When deciding whether to store solar power or sell it back to the grid, homeowners should compare their electricity supplier's export rate (how much they are paid for sending excess power back) with their import rate (how much they pay for electricity they buy from the grid). Phil Steele, a future technologies evangelist at Octopus Energy, explains that storing solar energy can be more financially beneficial if a household uses the stored energy later to avoid buying more expensive grid electricity. For example, if a household forgoes a 15p export rate but avoids paying 27p for imported electricity later, storing one kilowatt-hour of energy could save 12p. Storing solar power can be especially useful for households that regularly use electricity after their solar panels stop generating, such as during the evening. A battery allows homeowners to shift solar generation from when it is produced to when it is needed. However, exporting electricity might be more beneficial in certain situations, such as when the battery is full, when stored electricity is unlikely to be used before the panels generate again, or when the export tariff offers a good rate. For example, if a home uses very little electricity during the evening and overnight, exporting might be more beneficial than storing. Modern batteries give households more control over their energy use by allowing them to store solar electricity when it makes sense, charge from the grid when electricity is cheap, and discharge or export electricity when prices are higher. This flexibility can make the economics of energy management more complex. Steele notes that with smart tariffs and automated battery controls, homeowners may need to make fewer manual decisions about when to store or use energy. When choosing a battery, homeowners should consider not only their solar panel system's output but also their actual electricity usage. Time-of-use tariffs, which charge different rates depending on the time of day, are increasingly influencing battery sizing to better match home use patterns rather than the size of the solar panel system. A battery that can power a household through the evening may be more useful than one with significant unused capacity. There is also a small penalty for storing electricity due to battery inefficiency, as some energy is lost during the charging and discharging process. If the difference between the import and export rates is large, these losses are unlikely to change the overall financial benefit of storage. However, if the rates are close, the financial advantage of storing solar power may be smaller.