sell power back to utility

[jzeeff]

What does it take to sell power to the utility?  Most now have "net metering" which allows the meter to turn backwards.  Is approval and paperwork difficult?

It looks like equipment usually has to be UL1741 approved.   So here is what I see:

Get a solar grid-tie inverter than takes in 240-600 volts DC and puts it into the grid. 

Run the generator at 240 volts and use diodes (full wave bridge) to get DC.  Add capacitors to smooth it out.





Cost isn't so attractive - $2000 for the inverter.

[carlb23]

I live in New Jersey and we currently have a 1.8kw wind turbine and 10kw of solar that are grid tied. We didn't have any trouble but we did need to submit a interconnection form and that had to be approved.   I don't think it makes much difference if you use solar, wind or you lister to supply DC voltage to your inverter as long as the inverter is approved for grid tie connection. You will also need a Disconnect outside where the utility can get to if and disconnect your generator from the grid if necessary.  I am no expert and you probably would want to contact you local utility before proceeding. 

I have actually been thinking of using my 6/1 to connect to one of my inverts and only run it at night when the solar is not producing.

Carl.

[ronmar]

I think to be approved for grid-tie, the inverter must be auto disconnecting.  IE, with no commercial AC on the incomming, line, the inverter will put no energy back into the grid.  For the same reason, you don't want to have your generator backfeeding the grid so an either/or transfer switch arrangement is used to prevent this.

I found it kind of funny at the grid-tie solar systems I have visited during the last few years during the National Solar Tour days, that when the commercial power goes out, the house is without power, even though the solar panels are generating power.

Ron   

[carlb23]

Ronmar,


The reason that the house has no power when the grid is down is is two fold.  The utility doesn't want you back-feeding the meter if there is an grid failure endangering the their workers. Secondly if the inverters were working but not back-feeding the grid and you were not using all of the power the inverters were putting out the inverters would overheat and derate or be destroyed. You can buy a grid tie inverter with battery backup and then you will have power when the grid goes down, but that would require more maintenance and much more expense.

Your other option would to take the feed from the panels before the inverter and power somethings but then you have to deal with in most cases over 225 volts DC so, other than heating water I don't know what you could use it for.



Carl

[buickanddeere]

http://www.hydroonenetworks.com/en/customers/generators/net_metering/

  It's possible but you must jump through a bunch of hoops.

[Jim Mc]

Most now have "net metering" which allows the meter to turn backwards. 

My utility does not net meter.  Better check on yours before you go further.  Here, they do have to buy back power from their customers, but they only have to pay their 'avoided cost'  which, last time I checked, was about $.02/kWh.  Cogen doesn't make economic sense at those rates...

[rcavictim]

Most now have "net metering" which allows the meter to turn backwards. 

My utility does not net meter.  Better check on yours before you go further. Here, they do have to buy back power from their customers, but they only have to pay their 'avoided cost'  which, last time I checked, was about $.02/kWh.  Cogen doesn't make economic sense at those rates...

Yet another utility truly born to become a Flying Leaper.

[carlb23]

I live in New Jersey and we have been net meetering since 2004.  We really had no problems with the utility.  We installed approved equipment (most solar or wind inverters are accepted  SMA, Fronius, Sharp, outback, Xantrax etc). We did have to fill out an interconnect form and have the system inspected by the local and the utility inspectors, but we never had a problem.  Electric bill free since 2004 and now we have a total of 10kw of solar and 1.8kw of wind.  We generate over 13MWH a year and heat and cool our house as well as run everything in the house.  We do have a gas range and a gas (on demand water heater) a gas range and a gas cloths dryer.


Carl 

[jzeeff]

Congrats, we need to see more of this.   In cases where solar/wind/hydro can't work, then a generator to generate electricity and heat.

Nobody better than the people here to build long lasting, quiet, efficient generators.

[cujet]

From an economic point of view, running a Listeroid simply to sell power makes no sense. If fuel were free, the cost of the genset, it's lifespan, it's maintenance and overhaul costs and the free labor involved exceed the KWH cost of most utility companies. I expect a listeroid to achieve 5000 hours before overhaul, run on very clean fuel. It could be more, but it is likely that full overhaul at 5K would prevent problems down the road. 40,000 hours is a pipe dream. Also a proper overhaul at 5K would mean another 5K of nearly troublefree service.

With fuel at 1 dollar per gallon, just the fuel cost would far exceed the KWH cost of most utility companies.

Now, remember that free fuel is not truly free, just in case you were thinking biodiesel or SVO. You must transport it, filter it, Store it,  deal with it and the problems it causes.

I see the Listeroid as a simple, reliable backup power supply. Or a remote power supply. In both situations, the cost of power is not as critical.

Right now, my Listeroid burns enough fuel dollars to cost about 5 times the Florida Power and Light rate. And my genset cost me a total of many thousands.

Chris

[jzeeff]

What if you were in Michigan and could make good use of the 80% of the energy in the fuel that doesn't go into electricity?

Or think of it this way - there are a lot of people burning  fuel just for the heat -  they can also  generate electricity for only the cost of equipment + maintenance.

Say one could get $100 worth of electricity per month for 6 months every year.   That might cover equip + maintenance, it depends on specifics.


 

[captfred]

Chris is correct, you can't beat the economies of scale present in utility power - even with heat as a bi-product and paying yourself nothing for your work to process "free" fuel.

But there is something to be said for grid independence.  During lower power demand times, run the roid to heat and centrifuge wvo (doing that) AND run DC power into a grid-tied inverter/battery bank and sell excess back to the grid (working on this).  Instead of running the roid 7 days a week, might only have to run it 4 days and use your built up credit on the off days.

Still don't plan on ever saving any money. but brandishing  my digitus medius in the direction of the power company, priceless.

Cheers, Fred

[jzeeff]

Here in MI (where the heat is valuable), to make it more economical than my nat gas furnace, I need to:

1) run nat gas in the engine
2) find a lower cost grid-tie inverter (or other approved device)
3) have a fairly durable engine so I'm not rebuilding it frequently

I believe that this is all doable although #2 might mean waiting awhile.

In the mean time, I'm working on a organic Rankine cycle generator - think auto air conditioner running in reverse off the heat in the water heater and driving an auto alternator..  It will use a Sanden scroll compressor with the check valve removed.

[cujet]

Before you spend a lot of time and money on such plans, please make sure you understand BSFC. Do the calculation in KW for an easy comparison.

You will not have 80% waste heat. The diesel engine is more thermally efficient than a gas engine. Somewhere in the 60's% is likely where you will be thermally. AND, only under high load.

Exhaust heat is very hard to capture on a listeroid, as the carbon will build up inside the heat exchanger, reducing the heat transfer. Most heat will go out the tailpipe.

[jzeeff]

I've done the calculation based on data people here have posted.  Yep, for a Listeroid, only 20% goes into electricity.  Less for a natural gas engine.  How efficiently one can capture the exhaust heat is a good question.