Complete transparency on assumptions, calculation methods, corrections, and uncertainty underlying the economic projections presented throughout this website. Updated December 2025 to reflect verified current BESS benchmarks.
Material correction — December 2025: Previous versions of this website cited total system savings of £161–187bn and BESS savings of £121–134bn. These figures used pre-2025 BESS cost assumptions of £250–300/kWh, which have been superseded by dramatic cost reductions in 2024–2025. Revised figures using verified 2025 benchmarks are presented throughout this site. The correction was first acknowledged in our Fourth Formal Representation to DESNZ (02/03/2026). We are committed to accuracy over advocacy.
| Parameter | Value Used | Source / Notes |
|---|---|---|
| Solar Capacity Target | 45–47 GW | UK Solar Roadmap, DESNZ, June 2025 |
| Analysis Timeframe | 30 years (2025–2055) | Conservative — modern panels often exceed 30-year warranty |
| Pipeline Scale | 65+ GW total | REPD October 2025: 41.2 GW sub-NSIP + 24.7 GW NSIP-scale |
| VBPV Energy Premium | 19–22% annual | Badran & Dhimish (2024), University of York — full year empirical |
| Duck Curve Reduction | 57% less severe | Derived from University of York generation profile comparison |
| Grid Hosting Capacity | +46% | Joutijärvi et al. (2023), Renewable & Sustainable Energy Reviews |
| Agricultural Productivity | 80–90% maintained | Riaz et al. (2021), IEEE Journal of Photovoltaics; Next2Sun data |
| Scenario | BESS Required | Basis |
|---|---|---|
| TMPV (47 GW) | 170–190 GWh | Required to manage duck curve and provide evening peak supply |
| VBPV (47 GW) | 78–87 GWh | 57% duck curve reduction → 53% less storage needed |
| Storage avoided | ~92–103 GWh | TMPV requirement minus VBPV requirement |
| Source | BESS Cost (2025) | Date |
|---|---|---|
| BloombergNEF Energy Storage Cost Survey 2025 | $117/kWh global average turnkey | December 2025 |
| Ember — "How Cheap is Battery Storage?" | $125/kWh all-in utility-scale | October 2025 |
| Previous assumption (now superseded) | £250–300/kWh | Pre-2025 data — obsolete |
Why the figure fell so dramatically: The BESS market has experienced extraordinary cost reductions — a 40% fall in 2024 alone (BloombergNEF), with further falls in 2025. The $117/kWh 2025 figure is approximately 75% lower than the $500+/kWh assumption used in 2023-era analyses. The reduction in savings headline does not weaken the VBPV case — it reflects market reality and is more defensible to policymakers.
Grid infrastructure savings derive from VBPV's 46% higher grid hosting capacity (Joutijärvi et al. 2023) and its superior demand alignment, which reduces the need for distribution network reinforcement, substation upgrades, and balancing services.
| Infrastructure Component | VBPV Saving (estimate) | Basis |
|---|---|---|
| Distribution network reinforcement deferral | £5–10bn | +46% hosting capacity → deferred DNO capex |
| Substation upgrade deferral | £3–7bn | Reduced peak loading from better demand alignment |
| Balancing services reduction | £2–4bn (over 30 years) | 57% less severe duck curve → less gas peaking, less curtailment |
| Transmission reinforcement | £5–4bn | Improved demand correlation reduces transmission constraint |
| Total grid savings estimate | £15–25bn | Conservative; independent verification needed |
Economic projections are inherently uncertain. The following caveats apply:
Independent Verification Encouraged. These projections represent our analysis of available research. We actively encourage independent verification by energy economics experts, peer review of methodology, and site-specific analysis for UK deployment locations. If you identify errors or have alternative methodological approaches, please contact the campaign.