Case Study · Residential Solar + Battery
Residential Solar Installation in Purley, Surrey — 10.2kW System with Sigenergy Battery
10.2 kWpSystem Size
10 kWInverter
13.5 kWhBattery
7,726 kWhAnnual Output
129%Energy Offset
5Y 6MPayback
The Opportunity: Solar Energy for Homes in Purley & Surrey
With energy costs continuing to rise, homeowners across Surrey and South London are increasingly turning to residential solar panels as a way to take control of their electricity bills and protect against future price increases. This property in Purley, CR8 — a leafy suburb between Croydon and Coulsdon — presented an ideal opportunity for a high-performance solar and battery storage installation, with a large west-facing roof and manageable shading.
The homeowner approached Sol4r Energy with a clear goal: dramatically reduce their annual electricity spend, generate surplus energy to sell back to the grid, and future-proof their home against rising tariffs. With an annual consumption of 6,000 kWh, the property was well suited to a system that could not just offset but exceed total demand — turning the home into a net energy exporter.
Using professional SAM modelling software, Sol4r Energy designed a 10.2 kWp system paired with a Sigenergy SigenStor EC 10kW hybrid inverter and 13.5 kWh battery storage — delivering 129% of the home's annual electricity needs and a payback of just 5 years and 6 months. For homeowners across Purley, Sanderstead, Kenley, South Croydon, Wallington and the wider Surrey area, this installation shows exactly what's achievable with the right system design.
Before & After: The Transformation
❌ Before Sol4r Energy
- 100% reliant on the grid for all electricity
- Annual electricity bills of approximately £1,671
- No battery backup or energy storage
- No way to earn from surplus generation
- Fully exposed to rising energy prices year on year
- No visible commitment to sustainability
✅ After Sol4r Energy
- 129% energy offset — generates more electricity than the home uses
- Bills go negative for 5 months of the year — the grid pays the homeowner
- 13.5 kWh Sigenergy battery maximising self-consumption and enabling tariff arbitrage
- 41.9% grid independence with solar + battery combined
- 2 tonnes of CO₂ saved every year
- £49,060 in net savings projected over 25 years
Solar Installation Photos – Purley, Surrey
22 × DMEGC 465W solar panels, Sigenergy SigenStor EC 10kW hybrid inverter & 13.5 kWh battery storage, Renusol mounting system, and full perimeter bird protection — all installed by Sol4r Energy's in-house team at a residential property in Purley, Surrey.
Project Overview — Residential Solar in Purley, Surrey
| Detail | Information |
|---|---|
| Location | Purley, CR8 — Surrey |
| Property type | Detached residential property |
| Installation date | 2026 |
| Roof orientation | Single aspect — west-facing (270° azimuth, 90° from South) |
| Roof tilt | 25° |
| Annual consumption | 6,000 kWh |
| Tariff recommendation | Octopus Intelligent — Day 31p (5am–11pm), Night 7p (11pm–5am) |
| Export tariff (SEG) | Smart Export Guarantee — 15p/kWh all day |
| Performance calculator | System Advisor Model (SAM) 2025.4.16 |
| MCS certified | Yes — all systems registered, certificates issued on completion |
Technical Specifications — Solar & Battery System
Every component in this residential solar installation in Purley, Surrey was selected for maximum output, smart energy management, and long-term reliability. Sol4r Energy only uses premium solar panels and battery storage systems with comprehensive manufacturer warranties:
| Component | Product | Specification |
|---|---|---|
| Solar Panels | 22 × DMEGC 465W | DM465G12RT-G48HBB · 10.23 kWp total · 30yr product & performance warranty |
| Hybrid Inverter | Sigenergy SigenStor EC 10kW | 10 kW single-phase hybrid inverter · on & off-grid capable · 10yr warranty |
| Battery Storage | Sigenergy | 13.5 kWh total · 10yr warranty |
| Power Sensor | 2 × Sigen SP-DH | Single-phase power meter · 1% accuracy · 100ms data refresh · full app monitoring |
| Generation Meter | Emlite EM-ECA2-BI | 1-phase bi-directional · 100A · 1000 pulse/kWh |
