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Match my grid consumption with a Grid Tie Inverter & Baterries (Read 12681 times)
tiggeroush
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Re: Match my grid consumption with a Grid Tie Inverter & Baterries
Reply #8 - Dec 21st, 2012 at 6:40pm
 
Where I live in North Carolina, if i put more power into the grid then I use the utility company keep it and I get nothing for it.
But still, I use more then 250 watts per hour all day long. If I put in 1000 watts I could run electric heat and be happy about it.
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Crishmartin
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Re: Match my grid consumption with a Grid Tie Inverter & Baterries
Reply #7 - Sep 26th, 2012 at 4:46am
 
Grid-tied inverters are the key component in a grid-tied renewable energy system. They are often used to feed power into the utility grid which can then be sold to the electric company. For example, if during a certain month a GTI system feeds 500 kilowatt hours into the utility grid, and of these hours 100 are used, they would receive a compensation for the 400 additional hours.
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electron
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Re: Match my grid consumption with a Grid Tie Inverter & Baterries
Reply #6 - May 29th, 2011 at 12:51pm
 
LEDs don't just change color without some kind of signal. In most cases each LED is driven, usually red, blue, and green, just like a TV has so they can create any color. You should open it up and see how it drives the thing, unless you are worried about the warranty of course. (post pics of the insides!)

The only other way is if it has a USB interface and then you could monitor it with a laptop and maybe make a script to do what you want. Drive a relay from the parallel port or something. But that would also take some power, probably about 25W 24/7 for a small laptop.

I have another idea, you could wire in a small 5V wall wart transformer (or whatever you have laying around) to the AC in the back of your fridge so it comes on when your fridge does.

Then you have a nice, low voltage signal that could pull in a relay or something to turn on the GTI.

You could go wireless if you could find something that would send out a wireless signal to a relay as long as it's powered up. Like maybe some sort of wireless alarm or doorbell. You would have to make sure it sends a signal all the time, or get in there and modify it so it does. Like on the doorbell, maybe you could just short out the door bell button.

Maybe with that you could have several senders that trigger the GTI for other loads.

With wireless there's always the chance of RF interference that might trigger the GTI when you don't want it to.

It's too bad you can't get a KAW to do this, they are only $15 and so it's not a problem to take them apart. There is a circuit someone built to send out the volts /amps from a KAW wirelessly. "Tweet-A-Watt".

They attach to the KAW at the points where it senses the V/A at a op-amp. It might be possible to make a circuit like they had but it simply sends a continuous wireless signal at some V/A amount you set. A lot of trouble that way though.

http://www.ladyada.net/make/tweetawatt/
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Chris
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Re: Match my grid consumption with a Grid Tie Inverter & Baterries
Reply #5 - May 29th, 2011 at 12:11am
 
Thanks for your advices; I think all LEDs are just changing to any color (green, bleu, purple, red) like the Philips LED lamp.
If something could detect the color green, then maybe it would be more simple.

Anyways I will first wait for these GTI to arrive and see how it works for me.
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electron
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Re: Match my grid consumption with a Grid Tie Inverter & Baterries
Reply #4 - May 25th, 2011 at 4:17pm
 
I see that the Wattson lights up green when you are putting energy into the grid, so it may be possible to connect into that circuit and if it goes green, you open a relay or SSR and that would stop the GTI.

You would also want to put some sort of delay in there and keep the GTI off for a while so it doesn't go on/off over and over. Possibly a simple one transistor circuit and a capacitor, just to keep things simple.

If the LEDs to create the colors are all separate it should make things easier.

Since a SSR is simply a LED for a driver, you might be able to connect it directly in place of the red LED, and as long as it is in the red mode then the GTI would be on. You may still need a delay, so since you need a circuit for that you probably want to just go for the green LED mode.

It looks like you will be configured for a 12V system, and if so then the GTIs you have ordered will only drop the batteries to 10.5V, which is a good thing.

You might want to consider going 24V someday, you will get more performance out of your system that way, and it looks like the GTIs will handle it but it will pull a 24V bank to 10.5V which probably isn't a good idea.

However, since the GTIs are isolated on the AC side it may be possible to connect them to each 12V battery in a 24V configuration. I don't know for sure and you would have to be very careful in doing that and measure everything to make sure there's no problems and both GTIs are really isolated properly.

Interesting project, keep me updated!
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Chris
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Re: Match my grid consumption with a Grid Tie Inverter & Baterries
Reply #3 - May 25th, 2011 at 2:36pm
 
Here is a video showing Wattson Energy Monitor:

http://www.youtube.com/watch?v=jnUjb7rna9M&feature=youtube_gdata_player

And the two gti I ordered:

500W MICRO GRID TIE POWER INVERTER DC 10.5V-28V AC 110V

http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=170494263998
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Chris
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Re: Match my grid consumption with a Grid Tie Inverter & Baterries
Reply #2 - May 25th, 2011 at 2:26pm
 
Hi Electron,

Thanks a lot for your long reply
Yes my meter is digital and won't turn backwards I was told,
I leave in France btw, so anythink I push back into the grid would be lost
I ordered from eBay two 250 power inverter to test this for real
Like I wrote I just got a great power monitor called Wattson and this mesure in Real Time my consumption, and my production, and it provides the net amount. Whith this information, as soon as it goes negative, I could lower the inverter's output to avoid wasting power
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electron
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Re: Match my grid consumption with a Grid Tie Inverter & Baterries
Reply #1 - May 24th, 2011 at 5:25pm
 
People have used a Solid State Relay on the AC side to turn off their GTI before, so it might be possible.

You would have to be able to monitor your power consumption somehow with a computer and then have it turn on your GTI when necessary.

The 24/7 power consumption of the computer would also have to be taken into account when considering this.

Or wire into your fridge and when it turns on, the GTI comes on.

The GTI will go to max output if you connect it to a battery, and it will pull a 24V bank down to 14V if you let it run. So it's going to be hard to regulate exactly to your loads.

I'm not sure why you wouldn't want it to just put as much energy into the grid as possible during the day, for solar that is.

Or just put the fridge and other things on a regular inverter.

Batteries are used at a loss. If you go directly to the grid you don't get that loss.

Are you talking about having a "smart meter" that doesn't turn backwards when you push more in than you are using?

You might want to read the actual law in your State, don't believe what the power company says, go look it up and read it. Some say that they have to supply you with a meter that goes both ways.

As far as I am concerned, if they don't let me turn the meter backwards they are stealing power from me. It may be possible to file a class action lawsuit over that principal.

And of course you could get really fancy and have one AC monitor for the house and one for the GTI and then have a computer decide how long to run the GTI to make up the difference.

Sounds like a lot more trouble than just connecting everything to a nice sine wave inverter.
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Chris
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Match my grid consumption with a Grid Tie Inverter & Baterries
May 24th, 2011 at 4:20am
 
Hi all,

I have been playing with solar panels, batteries, solar charge controllers for a year and I recently got a Wattson (Energy monitor very well done) and can now see my real time grid consumption. I have also been looking at grid tie inverters.

I have an idea / goal: I would like to be able to match my grid consumption using a grid tie inverter and my 12 V AGM batteries (2 x Yuasa 65 AH)
I know how a GTI works, but do you think it would be possible to control its AC output so that I use just the required amount of battery energy to match my consumption;
For example: my fridge starts for 5 minutes, using 100 W, and I would like the GTI  to start and give an output of 100 W during these 5 minutes and then stop or reduce its output to match the remaining house loads
I thought of a "dimer" plugged on the GTI output, before plugging the socket into the wall

Any ideas ?
Thanks a lot in advance

Chris


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