NERSA's 4 September 2026 invitation to comment on the ERTSA 2027-28 tariff structure — with submissions closing 2 October 2026 — is the forward-tariff wildcard every C&I solar buyer must model before signing any PPA or wheeling agreement, as Eskom's fixed-cost glide path reaches 100% and gen-wheeling credit rates face further structural adjustment from April 2027.

Why the ERTSA 2027-28 Consultation Is the Most Important Document on Every C&I Energy Buyer's Desk Right Now

On 4 September 2026, NERSA issued its formal Invitation to Comment on the Eskom Retail Tariff Structural Adjustment (ERTSA) for the 2027-28 Financial Year. The submission window closes on 2 October 2026 — less than four weeks away. For commercial property owners, manufacturers, and C&I energy buyers currently negotiating a Power Purchase Agreement (PPA) or wheeling agreement, this consultation is not background noise. It is the single most consequential forward tariff variable you must model before countersigning anything.

Here is what is at stake, what is actually being proposed, and what it means for your all-in energy cost from April 2027 onward.

What the ERTSA 2027-28 Consultation Actually Does — and Does Not — Change

First, a critical clarification. NERSA's Executive Manager for Electricity, Rhulani Mathebula, confirmed that this consultation does not revisit the total revenue amount determined in 2025 — it focuses specifically on how that revenue is allocated between basic fees, service charges, and variable energy rates. The headline tariff number — an average 8.83% price increase for direct Eskom customers and an 8.84% adjustment for municipal bulk supply, set to kick in on 1 April 2027 — is already fixed under the MYPD6 framework. NERSA has set Eskom's allowable revenue at R419.4 billion for 2027/28, and public submissions can directly alter how those costs are structured and distributed across customer bands — but not the total quantum.

What can change through this process is the structure of how you pay: the split between fixed daily service fees, the Generation Capacity Charge (GCC), and the variable energy rate per kWh. That structural split is where C&I solar economics live or die.

The Fixed-Cost Glide Path: Why 2027 Is the Critical Year

The ERTSA 2027-28 consultation arrives at a pivotal inflection point in Eskom's multi-year fixed-cost unbundling programme. According to NERSA's consultation documentation, Eskom is entering the final phase of a three-year glide path to unbundle its fixed infrastructure charges — currently sitting at 66.6% implementation — with the proposed 2027 structure pushing fixed costs up to 100%, alongside a nearly 50% jump in separate service and administration fees.

The 2026-27 year already reflected this trajectory. For 2026/27, the Generation Capacity Charge (GCC) rate was increased to 30% of the originally proposed 2025/26 Retail Tariff Plan rand-value, up from the previous 20%, with energy rates for affected tariffs lowered to offset this. The ERTSA 2027-28 proposal completes that shift. The new GCC will be updated in FY2027 and FY2028 to implement the NERSA decision to phase it in over a three-year period, and residential fixed costs for retail will be further phased in over FY2027 and FY2028.

For C&I buyers, this matters because higher fixed charges erode the savings logic of behind-the-meter solar. When you self-generate, you reduce your variable (energy) consumption from the grid — but you still pay unavoidable fixed network costs. As the fixed-to-variable ratio shifts toward 100% fixed cost recovery, the per-kWh savings from a rooftop solar system or small embedded generator shrink. Payback periods extend. Internal rate of return projections made in 2024 or early 2025 may no longer hold.

The Gen-Wheeling Credit Rate: The Wildcard Inside the Wildcard

For buyers pursuing off-site wheeled PPAs, the stakes are even more pointed. The current Eskom tariff framework already contains an important carve-out that buyers must understand: the remaining 70% of the GCC included in the energy charge is excluded from the energy credit provided under wheeling and net-billing arrangements. In plain language, Eskom's wheeling credit rate does not reimburse the full energy charge — it excludes the GCC component embedded in that charge.

The ERTSA 2027-28 process raises the prospect of a further structural adjustment to the gen-wheeling credit rate as fixed cost recovery reaches its terminal level. If NERSA approves a structure that increases the GCC share of the tariff while holding the wheeling credit formula constant, the effective net benefit to a wheeled-PPA offtaker narrows — potentially by several cents per kWh. NERSA has published its regulatory rules on network charges for third-party wheeling, including methodologies for transmission and distribution use-of-system charges, replacing the 2012 rules, and these are designed to determine applicable charges for the use of the system by both generators and loads. Any structural adjustment to how those charges are weighted will flow directly into the economics of every active wheeling agreement.

NERSA is developing a standardised wheeling tariff framework, expected to be finalised in 2026-2027, and standardisation is expected to significantly reduce transaction costs and unlock the private corporate PPA market. But standardisation cuts both ways: it also locks in whatever cost-reflective network charge methodology NERSA finalises through processes like this one.

