How is energy calculated from power?

Does anyone know the formula to calculate energy from power? I just cannot figure it out.

I am trying to compare my revenue grade meter production to the inverter. The api does not have an option to pull the inverter production when the meter is enabled.

Energy is power over time. One kW (power) for one hour is 1 kWh.


If the update interval is 5 minutes, there are 12 intervals per hour. If only power is reported as 1.2 kW, then energy will increase by 0.1kWh each interval.

Depending on how often your service reports your data may be in blocks of time from hour, 15 minutes, or 5 minutes. The average power for these time intervals are used to estimate the actual power by multiplying the interval in hours by the average wattage recorded then summed over the day. The total is your production in kilo Watt hours or kWh. The shorter the interval the more accurate the calculation of Energy.

Energy = Power * Time

e.g. Generating 500W over 5 minutes the amount of energy in watt hours

= 500 * 5 / 60
= 41.67Wh