Fixed, time-of-use, smart and flexible — which tariff structure fits?
The right answer depends on your usage shape, your assets and your appetite for price variability. Here’s how the four main UK structures compare.
Fixed tariffs
Best for
Predictable budgets, simple usage patterns.
One unit rate, one standing charge, locked for a term. Easy to budget, but doesn’t reward shifting usage off-peak or exporting solar.
Time-of-use tariffs
Best for
EV owners, batteries, heat pumps, businesses with shiftable load.
Different rates at different times — typically a cheap overnight window. Strong fit when you can move charging, hot water or battery cycling into low-priced hours.
Smart tariffs
Best for
Modern, electrified homes and small commercial sites.
Half-hourly or dynamic pricing tied to wholesale costs. Can reward automation through batteries or smart EV charging. Variable by nature — worth modelling against your real profile.
Flexible procurement & flexibility markets
Best for
Larger commercial sites, multi-site portfolios, sites with on-site assets.
Wholesale-linked purchasing, demand response and behind-the-meter optimisation. Solful prepares eligible sites for flexibility revenue as markets open up — we won’t pretend to be a full corporate procurement desk on day one.
Why structure matters more than headline price
A low unit rate can still cost more than a smart tariff that rewards overnight EV charging or battery cycling. Solful models your actual usage shape against eligible tariffs, so the ranking reflects what you’d really pay — not just the advertised rate.