Can I grid tie like this?

[BioHazard]

I'm looking at building some sort of gas powered generator mostly for making heat in my inudstrial shop. My plan is to run only a small percentage of my current electrical load on an inverter or generator head from the engine. That is to say, I'll never generate more kilowatts than I'm actually using. (I have a ton of lighting to power)

I could wire certain lighting circuits to a transfer switch and run them from the generator/inverter while it's on. No grid tie this way, working the same as a power outage.

On the other hand, I'd rather use a grid tie inverter. Let's say I have a 3kw grid tie inverter, and I'm currently burning 5kw of electricity from the grid. Can I hook up the inverter to backfeed 3kw into my main panel, while at the same time I'm still drawing 2kw from the grid for the 5kw total?

Or rather, can I do that without the power company knowing about it? I don't want to spin my meter backwards, only slow it down. They will allow grid tie systems, but not gas powered ones. Additionally I have a fancy digital electric meter, I doubt it works in reverse, and I don't know if it can "tattle" on me.

Basically, I don't want to have to flip a transfer switch every time I turn on the inverter. I'd rather just turn on a grid tie inverter, so there is no switchover. I'm pretty sure I could do this if I invested in a fancy solar system and the power company would give me a net metering deal, but like I said, they don't need to know I'm burning gas.

[mike90045]

At some point, for 20 seconds, your house loads will be less that what you are generating, and the meter will flag the sale of 14 cents of electricity.  Then you are busted.

[BioHazard]

At some point, for 20 seconds, your house loads will be less that what you are generating, and the meter will flag the sale of 14 cents of electricity.  Then you are busted.

Not likely. I lease a large industrial shop, and, in addition to that, I have 3 other neighbors that share my meter. My power bill says we average 120KWH/day together, so I've got a LOT of overhead to hide in. Additionally, my lights alone are more than 3kw, so if that's the inverter I had, it could never happen unless I turned the lights off. Maybe I could hookup a relay that only allows the inverter to run when the lights are on. If the neighbors are "home", there's an easy 20kw constant load on my meter.

I don't think any unusual load changes would be a red flag here, because I share the meter with other people, and people move in and out of these buildings all the time - so it's not uncommon for the bill to drop by half one month....

...But if it did happen, they'd have a lot of trouble blaming it on me vs the other 3 neighbors.

But then again I have thought about buying a small, nearly worthless solar panel and 200w grid tie inverter just to show the power company, so I have a reason to get a real net metering meter....

[BioHazard]

Another thought - I have 3 phase "120/208Y" service at my shop, though I do not have any 3 phase loads. Can I hook a 120v grid tie inverter to a three phase system the same as a normal household split phase 120/240 system? Or must I purchase a special 3 phase inverter?

[LowGear]

I'm surprised the power company condones four households on one meter. 

Casey

[BioHazard]

I'm surprised the power company condones four households on one meter.  

Casey

It's an industrial building, not a house. I would have my own dedicated meter but I would need to spend about a thousand dollars in new cables alone...(my building is quite a ways from the transformer in the street)

If I did this I would install a seperate submeter on my building so I can keep track of exactly how much power I use and how much I generate, right now we only make guesses on who should pay how much every month...

[billswan]

Biohazard

I think unless you are the landlord or you are sure you are getting the better end of the deal you should invest in a separate meter. How else are you going to know what you use, guessing is not going to cut it, that is how I see it.
If you do build a gen how will you know how much it might save you without meters?

So your section of the building is not wired separate it is all run together? If that is right I sure hope the rent is reasonable.........
Billswan

[BioHazard]

Yeah, like I said, if I did this I would install a submeter seperate from the utility on my main panel measuring input and output kWh. In order to have a seperate meter for my building from the power company I would have to buy five conductors (3 phase) large enough to carry 200A about 300 feet. I'm not even sure what size cable I'd need, and I don't want to know how much 1500 feet of it cost...

Edit: something like this: http://cgi.ebay.com/3-phase-kWh-Electric-Power-Smart-Watt-Meter-Three-Ph-23-/170515730053?pt=LH_DefaultDomain_0

Right now the landlord just splits the bill and nobody is happy with their share...

