🔋 Battery Storage

Solar battery storage system • Watten, Scottish Highlands

🔧
Duracell Battery System
Battery integration in progress • API connectivity being established
🔋

Battery Storage System

Installation Scheduled: February 2026


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Battery Capacity
15 kWh
3× Duracell Dura5 5.12kWh
Solar System
12.6 kW
28 × 450W Panels
Inverters
2× Dura-i
Hybrid Master/Slave
📊 Battery Simulation (Based on Last 30 Days)

What would an 18.8kWh battery save you based on your actual usage patterns?

💷 Projected Savings
£30.23
Per Month
£367.83/year
⚡ Grid Avoided
8.6 kWh
Per Day (avg)
180.1 kWh over 21 days
☀️ Solar Captured
9.5 kWh
Per Day (avg)
Currently exported, would be stored
🌱 Self-Sufficiency
14%
→
31%
Current → With Battery
📅 Est. Payback
13.6 years
At ~£5,000 system cost
📈 Simulation Details
Assumptions:
  • 15kWh capacity (3× Duracell Dura5 5.12kWh)
  • 90% usable capacity (10-100% DoD)
  • 90% round-trip efficiency
  • Blended rate: 28.42p/kWh
Notes:
  • Based on your actual 30-day history
  • Real savings may be higher with Flux tariff optimisation
  • Doesn't account for seasonal variation
  • Summer months will show better returns
⚡ Flux Tariff Arbitrage

Extra savings by charging during Cheap period (16.93p) and discharging during Peak (39.51p)

💰 Arbitrage Spread
29.5p/kWh
Peak (39.51p) - Cheap (16.93p)
After 90% efficiency: 20.3p/kWh profit
🔄 Daily Arbitrage
£1.40
Per Day (est.)
Using ~6.9 kWh for arbitrage
🎯 Combined Savings
£72.37
Per Month
Solar + Arbitrage: £880.53/year
📅 Improved Payback
5.7 years
With Arbitrage
vs 13.6 years solar only
📊 Monthly Savings Breakdown
Solar Storage: £30.23
Flux Arbitrage: £42.14
Total: £72.37/month
⏰ Optimal Battery Schedule for Flux
🔋 CHARGE (Cheap: 16.93p)
  • 04:00 - 07:00 (3 hours)
  • 13:00 - 16:00 (3 hours)
  • 22:00 - 00:00 (2 hours)
⚡ DISCHARGE (Peak: 39.51p)
  • 16:00 - 19:00 (3 hours)
  • Power home from battery
  • Avoid expensive peak grid
☀️ SOLAR PRIORITY
  • Daytime: Store excess solar
  • Evening: Use solar first
  • Export only when full
💷 Battery Savings by Tariff

Compare potential battery savings across different Octopus tariffs

✓ Your Current Tariff
Octopus Flux
Battery savings: £100.38/month
🏆 Best for Battery
Octopus Flux
Battery savings: £100.38/month
Tariff Spread Arbitrage Solar Monthly Payback
🥇 Octopus Flux
Best for battery export
 22.6p £42.14 £72.59 £100.38 4.1 yrs
🥈 Octopus Go
Best for EV charging
 22.6p £42.25 £50.98 £93.23 4.4 yrs
💡
Key Insights:
  • Flux has a 22.58p arbitrage spread plus 28.73p peak export rate
  • Go has cheap overnight rates but smaller spread for arbitrage
  • Flux offers better export rates which boosts returns if you export
  • Agile rates vary - can be very profitable on high-spread days
  • Flexible has no arbitrage benefit (flat rate)
📅 Seasonal Projections

Projected battery savings across seasons based on Scottish Highlands solar potential and heating patterns

☀️ Annual Solar
6,325 kWh
Projected generation
🔥 Annual Heat Pump
6,552 kWh
Projected usage
💷 Annual Battery Savings
£389.43
Projected total
📅 Realistic Payback
12.8 years
Seasonal adjusted
❄️ Winter
Dec - Feb
Minimal solar, high heating
Solar
3.5 kWh/day
Heat Pump
35.0 kWh/day
Grid Avoided
16 kWh
Battery Savings
£129.75
Solar vs Demand 8%
🌸 Spring
Mar - May
Good solar, moderate heating
Solar
19.0 kWh/day
Heat Pump
15.0 kWh/day
Grid Avoided
246 kWh
Battery Savings
£113.95
Solar vs Demand 83%
☀️ Summer
Jun - Aug
Peak solar, minimal heating
Solar
35.0 kWh/day
Heat Pump
2.0 kWh/day
Grid Avoided
0 kWh
Battery Savings
£27.74
Solar vs Demand 350%
🍂 Autumn
Sep - Nov
Declining solar, rising heating
Solar
12.0 kWh/day
Heat Pump
20.0 kWh/day
Grid Avoided
123 kWh
Battery Savings
£118.00
Solar vs Demand 43%
📊 Seasonal Comparison
£130
❄️
Winter
£114
🌸
Spring
£28
☀️
Summer
£118
🍂
Autumn
🌍
Scottish Highlands Factors:
  • Summer: Up to 18+ hours daylight, solar panels can generate 15+ kWh/day. Battery captures excess for evening use.
  • Winter: Only ~7 hours daylight with low sun angle. Battery value comes mainly from tariff arbitrage, not solar storage.
  • Heat Pump: Major consumer in winter (~35 kWh/day), minimal in summer (~2 kWh for hot water only).
  • Best ROI: Summer months provide best battery returns due to excess solar capture.
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backgroundColor: '#8b5cf6', borderRadius: 4 }] }, options: { responsive: true, maintainAspectRatio: false, plugins: { legend: { display: false } }, scales: { x: { ticks: { color: '#6b6b6b' }, grid: { display: false } }, y: { ticks: { color: '#6b6b6b' }, grid: { color: '#333333' }, title: { display: true, text: 'kWh', color: '#6b6b6b' } } } } }); */