Industrial Archives

Project Overview

Chokphoethong Transport 2012 Co., Ltd. operates a water bottling and distribution facility in Si Racha, Chonburi — running 24 hours a day, seven days a week. With monthly electricity bills consistently exceeding THB 300,000, the business was paying one of the highest ongoing costs of any operation its size. As an industrial-scale TOU (Time of Use) tariff customer on a 22–33kV connection, they were being charged peak rates of over 4.18 THB per kWh for daytime consumption — exactly the hours when solar generation is at its highest.

Kunini Solar EPC was engaged to design, fund, install, own, and operate a 198kWp rooftop solar system under a Private Power Purchase Agreement (PPA) — allowing the business to access the benefits of solar with zero capital expenditure and no technical burden.

The Challenge

The facility’s large corrugated metal roof required a robust, non-penetrating mounting solution that would not compromise the roof’s integrity or the plant’s watertight requirements — a critical consideration for a food-grade production facility. With operations running around the clock, installation had to be managed carefully to avoid disrupting production below.

The scale of the system — 198kWp across a single roof structure — also required a detailed structural engineering assessment, precise string design across 18 DC combiner circuits, and full PEA compliance documentation for a Medium Voltage (22–33kV) interconnection, which involves more complex grid protection requirements than a standard Low Voltage connection.

The Kunini Solution

Kunini’s in-house engineering team designed a 198kWp system using approximately 307 LONGi 645W monocrystalline panels, mounted on Antai metal roof clamps — a zero-penetration mounting solution that preserves the roof membrane and carries no structural load beyond the design capacity of the existing purlins. A central safety walkway with fiberglass anti-slip grating runs the full length of the ridge, providing safe access for ongoing O&M.

A Solis 150kW commercial three-phase inverter was selected for its proven reliability in industrial environments and its native compatibility with the facility’s 22–33kV metering setup. An 18-string DC combiner box, custom AC solar panel, and DC solar panel were engineered and installed in a dedicated inverter room adjacent to the main electrical switchroom. A crane was deployed to lift panels to roof level efficiently, allowing the installation to be completed without disrupting plant operations below.

As the system owner under the PPA agreement, Kunini manages all ongoing performance monitoring, maintenance, and insurance throughout the contract term. Chokphoethong pays a fixed monthly PPA service fee for the solar energy delivered — replacing a portion of their grid electricity spend with a predictable, lower-cost alternative.

The Result

The system generates approximately 25,000 kWh of clean solar electricity per month — offsetting around 33–35% of the facility’s total grid consumption. Given that the plant operates continuously, the solar system delivers its generation entirely during peak daytime tariff hours, where the grid rate exceeds 4.18 THB/kWh — maximising the value of every kilowatt-hour produced.

The facility’s first PPA invoice was issued in August 2026 following commissioning, replacing what would otherwise have been a significant portion of their monthly PEA bill. With the PPA rate locked in below current grid tariffs, the business now has greater electricity cost predictability for planning purposes — regardless of future Ft charge adjustments.

A Phase 2 expansion to increase system capacity is currently under assessment, planned for Q4 2026, as the business continues to grow its production volumes.

System Highlights

Is a Private PPA Right for Your Business?

If your monthly electricity bill exceeds THB 80,000 and you have suitable roof space, Kunini can assess your site and model a PPA proposal at no cost. Zero upfront investment. Immediate savings from day one.

Hua Hin: +66 (0) 61 413 4850

Pattaya / Si Racha: +66 (0) 82 056 7906

Email: info@kunini.com

Web: www.kunini.com

Project Overview

AFR Plasmold Co., Ltd. is a plastic injection moulding manufacturer based in the Rayong industrial corridor — one of Thailand’s most active manufacturing hubs. Operating injection moulding machinery and production equipment throughout working hours, the factory draws a significant and predictable daytime electricity load, making it an excellent candidate for rooftop solar.

Kunini Solar was engaged to design and install a solar system sized to the available roof area and inverter capacity, with this installation treated as a pilot project — giving AFR a proof-of-concept before committing to further capacity as the business grows. The resulting 61.92kWp DC system was commissioned in June 2026 and operates as a zero-export site — every kilowatt-hour generated by the panels is consumed directly within the factory, reducing the amount of electricity purchased from the PEA grid at full industrial tariff rates.

The Challenge

The roof at AFR Plasmold is a trapezoidal metal sheet industrial roof — common across Rayong’s factory estates, but requiring a mounting system specifically engineered to avoid roof penetrations, maintain weatherproofing integrity, and accommodate the thermal expansion characteristics of the sheet material.

