Wandsworth is the borough where "check your address, not your postcode" stops being generic advice and becomes essential. Its Article 4 directions are drawn more finely than almost anywhere else in London.
Most boroughs apply Article 4 directions to a whole conservation area. Wandsworth frequently doesn't. Directions here are routinely written to cover specific streets, one side of a street, or a numbered range of houses within a single conservation area — so two neighbours on the same road, in the same conservation area, in visually identical houses, can genuinely be under different planning regimes.
Conservation coverage is extensive, taking in much of the borough's Victorian terraced stock across Battersea, Clapham Common West Side, Wandsworth Common and Putney. The practical consequence: "my conservation area doesn't have an Article 4 direction" is not a safe conclusion in Wandsworth, because the direction may apply to your specific stretch of road and not the rest of the area. Check the council's interactive map against your actual address before you commission anything.
Wandsworth has no borough-wide HMO Article 4 direction, so unlike many outer boroughs, any Article 4 flag on a Wandsworth address is more likely to be genuinely relevant to alterations.
This is classic London Victorian terrace territory — long, narrow plots with a side return, and the same 1-metre heat pump boundary constraint that affects Chiswick and Islington. Many Wandsworth terraces have had the side return filled in by a kitchen extension, which removes the most obvious siting position and pushes the unit further down the garden, adding pipework runs and cost.
Roof geometry is the other consideration. Terraced roofs here are typically front-and-rear pitched with limited unshaded area, and rear slopes often face east or west rather than south. That doesn't rule out solar — an east-west split array produces a flatter, longer generation curve that can suit a household using power through the day — but it does mean the headline output figures quoted for an ideal south-facing roof won't apply.
Battersea and Nine Elms add a further wrinkle: much of the newer stock there is flats, which have no permitted development rights at all, and where freeholder consent under your lease will matter as much as planning.
For costs, grants and how the national rules work, see the heat pump guide, solar guide, air conditioning guide and insulation guide.