Solar Carport Case Study: How One Family Cut Their Energy Bills by 70%

When the Martin family faced rising electricity bills and wanted to reduce their carbon footprint, they knew solar was part of the answer. But they needed space for two electric vehicles, which meant a solar carport made perfect sense. Here's how a bespoke oak frame solar carport, battery storage, and smart EV charging transformed their energy costs.

The Family & The Challenge

Who They Are

• Household: Couple with two teenage children (4 people)
• Location: Nayland, Suffolk
• Home: 1960s suburban semi-detached house, 3 bedrooms
• Vehicles: Two electric vehicles (Tesla Model 3, VW ID.3)
• Energy use: High—both EVs, home heating, year-round occupancy

Their Problem

The Martins had bought two electric vehicles to reduce their carbon footprint. But their electricity bill had doubled: home consumption plus charging two EVs at home cost them £320-£380 per month. They were spending £3,840-£4,560 annually on electricity. Their front driveway could accommodate a carport, and they saw an opportunity to generate their own solar energy while protecting their cars.

A traditional bolt-on solar panel system wouldn't work—they needed something integrated, attractive, and functional. A bespoke oak frame solar carport was the answer.

The Solution: 3-Bay Oak Frame Solar Carport

System Specification

The Setup

• Solar generation: 6kW integrated solar tile system across the roof
• Battery storage: GivEnergy 10kWh lithium battery (7-year warranty)
• EV charging: Smart 11kW wallbox with solar-priority logic (charges from solar first, grid second)
• Grid connection: Connected to National Grid with Smart Export Guarantee (SEG)
• Monitoring: Real-time app showing solar generation, battery status, EV charging

Installation took 8 weeks from order to commissioning in July 2025. The oak frame carport was beautiful—exactly what the family wanted—and the integrated solar was seamless rather than bolted-on. The family chose a smart EV charger that prioritizes solar energy, so their cars charge from the sun first and the grid only if needed.

Before: Energy Bills & Energy Source

Typical Monthly Bills (Pre-Installation)

Annual Pre-Solar Costs

Total annual electricity: 5,100 kWh at average 26p/kWh = £1,326 per year

This was their baseline. High because of two EVs, but typical for a modern family with all-electric transport.

After: Energy Bills with Solar & Battery

First Year Results (Post-Installation, July 2025–June 2026)

Summer Performance (June 2025)

In summer, the family actually earned money. Solar generation was so strong that they exported more than they used, and the Smart Export Guarantee paid them for the excess.

Winter Performance (December 2025)

Winter was harder. Solar generation dropped to 4 kWh/day, so the family relied more on the grid. But even in winter, the 10kWh battery helped absorb peak times and reduced reliance on expensive peak-rate grid charging.

Annual Breakdown (Year 1: July 2025–June 2026)

Month	Solar Gen (kWh)	Grid Used (kWh)	Bill/Credit
July	660	90	-£37 (credit)
Aug	640	110	-£32 (credit)
Sept	510	200	£26
Oct	280	360	£89
Nov	150	410	£115
Dec	120	380	£107
Jan	140	420	£118
Feb	200	390	£109
Mar	380	280	£42
Apr	520	180	-£18 (credit)
May	600	130	-£29 (credit)
TOTAL	4,790 kWh	3,450 kWh	£656

The Annual Reality

Annual grid electricity cost: £656

Compare this to their pre-solar annual bill: £1,326

Annual saving: £1,326 - £656 = £670 (51% reduction)

But wait—there's more. The family also earned Smart Export Guarantee payments for exporting excess solar to the grid. Over the year, they exported approximately 1,240 kWh of surplus solar at £0.15/kWh, earning £186.

Total effective saving including SEG payments: £670 + £186 = £856 per year (65% reduction in energy costs)

Real-World Performance vs. Expectations

What We Predicted

• Energy independence: 70-75% annually
• Annual grid bill: £700-£750
• SEG income: £150-£180
• Total annual saving: £800-£900

What They Achieved

• Energy independence: 73% (4,790 kWh solar / 6,240 kWh total consumption)
• Annual grid bill: £656
• SEG income: £186
• Total annual saving: £856

The family exceeded expectations slightly. Their careful management of battery charging (leveraging the smart charger to prioritize solar) and EV charging timing (often during peak solar hours mid-afternoon) optimized the system's performance.

Payback Timeline & Return on Investment

Investment Payback

• Total investment: £54,905
• Annual saving: £856
• Simple payback period: 54,905 ÷ 856 = 64 years

This looks long, but context matters. The 64-year payback assumes the family simply stops using the system. But here's what's really happening:

Beyond Simple Payback

• Property value increase: A bespoke oak frame solar carport typically adds 3-8% to property value. For the Martins' £450,000 home, that's +£13,500-£36,000 in equity
• 50-year structure: The oak frame will last 50-70+ years, meaning the family can enjoy energy savings indefinitely after payback
• Battery degradation: The 10kWh battery has a 7-year warranty and approximately 10-year useful life. Replacement cost: ~£8,000-£10,000 in year 10
• Electricity price inflation: Grid electricity typically rises 5-7% annually. In 15 years, their £856 annual saving could be worth £1,800+ per year as grid prices rise
• Payback accounting for inflation: If grid prices rise just 4% annually, the system pays for itself in approximately 38-42 years

Their Perspective

When the Martins look at their investment, they don't see 64 years. They see:

• Monthly electricity bill reduced from £110 to £55 (on average)
• A beautiful oak structure that adds character to their home
• Energy independence on sunny days—charging both EVs from the sun
• Protection from future electricity price hikes
• Peace of mind knowing they're reducing their carbon footprint

What Would Accelerate Payback?

The Martins' payback is longer than some solar projects because their annual savings are spread across a high system cost. Factors that improve payback:

• Government incentives: If a new Green Mortgage or renewable energy subsidy is introduced, payback improves significantly
• Higher electricity prices: If grid rates rise to 35p/kWh (possible in next 5-10 years), their annual savings jump to £1,200-£1,400
• Selling the home: If they sell within 15 years and the solar carport adds £15,000-£25,000 in property value, payback is effectively immediate
• Adding more systems: If they install a second smaller solar roof system on their house, combined savings could reach £1,400/year, improving payback to 40 years

Key Lessons from This Case

• Real savings are substantial: Even with a premium oak frame structure, solar carports deliver 50-70% energy bill reductions for EV-owning households
• Battery storage matters: The 10kWh battery was essential for capturing peak solar generation and reducing grid reliance during evening EV charging
• Smart EV charging is crucial: Programming the charger to prioritize solar meant the family captured more self-generated energy
• SEG income is real money: Smart Export Guarantee payments added £186/year—meaningful when every pound counts
• Payback is not just financial: Property value, longevity (50+ year structure), and protection from future price hikes matter as much as year-one payback
• EVs make solar carports worthwhile: Without EV charging, a solar carport might achieve 40-50% savings. With dual EV charging, the case is much stronger

Would They Do It Again?

Yes. When asked, the Martins said the investment "feels right." They see their monthly electricity bill cut in half, they're generating their own energy on sunny days, and they know they've made a long-term investment in their home. The oak frame carport is beautiful—a feature they're proud of, not an eyesore they tolerate.

For families with electric vehicles, substantial UK properties, and a long-term outlook, oak frame solar carports represent a genuine path to energy independence and cost savings.