Solar vs Energy Prices: The Maths for West Wales
Real-world analysis of solar savings against rising energy costs. Export tariffs, winter performance, and sensitivity analysis for Welsh homes.
With energy prices remaining high following global market disruption, many West Wales homeowners are evaluating solar panels as protection against future price increases. But how much can solar really save on your energy bills?
This analysis uses real data from Ofgem price cap figures and local solar generation data to show actual savings potential for Welsh homes. Electricity rates are based on the Ofgem cap for July–September 2026 and are revised quarterly — your supplier rate may differ.
Baseline Usage & Tariff Assumptions
Understanding your current energy costs is essential for calculating solar savings. According to BEIS household energy statistics, average Welsh homes consume 3,500–4,500 kWh annually, with usage patterns that align well with solar generation.
Current Energy Pricing (Ofgem cap 1 Jul–30 Sep 2026, revised quarterly)
Standard Variable Tariff
- Unit Rate: 26.11p per kWh (Ofgem Price Cap, July–September 2026)
- Standing Charge: 57.19p per day
- Annual Standing: £209
- Usage Cost (4,000 kWh): £1,044
- Total Annual Bill: £1,253
Note: standing charge cannot be reduced by solar generation — only unit-rate costs are offset.
Typical Household Profile
- Property Type: 3-bed semi-detached
- Annual Consumption: 3,800–4,200 kWh
- Peak Usage: Evening 17:00–21:00
- Heating: Gas central heating
- Summer/Winter Ratio: 1:1.8
Low User (2,500 kWh)
Average User (4,000 kWh)
High User (6,000 kWh)
Solar Savings: With Battery vs Without
Solar savings depend significantly on how much generated electricity you can use directly (self-consumption) versus how much you export to the grid. Battery storage typically improves self-consumption rates from around 35% (without battery) to around 72% (with battery), based on a typical West Wales household profile. Standing charges cannot be reduced by solar and are excluded from the savings calculations below.
Scenario A: ~5.2 kWp Solar System — Without Battery
A ~5.2 kWp array (e.g. 13 × 400 W panels) yields approximately 5,100 kWh/year in West Wales at ~975 kWh/kWp. Figures use the Ofgem cap for July–September 2026 (26.11p/kWh, revised quarterly).
Annual Generation & Usage
- Total Generation: 5,100 kWh
- Self-Consumption (35%): 1,785 kWh
- Grid Export (65%): 3,315 kWh
- Grid Import Reduction: 1,785 kWh
- Remaining Grid Import: 2,215 kWh
Financial Impact
- Import Savings: £466 (1,785 × 26.11p)
- Export Income: £398 (3,315 × 12p, typical fixed SEG tariff)
- Total Annual Benefit: £864
- New Annual Bill: £787 (usage + standing)
- Bill Reduction: 37% on usage costs; export income (£398) earned separately
Based on a £10,200 installation cost (example list price at time of writing — request a current quote for live pricing) and £864/year total benefit at the current cap rate.
Scenario B: ~5.2 kWp Solar + Battery — With Battery Storage
Battery storage raises self-consumption from ~35% to ~72% by capturing daytime surplus for evening use. Figures use the Ofgem cap for July–September 2026 (26.11p/kWh, revised quarterly).
Enhanced Self-Consumption
- Total Generation: 5,100 kWh
- Self-Consumption (72%): 3,672 kWh
- Grid Export (28%): 1,428 kWh
- Grid Import Reduction: 3,672 kWh
- Remaining Grid Import: 328 kWh
Superior Financial Returns
- Import Savings: £959 (3,672 × 26.11p)
- Export Income: £171 (1,428 × 12p, typical fixed SEG tariff)
- Total Annual Benefit: £1,130
- New Annual Bill: £295 (usage + standing)
- Bill Reduction: 76% on usage costs; export income (£171) earned separately
Based on typical solar + battery installation cost and £1,130/year total benefit at current cap rate.
Export Tariffs & Smart Meters
Export tariffs under the Smart Export Guarantee (SEG) provide income for surplus solar generation. While rates are modest compared to import prices, they still contribute meaningfully to solar returns, especially for systems without battery storage.
Current SEG Tariff Rates (2026)
Leading Flat SEG Tariffs (Aug 2026)
- • Range across leading flat-rate SEG suppliers
- • Smart meter required
- • MCS certified systems
- • Rates change frequently — check Ofgem's SEG tariff table
Export income examples use 12p/kWh (conservative lower bound of the ~12–15p/kWh range, checked Aug 2026). British Gas Export & Earn Plus was withdrawn in June 2026. Always verify current rates against Ofgem's SEG comparison table before deciding.
