Load sensing grid tie inverter?

[BioHazard]

Around here the power company is all for grid tied solar, wind, and hydro projects where you can simply turn your electric meter backwards, however, they are not so friendly to those of use who chose engines as prime movers. They will not buy any juice I make with an engine, I can't use it to turn my meter backwards, legally.

What I can do, is use a grid tie inverter to displace other household loads, but when the power useage in the house falls below what my inverter puts out, I don't want anything extra to go into the grid. I suppose this could be acomplished with multiple small inverters all working together, turning them off as necessary? What I wonder is how can I automate something like this...or does somebody already make such a product? Something that would detect the household useage, and "invert" no more electricity than is being used, while still being grid tied.

Does anyone understand what I'm saying? 

[BioHazard]

yeah, so what is the problem <wink>

The bastards at the power company took my old spinner and gave me a meter that has it's own long distance wireless communications system, I'm sure if I sent any power backwards through it I'd be on the FBI's top ten list in a few hours. *sigh*

[LowGear]

How is the utility going to know how the power was produced?

Casey

[BioHazard]

How is the utility going to know how the power was produced?

Casey

They don't, but if I want to "net meter" I have to sign an agreement with them about the whole setup, and explain how many solar panels or whatever I have. There is probably some sort of inspection. They might wonder how I'm making a few kilowatts in the middle of the night. I imagine there is a lot of fine print that says I will be in big trouble if my power comes from another source than what I listed.

They do have an option for buying back customer generated power, regardless of how you make it, but they won't pay as much as the rate they charge me! All I want is to be able to turn my meter back to zero or close to it...

[rcavictim]

How is the utility going to know how the power was produced?

Casey

They don't, but if I want to "net meter" I have to sign an agreement with them about the whole setup, and explain how many solar panels or whatever I have. There is probably some sort of inspection. They might wonder how I'm making a few kilowatts in the middle of the night. I imagine there is a lot of fine print that says I will be in big trouble if my power comes from another source than what I listed.

They do have an option for buying back customer generated power, regardless of how you make it, but they won't pay as much as the rate they charge me! All I want is to be able to turn my meter back to zero or close to it...

If you are prepared to put enough fuel through your diesel generator to zero your meter on a regular basis that means you are generating all the power you consume with your own generator.  What the heck do you need the utility and their meter for at all?  Just go off grid and save the connection fees.

[BioHazard]

I only want to generate power during peak periods, for which I'm charged the highest price per kilowatt. (around 12.5 cents/kwh) During the off peak times power drops to 4 cents/kwh and I can't compete with that. I'll store the heat I generate during the peak power period for use throughout the day.

[billswan]

I only want to generate power during peak periods, for which I'm charged the highest price per kilowatt. (around 12.5 cents/kwh) During the off peak times power drops to 4 cents/kwh and I can't compete with that. I'll store the heat I generate during the peak power period for use throughout the day.

Well just use a power transfer switch. When that time of the day comes start the gen transfer from grid to gen. No need to sign anything or grid connect. The city's meter stops and so does the bill for higher power cost. No need to match the power quality so no fancy equipment needed.

Billswan

[BioHazard]

Right...but I'm trying to avoid the power lapse during switching, so clocks, computers, and every other electronic thing doesn't get pissed off. I don't think it's feasable to hook everything to a UPS.

[rl71459]

I understand what you want to do.... If you use a induction motor/generator you can throttle the engine to adjust the percentage of power that is output from zero to the max the your system can create. By doing this carefully (Smooth, Slow, Throttle Control) you can make your ouput nearly invisable at the meter if thats what is desired.

Or if you have a big motor crank it up and spin that bastard backwards like a top!

Note: I do not recomend the latter as it may land you in BIG TROUBLE with the PowCo!

Although I would never do it.... You can effectively adjust the speed of the meter with the first method which will appear no different to them than you just being conservative.

If they are indeed watching... It will be very easy for them to tell when you connect a synchronous generator because unlike the "Ramped in" induction method there will be a significant event (Reversal) of power flow when the system is connected. The quality of syncronization and KW output have a big influence on how the event will appear to their monitoring devices.

