Plug-in Solar Savings: What £1,100 Over 15 Years Actually Means

Analysis published by Carbon Brief puts a number on the lifetime value of plug-in solar for a typical UK household: £1,100 saved over 15 years from an 800W south-facing system in London, based on current electricity prices and typical self-consumption patterns.

The figure assumes the household uses most of what it generates during daylight hours — reasonable for anyone working from home, retired, or running appliances during the day. It doesn't include export income, currently unavailable to self-installed plug-in systems without a Smart Export Guarantee arrangement.

Breaking down the £1,100 figure

At £499 for a base EcoFlow STREAM kit, a 15-year saving of £1,100 implies a net return of roughly £600 after costs — a 120% return. The implicit annual saving is around £73. This sounds modest until you consider the system requires zero maintenance, has no moving parts, and panels carry a 25-year performance warranty. For a more detailed breakdown tailored to your household, use our payback calculator.

The Carbon Brief figure is based on London irradiance and standard tariff rates. For homes in Wales or the north of England, expect £900–£1,000 over 15 years. For homes on Octopus Agile, the figure is higher — you're effectively arbitraging cheap overnight rates against your daytime solar generation.

Does the maths still work at July's higher cap?

Yes — and more so. Every price cap increase makes self-generated electricity more valuable. The July cap is now forecast at £1,837, higher than the rates used in the Carbon Brief calculation. The actual 15-year saving for a system installed now is likely to exceed £1,100. For a comparison of which kit gives the best return, see our EcoFlow vs Anker comparison.