What to do with surplus solar electricity
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Surplus solar electricity can be used in the home, stored in a physical battery or exported under agreed conditions. Export sale, virtual-battery services and electricity sharing use different settlement arrangements and should be assessed separately.
Establish when the surplus occurs
Use monitoring and metering to identify the volume and timing of electricity left after household demand. Compare weekdays, weekends and seasons. An annual surplus total cannot show whether a battery, water heater or vehicle can use it at the right time.
Begin with existing useful loads that can be shifted safely. Water heating has limits from the tank, controls and actual hot-water demand; vehicle charging depends on the car being connected.
Compare the net alternatives
For new equipment, include investment, losses, operating costs and the export income forgone. For supplier services, read the full fees, valuation, eligibility and settlement cycle. Exporting without the appropriate contract does not automatically lead to payment.
Do not count the same electricity as both sold, credited and shared. A sound comparison uses consistent flows and explicitly identifies which option applies to each amount.