Grid Tie for Diese generators

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Does anyone have any information on the existence of a grid tie for diesel generators. In my country Nigeria, there are a lot of industrial generators and I'm looking for a technology that will allow the consumers re-sell the excesses generated from those huge diesel generators back to the utility companies. Any insight into this tech anyone?

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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
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    Re: Grid Tie for Diese generators

    Grid-Tie inverters require 5 minutes of pretty stable voltage and frequency, before they will engage and begin to sell back. They generally start out with several hundred volts DC (from a PV array) and convert that to 50 or 60 hz AC. What sort of output do all the industrial generators you have, produce ? AC, DC ?

    Will the utility companies actually pay you cash, or just allow a credit on your bill?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Re: Grid Tie for Diese generators

    You probably need to talk with your local generator supplier(s) and get a quote.

    Since multiple generators can be sync'ed together, they can also be synced with the AC line... Since national power grids (generally) have multiple sources of power distributed around the region/country, all of these sources have to be sync'ed and controlled by the power authority.

    For our "small" systems, they are so small that they don't affect the grid very much at all (total "home RE" Grid Tied capacity just a few percent of our entire state grid).

    The "owner" of a large generator station could not just decide how much energy to crank back into the power grid. This would have to be done based on capacity and amount of energy the utility can absorb.

    And, you would have to work with your local utility. The problem with local generators are safety, network reliability, and revenue.

    Obviously, you need to coordinate with the utility so that you don't (for example) pump energy into the grid when the lines are down in the neighborhood (safety).

    You also cannot pump more energy into the local network than can be absorbed by the local grid (overheat local distribution) and you don't back feed certain distribution hubs (i.e., in downtown San Francisco, there are substations that will shut down if they back-feed power--obviously will not work with local generation). You also will need to have an understanding of how much and how fast you can ramp up and ramp power back into the network--assuming you have a relatively large generator plant (reliability).

    And lastly, you would need an agreement with your local utility to agree on when and how much power you will supply. And how much you will "earn" from feeding the grid. Here in California, the price of the power is only, roughly, 1/2 the price to the end consumer (distribution and other "costs" are the rest). You will need to have a contract with your local utility so that you can make money on "selling power" and the utility "saves" money by having you supply power (perhaps, you provide "peaking power" during summer heat spells, or provide emergency power during central/distribution failures.

    You will have many responsibilities in this project and it would be difficult for anyone here on a solar energy board really give you much guidance for utility policies in your country.

    Lastly, unlike Renewable Energy (like Solar or Wind grid tied systems) where we have "excess capacity" (sunny mid-day or windy time of year) where we use the grid like a giant battery (and our fixed costs are the same, whether or not we are generating power or not)--Your generators will, typically, use more fuel as you start cranking energy back into the grid. So, once you are over 10-20% capacity of your generator(s), your fuel flow will rise in proportion of the amount of power you push back into the grid. So, in this case, you are not getting something for nothing ("free electricity" from your diesel power plant).

    It then comes down to whether or not you can generate and distribute power back into the grid for less cost than the utility can provide power. And that is probably a pretty straight forward calculation... What is the price of power per kWh in Nigeria vs how much diesel fuel+power station costs are per kWhr. In the US, it is very difficult to compete with utility power... And many utilities are very unfriendly to "local" competitors.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset