Heat Pump with Solar PV + Battery UK 2026
Pairing a heat pump with solar PV + home battery: realistic self-consumption rates, summer vs winter economics, system sizing, payback maths.
If you're planning a heat pump + already have (or want to add) solar PV + battery storage, the three together are a strong UK 2026 home-energy setup. This guide covers the seasonal realities, system sizing, and what payback actually looks like.
The seasonal mismatch (which matters most)
Summer is solar-surplus, winter is solar-zero - the heat pump runs hardest then.
UK solar generation is heavily seasonal:
- June-July: ~120-150 kWh/kWp per month for typical UK installs. A 4 kWp system generates ~500-600 kWh/month.
- December-January: ~15-25 kWh/kWp per month - roughly 8-10x lower than summer. Same 4 kWp system generates ~60-100 kWh/month.
Heat pump demand goes the opposite way:
- June-July: ~80-120 kWh/month (hot water only, no space heating).
- December-January: ~1,200-1,800 kWh/month (peak space heating + hot water).
Result: in summer you generate 5-8x more than the heat pump uses; in winter you generate 5-15% of what it uses. Self-consumption rate:
- April-September: ~70-80% of solar generation goes to home use (including heat pump for hot water + cooking + EV); ~20-30% exports.
- October-November / February-March: ~50-60% self-consumed.
- December-January: 15-25% self-consumed - solar generation is so low that even minimum house load consumes most of it.
What a battery actually does (and doesn't do)
Time-shifting hours, not months.
Home batteries (Tesla Powerwall 3, GivEnergy, Sunsynk, Sigenergy etc.) store solar surplus during the day and discharge in the evening when the heat pump is running but the sun isn't. The benefit is diurnal (hours-scale) not seasonal (months-scale):
- Within a summer day: battery lets you capture midday solar surplus + discharge it during evening heat-pump hot-water reheat. Self-consumption rate rises from ~70% (no battery) to ~85-90% (with battery).
- Across a summer week: battery doesn't really change weekly self-consumption much - the daily cycle does most of the work.
- From summer to winter: battery cannot store enough to make a meaningful difference. You'd need a 200+ kWh battery to time-shift summer generation into winter - and that's not economic at residential scale.
Battery sizing: 10-15 kWh is the residential sweet spot. Smaller (5-7 kWh) limits the diurnal capture; larger (20+ kWh) hits diminishing returns + faster depreciation. Cost: GBP 8,000-15,000 for a 10-15 kWh battery + inverter + install.
Realistic UK 2026 cost analysis
What the full stack costs + how long it pays back.
For a typical UK 3-bed semi with no existing renewables (currently on gas + standard electricity), the full heat pump + solar + battery install:
- Solar PV (4-5 kWp): GBP 6,000-9,000 install
- Battery (10-13 kWh): GBP 8,000-12,000 install (often discounted ~20-30% when bundled with solar)
- Heat pump (8 kW Cosy 6 or equivalent): ~GBP 11,000 pre-grant - £7,500 BUS = ~GBP 3,500-5,500 net
- Combined total: ~GBP 17,500-26,500
Annual run-cost saving vs the baseline (gas + standard electricity):
- Year 1-3: ~GBP 1,800-2,400 (heat pump on Cosy Octopus + solar self-consumption + battery time-shift + SEG export income)
- Years 4+: similar profile; minor degradation of panels + battery cells
Payback period: 7-10 years for the full stack vs business-as-usual gas + standard electricity. Faster than solar+battery alone, faster than heat-pump alone, because the heat pump utilises summer solar surplus that would otherwise be exported at lower rates than retail.
Install order: which comes first
If you can't afford the full stack at once.
For households doing this in stages, the financial-optimum order is usually:
- Solar PV first. Cheapest entry point (~GBP 6-9k), longest depreciation tail (25+ year panels), eligible for SEG export payments immediately. Pays back in 6-9 years standalone.
- Heat pump second. Use the £7,500 BUS grant. The presence of solar PV improves the heat pump's run-cost economics from day one even without a battery (summer hot-water reheats run on free solar).
- Battery last. The optimal sizing is much easier to judge once you've seen real solar + heat pump consumption patterns for a year. Pre-buying the battery often results in over- or under-sizing.
For households building all-new (new-build or major retrofit), do everything together - install discounts when bundled are typically 10-20% across the components, and the system commissioning is cleaner with one project.
Coordination matters: smart-home integration
Without integration, you're paying retail for what could be solar.
The combined system reaches its potential when the components coordinate:
- Heat pump schedules hot-water reheat during midday solar peak (rather than evening when the heat pump uses grid electricity).
- Battery discharges to cover heat pump evening + early-morning load (when sun is gone but heat pump still running).
- Grid import only during overnight off-peak windows (Intelligent Octopus Go or Cosy Octopus low rates) for top-ups.
This coordination requires either:
- Manufacturer ecosystem alignment (e.g. Octopus Cosy 6 + Octopus battery solution + Octopus tariff), or
- Home Assistant + Modbus + scripting for users running mixed-vendor equipment.
See our smart home integration guide for the detailed setup options.