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The translator that lets battery DC speak wall-socket AC
Your battery speaks 12/24V DC; your kettle, laptop brick and TV expect 230V AC. The inverter translates — switching DC rapidly through a transformer and shaping the output into a wave.
The shape matters. A pure sine wave inverter reproduces the smooth oscillation of grid power; a modified sine inverter approximates it with a chunky staircase, which makes motors run hot, audio buzz, and some electronics sulk or die. Two ratings matter: continuous watts (what it sustains) and surge watts (the 2–3 second burst for things like fridge compressors and power tools starting up — often 2–3× their running draw). Inverters also idle-drain a few watts constantly, which is why small systems benefit from a remote switch — or no inverter at all.
Off-grid pure sine inverters: 300W ~£40–80 (laptop/lights territory), 500W ~£60–120, 1,000W ~£90–180, 2,000–3,000W ~£150–350 (heater/kettle class — with the battery bank to match). Hybrid and grid-tie inverters (£400+) are a different species: they synchronise with the grid and legally require professional installation and DNO paperwork.
The new arrival worth knowing: the micro-inverter (£80–180) — a panel-mounted unit converting a single panel's DC straight to grid-synchronised 230V AC. It's the engine of the balcony/plug-in solar category, capped at 800W output in the UK's new framework. Hoymiles and Enphase dominate.
The inverter is your bridge to the world of normal plugs — size it to your worst-case *simultaneous* load plus surge headroom, not your daily energy. It's also the component most worth questioning: every watt through it loses 8–15%, so a 12V-native shed (LED lighting, USB-C laptop charging) that skips the inverter entirely is simpler, cheaper and more efficient.
From EcoPowerful — plain-English DIY solar & wind guidance for UK homes, with a free instant system plan builder. Guidance is general; 230V fixed wiring always needs a qualified electrician. Last updated 2026-06-13.