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.