I am right now concern on if the power is able to find its way to where its needed without advance electrical knowledge and work. I was hoping just to plug it into a plug and have it back feed to the entire house and it can just sort of use what it needs but you are saying you need to direct it right the a large load circuit directly?
Grid tied solar is quite simple to understand. Electricity is not much different than water flowing. It wants to take the easiest path. Grid power comes in through the main breaker at the breaker panel. Without solar power, that power input has to feed all of the loads in the building. We will ignore power factor to keep this simple, the current of all of the individual loads all add up and pull from the main breaker.
When you add grid tied solar into the mix, it is not really a power source. The grid tied inverter is a current source. Instead of a load taking energy, it is an energy feed into the system. If the building has 5,000 wats of loads, and no solar, then all of the power comes from the grid input. But if you now add 1,000 watts of grid tied solar, what you are really doing is pushing just over 4 amps of current into the breaker panel. This current will help power all of the loads. So now the grid input only needs to provide 4,000 watts at the same 240 volts. The grid input does not know the difference between this being only 4,000 watts of load, or the 5,000 watts of loads and 1,000 watts of solar input. The grid power meter will not know the difference at all. If clouds come over, then the grid current will increase to cover the loss of the solar. But again, the meter just sees an increase in load.
The only way the meter sees anything different is if the solar power being pushed into the system exceeds the loads after the power meter. If you happen to have 4,000 watts of solar pushing in at high noon, and the same 5,000 watts of loads running, the grid still sees it as a load, but now only pulling 1,000 watts. Still no problem. But then a machine pulling 2,000 watts turns off. Now the load is only 3,000 watts. The grid tied solar is still pushing 4,000 watts. This is when the electricity will go backwards. You will now have 1,000 watts flowing out to the grid. An old mechanical meter will actually spin backwards. The digital meters will most likely report the reverse power on a separate readout. They actually had to make special meters to count forwards with reverse current. Some very early meters were still internally mechanical with the spinning disk. But to make them remote readable, it had a counter that just counted disk rotations. It was a single pulse, so it would count up with backwards current, and they didn't want to fix that. If you put in solar and pushed extra power, that meter would bill you for power you gave the utility. The newer all electronic meters are much smarter. They will rat on you and tell the utility you pushed power out. It is illegal to push power into the grid without a connection agreement.
As long as you are certain you will never push more solar power than the power you consume, this is not really an issue as the meter, no matter how smart, it will never know. What is the lowest wattage you ever see being pulled while the sun is shining? If your solar never exceeds that, then it will never be detected. But if something big turns off, it might happen.
But if you do start pushing a decent amount of grid tied PV solar power, getting close to your consumption, you have to be very careful about big loads turning off. There is no zero export grid tied inverter that is fast enough to eliminate an export current when a big load turns off. Some are faster, but my setup takes about 8 to 15 seconds to fully zero the grid current when my central A/C turns off. If it is when the sun is shining, it has to do it by turning up the battery charge current to use up the extra solar production. I do net out zero, because when the A/C turns on again, it takes the same time for it to see the load and crank up the output to zero the power again. It is a constant balancing act as the load current changes. At 5 pm, my solar only makes half the power my A/C needs. So my system switches up and back from charging the battery to inverting from battery to still keep the grid current near zero all the time. The A/C uses about 4,000 watts. Solar is making 2,000 watts. It pulls 2,000 watts from battery to run the A/C with no grid current. But when the A/C turns off, it has to charge the battery at 2,000 watts so the solar does not export to the grid. Obviously, I have a lot of other loads as well, so this is going on all the time for every load.
How bad is it to get a net metering deal? What does it do to your billing? I made the mistake of not asking these questions when I was getting solar quotes. No installer mentioned that my billing would change at all. They just subtracted the expect solar energy production from my bill and said I would save 70%. Well, that didn't happen. I only ended up saving 30%, but that is still a decent savings. If they were honest with me up front about the billing change, I probably would have bought a bigger system and they would have made more money.
