Plug-in Solar vs Rooftop Solar: The Honest UK Comparison

Plug-in solar and rooftop solar are both solar. That's where the similarity largely ends. They serve different buyers, require different budgets, and the decision between them is more nuanced than most guides suggest. This is the honest UK comparison.

Cost

Plug-in solar: £419–£499 for an 800W kit — see our best kits guide for current options. No installation cost. Total outlay: £419–£499.

Rooftop solar: £8,000–£15,000 for a typical 3.5–5kWp system including MCS installation. Battery storage adds £3,000–£5,000. The cost difference is roughly 20–40x. That's the central fact of this comparison.

Generation

Plug-in solar (800W): 580–780kWh annually. Rooftop solar (4kWp): 3,200–3,800kWh annually — approximately five times as much. But savings are closer to 3–4x, because rooftop solar exports significant generation to the grid at around 15p/kWh on SEG, whereas plug-in solar owners currently export for free.

Who rooftop solar is right for

Homeowners who own their property, have a south-facing roof, plan to stay 10+ years, and have the capital for a large upfront investment. Annual savings of £800–£1,400 with battery give a payback of 8–15 years — long, but positive over the 25-year panel lifespan.

Who plug-in solar is right for

Renters — see our renters guide and legal rights article — homeowners who want to start without a large outlay, and people in flats or houses without suitable roofs. Use our payback calculator to understand exactly what the return looks like for your household.

Can you have both?

Yes. Plug-in solar on a south-facing fence or garden structure generates independently of rooftop panels and can use surfaces MCS installers wouldn't normally access. With July bills rising sharply, maximising self-generation from every available surface is increasingly worth considering.