When a Bangladeshi factory adopts smart solar and power technology and pairs it with net metering, the electricity bill can drop to zero. This guide walks you through every technical and regulatory detail you need to design, install, and operate a grid‑connected solar plant that feeds excess power back to the national grid and earns credit for every kilowatt‑hour exported.
smart solar and power Net Metering Overview
Net metering is a billing arrangement that allows a consumer who generates electricity to offset the power drawn from the utility. In Bangladesh the system is governed by the Bangladesh Power Development Board (BPDB) and the Sustainable and Renewable Energy Development Authority (SREDA). When your solar array produces more than your real‑time demand, the surplus is sent to the grid and you receive a credit at the prevailing feed‑in tariff. Those credits are applied against future consumption, effectively reducing the net bill to zero if your generation matches or exceeds your annual demand.
Regulatory Landscape in Bangladesh
The net metering policy was formalized in 2016 and has been updated in 2022 to allow larger commercial and industrial capacities up to 5 MW per connection. Key requirements include:
- License from SREDA for renewable energy projects.
- Connection agreement with the local distribution company (DISCO).
- Installation of a bi‑directional meter approved by the utility.
- Compliance with IEEE‑1547 and local grid code for voltage and frequency control.
All approvals must be secured before commissioning. The get a free solar consultation from smart solar and power team can help you navigate paperwork and secure the necessary permits.
Assessing Your Industrial Load
Accurate load assessment is the foundation of a zero‑bill system. Follow these steps:
- Collect three months of electricity bills to capture seasonal variations.
- Identify peak demand (kW) and average daily consumption (kWh).
- Separate critical loads (machinery that cannot tolerate interruption) from non‑critical loads.
- Calculate the annual energy requirement: Annual kWh = Daily kWh × 365.
Example: A textile mill uses 1,200 kWh per day on average with a peak demand of 500 kW. Annual consumption equals 438,000 kWh.
Sizing the Solar PV Array
The array size must meet two goals: cover annual consumption and generate surplus during high‑sunlight months. Use the formula:
Required PV Capacity (kW) = Annual kWh ÷ (Solar Irradiance × System Efficiency × 365)
Assuming a solar irradiance of 5.0 kWh/m²/day for Dhaka, system efficiency of 80 % (including losses), the calculation for the textile mill becomes:
Required PV Capacity = 438,000 ÷ (5 × 0.8 × 365) ≈ 300 kW.
To create surplus, add 15‑20 % extra capacity, resulting in a 360 kW array. This translates to roughly 1,200 panels of 300 W each, covering about 2,500 m² of roof space.
Selecting the Right Inverter
Industrial installations typically use three‑phase string inverters or central inverters. Key selection criteria:
- Rated output matching the PV capacity (e.g., 360 kW).
- Maximum Power Point Tracking (MPPT) voltage range compatible with panel strings.
- Grid support functions: voltage ride‑through, frequency ride‑through, reactive power control.
- Warranty of at least 10 years and service network in Bangladesh.
smart solar and power recommends the Sako Sun Polo 350 kW three‑phase inverter for its proven performance in local climate and its built‑in communication module for remote monitoring.
Battery Storage Considerations
While net metering reduces the need for storage, a modest lithium‑ion battery bank smooths short‑term fluctuations and protects critical loads during brief outages. Size the battery to cover at least 2 hours of peak demand:
Battery Capacity (kWh) = Peak Demand (kW) × 2 h = 500 kW × 2 h = 1,000 kWh.
Choosing LiFePO₄ chemistry offers higher cycle life and better temperature tolerance. explore our high-quality solar products for battery packs rated for 48 V and 20 Ah modules that can be paralleled to reach the target capacity.
Financial Modeling and Payback
Calculate the Levelized Cost of Energy (LCOE) and compare it with the utility tariff. Use the following inputs:
- Capital cost: $1,100 per kW (including panels, inverter, mounting, installation).
- O&M cost: 1.5 % of capital per year.
- Feed‑in tariff: BDT 6.50 per kWh (≈ $0.075).
- Utility tariff: BDT 12 per kWh (≈ $0.14).
