Battery Energy Storage Systems (BESS) and Energy Storage System Policy

Battery Energy Storage Systems (BESS) are grid-scale electrochemical storage facilities that absorb surplus electricity during periods of excess renewable generation and discharge it when demand exceeds supply. In the PEP 2023-2050, BESS is the primary tool for managing the intermittency of variable renewable energy (VRE) — particularly solar and wind — as their shares in the generation mix increase [PEP 2023-2050 Vol. I, p.79, 2023].

Why BESS Is Required

Solar and wind generation are intermittent — they produce electricity only when the sun shines or wind blows. As their combined share of the generation mix grows from 2.5% (2022) toward the 50%+ RE targets , the grid faces increasing volatility in supply. BESS provides the balancing service that previously came from dispatchable thermal plants: absorbing excess midday solar and discharging during evening peaks [PEP 2023-2050 Vol. I, p.79, 2023].

BESS Requirements Under REF

The REF models BESS energy requirements beginning in 2030, once VRE penetration is high enough to require dedicated storage:

[PEP 2023-2050 Vol. I, Tables 16–17, 2023]

Under REF, BESS capacity grows from 156 MW (2022) to 3.8 GW (2050) — a 24× increase. BESS energy capacity reaches 1,021 GWh by 2050, equivalent to approximately 2.25 hours of storage at the 2050 peak demand level.

BESS Requirements Under CES

Under CES, the far higher VRE penetration (driven by 19–50 GW of offshore wind and expanded solar) requires dramatically more storage:

[PEP 2023-2050 Vol. I, Table 1, 2023]

CES-1 requires 22 GW of BESS by 2050 — nearly 6× the REF requirement. CES-2 requires 24.7 GW. This is the largest single investment divergence between the CES and REF scenarios. See PEP 2023-2050 Investment Requirements for the investment cost breakdown (BESS under CES-2 reaches PhP 899.9B in 2029–2050 investment vs PhP 56.4B under REF).

BESS in the Generation Stack

BESS generation output (discharge) under REF:

[PEP 2023-2050 Vol. I, Table 16, 2023]

By 2050, BESS contributes 11 TWh — a small share of total generation (453.8 TWh) but essential for grid stability. BESS also reduces the need for spinning reserve from gas-fired plants, indirectly lowering LNG import requirements under CES. See LNG Imports as Transition Fuel .

Policy and Investment Context

BESS deployment is a critical enabler of the RE targets . Without adequate storage, the grid cannot reliably absorb the variable output of 19–50 GW of offshore wind plus expanded solar. The PEP frames BESS as infrastructure — not optional — for the CES pathways.

BESS investment under CES-2 represents one of the top three divergences from REF spending (alongside OSW and EVs/EVCS). This investment falls primarily in 2029–2050 as VRE penetration crosses thresholds that require dedicated storage rather than simple curtailment or thermal backup.

BESS in PDP 2023-2050 CEM (Grid-Level New Builds)

The PDP 2023-2050 Capacity Expansion Model provides grid-level BESS new build requirements by scenario, consistent with the PEP aggregates [PDP 2023-2050, Chapter 2 Section 4.2, pp.64–89, 2025]:

The CES system totals (~19.8 GW and ~22.4 GW) are consistent with the PEP Vol. I aggregates (22 GW CES-1 / 24.7 GW CES-2), with the difference attributable to already-committed BESS projects counted against the new build requirement.

Committed BESS pipeline (Table 48, DOE as of 31 May 2023): 2,084 MW Battery ESS scheduled for COD 2023–2025 (780 MW in 2023; 784 MW in 2024; 520 MW in 2025) [PDP 2023-2050, Table 48, p.91, 2025]. This cross-checks with the PEP Vol. II figure of 2,024 MW committed BESS (41 projects, as of September 2023); the ~60 MW difference reflects the different reporting dates. Together, these confirm a near-term committed BESS pipeline of approximately 2 GW, largely concentrated in Luzon and connected to NGCP ancillary service procurement.

VPP and Distributed Energy Resources (DER) Policy

ERC Resolution No. 17, Series of 2023 (13 September 2023) defines Distributed Energy Resources (DERs) as power sources connected to the Distribution System or End-User’s electrical system that can be aggregated to meet demand — covering small-scale solar, wind, hydro, storage systems, intelligent grid management technologies, and demand response mechanisms [PDP 2023-2050, Ch.3 Sec.1.5, p.103, 2025].

A Virtual Power Plant (VPP) is an aggregator that bundles and optimizes DERs — operating them as a unified entity for wholesale market participation. The DOE ’s PDP 2023-2050 roadmap identifies VPP/DER policy as a medium-term (2025–2028) action under the Generation roadmap: developing a policy framework covering market participation pathways, interoperability mechanisms, and grid-readiness requirements [PDP 2023-2050, Ch.3 Sec.1.5, p.103, 2025].