As an industrial consumer under a PEA time-of-use tariff, AFR’s primary objective was reducing daytime demand charges rather than generating feed-in revenue. The system therefore had to be sized and controlled to ensure that generated power never exceeded the factory’s instantaneous consumption — requiring zero-export functionality to be built into the inverter configuration.

Additionally, with 96 panels distributed across the roof, module-level safety and performance optimisation were priorities. Industrial rooftops present shading risks from vents, exhaust stacks, and roof-mounted equipment, and rapid shutdown capability was required to ensure safe access for maintenance personnel.

The Kunini Solution

Kunini designed a 61.92kWp DC / 50kW AC system using 96 LONGi LR5-72HTH 645W Bifacial solar panels — a high-efficiency monocrystalline bifacial module that captures light from both the front and rear surfaces, providing incremental yield from light reflected off the metal roof surface below.

A Huawei Smart PV Optimizer was installed on each of the 96 panels. These devices perform module-level maximum power point tracking (MPPT), ensuring that a single underperforming panel — whether due to dust, partial shading from roof equipment, or soiling — does not reduce the output of an entire string. Each optimizer also functions as a Rapid Shutdown Device (RSD), cutting DC voltage at panel level within seconds when the inverter is de-energised. This is a critical safety feature for maintenance staff and emergency responders, and a requirement under current PEA installation standards.

A single Huawei SUN2000 50kW three-phase string inverter manages the full array. Zero-export control is configured directly within the inverter firmware: the unit monitors real-time factory consumption and automatically modulates its output to match demand, ensuring that at no point does generated power exceed the building’s load and flow back into the PEA network. The system was installed and commissioned in full accordance with PEA regulations.

Antai Solar aluminum racking was used throughout — a system engineered specifically for trapezoidal metal sheet roof profiles, providing secure, weatherproof mounting without roof penetrations. A dedicated service walkway and permanent access ladder were installed alongside the panel array, ensuring the system can be safely inspected and cleaned throughout its operating life.

The Result

The AFR Plasmold system generates approximately 276 kWh per day and around 8,300 kWh per month — with 100% of that generation consumed on-site. At current PEA industrial tariff rates, this translates to a monthly electricity cost saving of approximately THB 35,000–45,000, depending on the applicable tariff block and time-of-use demand profile.

In the system’s first full month of operation (July 2026), the Huawei FusionSolar monitoring platform recorded electricity savings of THB 45,626 — validating the pre-installation savings projection and giving AFR management a clear, data-backed view of ongoing returns.

Solar now accounts for approximately 27% of the factory’s total electricity consumption, directly offsetting grid purchases during peak production hours — typically 08:00 to 17:00. On an annual basis, the system is expected to offset approximately 100,000 kWh of grid electricity, equivalent to avoiding around 55 tonnes of CO₂ emissions per year based on Thailand’s current grid emission factor.

The live monitoring dashboard — accessible via Huawei FusionSolar — gives the AFR management team real-time visibility into generation, consumption, and grid import data, with historical performance reports available on demand for ongoing cost management and reporting.

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System Highlights

96 × LONGi LR5-72HTH 645W Bifacial panels — front and rear generation for improved yield on metal roof
Huawei Smart PV Optimizer on every panel — module-level MPPT and Rapid Shutdown Device (RSD) on each module
Huawei SUN2000 50kW string inverter — single-inverter simplicity with full cloud monitoring
Zero-export control via inverter firmware — 100% self-consumption, PEA compliant, no CT metering required
Antai Solar aluminum racking — engineered for trapezoidal metal sheet roof, no roof penetrations
Service walkway and permanent access ladder — safe, permanent access for inspection and cleaning
Live monitoring via Huawei FusionSolar — real-time generation, consumption, and grid import data
~55 tonnes CO₂ avoided per year — pilot system with planned expansion as AFR’s business grows

Solar for Your Factory or Industrial Building?

If your factory’s monthly electricity bill exceeds THB 50,000 and you have suitable roof space, Kunini can carry out a no-cost site assessment and provide a detailed savings proposal. Whether you’re looking at a direct purchase EPC contract or exploring a Private PPA with zero upfront investment, we’ll design a system around your facility’s actual consumption profile and tariff structure.

Hua Hin: +66 (0) 61 413 4850

Pattaya / Si Racha: +66 (0) 82 056 7906

Email: info@kunini.com

Web: www.kunini.com