Found this in another post:
"600W X 18 hours = 10800WH Then we can Convert to KWH: 10800WH/1000 = 10.8KWH (this is how much KWH per day the 600 watt will draw) We're running it for a month: 1 month = 30 days (or 31 days) 10.8KWH X 30 = 324KHW / month. Now we calculate cost using the rate of 23.5 cents / KWH. 324 KWH X .$235 = $76.14"
Haven't dont calculations myself but I run 2 x 600, 1 x 250, 1 x T5 (4 bulb 2 ft used only for the first 3 weeks of germ) plus 2 x 6" fans no AC (think I've turned on my house AC about 7 days this summer when it was really hot) and my total electric bill for entire house is 200ish pretty consistently. Here is most recent bill which was 191. This was with the 1 x 600 and 1 x 250 plus 1 x 6" fan on 12/12 and the other 600w and 6" fan at 18/6 for the entire month (keep in mind this is my whole house usage TV's, comps, lights, appliances and ceiling fans in upper 2 floors)
Xcel Energy
Average Daily Temperature 73 F 75 F
Electric/kWh per Day 45.3 kWh 0.0 kWh
Electric/Cost per Day $ 6.54 $ 0.00
Service & Facility $6.75
Summer Tier 1 500kWh $0.046040 $23.02
Summer Tier 2 996kWh $0.090000 $89.64
Elec Commodity Adj 498.67kWh $0.038060 $18.98
Elec Commodity Adj 997.33kWh $0.035930 $35.83
=======================================
$174.22
Theres a few other nickel and dime fees/adjustments on mine that push it closer to 190 for this bill.
Doing some quick math on my lights and estimating fans/T5 at 100kwh (in reality its probably less than this) a month, I'd say my lights/fans alone are about 100 of this bill calculated at the Tier 2 rates
1 x 600w at 18h = 324kWh / month
1 x 600w at 12h = 216kWh / month
1 x 250w at 12h = 90kWh / month
I usually do 6 weeks veg and 9 weeks flower avg so each harvest is around $350-$375 in electric costs probably less cause I dont think the fans actually use that much but dont have the wattage on them handy.
Edit: Its a lot less actually cause I have them cycled. If I turned off the other 600w when I moved to flower it would make it around $250/harvest I think. Math above assumes they're all on every day. Which they are but only cause I have more plants coming behind it using the veg lights when I switch over to flower.
For you:
2000w at 12h = 720kWh / month
2000w at 18h = 1,080kWh / month
Edit: Added in some more detailed calcs cause Im bored and love math.