The Grid tab in the Simulation Results window displays details about the buying and selling of electricity from and to the grid, and the resulting costs. The outputs table contains the following variables.
Variable 
Description 
Energy Purchased 
The total amount of electricity purchased from the grid, in kWh 
Energy Sold 
The total amount of electricity sold to the grid, in kWh 
Net Energy Purchased 
The net electricity purchased from the grid, in kWh 
Peak Demand 
The peak power demand serviced by the grid, in kW 
Energy Charge 
The total amount paid in energy charges, in $ 
Demand Charge 
The total amount paid in demand charges, in $ 
If you defined more than one rate in the Grid Inputs on the Grid page, the Rate Schedule dropdown menu allows you to choose a rate, or select All to see the summation over all rates.
If net metering does not apply, HOMER calculates the total annual energy charge using the following equation:
where: 



Egridpurchases,i,j 
= 
the amount of energy purchased from the grid in month j during the time that rate i applies [kWh] 

cpower,i 
= 
the grid power price for rate i [$/kWh] 

Egridsales,i,j 
= 
the amount of energy sold to the grid in month j during the time that rate i applies [kWh] 

csellback,i 
= 
the sellback rate for rate i [$/kWh] 
If net metering applies and net generation is calculated monthly, HOMER calculates the total annual energy charge using the following equation:
where: 



Enetgridpurchases,i,j 
= 
the net grid purchases (grid purchases minus grid sales) in month j during the time that rate i applies [kWh] 

cpower,i 
= 
the grid power price for rate i [$/kWh] 

csellback,i 
= 
the sellback rate for rate i [$/kWh] 
If net metering applies and net generation is calculated annually, HOMER calculates the total annual energy charge using the following equation:
where: 




Enetgridpurchases,i 
= 
the annual net grid purchases (grid purchases minus grid sales) during the time that rate i applies [kWh] 

cpower,i 
= 
the grid power price for rate i [$/kWh] 

csellback,i 
= 
the sellback rate for rate i [$/kWh] 
HOMER calculates the total annual (listed after December) grid demand charge using the following equation:
where: 




Pgrid,peak,i,j 
= 
the peak hourly grid demand in month j during the time that rate i applies [kWh] 

cdemand,i 
= 
the grid demand rate for rate i [$/kW/month] 