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Vava’u Tonga Microgrid

Current status, energy mix, organizations, suppliers, equipment, controls, reported specifications, and project updates—with source-level citations.

CoverageDetailed public record
Named organizations9
System facts25
Sources reviewed10
Evidence reviewed2026-07-20

Vava'u now has two distinct solar-microgrid generations that must be separated. The original La'a Lahi plant was commissioned in 2013 at roughly 500-512 kW with SMA diesel-integration controls and small lead-acid support batteries, but Tonga Power's FY2022/23 report says the aging plant suffered a major failure and required comprehensive panel/inverter replacement. A separate Tonga Renewable Energy Project plant—300 kW solar plus a high-power 900 kW/450 kWh grid-forming BESS—was commissioned in March 2023 and received its completion certificate in October 2024. The newer plant is confirmed operating; restoration of the original plant has not been publicly confirmed.

Research status
New 300 kW solar + 900 kW/450 kWh BESS plant operational, contract completed/closed in 2024. Original La'a Lahi solar plant reported failed in FY2022/23 with replacement funding under consideration; later restoration not verified.
Historical classification
Commercial & demonstration
Reported capacity
1,442 kW
Coordinates
-18.68052, -173.98619
Evidence note: “Every company” cannot be proven from public material alone. This page lists every organization found in the recovered record and reviewed sources, preserves unknown roles, and explicitly marks undisclosed controller or equipment details.
Report missing evidenceResearch methodology

Project delivery

Who was involved in Vava’u Tonga Microgrid?

9 publicly identified organizations. Where a recovered source named a participant without explaining its work, the role remains explicitly unspecified.

Organization

Asian Development Bank

Administrator/financier of the Tonga Renewable Energy Project and source of completion reporting. [7][8]

Organization

Government of Australia and Green Climate Fund

Co-financiers of the broader Tonga Renewable Energy Project. [7][8]

Organization

Government of the United Arab Emirates

Grant funder [1]

Organization

Infratec-NETcon Joint Venture

Engineering, procurement and construction contractor for the Vava'u and 'Eua TREP solar/BESS package. [3][4]

Organization

Ingenero

EPC/integration contractor for the original 2013 La'a Lahi plant. [2][10]

Organization

Masdar

Grant and project manager [1]

Organization

Masdar / Abu Dhabi Fund for Development

Project manager/developer and financier, respectively, for the original La'a Lahi solar plant. [9][10]

Organization

SMA Solar Technology

Supplied PV inverters, Sunny Backup units and the Fuel Save Controller for the original diesel-solar hybrid system. [2][10]

Organization

Tonga Power Limited

Owner/operator of the Vava'u grid, La'a Lahi solar plant and 2023 TREP solar/BESS installation. [3][4][5]

System evidence

Energy mix, capacity, and specifications

Values can describe different project phases, generation sources, storage systems, or other components. Source citations are attached to each figure so discrepancies remain visible.

Installed PV
500 kW; 1,680 PV modules [1]
Diesel generation
2 × 600 kW, 2 × 186 kW, and 1 × 300 kW [1]
Battery bank
120 × 1,000 Ah batteries [1]
Reported annual yield
695 MWh [1]
Reported diesel savings
225,000 liters per year [1]
Original La'a Lahi PV capacity
approximately 500-512 kW originally reported — SMA reported 500 kW and 1,680 modules; regional project records reported 512 kW. Tonga Power's later rehabilitation scope refers to a 550 kW panel set and 420 kW AC inverter capacity, indicating later configuration/accounting changes. These values should not be summed. [2][5][9][10]
Original La'a Lahi projected output
approximately 866-873 MWh per year — Pre-/early-operation projections, not recent production. Sources also projected roughly 225,000-280,000 litres of annual diesel savings and about 17% of island annual electricity. [9][10]
Original diesel fleet
2 × 600 kW, 2 × 186 kW and 1 × 300 kW = 1.872 MW — 2013 configuration reported by SMA; current generator fleet and available capacity were not found. [2]
Original support batteries
120 × 1,000 Ah cells/units — SMA reported the count and amp-hour rating but not enough voltage/series-parallel information to calculate a defensible kWh capacity. They were control/backup components, not a utility-scale BESS. [2]
New TREP solar plant
300 kW — Connected to the existing low-voltage Vava'u bus; operational from March 2023 with project close-out in October 2024. [3][4][6]
New TREP BESS
900 kW / 450 kWh — A 0.5-hour high-power, grid-forming battery designed primarily for frequency/voltage support and enabling future diesel-off operation, not long-duration backup. [4][6]
Renewable penetration target after TREP
approximately 16% — Tonga Power design expectation for the Vava'u grid, not a verified recent annual generation share. [4]
FY2022/23 reported fuel savings
119,579 L attributed to La'a Lahi and 92,880 L attributed to TREP solar/BESS — Tonga Power report values. The accompanying 3.95% and 3.06% figures are shares of TPL's national renewable fuel-savings table, not Vava'u energy-mix percentages. [5]

Controls and hardware

Equipment and controller details

Manufacturer and model are shown only when a source names them. Generic descriptions are not converted into guessed product assignments.