[LowGear]

Aw Come on BioHazard,

The guy that has his area at 68 degrees in the summer and 76 in the winter thinks its a great idea.   

I like the meter on Ebay.  Some places are just too darn complicated to meter individually.  Especially if the development was more of an evolutionary experiment rather than a planned community.  Most of my apartments run off two meters.  Some for this and the other for that.  Fish a ground wire all the way back to the panel through a 1.5/12 attic or just sneak downstairs to the existing grounded circuit?  My decision exactly.

Casey

[BioHazard]

Aw Come on BioHazard,

The guy that has his area at 68 degrees in the summer and 76 in the winter thinks its a great idea.  

That's exactly the problem! Because in my shop right now it's about 85 degrees and come December it will be about 40. Nobody is willing to/or knows how to estimate their loads correctly for the landlord for billing besides me, I disagree with how much I pay, and she thinks it's too low. She also doesn't know what a watt or a volt is, but somehow she thinks she can accurately split the power bill between 4 users...

And you're exactly right, my building was built several years after the main building, and power was just taken from there. And then they added another building and tapped the power again.  

[billswan]

And you're exactly right, my building was built several years after the main building, and power was just taken from there. And then they added another building and tapped the power again.  

Bio

If you have a main meter on the main building and you were to buy a meter like you linked to and installed it at the tap point and then again at the next tap and so on down the line wouldn't you be able to figure out the usage with a little math?

no wires needed just meters and the ability to subtract. Except the last meter would be the usage for the last building or apartment in the complex.

With the price of power i would think it would be worth the money to get it right. Of course if it turns out the meters prove someone was getting the shaft it could case quite a stir if all of a sudden someone starts having to pay a lot more for power. Even the guy that has his drop could be mad if he starts to think about how much cash went down a  rat hole.

Billswan

[BioHazard]

If you have a main meter on the main building and you were to buy a meter like you linked to and installed it at the tap point and then again at the next tap and so on down the line wouldn't you be able to figure out the usage with a little math?

Yeah, that would be too easy.   I suggested the idea to the landlord but she's far, far, far too cheap to buy even one meter let alone 3. (actually there's 8 tennants on 3 meters total) It was a big deal when I decided I wasn't going to pay an equal 25% anymore, due to the fact that my neighbors have bigger buildings than I do, and, they spend more time there than I do. So I carefully measured and calculated everything I use and came up with about 8% of the power bill, I rounded up to 10% for "extras". Then the clueless landlord tried to figure out how much the neighbors are using individually and says she comes up about $100 short based on what everybody tells her. So either the neighbors are lying or she's just stupid, probably a little of both.   I said 10% or prove otherwise, I'm still waiting for proof.

This summer hasn't been bad, one of the buildings with AC is empty, but come heating season I'll probably buy my own meter and let the landlord split the bill between the remaining three, minus me. Pretty much everybody is cranky about the electric bill, the landlord is just too incompetent to setup her building the way it should be. (she also tries to do the same for natural gas, fortunately my building doesn't have any) I'd love to get a meter and prove that my useage is actually lower than 10%, she wants me to pay 15%.

The moral of the story: Checkout your landlord CAREFULLY before you sign a lease and make sure she's not insane. Then again, having a dumb landlord means I can modify the electrical however I want and she won't notice or care...

[mike90045]

Used, reconditioned meters are cheap, but the SOCKET for them has to be bought new, unless you are really lucky.

[BioHazard]

Used, reconditioned meters are cheap, but the SOCKET for them has to be bought new, unless you are really lucky.

Yeah, I've been keeping an eye out for a good one, but, since I have three phase power the three phase meters are a little more expensive, and so is the socket. I just hate investing money in a building that isn't mine, especially with an unappreciative landlord. I'm thinking about building my own shop within a year or two, so I like stuff I can take back with me...

There's a local used/surplus building supplies place that often has a lot of meters/sockets/breaker panels for cheap, but, I have yet to find a 3 phase model...

[billswan]

Bio

Good luck, it seems you are caught between a rock and a hard spot.

Get out at your first opportunity seems like the best route.

Billswan