Techno-Economic And Environmental Assessment Of Grid-Connected Solar Photovoltaic Systems For Urban Sewage Treatment Plants: A Case Study Of Jabalpur, Madhya Pradesh

Table I. Project And Energy Parameters Reported In The DPR.

Fig. 1. Conceptual architecture of the proposed grid-connected PV system for the two STPs.

IV. PV SYSTEM CONFIGURATION

The DPR proposes a grid-connected, net-metering configuration without battery storage. The inverter output is connected to the existing LT panels, and surplus energy is intended to be exported through a bi-directional meter under the applicable state net-metering arrangement [16]. At Kathonda, the PV deployment combines rooftop, ground-mounted and vehicle-parking-shade areas. The DPR identifies approximately 79,105 ft² of total available area and an installable capacity of 1039 kW. At Lalpur, approximately 16,355 ft² of total available area is reported, with an installable capacity of 198.83 kW [16].

The technical specification calls for high-efficiency crystalline PV modules of at least 590 W, module efficiency above 22% under STC, IEC/BIS-compliant certification, RFID-based identification/traceability and long-term performance warranty provisions. The mounting structures are specified for corrosion resistance and wind speeds up to approximately 150 km/h. The inverter specification includes 415 V, three-phase, 50 Hz operation, MPPT control, THD below 3%, inverter efficiency above 95% at full load and operating capability up to approximately 55 °C [16].

V. METHODOLOGY AND EQUATIONS

The analysis uses the DPR values as source data and applies transparent secondary calculations. The following indicators are used.

Specific PV yield:   Y_f = E_PV / P_PV

Capacity utilization factor:   CUF = E_PV / (P_PV × 8760) × 100

Gross annual electricity value:   S = E_self × C_e

Simple payback period:   SPP = C_0 / S

Avoided carbon emissions:   M_CO2 = E_grid,displaced × EF_grid

Levelized cost of electricity:   LCOE = Σ[C_t/(1+r)^t] / Σ[E_t/(1+r)^t]

where E_PV is annual PV generation, P_PV is installed PV capacity, C_e is electricity tariff, C_0 is initial capital cost, E_grid,displaced is grid electricity displaced, EF_grid is the applicable grid-emission factor, C_t is annual cost, E_t is annual electricity generation and r is the discount rate.

Because the DPR does not provide an hourly load profile, the paper does not claim an hourly self-consumption ratio. The term 'gross annual electricity-offset value' is therefore used rather than guaranteed cash saving.

VI. RESULTS AND ANALYSIS

Fig. 2. Proposed PV capacity and projected annual generation at Kathonda and Lalpur.

The combined proposed PV capacity is 1237.83 kW and the projected annual generation is 18.07 lakh kWh. The corresponding specific yield is approximately 1,459.8 kWh/kWp-year. The implied CUF is approximately 16.66%. The source DPR separately specifies a minimum plant CUF of 17%; the projected generation of 18.07 lakh kWh therefore corresponds to a CUF slightly below that threshold when calculated directly from the stated installed capacity. This is a source-data consistency issue that should be checked against the final PV simulation and sanctioned capacity.

Fig. 3. Comparison of reported annual STP electricity consumption and projected annual PV generation.

The projected annual PV generation (18.07 lakh kWh) is approximately 0.39% higher than the reported annual electricity consumption (18.00 lakh kWh). This near-equivalence supports the DPR's objective of annual energy offset. However, it should not be interpreted as 100% real-time energy independence because PV output is intermittent and the STP load persists at night and during low-irradiance periods.

Table II. Derived Performance Indicators.

VII. ECONOMIC ANALYSIS

The DPR reports a total project cost of ₹723.00 lakh including the solar PV systems and associated vehicle-washing-centre shading/civil infrastructure. The solar PV components alone are reported at ₹564.27 lakh. The remaining ₹158.73 lakh is associated with the additional civil/shading infrastructure [16].

Fig. 4. Cost allocation reported in the DPR.

Using the DPR generation projection and tariff, the gross annual electricity-offset value is ₹225.88 lakh/year. Using the full project cost of ₹723.00 lakh gives a simple payback of approximately 3.20 years (38.4 months). Using only the reported solar-system cost of ₹564.27 lakh gives approximately 2.50 years. These are simple, pre-financing payback indicators and exclude O&M, degradation, tariff escalation, financing cost, net-metering settlement and downtime.