01

Microgrid / hybrid controller

SMA — Fuel Save Controller

Coordinates demand-based PV feed-in with the operating diesel network. [1]

02

PV inverter

SMA — Sunny Tripower 20000TL Economic Excellence

21 units. [1]

03

Battery inverter

SMA — Sunny Backup SBU 5000

15 units. [1]

04

Original PV array

Trina Solar — Module model not disclosed

Quantity/status: Approximately 1,680 modules originally; later report refers to about 700 panels needing replacement — The difference likely reflects a changed/reduced rehabilitation scope or later module configuration. The FY2022/23 report says the plant had suffered a recent failure. [2][5]

05

Original PV inverters

SMA Solar Technology — Sunny Tripower 20000TL

Quantity/status: 21 — Tonga Power later proposed replacing the inverter fleet with twenty-one 25 kW string inverters, 525 kW AC total, but funding/installation was not confirmed. [2][5][10]

06

Original hybrid controls and battery interfaces

SMA Solar Technology — Fuel Save Controller and 15 Sunny Backup SBU 5000 units

Quantity/status: One control system and 15 backup inverters — Coordinated solar with the diesel station and small lead-acid battery bank. [2][10]

07

TREP grid-forming BESS and PV plant

Not disclosed in public completion pages — Not disclosed

Quantity/status: 900 kW/450 kWh BESS plus 300 kW PV — Delivered by the Infratec-NETcon JV; chemistry and inverter model were not found in reviewed primary sources. [3][4][6]

Technical record

Architecture, performance, and project updates

Concise technical facts, milestones, operating results, and later developments. Dated notes distinguish historical design claims from current evidence.

  • Two-project boundary

    La'a Lahi is the original 2013 diesel-solar installation. TREP03 is a separate 2023 plant with 300 kW solar and a 900 kW/450 kWh BESS. Their capacities can be discussed together at island level only when operational status is explicit; the original plant's failure means nominal sum is not a defensible current available-capacity figure. [3][4][5][9]

  • New BESS operating role

    The BESS is power-heavy relative to its energy capacity. It provides voltage and frequency regulation and grid-forming capability on the low-voltage bus, with a design goal of allowing diesels to switch off during favorable renewable/load conditions. At full rated power, nominal duration is only 30 minutes. [4]

  • Completion status

    The new system was commissioned in Neiafu on March 14, 2023. Tonga Power reports that commissioning tests were successful, the completion certificate was issued in October 2024, the plant is in operation and the contract is closed. [3][6]

  • Original plant condition and unresolved update

    Tonga Power's FY2022/23 annual report says a recent failure left La'a Lahi needing comprehensive replacement of roughly 700 Trina modules and inverters; the proposed new inverter capacity was 525 kW AC versus 420 kW AC then installed. Funding was still under consideration. A live promotional webpage may still describe La'a Lahi as operating, but no later source reviewed proves that rehabilitation was completed. [5]

  • Energy-mix caution

    Early claims of 17% solar and the later approximately 16% TREP figure are design-era expectations, not additive shares or a current measured mix. Current diesel generation, total load, solar curtailment and full-year BESS performance are not publicly quantified in the reviewed sources. [4][9][10]

Provenance

10 sources

Primary owner, government, university, supplier, and engineering sources are preferred. Archived references preserve claims whose original pages moved or disappeared.

  1. [1]
  2. [2]
    Vava'u, Kingdom of Tonga Reference

    SMA Solar Technology · Primary source

  3. [3]
    TREP03 Lot 1 Solar and BESS Project Update

    Tonga Power Limited · Primary source

  4. [4]
    'Eua and Vava'u Solar and BESS

    Tonga Power Limited · Primary source

  5. [5]
    Tonga Power Annual Report 2022/23

    Tonga Power Limited · Primary source

  6. [6]
  7. [7]
    Tonga Renewable Energy Project

    Asian Development Bank · Primary source

  8. [8]
    ADB and Partners Open Renewable-Based Minigrid in Tonga

    Asian Development Bank · Primary source

  9. [9]
    Tonga La'a Lahi 512 kW Solar PV Facility

    Pacific Regional Data Repository / Pacific Community · Primary source

  10. [10]
    SMA Fuel Save Solution Commissioned for First Time in APAC

    SMA Solar Technology / PresseBox · Primary source

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