Tools
Balcony Solar Tools & Calculators
Three free tools for UK balcony and plug-in solar: check whether a kit meets the legal specification, estimate what it would save you, and ask your landlord properly.
Plug-in solar becomes legal in the UK on 27 August 2026 under SI 2026 No. 848, but only for kits that meet the Interim Product Specification. These tools cover the two questions that follow from that — whether a particular kit qualifies, and whether it is worth buying — plus the permission letter most renters need before either matters.
Plug-In Solar Compliance Checker
Work through every rule in the UK's Interim Product Specification — 800 VA output, 3.5 A current, 2,000 W of panels, the DC array and 120 V limits, a factory-fitted BS 1363 plug, no battery, a verified ENA register listing, socket-circuit and connection restrictions, and prohibited mounting surfaces — and see exactly which ones a kit fails.
Says "we can't tell" rather than guessing.
Check a kit →Balcony Solar Savings Calculator
Estimate annual generation, savings and payback for a balcony system, using PVGIS irradiance data for your UK region plus your orientation, panel wattage and electricity unit rate.
Assumptions and formula shown in full.
Calculate your savings →Landlord Permission Letter Template
A drafted letter you can adapt and send to a landlord or managing agent requesting permission to install balcony solar, framed around the portable, non-structural nature of the system.
Written for private renters and leaseholders.
Get the template →A note on what these tools can and can't do