Export Income Calculation Example (12p/kWh — conservative lower bound of ~12–15p/kWh range, Aug 2026)
~5.2 kWp system without battery: 3,315 kWh export × 12p = £398 annual income
~5.2 kWp system with battery: 1,428 kWh export × 12p = £171 annual income
For current rates, see Ofgem's SEG tariff comparison — rates are not guaranteed and change frequently.
Seasonal Output & Winter Performance
West Wales solar generation varies significantly by season, with summer producing 3–4 times more electricity than winter months. Understanding this variation helps set realistic expectations for bill reduction throughout the year.
Monthly Generation Profile (~5.2 kWp System)
Winter (Dec–Feb)
Spring (Mar–May)
Summer (Jun–Aug)
Autumn (Sep–Nov)
Bill offsets shown at 26.11p/kWh (Ofgem cap, July–September 2026). Seasonal kWh figures are indicative estimates; actual output depends on roof orientation, pitch, and local shading.
Winter Performance Factors
Challenges
- • Lower sun angle (15–20° in December)
- • Shorter daylight hours (7–8 hours)
- • More frequent cloudy weather
- • Higher household electricity demand
- • Occasional snow covering (rare in West Wales)
Advantages
- • Cooler panels operate more efficiently
- • Maritime climate prevents extreme cold
- • Consistent winter generation (20–25% annual)
- • Good diffuse light capture capability
- • Minimal snow persistence in coastal areas
Price Sensitivity: What If Energy Costs Change?
Solar investment returns are sensitive to future energy price changes. The Ofgem cap resets quarterly, so long-term payback calculations are inherently uncertain. The table below shows how the same ~5.2 kWp system (Scenario A, no battery) performs across a range of unit rates, keeping the SEG export rate fixed at 12p/kWh.
Sensitivity Analysis: ~5.2 kWp System (No Battery)
| Electricity Price | Annual Benefit | Payback Period | 25-Year Returns |
|---|---|---|---|
| 20p/kWh | £755 | 12–14 years | — |
| 26.11p/kWh (Ofgem cap, July–September 2026) | £864 | 9–12 years | — |
| 35p/kWh (+34%) | £1,023 | 7–9 years | — |
| 45p/kWh (+72%) | £1,201 | 6–8 years | — |
Annual benefit = import savings (1,785 kWh × unit rate) + export income (3,315 kWh × 12p). Payback based on a £10,200 example install cost (list price at time of writing — request a current quote). 25-year returns removed — they required an unverified price-escalation assumption.
Key Insights
- • Solar provides protection against energy price volatility
- • Higher future prices improve payback period
- • Even at current cap levels, solar offers a viable long-term return
- • Battery storage becomes more attractive with higher unit rates
Rudbaxton Water, Haverfordwest — Monitored System Performance
The generation, self-consumption, export and import figures below are real monitored data from this project. The £ savings and bill figures are illustrative calculations applying the current Ofgem cap rate (26.11p/kWh, July–September 2026) and SEG rate (12p/kWh) to those monitored kWh figures — they are not claimed real bills. See the Rudbaxton case-study page for the full project story.
Property (Before Solar)
- Property: Large detached house, south-facing roof
- Annual Consumption: 11,000 kWh
- Illustrative pre-solar bill: £3,081 (11,000 kWh × 26.11p + £209 standing charge — illustrative at July–September 2026 cap)
- Heating: Heat pump system
- Usage Pattern: High all-day demand
- Location: Haverfordwest, Pembrokeshire
- Roof Suitability: Excellent (south-facing)
- Shading: Minimal
After Solar (11.6 kWp + 10.36 kWh Battery) — Monitored Data
Monitored System Performance
- Annual Generation: 9,860 kWh (monitored)
- Self-Consumption: 8,874 kWh (90%) (monitored)
- Grid Export: 986 kWh (monitored)
- Remaining Grid Import: 2,126 kWh (monitored)
Illustrative £ Calculation at Current Cap Rates
- Import savings: £2,317 (8,874 kWh × 26.11p)
- Export income: £118 (986 kWh × 12p SEG)
- Illustrative remaining bill: £764 (2,126 kWh × 26.11p + standing charge)
All £ figures are illustrative calculations at the Ofgem cap for July–September 2026(26.11p/kWh, SEG 12p/kWh) applied to the monitored kWh figures. The cap resets quarterly; actual savings depend on the tariff at the time.
Is Solar Right for Your Energy Bills?
Solar PV offers substantial protection against rising energy costs while providing predictable electricity generation for 25+ years. The mathematics strongly favour solar investment for most West Wales properties.
Best Returns Expected
- • Annual electricity bills £800+
- • High daytime electricity usage
- • South-facing roof with minimal shading
- • Long-term homeownership plans
- • Concern about future energy price rises
Consider Alternatives
- • Very low electricity consumption (<2,000 kWh)
- • Significant roof shading issues
- • North-facing roof only
- • Short-term property ownership
- • Major roof renovation needed soon