Do I need a permit for solar panels in
Watertown, MA?

Watertown sits in National Grid's Massachusetts service territory, which means the utility's interconnection rules are as binding as the city's building code. The City of Watertown Building Department enforces the 2015 Massachusetts Building Code (which has adopted NEC 2014), but what sets Watertown apart is that the city's expedited permitting process for solar is NOT as aggressive as some nearby communities. Unlike some Route 128 towns that issue solar permits same-day, Watertown typically takes 2–4 weeks for electrical plan review because the department staffs shared inspectors across multiple trades. Watertown also requires separate electrical and building permits (not a combined 'solar permit' like some jurisdictions), meaning two fee payments and two inspection workflows. Roof-mounted systems over 4 lb/sq ft trigger a structural engineer letter — critical in Watertown because much of the housing stock is pre-1950 wood-frame with smaller rafter sections than modern code allows. Battery storage systems add a third fire-safety review from the Watertown Fire Department, adding 1–2 weeks. The takeaway: budget 4–6 weeks and two separate permit applications, plus pre-approval from National Grid before the city electrical inspector will sign the final.