[quote threadkiller]
I’m a little confused, I thought legislation was just written to ensure the consumer/producer could sell the electricity back to SDG&E.
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Yes, such legislation was put in place w/in CA. There have been lawsuits, mostly up north when PG&E made it hard to connect the system to the grid. PG&E lost, so there is now legal precedence.
[quote threadkiller]
I’m thinking about doing it, I suppose what is keeping me from doing it is I don’t fully understand how the electricity gets back to SDG&E. I assume it goes to the neighbors. Does anybody know if SDG&E meters at the stepdown transformer. I doubt that they do, so they are just trusting the meter I suppose.
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This is actually a pretty good question. I’ll see if I can answer it clearly.. so bear with me. The first problem is that the power lines are AC which is more complicated, so I will first describe what happens with DC — followed by AC’s difference.
DC:
Imagine two batteries. One is yours and one is the power companies. Which ever battery is producing the higher voltage will be handling the ‘load’. Current flows from higher voltages to lower voltages – please guys, I know the ‘quantum’ truth on electricity, so lets don’t complicate things. The other battery will not be doing anything (except maybe getting recharged). The truth is that the electrical ‘load’ is not taken completely by one or the other battery, so I am going to add a ‘complication’.
This complication is known as electrical line resistance and distance. Even copper wire has resistance. So we now have a much longer system with two batteries, one at each end, and multiple loads in between. If only one battery was connected at the end, the voltage between the wires would drop as you travel away from that battery. Each ‘load’ or consumer would see slightly lower voltages as they move away from the battery. Now if we add a battery at the other end, there will be a balance in who is supplying the current for the load that is dependent upon the ratio of voltages, currents, loads and line resistances. If your battery ‘ups’ its output voltage, it will pick up more of the load. If it produces less voltage, it will shed the load until your system is producing voltage below what the other ‘battery’ would provide at that distance.
So on to AC or Alternating Current and its associated alternating voltage. The rough equivalent of increasing your battery’s voltage would be to increase the peak-to-peak voltage you are generating on the line while keeping your generated voltage phase in sync with the power station’s (The power station’s voltage goes up, yours goes up, the power station’s voltage goes to a negative peak, so does your system’s). You don’t want to get out of phase because that will cause current that will only heat up the wire. Because you are now producing a slightly higher voltage – peak to peak, you will source current onto the power line and pick up a percentage of the load.
The electric meters work on current. They sense direction of current vs voltage. If the voltage is positive and current is going into the house, it is metered as consumption. If the voltage is positive but current is going out of the house, it is metered as production. The negative voltage version is different: if the voltage is negative and the current is coming out of the house, it is consumption(vs production for the positive voltage) and if the voltage is negative and the current is going into the house, it is production. This ‘flip’ in behavior is due to how AC works. AC works by working against a ground wire which is near zero in voltage or against a capacitive ‘sink’. AC is kind of a ‘push-pull’ type of electrical system.
