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CHP connection to the grid

  • 05-01-2011 12:58am
    #1
    grass
    Registered Users Posts: 49 ✭


    Hi

    I am looking for a little help. we are thinking of building a 20kw ChP plant to supply electricty and heat to our house. Excess electricity we would hope to supply back to the grid, as I understand only up to 6kw of power can be sold back to the grid on a single phase connection. Does anyone know if it exceeds the 6kw what happens ?


Comments

  • #2
    quentingargan
    Registered Users, Registered Users 2 Posts: 1,627 ✭✭✭quentingargan


    grass wrote: »
    Hi

    I am looking for a little help. we are thinking of building a 20kw ChP plant to supply electricty and heat to our house. Excess electricity we would hope to supply back to the grid, as I understand only up to 6kw of power can be sold back to the grid on a single phase connection. Does anyone know if it exceeds the 6kw what happens ?

    The 6kw limit for single phase supplies is quite universal, so I should imagine that the CHP has this limit built in, at least as an option (actually, it is 25A which is 5.75Kw). You don't say what units you're looking at, but I assume you mean 20Kw of heat. The Baxi 20kw unit for example only puts out 5kw of electricity. Other units I have seen have current limiting.

    I'm not sure if your CHP has an inverter built in? Inverters to be connected to the Irish grid must be compliant with specific Irish variations to EN50438 and certified as such. That may cause you a bit of a headache when you apply for the two-way meter...

    If the inverter is external, you could control dump loads using a microprocessor which measures the voltage coming into the inverter from the CHP. I have heard of this being done with 10Kw wind turbines being connected to the grid.


  • #3
    Mike2006
    Registered Users, Registered Users 2 Posts: 689 ✭✭✭Mike2006


    When I first saw these I was very interested in them as they looked to be very progressive. As I was about to build a new house I delved in a bit deeper and then they did not appeal to me as much.

    The main reason was that they seem to be more suited to older poorly insulated properties as they require a substantial thermal load (3 to 7 kW) for reasonably long periods to make them economical. With a new build which was to be built with a high level of airtightness and insulation, I was not going to achieve the required thermal load to let the unit run efficiently..

    They are a great system and I think they will play a big part in home in the future but it is just something to consider if you are seriously looking into one.
    At a saving of about €500-€600 per year on your electricity bill (when ran at full efficiency) there would be a 10-12 year payback on one of them I reckon..

    Mike.


  • #4
    holdfast
    Registered Users, Registered Users 2 Posts: 1,152 ✭✭✭holdfast


    Unless you have a swimming pool, forget it your mad. where do you put the heat load in the summer. :cool:


  • #5
    Mike2006
    Registered Users, Registered Users 2 Posts: 689 ✭✭✭Mike2006


    You don't...
    You only produce electricity when you are running the CHP as a boiler.
    During the summer when the heating is off, you get your electricity from ESB sam as everyone else..

    Mike..


  • #6
    holdfast
    Registered Users, Registered Users 2 Posts: 1,152 ✭✭✭holdfast


    I can see payback in decades so, buy a machine that only runs for a half a year and the cost of the electricity its paid for from the ESB is so low when it does run. Not a runner at all for a domestic hse.


    CHP is only really suitable for Hotels, schools with a base heating load in the summer. Even then a very good payback, feasibility report needs to be done and allow for the possible inflation of the fuel. (GAS could be cheap this year but nest year it could be mad, an allowance has to be made for such a situation. This process has given CHP a bad name with fuels variance affecting the payback greatly)


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  • #7
    fclauson
    Registered Users, Registered Users 2 Posts: 1,691 ✭✭✭fclauson


    Have you looked at the CHPs from Baxi and Calor

    any thoughts on if they are good or not ??

    Francis


  • #8
    Agri contractor
    Registered Users Posts: 141 ✭✭Agri contractor


    Anyone have information on connecting to the grid for a 100kw biomass unit? tarriffs,and connection fees ?


  • #9
    Refeek Maher
    Registered Users Posts: 23 ✭Refeek Maher


    Actually, waste heat can be used to run a stirling engine which could run a generator. Thus providing even more electricity.

    I know it's not practical at all and would be very expensive (and complicated) but it's a cool concept that is being used by companies that don't want to waste all there heat.

    As far as I know (do not quote me on this), you would have to call up your electricity provider and get a quotation from them on how much they would pay you per kW or unit. They would need to send out an engineer to inspect your generator and an electrician to install what is needed for connection to the grid. As far as I know this could cost between 7,000 and 30,000 euro, depending on the application.

    If I am wrong, please someone correct me, as I am interested in knowing myself.


  • #10
    ted1
    Registered Users, Registered Users 2 Posts: 23,658 ✭✭✭✭ted1


    Refeek Maher wrote: »
    Actually, waste heat can be used to run a stirling engine which could run a generator. Thus providing even more electricity.

    I know it's not practical at all and would be very expensive (and complicated) but it's a cool concept that is being used by companies that don't want to waste all there heat.

    As far as I know (do not quote me on this), you would have to call up your electricity provider and get a quotation from them on how much they would pay you per kW or unit. They would need to send out an engineer to inspect your generator and an electrician to install what is needed for connection to the grid. As far as I know this could cost between 7,000 and 30,000 euro, depending on the application.

    If I am wrong, please someone correct me, as I am interested in knowing myself.
    For micro generation you don't need to do anything other than fill up a firm to telk then your connecting to the grid. You do need to install a invertor.


  • #11
    quentingargan
    Registered Users, Registered Users 2 Posts: 1,627 ✭✭✭quentingargan


    ted1 wrote: »
    For micro generation you don't need to do anything other than fill up a firm to telk then your connecting to the grid. You do need to install a invertor.
    Yes - except that if you go over 11kw on 3 phase or 6kw on single phase, you will also need a desktop survey done, but it is only a few hundred euro. You will also need a disconnection relay type tested with Irish version of EN50438 on it. That'll cost another grand or so.

    The NC5 form is a bit scary about prices, but apparently you don't have to pay if you are below 50kw.


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