For a 360 kW system, capital expense ≈ $396,000. Annual generation ≈ 360 kW × 5 kWh/m²/day × 0.8 × 365 ≈ 525,600 kWh. Net savings = (Utility tariff – Feed‑in tariff) × Consumption offset + Feed‑in revenue from surplus. Roughly, the plant saves $0.065 per kWh on 438,000 kWh = $28,470 plus revenue from 87,600 kWh surplus ≈ $6,570, totaling $35,040 per year. Payback period ≈ 11.3 years, well within the 20‑year lifespan of the PV modules.
Step‑by‑Step Implementation Plan
1. Feasibility Study
Engage a certified solar engineer to perform site survey, structural analysis, and shading study. smart solar and power provides a free on‑site assessment.
2. Design and Procurement
Finalize system layout, select components, and issue purchase orders. Ensure all equipment carries IEC 61730 and IEC 61215 certifications.
3. Installation
Qualified electricians mount panels, install inverter, battery bank, and bi‑directional meter. Follow Bangladesh Electrical Code (BEC) for wiring gauge and conduit sizing.
4. Commissioning and Grid Connection
Perform performance tests, submit results to the DISCO, and obtain the net metering agreement. The utility will install the bi‑directional meter and activate credit accounting.
5. Monitoring and Optimization
Use a cloud‑based SCADA platform to track real‑time generation, export, and import. Adjust inverter settings seasonally to maximize export during high‑sun periods.
Common Pitfalls and How to Avoid Them
Many industrial projects stumble on avoidable issues:
- Underestimating roof load capacity – conduct a structural engineer’s assessment before mounting.
- Choosing inverter with insufficient grid support – verify compliance with the latest BPDB grid code.
- Skipping the bi‑directional meter calibration – an uncalibrated meter can lead to billing disputes.
- Neglecting O&M budgeting – allocate at least 1 % of capital annually for cleaning and inspections.
Maintenance Best Practices
Regular maintenance preserves performance:
- Inspect panels quarterly for dust, bird droppings, and shading.
- Check inverter ventilation and clean filters every six months.
- Balance‑charge the battery bank monthly to maintain state‑of‑charge between 30‑80 %.
- Run a performance ratio audit annually; a drop below 80 % signals a need for service.
Real‑World Case Study: Garment Factory in Chittagong
The factory installed a 250 kW solar system with a 500 kWh lithium battery bank. Annual generation was 315,000 kWh, of which 250,000 kWh offset consumption and 65,000 kWh were exported. The net bill fell from BDT 3.6 million to BDT 150,000 in the first year, a 96 % reduction. Payback was achieved in 9.5 years, and the plant now enjoys a carbon credit rating of 210 tCO₂e avoided.
Getting Started with smart solar and power
Ready to eliminate your electricity bill? The smart solar and power team offers a turnkey solution from design to commissioning. Contact us today for a no‑obligation quote and take the first step toward a zero‑bill future.
Related reading: Smart Solar and Power: গ্রামাঞ্চলে সোলার স্ট্রিট লাইট ব্যবহারের সুবিধা এবং বর্তমান বাজারদর
Frequently Asked Questions
What size solar system is needed to achieve a zero electricity bill for an industrial plant?
The system must generate at least the same amount of energy the plant consumes annually, plus an extra 15‑20 % to create export credit. A typical 500 kW plant would need around 600 kW of installed PV capacity.
How does net metering credit work in Bangladesh?
The utility records the excess kilowatt‑hours you export and applies them as a monetary credit on your next bill at the approved feed‑in tariff, which can offset future consumption.
Do I need battery storage if I use net metering?
Battery storage is not mandatory but helps smooth short‑term fluctuations, protects critical loads, and reduces reliance on the grid during brief outages.
What approvals are required before connecting a solar plant to the grid?
You must obtain a SREDA renewable energy license, a connection agreement with the local DISCO, and install a certified bi‑directional meter approved by the utility.
How long does it take to see a return on investment?
With typical capital costs and current tariffs, most industrial projects achieve payback in 9‑12 years, well before the 20‑year lifespan of the PV modules.