# Power Grid, Smart Grid, and Smart Meter

#### endiewibowo

Joined Nov 16, 2015
1
Hi, I am new here. I have this project about smart grid. However, I still have trouble in understanding the AC power distribution, etc.

So, I need your help to understand some of these matters:

1. How do utility companies know the power demand in a certain area at a certain time? Where do they put the measurement device?
2. How does kWh meter measure the energy usage in a house? Is this meter placed right before the distribution lines of the sockets, or not? I believe this meter is placed in a single point of the whole circuit at the house, right?
3. I understand that if the load is resistive, the voltage and current will be in phase. And if the load is inductive or capacitive, there will be phase difference. But let's say I use 4 sockets with different loads at the same time. How the meter calculate the total energy usage? How are the voltage, current, and phase difference at the point the meter is measuring at that time?
4. Let's say I install a solar panel at home. How do I connect the panel to the power grid?
5. How to make the loads (TV, refrigerator, etc) draw energy from he solar panel as maximum as they can first, then if the energy is not enough, they can draw from power grid (utility company)?
6. How does the smart meter know that the used energy at that time comes from the panel, not from the power grid? Let's say the load is resistive. Is the direction of the current oppose the direction of voltage (producing negative power)? What if the loads are varies?

I know that some of the questions seem stupid. But I really need your help to understand this. I also need further source for me to read, if you have any.

Thank you.