80 kWp Solar + 60 kWh ESS Cuts Setiu Fish Farm's Diesel Bill From RM 12k to RM 1.8k/Month

The Aerator Problem: Why Aquaculture Has Malaysia's Worst Electricity Economics

A marine fish farm in Setiu, Terengganu is not a passive operation. High-density aquaculture — particularly the rearing of kerapu (grouper), siakap (barramundi), and red snapper for the domestic and export restaurant trade — requires continuous dissolved oxygen management via electric aerators running 24 hours a day. The moment an aerator stops, dissolved oxygen levels begin to decline. At densities typical of a commercial marine cage or pond system, oxygen depletion can trigger mass mortality within hours.

For this farm operator in Setiu — managing 18 floating cages and 6 shore-based holding ponds — the combination of aerators (12 units, 1.5 kW each), UV sterilisers (4 units, 500W each), lighting, water pumps, and office equipment produced a continuous 24/7 load of approximately 22 kW. TNB grid supply at this location is unreliable: the operator had documented seven outages exceeding four hours in the preceding twelve months, each requiring the farm's diesel generator to start manually at 02:00 or 03:00 in the morning.

The monthly energy cost structure: approximately RM 8,500 in diesel fuel for the primary generator (which the operator ran continuously rather than relying on TNB's unstable rural supply), RM 2,800 in TNB bills for periods when grid supply was stable, and RM 700 in generator maintenance — totalling RM 12,000 per month in energy costs for a single-site operation that was netting RM 18,000–22,000 per month in fish sales.

Energy was consuming 55–60% of operating revenue. The payback calculation was immediate.

Engineering Constraints: Saltwater, Humidity, and Monsoon

A coastal aquaculture site in Terengganu imposes equipment requirements that are fundamentally different from an inland commercial or industrial installation. Trexon's site assessment in October 2025 identified four constraints that shaped the system architecture:

1. Corrosive salt-air environment. The farm's proximity to the South China Sea (approximately 800 m from shore) means structural components, cable management hardware, and inverter enclosures are exposed to Class C5 corrosivity per ISO 9223. All racking was specified in hot-dip galvanised steel (not standard aluminium), all cable management in Schedule 40 PVC conduit sealed at penetrations, and inverters selected for IP65-rated enclosures.

2. Northeast Monsoon (November–March) structural loading. Terengganu's northeast monsoon brings sustained wind speeds of 30–45 km/h with gusts to 80 km/h. Structural engineering confirmed that the farm's existing shed framing — a light steel portal frame — required supplementary cross-bracing before any panel loading could be added. This was completed as part of the project scope.

3. Continuous load with no demand flexibility. Unlike an industrial facility where peak shaving can defer loads, aerators cannot be interrupted. The battery sizing had to guarantee coverage for the aerators and UV sterilisers through the overnight period (19:00–07:00) when solar generation is zero, with a safety margin for the monsoon season's reduced irradiance.

4. Remote monitoring requirement. The farm owner, who manages a second farm site 40 km away, required remote monitoring with alarm notifications for low battery state-of-charge, inverter fault, and aerator loss-of-power events — functionalities that guided the inverter selection.

System Architecture: 80 kWp PV + 60 kWh Sungrow SBR

PV Array: 128 × Trina Vertex 625W

128 units of Trina Solar Vertex 625W panels were installed on the farm's main processing shed roof (60 panels, south-facing) and on a newly constructed freestanding walkway canopy between the shore-based holding ponds (68 panels). The walkway canopy serves a dual purpose: generating electricity and providing shade over the pond aeration walkways, reducing thermal loading on the water surface and improving dissolved oxygen retention during the hottest months. Trina Vertex 625W was selected for its saltwater-resistance coating on the anodised aluminium frame and its 25-year linear power warranty — the longest available from a Tier-1 manufacturer for marine-environment installations.

Hybrid Inverters: 4 × Sungrow SG5.0RS-L

Four Sungrow SG5.0RS-L hybrid inverters (5 kW each, 20 kW total) were installed in a ventilated indoor cabinet in the farm's control room. The SG5.0RS-L was selected for its native compatibility with Sungrow's SBR battery series, its IP65 enclosure rating, and its iSolarCloud remote monitoring platform — which provides the farm owner with real-time system status, state-of-charge alerts, and historical generation data accessible via mobile phone.

Battery ESS: Sungrow SBR60 (60 kWh)

Three Sungrow SBR20 battery modules (20 kWh each, 60 kWh total) were installed in a floor-mounted rack in the control room. The SBR series uses lithium iron phosphate (LFP) chemistry, which provides superior thermal stability compared to NMC alternatives — important in a non-air-conditioned rural control room where ambient temperature can reach 38–40°C in the hot season. At 60 kWh, the battery system covers the full overnight aerator and UV steriliser load (approximately 5 kWh/hour for 12 hours = 60 kWh) with zero margin available for discharge. The battery management system is configured to maintain a 10% state-of-charge reserve as emergency aerator backup, effectively providing 54 kWh of usable overnight storage.

A Sungrow SBH5.0 backup module provides automatic transfer to battery-only operation within 20 ms of a TNB grid outage — eliminating the previously necessary manual diesel generator start for short outages.

Monsoon Season Performance: The Critical Design Test

The northeast monsoon (November–March) reduces irradiance in Terengganu by approximately 30–40% compared to the dry season. The system was designed to remain operationally viable during this period. Design calculations for the worst-case monsoon month (December, at 50% of peak irradiance) showed:

• Daily generation: approximately 160 kWh (versus 320 kWh in the dry season)
• Daily aerator and UV steriliser consumption: approximately 120 kWh
• Net daily surplus for battery charging: 40 kWh
• Battery state-of-charge by 19:00: approximately 75%
• Battery discharge overnight (12 hours at 5 kW): 60 kWh
• Battery state-of-charge by 07:00: approximately 15% (above the 10% emergency reserve threshold)

The monsoon season design margin is tight but safe. The farm owner was briefed on the monsoon performance profile and accepted that during the worst three days of each monsoon month, the TNB grid would supply supplemental power if available, or the diesel generator would run for 4–6 hours rather than 24 hours — a substantial reduction from the previous diesel-only operation.

Results: Three Months of Live Data (March–May 2026)

Financial performance:

The first three months of operation (March–May 2026) covered the transition from the tail of the northeast monsoon (March) into the dry season (April–May).

Average monthly generation: 16,800 kWh. Average monthly diesel fuel purchase: RM 480 (generator runs an average of 4 hours per month as emergency backup only). Average monthly TNB bill: RM 1,320. Total average monthly energy cost: RM 1,800 — an 85% reduction from the previous RM 12,000.

Simple payback period: 4.2 years at current fuel and electricity prices.

Operational performance:

The farm operator reported zero aerator power interruptions in the first three months. The iSolarCloud platform sent two low-battery alerts during the monsoon tail in March (triggered at 20% SoC), both during extended overcast periods. On both occasions, the TNB grid supply was available and the system automatically drew supplemental power from the grid to maintain aerator operation — exactly the hybrid-grid behaviour that the system was designed to provide.

Water quality:

Fish mortality in the 18 floating cages averaged 2.1% over the three-month period — below the farm's historical average of 4.8%, which the farm owner attributes partly to more consistent dissolved oxygen levels and partly to the elimination of diesel exhaust contamination near the cage arrays (the diesel generator has been relocated to a standby-only position 30 m from the cages).

Note: Financial figures represent indicative modelling based on Trexon installation data and Terengganu diesel fuel prices. Specific client details are anonymised per B2B confidentiality.

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