Plug-in solar and rooftop solar solve different problems. One is small, quick and yours to take with you. The other is bigger, fixed to your roof, and built to cover most of your home's power.
What plug-in solar can and can't do
A plug-in kit tops out at 800 W. Current network rules allow just one per household while G98 stands as it is today. You plug it straight into a normal socket yourself, no electrician needed. You can take it with you if you move. It can't include a battery — the rules for plug-in solar don't cover battery systems at all.
What rooftop solar can and can't do
A typical rooftop system fits 8 to 12 panels, around 3.5 to 4.5 kWp. Each modern panel makes about 350 to 450 kWh a year in the UK. It needs an MCS-certified installer and proper wiring under the full electrical rules, not a plug-in hook-up. In return, it can include a battery and can earn you export payments for the power you don't use.
How much of your electricity could each one cover?
An 800 W plug-in kit makes up to about 690 kWh a year if it faces south and is tilted. Flat on an east or west wall, it makes about 378 kWh. Ofgem's typical medium use is around 2,500 kWh a year. Against that, plug-in solar makes about 15% to 28% of a typical home's electricity, and the home uses only part of it. A 3.5 to 4.5 kWp rooftop system can make about 3,150 to 4,050 kWh a year. That's enough to cover most homes' use and leave some to export.
So which one should you pick?
If you rent, can't touch the roof, or just want to start small, plug-in solar is the easier first step. Say you own your home and want to cover most of your bill. Rooftop solar with a battery does far more. It's worth comparing a few MCS-certified quotes. Neither choice is wrong — they just answer different questions.
The quick version
- Plug-in solar: up to 800 W, portable, no battery.
- Rooftop solar: 3.5–4.5 kWp typical, battery and export possible.
- Rooftop covers far more of a typical home's usage.