What Current Wheeled PPA Pricing Looks Like — And What Must Be Stress-Tested

Wheeled PPA tariffs delivered to an offtaker's site (all-in, including generation, wheeling fees and losses) have compressed materially over the past 18 months, with indicative all-in tariffs in early 2026 typically ranging from R1.15 to R1.45 per kWh for solar-only wheeled PPAs. This remains attractive against Eskom's current non-residential rates. Wheeling a solar project from the Northern Cape to a Gauteng offtaker adds R0.13 to R0.27/kWh in transmission and distribution charges, plus 5–8% energy losses, which must be factored into PPA pricing.

However, any PPA or wheeling agreement signed today on the basis of current tariff assumptions carries a forward-pricing risk that the ERTSA 2027-28 outcome will crystallise. If fixed cost recovery rises to 100% and the wheeling credit is further adjusted downward, the effective grid cost component of your all-in delivered price could rise by 10–20% in the first year of the agreement alone — even if the generator's tariff is locked.

Practical rule: Before signing any PPA or wheeling agreement with a start date of April 2027 or later, run a sensitivity scenario in which the wheeling network charge increases by 15–25% relative to the 2026-27 baseline. If your all-in economics still work under that scenario, proceed. If not, renegotiate the price formula or insist on a tariff pass-through protection clause.

BESS Dispatch Optimisation: Re-Running Your Stack for a Post-ERTSA World

Battery Energy Storage Systems (BESS) have been sold to C&I buyers primarily on two value stacks: peak-demand shaving (reducing the Notified Maximum Demand charge) and Time-of-Use (TOU) arbitrage — charging during off-peak low-rate periods and discharging during peak high-rate periods. Both stacks are sensitive to the variable-vs-fixed cost split.

As Eskom's restructuring moves more revenue into fixed charges and reduces variable energy rates to compensate — Eskom's proposal raises fixed costs to better reflect the actual cost of supplying electricity, and to keep the overall average increase at 8.83%, the utility plans to offset those higher fixed charges by reducing variable energy rates — the TOU arbitrage spread available to a BESS narrows. A BESS that was pencilled in to earn R0.45/kWh in TOU spread under 2025 assumptions may only earn R0.30–0.35/kWh in 2027 if the peak-to-off-peak energy rate differential compresses as fixed charges absorb more of the tariff stack.

BESS developers and buyers must re-run their dispatch optimisation models with post-ERTSA 2027-28 tariff inputs the moment NERSA publishes its final decision — expected before March 2027. Projects whose BESS ROI was marginal on 2026 assumptions may need to be redesigned around larger capacity, longer durations, or demand-charge optimisation as the primary revenue driver rather than TOU energy arbitrage.

Five Practical Steps Every C&I Buyer Should Take Before 2 October 2026

Download and read the ERTSA 2027-28 consultation paper. NERSA has published the consultation paper on its website under 'Electricity > Consultations > Documents', and stakeholders are requested to comment in writing. Your energy advisor should be doing this on your behalf.
Submit a formal comment. Public submissions can directly alter how costs are structured and distributed across customer bands. C&I buyers who oppose the proposed fixed-cost shift have legal standing to say so — and NERSA is required to consider those submissions before finalising the structure.
Rebuild your PPA financial model with ERTSA 2027-28 scenarios. Use three variants: tariff structure approved as proposed; partial adjustment; and status quo. All three are plausible outcomes.
Insert tariff pass-through or adjustment clauses into any PPA being negotiated now. Any agreement signed before NERSA's final ERTSA 2027-28 decision (likely February–March 2027) should include explicit language on how changes to wheeling credit rates and network charges are allocated between generator and offtaker.
Re-model your BESS dispatch stack. For developers modeling solar-plus-storage projects, pre-built BESS dispatch optimisation and revenue stacking modules are available — use them with 2027 tariff inputs as the base case, not 2026 actuals.

The Bottom Line for Commercial Property Owners

The ERTSA 2027-28 consultation is not a background regulatory process — it is an active repricing event for every C&I energy contract that extends into or beyond April 2027. Energy analysts and civil society bodies warn that the actual financial hit for businesses will be far more severe than the headline 8.83% figure suggests, due to aggressive restructuring of fixed daily service fees. The shift toward full cost-reflective network charges is a structural, multi-year policy direction — not a one-cycle anomaly. Buyers who model for it now, engage the consultation process, and build appropriate protections into their agreements will be significantly better positioned than those who sign on current assumptions and absorb the repricing shock in April 2027.

NERSA will collate all comments and incorporate them into its final decision. Once the submission window closes, NERSA will evaluate all feedback received before making a final decision on the structural approval of the tariff design. The window is open. Use it.