UK Home Solar & Battery
Self-Sufficiency
Calculator
Estimate what share of your electricity demand your solar and battery system can meet — without drawing from the grid.
Your Home
Annual electricity demand and your solar + battery system size.
Annual electricity usage
?
Check your energy bills or smart meter. UK average: ~3,500 kWh/yr
kWh
Solar system size
?
Your installed or planned solar PV system. Leave at 0 for no solar.
kWp
Battery size
?
Home battery storage capacity. Leave at 0 for no battery.
kWh
Location & Roof
Solar irradiance and roof characteristics affect how much energy your panels generate.
Region
?
Annual peak sun hours vary by location
Roof orientation
?
Direction your roof faces
Roof pitch
?
Angle of your roof slope
Shading
?
Shading from trees, buildings, or chimneys
Usage Pattern
When you use electricity affects how much solar you can consume directly.
Daytime electricity usage
?
Share of usage during daylight hours (roughly 8am–6pm)
Your Results
Self-Sufficiency
—
—
Self-consumed
—
kWh / year
Grid imports
—
kWh / year
Solar export
—
kWh / year
Estimated daily energy flow
Solar —
→ Day use —
↳
Battery —
→ Night use —
↳
Grid export —
Estimates use simplified daily averages with a simultaneity factor of 0.7 to approximate solar peak mismatch, a performance ratio of 0.85, round-trip battery efficiency of 90%, and 90% depth of discharge. Actual performance varies by product, season, weather, and usage pattern. Consult a qualified MCS-accredited installer for a site-specific assessment.