ERC Resolution No. 11, Series of 2022 (19 October 2022) provides the existing rules governing DER interconnection to the distribution system — covering interconnection requirements, COC processes, DER pricing methodologies, and data-based energy planning. The DOE plans supplemental policy to incentivize prosumers (e.g., tax credits) analogous to RE technology incentives [PDP 2023-2050, Ch.3 Sec.3.6, pp.112–113, 2025].

ESS Policy History

Original ESS Framework (DC2019-08-0012)

DC2019-08-0012 — “Providing a Framework for Energy Storage System in the Electric Power Industry” — was the original ESS policy [DC2019-08-0012, §1, 2019]. It established the same four technology types (BESS/CAES/FES/PSH) and substantially the same participant-class structure as the current DC2023-04-0008.

Key differences from DC2023-04-0008:

Nine ESS purposes (2019) vs. eight (2023): DC2019-08-0012 listed a standalone Transmission Congestion Relief purpose (§5.6 — ESS at appropriate nodes mitigates congestion when demand exceeds transmission capability). DC2023-04-0008 folded this function into the upgrades deferment purpose, reducing the list to eight [DC2019-08-0012, §5, 2019].

AS provider sizing threshold: Set at ≥20 MW for Luzon Grid and ≥5 MW for Visayas and Mindanao Grids — carried over unchanged into DC2023-04-0008 [DC2019-08-0012, §5.1, 2019].

FiT-VRE integration constraint: The rule that ESS integrated in a FiT-eligible VRE plant may not increase the VRE’s FiT entitlement and may only be charged from VRE output was present from 2019 [DC2019-08-0012, §5.3, 2019].

TNP and SO ownership prohibition: Both the Transmission Network Provider and the System Operator were prohibited from owning/operating ESS from the outset [DC2019-08-0012, §§4.6.1, 4.7.1, 2019].

QTP ESS for off-grid: Qualified Third Parties were explicitly authorized to own/operate ESS in conjunction with RE-based facilities or hybrid power systems to provide continuous service in off-grid areas via micro-grid or DER [DC2019-08-0012, §4.5, 2019].

90-day SO mandate: The SO had 90 days from effectivity to develop ESS testing standards, procedures, and accreditation processes with stakeholders — the precursor to the ERC accreditation framework elaborated in DC2023-04-0008 [DC2019-08-0012, §4.7.2, 2019].

DC2020-02-0003 (6 February 2020) — “Providing a National Smart Grid Policy Framework for the Philippine Electric Power Industry and Roadmap for Distribution Utilities” — defined smart grid as an enhanced electrical grid using two-way/multi-way communication technologies with real-time monitoring, automation, and control systems. Primary objective: support high penetration of variable RE while transforming the grid to be secure, stable, flexible, sustainable, digitally-enabled, and interoperable [NREP 2020-2040, p.38, 2022].

ESS Policy Framework (DC2023-04-0008)

On 20 April 2023, the DOE issued DC2023-04-0008 titled “Prescribing the Policy for Energy Storage System in the Electric Power Industry,” repealing the earlier ESS policy framework (DC2019-08-0012). The Circular recognizes the benefits of ESS given the high influx of variable renewable energy in the Philippine power system [PEP 2023-2050 Vol. II, p.78, 2023].

ESS Technology Types

DC2023-04-0008 covers four ESS technology categories [PEP 2023-2050 Vol. II, p.78, 2023]:

Eight Permitted ESS Purposes

ESS proponents may apply and register for one or more of the following purposes [PEP 2023-2050 Vol. II, p.78, 2023]:

1. Provision of ancillary services
2. Provision of energy through bilateral supply contracts or WESM trading
3. Manage the variability of renewable energy
4. Auxiliary load management for generation companies
5. Transmission and distribution facility upgrades deferment
6. Transmission and distribution utility power quality management
7. End-user demand management
8. Distribution utility demand management

COC Framework for ESS Configurations

DC2023-04-0008 §6 establishes four COC structures depending on ESS configuration [DC2023-04-0008, §6, 2023]:

WESM Registration Thresholds

WESM registration is mandatory for [DC2023-04-0008, §8, 2023]:

• ESS connected to the transmission system (any capacity)
• ESS connected to the distribution system with capacity ≥10 MW (Luzon), ≥5 MW (Visayas), ≥5 MW (Mindanao)

ESS below these thresholds may register voluntarily.

SO Dispatch Priority Rule

The System Operator (NGCP/SO) may use its own BESS or FES for ancillary services only after determining that no contracted AS capacity is available [DC2023-04-0008, §5.6.1–5.6.2, 2023]. Contracted AS procured through CSP and the Reserve Market must be dispatched first. This rule protects the commercial viability of private AS providers and preserves merit-order dispatch principles.

ESS Deployment Pipeline (as of September 2023)

[PEP 2023-2050 Vol. II, Tables 42–43, 2023]

Committed BESS: 41 projects totaling 2,024 MW (69 Luzon / 17 Visayas / 11 Mindanao). Indicative BESS: 46 projects totaling 1,826.6 MW — representing a substantial near-term pipeline beyond the CES long-term targets established in Vol. I. See Smart and Green Grid Plan (SGGP) for the transmission implications of large-scale ESS deployment.