{"id":3924,"date":"2026-07-25T09:33:23","date_gmt":"2026-07-25T01:33:23","guid":{"rendered":"https:\/\/www.solidess.com\/?p=3924"},"modified":"2026-07-25T09:33:23","modified_gmt":"2026-07-25T01:33:23","slug":"south-africa-wheeling-bess","status":"publish","type":"post","link":"https:\/\/www.solidess.com\/af\/south-africa-wheeling-bess\/","title":{"rendered":"How to Size BESS for Electricity Wheeling in South Africa"},"content":{"rendered":"\t\t
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A wheeling agreement can reduce the cost and carbon intensity of industrial electricity, but it does not automatically align remote renewable generation with a factory\u2019s operating profile.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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MegSolid sizes a South Africa wheeling BESS from three interval datasets: the generator export profile, the eligible wheeling settlement profile and the factory load profile.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Eskom allocates wheeled energy to the buyer on a time-of-use basis. The factory still receives a bill for the electricity measured at its point of delivery, followed by a credit for eligible wheeled energy after the applicable losses. Network, connection, capacity and administration charges remain relevant.<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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The direct engineering answer is:<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Do not size the battery from annual PPA energy. Size it from the maximum interval mismatch, its duration, the permitted site import and the SOC reserved for backup.<\/strong><\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\tContact MegSolid today for a tailored energy storage plan<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Why Wheeled Energy Does Not Equal On-Site Power<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Wheeling is a network-access and energy-accounting arrangement. The factory continues to receive physical electricity through its local point of delivery.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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A remote solar or wind PPA therefore does not energise the factory bus when the local network is unavailable. Eskom also states that customers receiving wheeled energy are not exempt from system load-reduction requirements.<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Project Objective<\/th>Primary Requirement<\/th><\/tr><\/thead>
Procure remote renewable energy<\/td>PPA and wheeling arrangement<\/td><\/tr>
Match renewable output to factory consumption<\/td>Generator-side or off-taker-side BESS<\/td><\/tr>
Reduce factory maximum demand<\/td>Off-taker-side BESS and site EMS<\/td><\/tr>
Maintain critical loads<\/td>Behind-the-meter BESS, PCS and isolation architecture<\/td><\/tr><\/tbody><\/table>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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A project requiring both renewable-energy matching and operational continuity must calculate those requirements separately.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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The Hybrid Solar-Storage Architecture for Unstable Grids<\/a><\/strong> explains how grid supply, local generation and battery storage can operate as coordinated but distinct energy sources.<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Separate Generation, Settlement and Factory Load Profiles<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Annual PPA production and annual factory consumption are not sufficient for BESS sizing. The engineering model requires three time-series profiles.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Generator export profile:<\/strong> Power exported from the renewable project at its grid connection point.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Wheeling settlement profile:<\/strong> Energy eligible for allocation after applying the agreements, meters, TOU periods and losses.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Wheeling settlement profile:<\/strong> Energy eligible for allocation after applying the agreements, meters, TOU periods and losses.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Use the settlement interval defined in the project documents. Fifteen-minute or 30-minute data usually provides a better engineering basis than monthly totals, but the analysis must follow the actual metering arrangement.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Eskom credits wheeled energy in the same TOU period in which it is generated. Energy generated during a standard period is not automatically exchanged for consumption during an off-peak or peak period.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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For each interval:<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Profile Mismatch(t) = Eligible Wheeled Energy(t) \u2212 Factory Load(t)<\/strong><\/p>\t\t\t\t<\/div>\n\t\t\t\t

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A positive result identifies potential charging energy. A negative result identifies the factory demand remaining after applying the eligible wheeling profile.<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Choose Generator-Side or Off-Taker-Side BESS<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Storage location determines which problem the system can solve.<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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BESS Location<\/th>Main Functions<\/th>Main Limitation<\/th><\/tr><\/thead>
Generator side<\/td>Smooth renewable output, reduce curtailment and enforce generator POI limits<\/td>Does not directly reduce factory demand or provide local backup<\/td><\/tr>
Off-taker side<\/td>Reduce demand peaks, manage factory import and preserve backup energy<\/td>Does not remove constraints at the remote generator<\/td><\/tr>
Both sides<\/td>Coordinate dispatchable renewable supply and factory demand control<\/td>Requires separate objectives, meters and controllers<\/td><\/tr><\/tbody><\/table>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Generator-side storage is suitable when the PPA requires a more predictable production profile.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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Off-taker-side storage is generally more useful when the factory needs to control maximum demand, transformer loading, on-site PV or critical-load continuity.<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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When batteries are installed at both locations, the dispatch hierarchy must prevent conflicting responses. The required point lists, command priorities and fallback modes should follow a project-specific BMS and EMS Communication Architecture in BESS<\/a><\/strong>.<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Calculate BESS Power From the Maximum Profile Mismatch<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Battery power is determined by the largest instantaneous correction the system must provide, not by daily energy alone.<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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For an off-taker-side BESS, evaluate:<\/p>\t\t\t\t<\/div>\n\t\t\t\t

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