Case Study · Residential Solar + Battery + EV Charger
8.37kW Residential Solar Installation with Sigenergy Battery & EV Charger in Sutton, Surrey
8.37 kWpSystem Size
8 kWInverter Capacity
18.08 kWhBattery
6,430 kWhAnnual Output
71%Energy Offset
4Y 11MPayback
The Opportunity: Solar, Storage & EV Charging for a Sutton Home
This residential property on Sutton Common Road in Sutton, Surrey (SM1) — just minutes from Sol4r Energy's own head office — had an annual electricity consumption of 9,000 kWh per year, putting the household well above the UK average. With annual electricity bills approaching £2,900 on an Octopus Tracker tariff and energy prices continuing to climb, the homeowner approached Sol4r Energy for a complete energy solution: solar generation, battery storage, and integrated EV charging — all in one system.
The property offered a multi-aspect roof with both flat and pitched sections, providing space for 18 DMEGC 465W panels across three groups. Beyond reducing bills, the homeowner wanted to future-proof for electric vehicle ownership with a Sigenergy 7kW EV charger powered by the same solar and battery ecosystem — charging the car from the sun rather than the grid.
The property on Sutton Common Road, Sutton — 18 DMEGC 465W panels installed across multi-aspect roof by Sol4r Energy.
Sol4r Energy designed an 8.37 kWp system paired with 18.08 kWh of Sigenergy battery storage, an 8 kW single-phase hybrid inverter, and a 7 kW Sigenergy EV charger. Using SAM (System Advisor Model) performance modelling, the system was engineered to offset 71% of the household's total electricity demand, deliver £2,621 in annual savings, and pay for itself in just 4 years and 11 months. Net savings over 25 years are projected at £126,626.
Installation Video — Sutton Common Road
Watch our team install the 8.37kW solar system at Sutton Common Road, Sutton.
Before & After: The Transformation
❌ Before Sol4r Energy
- 100% reliant on the grid — annual bills approaching £2,900
- 9,000 kWh consumed per year with zero on-site generation
- No battery storage — unable to shift energy to cheaper hours
- Fully exposed to rising energy prices — 7%+ annual increases
- No EV charging infrastructure
- No way to reduce the household's carbon footprint
✅ After Sol4r Energy
- 71% energy offset — generating 6,430 kWh per year on-site
- 18.08 kWh Sigenergy battery maximising overnight and peak usage
- 7 kW Sigenergy EV charger — charging from solar and cheap overnight rates
- £2,621 annual savings from day one
- 2 tonnes of CO₂ eliminated every year
- System pays for itself in 4 years 11 months — then generates pure savings
Installation Photos — Sutton, Surrey
18 × DMEGC 465W solar panels across multi-aspect roof with tilt racks, Sigenergy SigenStor EC 8.0SP single-phase hybrid inverter, 2 × SigenStor BAT 10.0 battery modules (18.08 kWh), Sigenergy 7kW EV charger & birds protection — all installed by Sol4r Energy's in-house team at a residential property in Sutton, Surrey.
Project Overview — Residential Solar, Sutton, Surrey
| Detail | Information |
|---|---|
| Location | Sutton Common Road, Sutton, SM1 3HP — Surrey |
| Property type | Residential property |
| Roof configuration | Multi-aspect — Group 1: 10 panels flat-mounted (0° tilt) · Group 2: 5 panels with tilt racks at 20° · Group 3: 3 panels at 37° tilt |
| Annual consumption | 9,000 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 & EV Charger
Every component was selected for reliable performance, intelligent energy management, and seamless EV integration. The Sigenergy ecosystem — inverter, batteries, and EV charger — operates as one connected system, delivering smart energy management from roof to road:
| Component | Product | Specification |
|---|---|---|
| Solar Panels | 18 × DMEGC 465W | DM465G12RT-G48HBB · Hengdian Group DMEGC Magnetics · 8.37 kWp total · 30yr product & 30yr performance warranty |
| Hybrid Inverter | 1 × SigenStor EC 8.0SP | 8 kW single-phase hybrid · IP66 rated · EMS built-in · 10yr warranty |
| Battery Storage | 2 × SigenStor BAT 10.0 | 18.08 kWh total · LiFePO4 · 314Ah cells · 10,000 cycles · 100% depth of discharge · 10yr warranty |
| EV Charger | 1 × Sigen EV AC Charger 7kW | 7 kW single-phase · solar boost charging · integrated with Sigenergy EMS |
| Generation Meter | 1 × Emlite EM-ECA2-BI | 1-phase bi-directional · 100A · 1000 pulse/kWh |
| Additional | Birds protection, tilt racks | 5-panel tilt rack system for optimal angle · full birds protection mesh |
Multi-Aspect Roof Design — Maximising Every Panel
The property's roof offered three usable aspects — including flat and pitched sections. Sol4r Energy designed the system to utilise all three, spreading 18 panels across three groups to extend generation across the full day:
| Roof Aspect | Orientation | Panels | Configuration |
|---|---|---|---|
| Group 1 | Southwest · 0° tilt (flat) | 10 panels (4.65 kWp) | Flat-mounted on flat roof section — captures all-day sun across the widest arc |
| Group 2 | Southwest · 20° tilt | 5 panels (2.325 kWp) | Tilt racks fitted to optimise angle — boosting output from the flat roof section |
| Group 3 | Northeast · 37° tilt | 3 panels (1.395 kWp) | Pitched roof section — captures early morning and late evening generation |
By utilising all three aspects, the system produces a broader generation curve than a single-aspect installation would achieve. The flat-mounted and tilted southwest panels capture the strongest midday and afternoon sun, while the northeast group extends generation into the early morning hours. Combined with the 18.08 kWh Sigenergy battery, excess solar from peak generation hours is stored and discharged during the evening and overnight — when electricity is most expensive. The tilt racks on Group 2 demonstrate how Sol4r Energy optimises output even on flat roofs, angling panels to catch more direct sunlight throughout the year.
