The Electricity Fee is calculated on a daily basis, users may choose to pay part of the Electricity Fee when first place an order (10 Days of Electricity Usage at least by default), and the remaining days under the plan period can be paid later in the Dashboard > Revenue by Order > “Add days”.
If you would like to add days to multiple plans at one time, click "add days to multiple plans" > "Electricity" under your account name and buy electricity usage days for all renewable plans under your account.
Please note to “add days” before the Maintenance days run out, otherwise, the mining and revenue of the plan will get interrupted.