Indoor electricity use
Small-scale growers won’t see their electric bills change too much. When I had my small-scale setup, I had around 250 to 300 watts of CFL grow lights with a couple small fans running 24/7 for ventilation, and the only time I ever noticed it affecting my electric bill was when the plant was in flowering and I had all my CFLs and fans running. Your seedlings and to a lesser extent your plants in veg, don’t need the full 200+ watts to grow and thrive like it will need in flowering.
If you’re worried about the extra wattage causing suspicion then you can rest easy. A 600 watt grow light only uses about as much electricity as a full-size refrigerator and that’s one of the larger bulbs you can buy. For growing one plant you won’t need anywhere near that amount of wattage.
You can usually calculate how much your setup is costing you by looking at your electric bill and seeing what the cost per watt is. This number will be different depending on where you live.