Energy Performance & Self-Consumption
| Performance Metric | Result |
|---|---|
| Total installed capacity | 8.37 kWp |
| Annual solar generation | 6,430 kWh |
| Annual household consumption | 9,000 kWh |
| Annual consumption offset | 71% — system produces nearly three-quarters of the household's demand |
| kWh/kWp yield | 813.8 kWh/kWp |
| Shade factor | 0.944 |
| Self-consumption — solar only | 2,826 kWh (31.4% self-sufficiency) |
| Self-consumption — solar + battery | 3,162 kWh (35.0% self-sufficiency) |
| Total energy discharged from battery per year | 12,790 kWh |
| Usable battery capacity | 17.52 kWh |
With 9,000 kWh of annual demand and 6,430 kWh of solar generation, the system offsets 71% of total household electricity consumption. The 18.08 kWh Sigenergy battery increases self-sufficiency from 31.4% (solar only) to 35% with storage, and — critically — enables the household to exploit the 24p/kWh differential between Octopus Intelligent's night rate (7p) and day rate (31p) through intelligent tariff arbitrage. With 12,790 kWh of annual battery throughput, the battery is working hard every single day — charging cheap and discharging expensive. For homeowners in Sutton, Cheam, Carshalton, Wallington, Morden, and across Surrey and South London, these results demonstrate what a well-designed residential solar system can achieve.
Monthly Savings Breakdown — Year 1
Every month of the year, this system delivers meaningful bill reductions — saving between £175 and £265 per month, with summer months putting the household into credit:
| Month | Solar Gen | Imported | Exported | Export Credit | Old Bill | New Bill | Saving |
|---|---|---|---|---|---|---|---|
| January | 135 kWh | 832 kWh | 0 kWh | £0 | £284 | £100 | £184 |
| February | 203 kWh | 729 kWh | 1 kWh | £0 | £277 | £86 | £190 |
| March | 425 kWh | 589 kWh | 85 kWh | £13 | £276 | £49 | £228 |
| April | 706 kWh | 429 kWh | 358 kWh | £54 | £237 | -£6 | £243 |
| May | 966 kWh | 345 kWh | 625 kWh | £94 | £213 | -£52 | £265 |
| June | 937 kWh | 313 kWh | 601 kWh | £90 | £203 | -£51 | £253 |
| July | 982 kWh | 300 kWh | 653 kWh | £98 | £197 | -£59 | £256 |
| August | 861 kWh | 317 kWh | 559 kWh | £84 | £193 | -£44 | £237 |
| September | 575 kWh | 390 kWh | 284 kWh | £43 | £211 | £2 | £208 |
| October | 351 kWh | 523 kWh | 102 kWh | £15 | £234 | £40 | £194 |
| November | 183 kWh | 706 kWh | 0 kWh | £0 | £264 | £77 | £187 |
| December | 107 kWh | 849 kWh | 0 kWh | £0 | £284 | £109 | £175 |
| ANNUAL TOTAL | 6,430 kWh | 6,322 kWh | 3,268 kWh | £491 | £2,873 | £251 | £2,621 saved |
Projections assume 7% annual energy price increase. Utility savings based on switch from Octopus Tracker Eastern to Octopus Intelligent tariff. From April through August, the household runs in net credit — earning money from the grid rather than paying it. The 18 kWh battery with tariff optimisation (charging at 7p overnight, discharging at 31p during the day) drives strong winter savings that a solar-only system couldn't achieve.
