Grid Tie Limiter Experimenting Part 1
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- เผยแพร่เมื่อ 23 เม.ย. 2022
- Trying different ways to make a limiter for a grid tie inverter. Part 2 to follow. Links bellow.
Limit Detection Relay
www.amazon.com/gp/product/B07...
Split Core Transformer 0-10A,20A,50A
www.amazon.com/gp/product/B00...
Normally Open Self-Powered Current Sensing Relay
www.amazon.com/gp/product/B08... - วิทยาศาสตร์และเทคโนโลยี
GroWatt sell 120v grid tie inverters with limiter via their own smart meter. Might be worth looking at. They abandoned CT clamps because they were too inaccurate. I think the problems come from the voltage varying.
Interesting. I have two of the same model current switches you showed at the end ready to go in my panel. Intended to use one for some of my higher amp feeds (that can physically be combined) on each leg, and they'll kick an interposing relay (each) to turn their leg's inverter on. I did take the time to test running the lower voltage input version of the Grid Tie from my 24v battery and it did pretty well , outputting from 7.7A early moving toward 6.7A steady state after about 15 minutes. I left it running that way for an hour Saturday, and I don't have much concern letting it go until the transfer switch battery cutout takes out the inverter, which I had set a couple of tenths voltage lower than I chose to go the first time on Saturday.
Not sure about your analog CT, but I'd think your issue with shutoff when crossing zero amps may be just part of a timing/race condition. Hard to tell what's in your black box of a meter/switch for frequency of measurement - it may be something that's better served by something like an Arduino so that you could measure and adjust to load swings quicker. That should also allow you to program it to be variably adjustable as you'd like as well.
Do you have an understanding of your house loads on L1/L2? I was surprised how small but steady most of my house load was. Most of the time I won't have a need to throttle regular PV input, as my house load is normally in the 500-1000W range. One leg may go slightly under 0 amps for a while between 1 and 3pm in good weather this time of year, but the total has been consistently higher. I'll need to keep a closer eye on the meter totalizer versus Emporia Vue to see if things are recording the same -- I know the Emporia is deducting my solar amps/watts. I don't know if the meter can intelligently compare L1 and L2 for major imbalance - or more specifically whether I should care, as mine doesn't have an instantaneous Watt/hour display I'll have to compare readings over a couple of time periods when I know I've gone below zero on one leg to know for sure.
But I do know if you move your inverters to of the breaker panel as far away from mains it well help the backfeed have a chance to supply the loads
Dude that's nonsense. 😂 the voltage is identical no matter where you are on the bus.
Well I have a grid tie inverter and I simply put it in non-export mode and it meets all of the loads in my home and if there are no loads in my home it throttles down to zero and never back feeds the grid. And no, I do not have a permit or in interconnection agreement.
I was wondering if he was using another dog on the other current shut line if it would pick up the Eddie current as bad ..
I think you need CT’s on both of your mains as well as your solar inputs…. If you take, for example, the Emporia energy monitor…. There are CT’s on solar inputs, and there are CT’s on the Maines The app basically takes one and subtract it from the other. The mains would be a + and the solar input would be a - …..when your 0 you’re even and when it goes into - numbers your back feeding…. The meter actually calculates watts (volts x amps) and uses that for the Calculation …. So you have + wattage coming from The utility and - wattage being produced by your inverter…. The net tells you what’s going on ….+ numbers your not back feeding
HOWdy KC
homemade LIMITER
Thanks
COOP
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Do you have links to the parts you used?
Add links to the Detection Relay and CT's in description. Thanks
First let me say, you are crazy-smart, mad-professor smart!
I think I know what you are doing. I think I know how you are doing it. (But I see the Growat in the background so maybe I don't know what you are doing). I'm going to try and explain what I think you are doing: You are using "dumb" inexpensive GTIs (no feedback) that you are attempting to control by CTs output that you have fed into a low voltage "current switch" (I don't know! I am a mechanical guy!) that directly controls a relay that switches the AC on-and-off for the GTIs. You have settable CTs and settable "current switch". I think the idea is to have your GTIs come on when a demand is sensed on specific legs/specific circuits of your panel, but you only supply your GTIs with enough solar such that demand will always outweigh supply so your meter never goes negative. Is that what you are doing????
You nailed it. With a simple on/off one set point the power demand has to be around 2 1/2 times of what your inverter will be supplying for it to reliably cycle with the demand. I was hoping to get the down to 1 1/2 times, but reliability went away as soon as current draw from the grid dropped below 5-6 amps. I haven't given up on it "yet", but jut want to keep moving forward with what works. This way solar can start paying me back while I experiment with things.
Yes, my project is two fold. A set of cheap grid tie inverters to help save a little on the eclectic bill, and a Growatt set-up for back-up power. The main reason I started the solar project was for back-up power, and found for a couple hundred bucks I could play with some grid tie stuff. Here in this part of Texas we have very reasonable electric costs, but with cheap comes a reliability issues.
Smart?? Nah, I just like to play and build things, but thank you for the kind words.