150 kWp Solar + 60 kWh ESS Turns PJ International School Roof Into an IB Classroom

The Sustainability Pressure No IB School Can Ignore

International Baccalaureate schools in Malaysia occupy a peculiar market position: they compete on academic outcomes, but increasingly also on values alignment. A growing segment of parents who pay RM 60,000–120,000 per year in tuition expect the school's physical operations to reflect the environmental ethics woven through the IB's Theory of Knowledge and CAS (Creativity, Activity, Service) frameworks. When a school's Year 12 students study climate systems in Environmental Systems & Societies and then look up to see diesel generators on the roof, the cognitive dissonance is commercially costly.

This particular IB World School in Petaling Jaya had been aware of the issue for two years. The sustainability committee — a cross-functional group of the Bursar, Head of Science, and two parent representatives — had prepared an internal report in 2024 recommending solar. The barrier was not conviction but financing structure: the school's budget cycle required capital projects above RM 400,000 to go through a three-year capital planning process. A hybrid solution combining a smaller PV array with battery storage, justified partly on curriculum grounds, could be approved within the annual Facilities budget.

Load Profile: The Weekend Challenge

Schools have a distinctive load profile that complicates solar economics. During term time on weekdays, consumption peaks between 08:00 and 15:00 — an ideal match for solar generation. But the school also runs significant weekend operations: Saturday academic sessions, sports coaching, library access, and continuous server room and security system loads.

Trexon's load analysis identified three key segments:

1. Weekday term time (07:30–16:30): 180–220 kW average, predominantly air conditioning (60%), lighting (18%), IT labs (12%), kitchen (10%)
2. Weekend term time (08:00–14:00): 90–120 kW average
3. School holiday base load (continuous): 25–35 kW (servers, security, refrigeration)

The holiday base load was important: without battery storage, the school would remain fully dependent on TNB during the six weeks of December–January holidays and the three-week mid-year break — periods when solar generation is at its annual peak but consumption is minimal, meaning most generation would be exported at the ATAP Displaced Cost rate rather than displacing RM 0.435/kWh of consumption.

A 60 kWh battery system — sized to cover the base load for approximately 2 hours — shifts enough solar energy into the evening security/server window to meaningfully improve self-consumption rate, raising the economics from marginal to compelling.

System Design: 150 kWp PV + 60 kWh LUNA2000

PV Array: 340 units of Trina Solar Vertex S+ 440W panels were installed across three rooftop sections: the main academic block (210 panels), the sports hall (80 panels), and the covered walkway canopy (50 panels). The walkway canopy panels serve a dual function — generating electricity and providing weather protection for students moving between buildings.

Ten Huawei SUN2000-15KTL-M0 string inverters (15 kW each) were selected at the recommendation of the school's electrical consultant, who noted their compact dimensions (suitable for the school's distributed roof areas) and the native FusionSolar integration that would enable the curriculum application the Science department was excited about.

Battery Storage: Three Huawei LUNA2000-20 kWh units (60 kWh total) were installed in a ventilated plant room adjacent to the main electrical panel. The battery management system is programmed to charge from solar between 10:00 and 14:00 and discharge from 17:00 to 19:00 (after school evening activities) and during weekends and holidays. A separate low-power mode preserves 20% state-of-charge as emergency backup for the server room in the event of a TNB outage.

FusionSolar Curriculum Integration: The school's IT team worked with Trexon to configure three FusionSolar dashboard views: a public-facing display screen in the main atrium showing real-time generation and cumulative CO₂ savings; a teacher portal with downloadable CSV exports of 15-minute interval data for science projects; and an admin portal for the Bursar with monthly savings reports. The Head of Environmental Systems & Societies integrated the school's own generation data into two internal assessments and one Extended Essay in the first semester.

Installation: School-Friendly Logistics

Installation was scheduled during the December 2025–January 2026 school holiday. Trexon's site team completed all rooftop work in 18 working days, with electrical fit-out and commissioning completed before the first day of the 2026 Spring term. Key considerations:

• All rooftop access via external scaffolding only; no internal disruption
• Noise-controlled working hours (08:00–17:00) to avoid affecting the December exam sitting in the adjacent secondary section
• Fire compartmentation maintained throughout — the battery room installation received a dedicated fire engineering sign-off before occupation
• TNB NEM 3.0 (ATAP) application submitted concurrently with installation; grid-tie approved and meter installed within 6 weeks of completion

Results: Financial and Pedagogical

Financial performance (January–April 2026, four months):

Average monthly generation: 18,750 kWh (consistent with P50 design estimate of 17,500 kWh/month).

Average monthly bill reduction: RM 6,650 — a 30% reduction against the equivalent months in 2025. With self-consumption rate of 71% (solar consumed directly or via battery) and the remainder exported at ATAP Displaced Cost rate, the system is tracking to deliver RM 79,800 in annual savings — rounded to RM 80,000 in communications with parents and the board.

Environmental performance:

The system offsets approximately 138 tonnes of CO₂ equivalent per year. This figure is displayed on the atrium dashboard and cited in the school's annual sustainability report, which is shared with parents at the Year 13 information evening.

Curriculum impact (Spring term 2026):

• Environmental Systems & Societies (HL): Two IA investigations using school generation and consumption data; one Extended Essay on local grid emission factors
• Physics (SL): Unit on photovoltaic principles using real-world system specifications
• CAS: Three students registered a CAS project titled "Carbon Literacy @ [School Name]" using the FusionSolar dashboard to educate Year 7 students about renewable energy

The Head of Science described the system as "the most valuable teaching resource we've added to the science department in five years — and it pays for itself."

Why Battery Storage Made the Difference

The 60 kWh ESS added approximately RM 85,000 to the project cost. Without it, the school's self-consumption rate would have been approximately 52%, and annual savings would have been RM 61,000 rather than RM 80,000 — a RM 19,000/year difference that pays back the battery premium in 4.5 years. But the non-financial justification was equally important: the battery's ability to provide backup power to servers and security during TNB outages removed the Bursar's principal objection to the project (concern about operational disruption).

Note: Financial figures represent indicative modelling based on Trexon installation data and TNB tariff schedules. Specific client details are anonymised per B2B confidentiality.

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