The source DPR also contains a separate financial-analysis table with OCR-readable payback statements that do not fully reconcile with the ₹564.27 lakh and ₹723.00 lakh costs and the 18.07 lakh kWh generation. The research version therefore uses the directly calculable values and recommends reconciliation against the final approved financial schedule.

Fig. 5. Indicative simple-payback sensitivity to electricity tariff, holding DPR generation and total project cost constant.

VIII. ENVIRONMENTAL ASSESSMENT

PV electricity can reduce indirect emissions associated with grid electricity consumption. The appropriate calculation is M_CO2 = E_grid,displaced × EF_grid. The final carbon result should use the Central Electricity Authority's applicable grid-emission factor for the reporting year rather than transferring an emission factor from another study or year [17]. The CEA maintains a COâ‚‚ baseline database for the Indian power sector, and its current database provides versioned emission-factor information [17].

Recent literature supports the environmental relevance of PV-WWTP integration. Chen et al. reported 10–40% carbon-emission reductions for the analyzed Chinese WWTP-PV cases [6], while Milani and Nabi Bidhendi reported that combined renewable-energy approaches can substantially reduce WWTP greenhouse-gas emissions [8]. A 2025 study of PV deployment in Chinese WWTPs reported an average annual electricity contribution of about 20% across 31 case projects and an average GHG reduction of about 11%, emphasizing the dependence of performance on panel coverage and solar resource [15].

IX. OPERATION, MAINTENANCE AND PERFORMANCE VERIFICATION

The DPR specifies routine module cleaning, inverter checks, cable and structure inspection, earthing tests, SCADA/remote-monitoring checks and periodic energy auditing. It calls for module cleaning approximately twice per month or according to dust level, monthly inverter checks, quarterly cable/structure inspections, biannual earth-resistance testing, monthly SCADA checks and monthly/quarterly energy reporting. It also proposes training at least two ULB staff members and maintaining essential spare parts [16].

The DPR specifies minimum plant availability of 98% and a minimum CUF of 17%, together with a 24-hour response arrangement for major faults [16]. For research-grade verification, the following additional measurements are recommended: plane-of-array irradiance, module temperature, inverter DC/AC power, hourly plant import/export energy, STP load, inverter availability, soiling condition, downtime cause and maintenance expenditure.

X. DISCUSSION

The Jabalpur proposal is consistent with the broader research direction toward renewable-energy-supported wastewater infrastructure. The proposed capacity is close to the annual electricity requirement on an energy basis, and the grid-connected configuration avoids the additional complexity and cost of battery storage. The project also uses multiple site surfaces—rooftops, ground areas and vehicle-parking structures—which can increase the usable PV footprint in a municipal facility.

Nevertheless, the distinction between annual energy offset and instantaneous self-sufficiency is critical. A PV system producing 18.07 lakh kWh/year cannot guarantee that 100% of the STP load is supplied by PV at every moment. Literature on PV self-consumption and WWTP energy optimization indicates that hourly load profiles, aeration scheduling, tariff structures and energy-management strategies can materially affect economic performance [2], [3], [7], [11].

Another important issue is the treatment of the reported CUF. Direct calculation from the stated 1237.83 kW capacity and 18.07 lakh kWh/year generation yields 16.66%, while the DPR specifies a minimum CUF of 17%. This difference is small but meaningful in a performance-guarantee context. The final EPC/PV simulation should therefore define whether the 1237.83 kW refers to DC module capacity, AC inverter capacity or another contractual basis.

XI. LIMITATIONS

The DPR is a project-planning document and does not provide a post-commissioning measured-performance dataset.

No hourly STP electricity-load profile was available for this research version; therefore hourly self-consumption and export cannot be quantified.

The DPR contains financial statements that do not fully reconcile when independently recalculated from the stated capacity, generation, tariff and project-cost values.

The minimum CUF requirement and projected annual generation produce a small internal consistency gap when calculated directly.

Carbon benefits should be recalculated using the applicable CEA grid-emission factor and actual grid electricity displaced.

Final economic performance depends on actual tariff settlement, net-metering rules, O&M expenditure, degradation, availability and financing conditions.

XII. RECOMMENDED POST-COMMISSIONING RESEARCH DESIGN

A 12–24 month measurement-and-verification program is recommended. The study should establish a baseline period using utility bills and plant SCADA data, followed by continuous PV and electrical-load monitoring. At minimum, monthly data should include PV generation, grid import, grid export, plant electricity consumption, irradiation, downtime, maintenance activity and electricity tariff. Preferably, 15-minute or hourly data should be retained.

Table III. Recommended Post-Commissioning Performance Metrics.