Most people on standard electricity tariffs pay the same rate per unit throughout the day. Time-of-use tariffs work differently: they charge less for electricity used at certain times, typically overnight, and more at peak periods. When combined with a plug-in solar system and battery storage, this pricing structure can significantly increase your annual saving.
How Octopus Go works
Octopus Go is one of the most popular time-of-use tariffs in the UK. It offers a significantly cheaper overnight rate for electricity used between midnight and 5am compared to the standard daytime rate. The principle is simple: use cheap overnight power when demand on the grid is low, and avoid drawing from the grid during expensive daytime and evening periods.
On its own, Octopus Go is most useful for EV owners who charge overnight. But when you add a battery to a plug-in solar system, it opens up a different strategy.
The combined approach
With a battery-integrated plug-in solar system and Octopus Go, the daily energy routine looks roughly like this. Overnight, the battery charges on cheap-rate electricity. During the day, solar generation tops up the battery and powers the home directly. In the evening, the battery discharges to cover peak consumption. If solar generation exceeds what the battery can store, the surplus goes to the grid.
The EcoFlow STREAM Pro and Ultra X both support time-of-use optimisation through their AI scheduling feature, which analyses tariff data and weather forecasts to decide each night how much cheap-rate electricity is actually needed. On a sunny day, it charges the battery less from the grid overnight because it knows the panels will do the work. On a cloudy day, it charges more.
What the numbers look like
A standard tariff household with a panel-only 800W kit in a good position might save £60 to £110 per year on electricity. The same household on Octopus Go with a battery-integrated system can save £220 to £280 per year according to modelling based on the April 2026 price cap. The difference is substantial and grows larger as electricity prices increase.
Is it worth switching tariff?
Switching to a time-of-use tariff without battery storage is unlikely to save most households money. The cheap overnight rate is only useful if you can actually shift consumption to those hours. A battery gives you that flexibility by storing cheap electricity for use whenever you need it.
If you are buying a plug-in solar system with battery storage, checking current Octopus Go rates and comparing them against your current tariff is worth doing before you connect the system. The additional saving is enough to meaningfully shorten your payback period.
Other time-of-use options include Octopus Cosy, which offers lower rates at specific midday windows and suits people who are home during the day, and Octopus Agile, which tracks wholesale electricity prices in half-hour slots and suits technically confident users who want maximum control. For most plug-in solar buyers, Octopus Go is the most straightforward starting point.