diesel-generator-powered pumping system, using a standard diesel-generator emission factor of 0.8 kg CO₂/kWh (IPCC, 2006).

3. Results and Discussion

3.1 Annual Energy Yield and Overall System Efficiency

Across the simulated meteorological year, the array received a total global solar radiation of 2100 kWh/m², from which 2800 kWh/year of usable array energy was estimated to be available (Table 1). This translated into an annual pumped volume of 9125 m³ — an average of almost exactly 25 m³ per day, which is reassuring, since it confirms that the hydraulic sizing carried out earlier held up once seasonal variability was folded into the simulation rather than assumed away. The resulting overall system efficiency of 48% (Table 1) is broadly in line with what one would expect for an electromechanical fluid-transport chain of this kind, once thermal losses in the array and mechanical losses in the centrifugal pump are accounted for; it is not an exceptional figure, but it is a believable one, and that arguably matters more for a system meant to be replicated elsewhere.

3.2 Seasonal Productivity and Loss Distribution

The normalized productivity analysis (Figure 2a) shows a system that behaves, on the whole, predictably across seasons — useful energy production (Y_f) averaged 4.63 kWh/kWp/day, with the expected seasonal dip during the winter months (November–February) attributable to shorter daylight hours and a lower solar incidence angle. Collection losses (L_c), averaging 1.26 kWh/kWp/day, were concentrated instead in the summer, when elevated module temperatures and the negative temperature coefficient of the monocrystalline cells eroded some of the gains from higher irradiance. This inverse seasonal relationship between energy availability and thermal loss is a familiar pattern in hot climates, though it is still worth flagging explicitly, since it means peak irrigation demand and peak thermal penalty arrive at more or less the same time of year.

The detailed loss diagram (Figure 2b) breaks this down further. Unused energy (L_u) — power generated once the storage tank is already full — was estimated at 1.20 kWh/day, suggesting a modest degree of intentional array oversizing (roughly 120 W) built in specifically to maintain

Figure 1. System architecture and field deployment of the standalone photovoltaic water pumping system (PVWPS). (a) Schematic block diagram of the electro-hydraulic components, showing the PV array, controller/inverter, well and pump assembly, and storage tank, with the Total Dynamic Head indicated. (b) Single-diode equivalent electrical circuit model of the deployed monocrystalline PV cell used for PVsyst modeling. (c) Electro-hydraulic integration diagram of the physical prototype as installed, showing water-level sensor placement, pump position, and pipe routing between the well, pump, and storage tank.

Figure 2. Simulated annual performance of the PVWPS over a full meteorological year. (a) Normalized specific productivity showing produced useful energy (Yf), collection losses (Lc), and system losses (Ls). (b) Simplified system component diagram used in the PVsyst loss model (array, inverter, injection point). (c) Monthly variation in Performance Ratio (PR), with an annual mean of 0.768. (d) Frequency distribution of the system’s useful output power across the annual operating cycle.

output during cloudy periods. Collection losses (L_c ≈ 0.85 kWh/day) and system-level conditioning losses (L_s ≈ 0.30 kWh/day) both remained within what would generally be considered acceptable bounds for this class of system. After these losses, the active energy delivered to the pump (Y_f) settled at 2.95 kWh/day, comfortably sufficient to overcome the 27.5 m TDH on a consistent basis.

3.3 Performance Ratio Stability

The monthly Performance Ratio trace (Figure 2c) stayed within a fairly narrow band around a mean of 0.768 (≈77%), with small month-to-month fluctuations tracking ambient temperature and local irradiance. It is tempting to attribute this stability entirely to good component selection, but the more accurate reading is probably that the P&O MPPT controller deserves much of the credit — by continuously repositioning the pump’s operating voltage toward the array’s instantaneous maximum power point, it appears to have limited the extent to which partial shading or elevated summer temperatures could drag performance down.

3.4 Field Deployment and Array Configuration

The physical prototype (Figure 1c) was built around five series-connected 300 W monocrystalline modules (32.2 V, 9.3 A at STC), mounted at the same 33° tilt used in simulation, and configured to deliver a target flow of roughly 5000 L/hour based on 25 m³/day and an assumed five hours of usable insolation. The plumbing layout was kept deliberately direct, with minimal bends between pump and tank, in order to avoid adding unnecessary friction losses beyond those already budgeted for in the TDH calculation. Water-level sensing at both ends of the system (well and tank) provided the feedback needed to protect the pump from dry-running or continuing to operate once storage capacity was reached. The overall electro-hydraulic architecture — from array, through controller and well assembly, to the storage tank — is summarized schematically in Figure 1a, alongside the single-diode equivalent circuit used to model the array’s electrical behavior in PVsyst (Figure 1b).

