Two systems (diesel system and wind-diesel system) are used to power the same load. The diesel system consists of 5 diesel generators of a rating of 1000 kW each. The wind-diesel system consists of the same 5 generators plus 6 wind turbines of a rating of 1.8 MW each. When the analysis were carried out, the total energy production of the diesel system is found to be 39,754,968 kWh/yr whereas in the wind-diesel system it is 64,215,572. Although, the two systems are using to supply the same load the total energy production is different. Therefore, my question is why the total energy production from the two systems are different while they are supplying the same load?

The wind-diesel system produces more energy per year than the diesel system because the wind-diesel system produces a lot of excess power during times of high wind.  HOMER reports that excess power production as ‘excess electricity’ on the Electrical tab of the Simulation Results window.