| Mounting System | Renusol MS+ P | Stainless steel & aluminium · TÜV certified · 10yr warranty |
| Bird Protection | Full perimeter mesh | Installed across all panels to prevent nesting & protect performance |
Energy Performance & Grid Independence
| Performance Metric | Result |
|---|---|
| Total installed capacity | 10.23 kWp |
| Annual solar generation | 7,726 kWh |
| Annual household consumption | 6,000 kWh |
| Annual consumption offset | 129% — system produces nearly a third more than the home uses |
| kWh/kWp yield | 808.4 kWh/kWp |
| Shade factor | 0.934 — 6.6% shading losses |
| Self-sufficiency — solar only | 36.8% |
| Self-sufficiency — solar + battery | 41.9% |
| Annual electricity exported | 5,193 kWh — earning income via Smart Export Guarantee at 15p/kWh |
The system generates nearly 30% more electricity than the home consumes annually, making this property a net energy exporter to the grid. Combined with the 13.5 kWh Sigenergy battery, the homeowner benefits from intelligent energy management — storing solar during the day and using it during expensive peak hours. Surplus generation is exported at 15p/kWh via the Smart Export Guarantee. The Octopus Intelligent tariff adds further value with its overnight rate of just 7p/kWh, enabling low-cost battery charging from the grid when solar isn't available. For homeowners across Purley, Croydon, Coulsdon, Sanderstead, Kenley, Caterham, Wallington, Sutton and the wider Surrey area looking at residential solar, these results show what's achievable with the right system design.
Monthly Savings Breakdown — Year 1
From April through September, this system generates enough electricity that the household bill goes negative — the grid is paying the homeowner, not the other way around:
| Month | Solar Gen | Imported | Exported | Export Credit | Old Bill | New Bill | Saving |
|---|---|---|---|---|---|---|---|
| January | 170 kWh | 487 kWh | 11 kWh | £2 | £164 | £53 | £111 |
| February | 257 kWh | 423 kWh | 53 kWh | £8 | £159 | £39 | £120 |
| March | 516 kWh | 347 kWh | 250 kWh | £38 | £160 | £5 | £155 |
| April | 860 kWh | 263 kWh | 608 kWh | £91 | £138 | −£56 | £193 ✦ |
| May | 1,174 kWh | 204 kWh | 924 kWh | £139 | £125 | −£107 | £232 ✦ |
| June | 1,110 kWh | 190 kWh | 870 kWh | £130 | £119 | −£101 | £219 ✦ |
| July | 1,164 kWh | 182 kWh | 930 kWh | £139 | £116 | −£110 | £225 ✦ |
| August | 1,025 kWh | 197 kWh | 811 kWh | £122 | £114 | −£91 | £204 ✦ |
| September | 691 kWh | 243 kWh | 481 kWh | £72 | £123 | −£38 | £161 ✦ |
| October | 411 kWh | 318 kWh | 218 kWh | £33 | £136 | £7 | £129 |
| November | 220 kWh | 406 kWh | 36 kWh | £5 | £153 | £41 | £112 |
| December | 127 kWh | 514 kWh | 1 kWh | £0 | £164 | £59 | £105 |
| ANNUAL TOTAL | 7,726 kWh | 3,774 kWh | 5,193 kWh | £779 | £1,671 | −£299 | £1,968 saved |
✦ Negative bill = the homeowner is being paid by the grid via Smart Export Guarantee at 15p/kWh. Projections assume 7% annual energy price increase. Utility savings based on switch from Loyal Octopus Fixed 12M to Octopus Intelligent.
Financial Returns — Residential Solar Investment
£1,968Year 1 Bill Savings
5Y 6MPayback Period
£60,960Lifetime Bill Savings
£49,060Net 25-Year Savings
412%Total ROI
18.2%Annual Rate of Return
With energy prices projected to rise by 7% annually, this residential solar system in Purley, Surrey pays for itself in under six years and delivers exceptional long-term financial security — £49,060 in net savings over 25 years. The 0% VAT on residential installations means the full £11,900 system cost includes zero tax, making home solar significantly more affordable than commercial equivalents. Combined with the Octopus Intelligent tariff (overnight rate of just 7p/kWh for low-cost battery charging) and 15p/kWh SEG export, the economics are compelling for any homeowner. For households across Purley, Croydon, Coulsdon, Sanderstead, Kenley, Sutton and the wider Surrey area looking to reduce their energy bills, residential solar with battery storage consistently outperforms any other home improvement investment. Book a free site survey to find out what solar could save your household.