3.5 Climatic Variability and Monthly Performance

Monthly climatic data (Figure 3a) confirm what the Introduction already implied — solar irradiance and agricultural water demand peak at almost the same time of year, but so does ambient temperature, which works against PV efficiency even as it drives demand upward. The monthly electrical yield and Performance Ratio trends (Figure 3b) reflect this tension directly: energy generation reaches its maximum during peak summer, precisely when it is most needed, but the Performance Ratio dips over the same period, a pattern consistent with thermal derating of monocrystalline silicon above STC reference temperature. That the PR nonetheless remained comparatively stable through this seasonal penalty is arguably the more interesting finding, and again points toward the MPPT controller as the main stabilizing factor.

The scatter relationship between incident radiation and daily useful energy (Figure 3c) was tightly linear, with operating points clustered closely along a single trajectory — a pattern that suggests the MPPT algorithm tracked the true maximum power point consistently, without major oscillation or tracking failure, across the full range of irradiance conditions encountered.

3.6 Output Power Distribution and Equivalent Circuit Behavior

The annual power output distribution (Figure 2d) shows the system spending most of its operating hours near its 1500 W rating, with a pronounced peak toward the higher end of the power spectrum — evidence that, despite the harsh environmental conditions described earlier, the array delivered high-efficiency output for the majority of daylight hours. Lower-frequency bands at the low-power end of the distribution correspond to short transitional periods around sunrise, sunset, and episodes of heavy cloud cover, rather than any sustained underperformance. The single-diode equivalent circuit model (Figure 1b) — comprising a light-generated current source, a shunt resistance, and a series resistance representing ohmic and leakage losses — underpinned the PVsyst modeling of these dynamics, and its series/shunt resistance values were an important determinant of how the simulated I–V curve responded to Al-Shomali’s particular temperature and irradiance profile.

3.7 Field Validation Against Simulation

Volumetric field testing, using a 1 m³ metering tank and digital timing at the design operating point of 27.5 m TDH, produced a measured Performance Ratio that came reasonably close to the simulated value of approximately 78% (Table 2), which is encouraging, though it should be read as an initial validation rather than a long-term average given the relatively short measurement window involved. Where the two diverged, localized soiling — fine dust settling on the panel surface, a near-daily occurrence

Figure 3. Field climatic conditions and empirical performance validation. (a) Monthly solar irradiance components (global horizontal, diffuse horizontal, global incident) and ambient temperature recorded at the Al-Shomali site. (b) Monthly electrical energy yield (array and useful energy) alongside monthly Performance Ratio. (c) Scatter relationship between daily global incident solar radiation and daily useful system energy output, illustrating the linearity of the array’s electrical response across the full range of irradiance conditions.

Table 1: Technical and physical specifications of the proposed PV pumping system in the Al-Shomali area.

Table 2: Analytical summary of annual simulation results and overall system performance indicators.

in this part of Iraq — appeared to be the most plausible explanation, alongside a degree of partial dust shading on portions of the array. The P&O MPPT controller again proved useful here, continuously repositioning the pump’s operating voltage to track the best available power point and thereby helping to prevent stalling as irradiance fluctuated through the day.

3.8 Techno-Economic Implications

Taken as a whole, these results point toward a system that is not just technically functional but plausibly the more sensible economic choice over time, given the ongoing fuel, maintenance, and downtime costs associated with diesel alternatives (cf. Kumar & Rosen, 2017). That said, the present study did not carry out a formal levelized-cost-of-water or payback-period calculation, and doing so — ideally incorporating local diesel fuel prices, capital cost of the PV/MPPT/pump package, and expected maintenance intervals — would considerably strengthen the techno-economic claims made here and is recommended as a priority for follow-up work.

4. Conclusion

This study designed, simulated, and field-tested a 1500 W standalone photovoltaic water pumping system for the Al-Shomali district of Babylon Governorate, sized to overcome a 27.5 m Total Dynamic Head while delivering approximately 25 m³ of water daily. Simulation and field measurements agreed reasonably well, yielding an average Performance Ratio near 78% and an overall system efficiency of about 48%, with the Perturb and Observe MPPT controller appearing central to maintaining that stability across variable irradiance and seasonal temperature swings. The system was estimated to avoid roughly 1.8 tons of CO₂ annually relative to diesel pumping. Taken together, these findings suggest that a carefully sized, site-specific PVWPS can offer a technically reliable and reasonably economical alternative to diesel-based irrigation in similarly water- and grid-scarce regions, though longer-term, multi-season monitoring and a formal economic (payback/LCOW) analysis would help confirm just how durable and cost-effective this solution proves to be at scale.

Acknowledgments

The author is grateful to the academic faculty who provided guidance throughout this research, and to the cooperative farmers of the Al-Shomali district for their practical support during field implementation.

Author Contributions

S.A.M.A.-H.: conceptualization, methodology, software, formal analysis, investigation, data curation, writing – original draft, writing – review and editing, visualization, project administration.

Funding

Self-funded research. No financial support or commercial grants were received during the preparation or execution of this study.

Competing Financial Interests

The author S.A.M.A.-H declares no competing financial interests, personal relationships, or commercial affiliations that could have influenced the work reported in this manuscript.

References