Financial Returns — Residential Solar Investment
£2,621Year 1 Bill Savings
4Y 11MPayback Period
£140,926Lifetime Bill Savings
£126,626Net 25-Year Savings
885%Total ROI
23.6%Annual Rate of Return
With energy prices projected to rise by 7% annually, this residential solar system pays for itself in under five years — then delivers over £126,000 in net savings across the remaining system lifetime. By 2035, annual savings are projected to reach £4,296, and by 2050 the system will be saving £10,557 per year. The financial case is compelling: an 885% total return on investment and 23.6% annual rate of return — outperforming virtually any other home improvement or capital investment. With 0% VAT on domestic solar installations, the £14,300 purchase price includes no hidden costs. For homeowners across Sutton, Cheam, Carshalton, Wallington, Morden, Mitcham, and the wider Surrey and South London area, residential solar with battery storage and EV charging is one of the most impactful financial decisions for your home. Book a free property survey to find out what solar could save you.
Battery & EV Charging: The Sigenergy Advantage
18 kWh battery + 7kW EV charger = one intelligent energy ecosystem
This isn't just panels on a roof — it's a complete home and transport energy management system. The Sigenergy ecosystem integrates inverter, batteries, and EV charger into one platform that powers, saves, and charges.
Solar-Powered EV Charging
The Sigenergy 7kW EV charger is fully integrated with the solar and battery system. During sunny hours, the car charges from free solar energy. At night, it charges at 7p/kWh on Octopus Intelligent — a fraction of the cost of petrol or standard grid charging.
Intelligent Tariff Arbitrage
Charges at 7p/kWh overnight on Octopus Intelligent, then powers the home at 31p/kWh during the day. That 24p/kWh differential, multiplied across 12,790 kWh of annual battery throughput, drives substantial savings year after year.
35% Grid Independence
Solar alone gives 31.4% self-sufficiency. The 18 kWh battery lifts this to 35% — shifting stored solar and cheap overnight electricity into the expensive daytime hours when it's needed most.
10,000-Cycle LiFePO4
Premium 314Ah LiFePO4 cells rated for 10,000 charge cycles and 100% depth of discharge. That's 27+ years of daily cycling — the battery will outlast the warranty by decades.
One Integrated System
Inverter, batteries, and EV charger all communicate through Sigenergy's built-in Energy Management System. No separate apps, no compatibility issues — everything works together intelligently from day one.
Compounding Savings
With energy costs rising 7% annually, savings compound dramatically. By 2035, this system saves £4,296/year. By 2050, £10,557/year — totalling £126,626 in net savings over 25 years.
Environmental Impact
2 tonnesCO₂ saved per year
313 treesEquivalent over lifetime
48,672 kmCar distance avoided
35 flightsLong-haul avoided
At 2 tonnes of CO₂ eliminated per year, this installation makes a real and measurable environmental contribution. Over the system's lifetime, that's the equivalent of planting 313 trees or removing a car from the road for over 48,000 kilometres. Combined with the Sigenergy EV charger — enabling the homeowner to drive on solar electricity rather than petrol — the total carbon reduction is even greater. Sol4r Energy installs residential solar systems across Sutton, Cheam, Carshalton, Wallington, Morden, Mitcham, Surrey, and nationwide.
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, 0% VAT, and all manufacturer warranties. Trusted by homeowners across Surrey and the UK.
🔬 Professional System Design
Using SAM (System Advisor Model) performance modelling, Sol4r Energy designed a multi-aspect system optimised for this specific property — accounting for flat and pitched roof sections, orientation, shading, and consumption patterns to maximise every panel's output.
📋 Complete End-to-End Service
From free survey to DNO application, tilt rack installation, EV charger wiring, MCS commissioning, tariff optimisation advice, and ongoing maintenance — Sol4r Energy handles everything. One team, one contact, no subcontractors.
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 Sigenergy Battery Warranty
2-Year Workmanship Warranty
2-Year Annual Maintenance Plan
All certifications issued on completion. Sol4r Energy is HIES-registered, NAPIT-approved, and TrustMark-endorsed — the highest level of consumer protection for solar installations in the UK. 0% VAT applies to all domestic solar installations.
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.
Solar Services — Sutton, Surrey & Nationwide
Get Solar Installed in Sutton, Surrey & Nationwide
Free property survey · No-obligation quote · MCS-certified · 0% VAT on domestic solar
0330 124 2945 Get a Free Quote Contact Us