Battery Benefits: Why Storage Makes All the Difference at Home
Why the battery makes all the difference
The Sigenergy battery doesn't just store solar energy — it transforms how this home interacts with the grid, unlocking savings and independence that panels alone can't deliver.
41.9% Grid Independence
Without batteries, only 36.8% of solar generation would be self-consumed. The 13.5 kWh Sigenergy battery boosts this to 41.9% — a meaningful step towards energy independence.
Smart Export Guarantee Income
Surplus solar exported at 15p/kWh via the SEG earns an estimated £779 in year one alone. The battery helps optimise when to export vs. when to store for home use.
Intelligent Tariff Arbitrage
Octopus Intelligent charges the battery at just 7p/kWh overnight, then the home runs on stored energy during the 31p/kWh daytime rate. That 24p/kWh differential compounds daily.
Evening & Cooking Hours Covered
When the family comes home and demand peaks — cooking, heating water, running appliances — the battery covers this demand from stored solar rather than expensive grid electricity.
Winter Resilience
The battery bridges the gap when solar generation drops in winter — providing stored energy during the long dark evenings when grid prices are highest.
Rising Utility Protection
With energy costs rising 7% annually, the household's savings compound each year. By 2035, annual savings are projected to reach £1,810 — and £3,494 by 2050.
Environmental Impact
2 tonnesCO₂ saved per year
376 treesEquivalent over lifetime
58,487 kmCar distance avoided
42 flightsLong-haul avoided
The DMEGC 465W panels used at this property are high-efficiency modules with a strong track record in UK residential installations. Even with a west-facing orientation and some shading, the system delivers an impressive 7,726 kWh per year — the equivalent of planting 376 trees over the system's lifetime. This home in Purley is now generating clean, renewable energy whilst dramatically reducing its carbon footprint. Sol4r Energy installs residential solar systems for homes across Purley, Croydon, Coulsdon, Sanderstead, Kenley, Caterham, Wallington, Sutton and throughout Surrey and London.
Why This Homeowner Chose Sol4r Energy
🏆 MCS-Certified, Award-Winning
UK Enterprise Award winner and MCS-certified (registration NAP-68781) — the certification needed for the Smart Export Guarantee and all manufacturer warranties. Trusted by homeowners across Surrey.
🔬 Professional SAM Modelling
We used industry-standard SAM 2025.4.16 software to model the roof orientation before a single panel was ordered — ensuring the system was optimised for maximum annual yield on the property's west-facing roof.
📋 Complete End-to-End Service
From free survey to DNO application, electrical wiring, MCS commissioning, Octopus Intelligent tariff setup, energy monitoring app, and 2-year maintenance — Sol4r Energy handles everything.
Certifications & Warranties Included
MCS Commissioning Certificate (NAP-68781)
30-Year DMEGC Panel Product Warranty
HIES Consumer Protection Warranty
30-Year Panel Performance Warranty
NAPIT Building Regulation Certificate
10-Year Sigenergy Inverter Warranty
Electrical Safety Certificate (EICR)
10-Year Battery Warranty
Workmanship Warranty (2-Year Minimum)
20-Year Online System Monitoring
All certifications issued on completion. Sol4r Energy is HIES-registered, NAPIT-approved, TrustMark-endorsed, and ISO 9001:2015 certified — the highest level of consumer protection for solar installations in the UK.
Solar PV Finance
Finance option available through Phoenix Financial Consultants Limited.
All finance applications are subject to status and approval by Phoenix Financial Consultants Limited. Sol4r Energy Ltd is an Introducer Appointed Representative (Financial Services Register No. 1005252) of Phoenix Financial Consultants Limited (FRN: 539195), which is authorised and regulated by the Financial Conduct Authority. Phoenix Financial Consultants Limited is a credit broker, not a lender.
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