generator line as local grid

[hassan]

Hello everyone:

I am new here and this is my first post after introduction.

Power is a scarce commodity where I live, an average of twelve hours a day without electricity. We have many small entrepreneur who steps in to fill the gap for the rest of the day.
They supply electricity through Generators around 500 KVA capacity. These Generators’ owners charge expensive rates, around fifty cents/kwh. In some areas, they charge more.
These generators provide better voltage and frequency than the public power company. My question is, can a Grid tie inverter solar system be a solution here using the generator grids
for the grid tie inverter.

Is there special setting at the generator side need to be done.

Your feedback is very appreciated

[inetdog]

If the frequency and voltage stability of the generator is good enough a grid tie inverter should be able to synchronize to it just as it does with a full grid source.
But there is problem which a simple standard grid tie inverter cannot deal with:

A standard grid tie inverter will always deliver into your wiring as AC all of the power that your solar panels are currently able to produce. If your local power usage at any moment in time is lower than what the GTI produces the extra power will be fed into the grid network. This then reduces the amount of power that the grid source must produce and your power is going back through your meter to be used by other grid customers.
But if the amount of solar power produced by all customers gets large enough the grid may suddenly be called upon to produce far less power and the grid power source may not be able to adjust quickly to the new demand. Similarly if the weather changes the solar production may suddenly go down, requiring the grid to produce more power. This can lead to unstable operation of the grid (in an area where the grid is not very stable to start with.)
But the worst case is when the sum total of solar production is greater than the amount the loads are consuming. There is no place for the extra power to be used and the GTIs will attempt to feed that power back into the generators supplying the grid. This will result in damage or a shutdown of the grid.
If instead of the large grid you have smaller generator systems (micro-grid) the problems that can be caused by large solar installations are proportionally greater.
So the operators of the Generators may not be at all happy with having you connect a PV system unless you can add the necessary electronics to make sure that it never tries to feed power back to the Generator.
There are specialty grid tie inverter systems which are designed for countries which do not allow backfeed into the grid ,either by throttling the solar power or adding in extra local loads, but they are more expensive and less available than standard GTIs.

[inetdog]

Copied from Hassan's introduction thread:

If your Grid interface is reliably intermittent, save your self big money and concentrate on battery storage charged from grid when it's avail. use a good quality inverter to feedback your micro grid when it is down. Once you have this basic system installed and running, you may add solar panels for an alternative source of power to charge the batteries. depending on where you are, solar may not be enough to fully charge batteries, unless you go with expensive over sizing.

Although this is a good strategy for an individual, it does nothing to relieve the usage pressure on the grid infrastructure.

For example, if one of the limiting factors on grid availability is fuel supply, more power going into charging batteries when the grid is up will just cause it to shut down sooner.
Use of PV, on the other hand, leaves the grid delivering less total power. Unfortunately this benefit of PV use goes mainly to the other users, not the person with the PV installation.
In this case, with the cost of grid power over $.50 per kWh, it may still make good sense to install a PV system with a small battery bank to be used mainly for supplementing grid power while the sun is shining. One model for this would be to use both grid power and PV to charge a battery bank at the same time that an off-grid inverter is supplying the loads. This would minimize the amount of battery cycling and avoid any technical and regulatory issues with installing grid interactive inverters.

[sensij]

There are specialty grid tie inverter systems which are designed for countries which do not allow backfeed into the grid ,either by throttling the solar power or adding in extra local loads, but they are more expensive and less available than standard GTIs.

Solaredge inverters are readily available and are priced about the same as the SMA sunny boy series, but have zero backfeed capability when coupled with a power meter (about US$500 extra).