Solar Potential for Any UK Property — Panel Yield via API
Instant solar potential for any UK property — pass a UPRN, get back a full assessment: roof area, panel count, system size, annual generation, savings, payback years, and CO₂ impact. Calculated from OS building footprints, EPC records, and 120 UK irradiance zones.
Free tier: 100 requests/month. No credit card required.
One UPRN. A complete solar proposal.
Pass any UK property's UPRN — we use the building's OS footprint, EPC floor area, and local irradiance data to calculate a full solar potential assessment. System size, annual generation, savings with and without battery storage, payback years, and CO₂ impact.
We also flag whether the property already has solar panels — useful for qualifying leads and avoiding wasted installer visits.
How roof area is estimated: OS building footprint (highest confidence) → EPC floor area + floor count → bedroom count fallback. Confidence level is returned in every response so you can surface it to users.
curl "https://api.homedata.co.uk/api/solar-assessment/10003469503/" \ -H "Authorization: Api-Key YOUR_API_KEY"
{
"property": {
"uprn": 10003469503,
"address": "14 Acacia Avenue, Manchester, M20 4LN",
"property_type": "Semi-Detached",
"bedrooms": 3
},
"roof": {
"estimated_area_m2": 72.0,
"usable_area_m2": 32.4,
"has_existing_solar": false,
"orientation_estimate": "mixed"
},
"solar_potential": {
"max_panels": 18,
"system_size_kwp": 7.56,
"annual_generation_kwh": 4787,
"annual_savings_gbp": 673,
"annual_export_income_gbp": 145,
"system_cost_estimate_gbp": 13230,
"payback_years": 19.7,
"co2_saved_kg_per_year": 694,
"trees_equivalent_per_year": 33
},
"with_battery": {
"annual_savings_gbp": 991,
"self_consumption_pct": 80,
"payback_years": 17.6
},
"assumptions": {
"panel_wattage_w": 420,
"electricity_rate_p_kwh": 24.5,
"export_rate_p_kwh": 5.5,
"system_efficiency": 0.82
},
"data_quality": {
"confidence": "medium",
"note": "Orientation assumed mixed"
}
}
Everything in the response
One API call returns everything a solar proposal needs — from roof dimensions to 20-year savings projections with and without battery storage.
System Size (kWp)
Recommended system capacity in kilowatt-peak based on the property's usable roof area (45% of estimated total). Accounts for spacing, edge offsets, and chimneys.
Generation & Savings
Annual kWh generation using local irradiance data (120 UK postcode zones) at 82% system efficiency. Savings calculated at current 24.5p/kWh. Export income (SEG) at 5.5p/kWh.
Payback Period
System cost estimate divided by total annual benefit (savings + export). Returned separately for solar-only and solar + battery configurations.
Battery Storage Scenario
Full battery-storage scenario including uplift to 80% self-consumption, additional battery cost (£4,200 est.), revised total system cost, and adjusted payback period.
Existing Solar Flag
Boolean flag from our property database (EPC + listing NLP). Indicates whether the property already has solar panels — critical for lead qualification and avoiding wasted installer visits.
Confidence Level
high (OS footprint area available), medium (EPC floor area), or low (bedroom estimate fallback). Always surface this to end users.
Calculation Assumptions
The inputs used in the calculation: panel_wattage_w (420W), system_efficiency (0.82), electricity_rate_p_kwh (24.5p), export_rate_p_kwh (5.5p SEG). Lets you verify or override the model in your own UI.
How roof area is calculated
Unlike simple lookup tables, we calculate from the actual property's physical characteristics. The confidence tier depends on what data is available for that UPRN.
Ordnance Survey building polygon gives the exact footprint area in m². Usable roof = 45% of footprint. Best accuracy.
EPC total floor area divided by number of floors gives estimated ground footprint. Available for ~18M properties with EPC records.
Fallback using UK average floor areas by bedroom count and property type. Sufficient for an initial quote, but Phase 2 LIDAR data is recommended for final proposals.
Built for solar-adjacent products
Any platform that touches a property and might surface energy upgrades has a use case for this API.
☀️ Solar installers & lead gen
Let homeowners enter their postcode → address → UPRN and get an instant personalised solar report. Pre-qualifies leads before a site visit — filter out flats, properties with existing solar, or north-facing roofs.
🔥 Boiler & heat pump platforms
When quoting for a heat pump installation, surface solar potential in the same flow — "your home could generate 4,787 kWh/year and save £673" is a compelling upsell. We already support the full postcode → UPRN → solar proposal chain.
🏠 Estate agents & portals
Add a solar potential badge to listing pages — "Up to £1,150/year savings possible". Particularly effective for properties with south-facing roofs. EPC C or below properties have the strongest uplift story.
🏦 Mortgage & green finance
Green mortgage products require evidence of a property's improvement potential. Solar assessment data supports loan sizing decisions for energy upgrade finance — pass through system cost and payback directly to underwriting models.
Phase 2: LIDAR roof orientation (coming soon)
Current assessments assume mixed orientation — south-facing roofs typically generate 10–15% more. Phase 2 will integrate 1m LIDAR data from the Environment Agency (free, full England coverage) to derive actual roof pitch and azimuth for each roof face. That gives ±5% accuracy vs Solar Wizard's satellite approach.
The data_quality.confidence field will automatically upgrade from medium to high when LIDAR data is available for a given property. No API changes required.
Full flow: address to solar report
Don't have a UPRN yet? Two API calls get you from a typed address to a complete solar assessment.
# Step 1a: typeahead find curl "https://api.homedata.co.uk/api/address/find/?query=14+Acacia+Avenue+Manchester" # Step 1b: retrieve UPRN from result curl "https://api.homedata.co.uk/api/address/retrieve/10003469503/" \ -H "Authorization: Api-Key YOUR_API_KEY"
address/find costs 2 calls (no auth needed for public endpoint). Retrieve costs 5 calls and returns the UPRN plus EPC, bedrooms, and other property data.
# Step 2: pass UPRN from step 1 curl "https://api.homedata.co.uk/api/solar-assessment/10003469503/" \ -H "Authorization: Api-Key YOUR_API_KEY" # Returns full assessment: # system_size_kwp, annual_generation_kwh, # annual_savings_gbp, payback_years, # co2_saved_kg_per_year, with_battery.*
Two requests total. One to resolve the address, one to get the solar report. Everything needed for a customer-facing proposal.
Get your free API key
100 requests/month on the free tier. No credit card. From signup to first solar assessment in under 5 minutes.