Solar & battery
Solar & battery
Solar PV, batteries, and the maths behind self-consumption — including the seasonal generation question.
Reading order — beginner first
What is solar PV?
Solar PV — short for photovoltaic — is the type of solar that turns sunlight directly into electricity. When sunlight hits a photovoltaic panel, it knocks electrons loose in silicon cells, and those electrons flow as electricity. A typical UK 4 kW system has around 10 panels, generates 3,000–4,000 kWh per year, and costs £5,000–£10,500 installed (battery optional).
Do solar panels work in winter?
Yes — solar panels work on daylight, not heat, so cold UK winter days still produce power. UK winter (December–February) typically generates 15–25% of a system's annual output; summer (May–July) generates 40–50%. Counterintuitively, cold weather slightly improves panel efficiency per unit of sunlight, because cells are less resistive when cool.
Solar without a battery vs solar with a battery — what changes
Without a battery, a typical UK 4 kW system self-consumes about half its generation; the rest exports to the grid. Add a 5–6 kWh battery and self-consumption rises to around 80%. Battery payback rarely beats the panels themselves, but it changes how independent your home is from peak-rate import pricing.