I would bet that all of the above is illegal! and can land you in a world of trouble!

[billswan]

Right...but I'm trying to avoid the power lapse during switching, so clocks, computers, and every other electronic thing doesn't get pissed off. I don't think it's feasable to hook everything to a UPS.

I think you should leave the clocks and computers on the grid it is much more stable. Even at the high rate they won't save anything significant switched to a gen. Just do some creative wiring and put your heaviest loads on the gen. You mentioned earlier about lot's of lighting.

Billswan

[LowGear]

Hi,

Our utility does have a grid tie power agreement and an inspection and requires that everything be county approved - NEC. 

They will NOT buy any excess power back but will allow you to dump your excess power into their grid.  This is based on the billing cycle.  They feel you can never pay too much for good reliable "on demand" power.  And that's where they have me or most of us by the short hair.

It sure would be nice to know how smart these new meters are.  They do talk to the power company over the electrical lines.  But do they actually tract "Customer Generator" power down to the hour?  Ours aren't, as far as I know, smart enough to charge according to peak power considerations. 

Ignorance can be a cruel and expensive master.

Casey

[BioHazard]

I was thinking something sorta like this:
http://cgi.ebay.com/1200w-300w-4pcs-GRID-TIE-POWER-INVERTER-solar-panel-/110631673955?pt=LH_DefaultDomain_0&hash=item19c2296063

So that as the load drops, inverters could be turned off one by one. Automating that is of course a different story...

I think I need to start by installing some sort of ammeter behind my power meter so I can get a better idea of what my average loads are. My house was not wired by an electrical geek like myself so it seems like just about every circuit has something on it that doesn't want it's power disconnected. Why does everything these days have to have a clock built into it?  Most of the lights in my house are connected to the same circuit as the wall outlets. I have considered rewiring the house with generator specific outlets throughout, but that would be a real PITA...

I might invest in a small grid tie solar system, few hundred watts or so, just to get the power company to come out and give me a netmetering contract and meter. It still won't account for as much power as I would like to make, but, it wouldn't set off alarms if I accidently let a little extra power out...

[Horsepoor]

Why not purchase the cheapest office supply wearhouse UPS devices for clocks, TVs, and computes that you can find or when they go on sale? You could then plug as many mission critical devices into the UPS at each location as the the device will handle. Cheap UPSs will not supply power to your essential items for very long, but I'll bet you'll get 5 minutes or so which would allow you to switch on your generator without any disruption and at the same time you might just added sometype of surge protection to your house.

Bruce

[BioHazard]

The problem is it seems like everything these days wants a constant power source. I could buy a ton of UPS's, but I'd need some pretty big ones too, and a ton of them. Just off the top of my head, the microwave/stove/coffee maker in the kitchen all have a clock and other settings. Then there's 3 seperate computers. A few TVs and cable boxes that lose their settings. A stereo that forgets all the station presets. I could go on....it just seems like every circuit in the house has at least one thing that hates interruption!

To top it off if things don't work JUST LIKE the grid, the others in the house are never going to understand why I'm doing this and get pissed off....

[vdubnut62]

I feel your pain BioHazard, my Wife Just can't wrap her head around why the satellite and multiple tv's have to be reprogrammed, and every clock in the house is blinking.
I finally broke down and bought a paralleling relay, and I think (hope) I can use a motor protection relay to kick everything off line if the grid goes down. I'm planning to just offset a part of my use without a lot of fuss and bother, plus capture the wasted heat from the prime mover to help heat the house.  I still have the old "spinner"meter and nothing will run without my being here to keep an eye on things.
I hope to have a gasifier wood boiler with a 500 gallon storage tank plus radiant floor in the works this summer.
I want all the "equipment" out in a separate shop/woodshed/workshop too.
A pretty big project, for me anyway. It helps that a certified electrician helps me out for beer!
All positive thoughts/energy, prayers or what ever your particular belief system supports will be greatly appreciated!
Ron