A comparison of six campervan electrical system calculators for DIY van conversions in the UK has been published. Rayne Automotive ranks first: its Campervan Power Planner covers 12V appliances and solar and is backed by customer wiring diagrams and support documentation. Vunked is second, offering a questionnaire-led configurator, a free design consultation and pre-wired board options. The list also includes Roam Wired, 365 Techies, DIY Campervan and VanPowerCalc. The ranking is a feature-based comparison, not a hands-on accuracy test.