Using a micro solar grid tie inverter with wind turbines

[makenzie71]

So in all my playing I wanted to find a way to use the electricity I was producing, but short of buying a $500+ 3-phase inverter PER turbine there didn't seem to be a lot of support.  I inquired a lot about using a DC grid tie inverter and got very little feedback, and a lot of shaking fingers, but I decided to try it anyway.

So this is my setup:



These are all inexpensive Chinese components...just like the turbines...so I'm sure none of the components are as efficient as they could be, but this is a toy hobby for me.  I'm not going to invest a whole lot until I'm actually producing 2kw+.

The turbines will come in through the bridge rectifiers on top.  I did solder the connections at the rectifiers.  I tried spades and crimps but they can't working their way loose.  It then runs 12g wire from the rectifiers to the watt meters.  These watt meters are nice and simple but the displays suck...if I redo it, I'll be looking at different meters.



I did setup my lugs for four meters, and I left room to add one more set of lugs.  Ultimately I will probably have five inputs all together.  Output from the meters all go to single lugs at the bottom, still 12g wire.  Each one has it's own wire...the battery lugs are the first point where voltages come together.  The battery lugs are where the batteries, inverter, and output all tie in.

The batteries are not very impressive, being all inexpensive lawn and garden batteries.  Currently there's four of them, plus the old battery from our Ford Expedition, and an old battery from my BMW 540i...both of which are old and were replaced because they had become unreliable in our cars.  They are arranged in a 36v bank.



The inverter is a generic 1000w model.  It does have island protection and I have tested it to make sure that feature does work properly.  These things are known for not be the most efficient, but it was inexpensive and it does shut down during a power outage.  I made the board with enough room to add another inverter if demand for it was there.

Lastly, after it leaves the inverter I have it going through an appliance power analyzer.  I like having this so I can log what's coming out of the inverter but I wouldn't advise going this route.  I have to run the thing backwards to get it to read...which requires me to have one of these amazing things to make it work.

How does it work?  Well, okay, I guess.

The biggest problem this system has is the batteries.  The inveter pulls current off the batteries and will keep pulling until they're tapped.  It's why I'm not investing in better batteries...and the batteries are only there for voltage regulation anyway.  I tried running the system without batteries...just turbines and the inverter.  The problem is that the inverter changes it's rate of draw really violently while the turbines spool up and down.  So long as the turbines are kicking out about 38~40v it's works awesome and I get a lot of power out of them.  The problem is that when they get a little faster, the inverter asks for more juice, and it chokes the turbines...or the breeze goes away and they slow down...but as current from the turbines goes down, the less stress the inverter puts on them.  And then a gust comes along, voltage spikes a little above 60v, and the inverter locks out.  I think that if I could find an inverter that could handle up to a 60v input it might work.

Watching the system work is also a little disappointing.  If the batteries are down enough that the inverter can't pull anything off of them, that's when it's working off the turbines only.  And then it's like a rubber band doing it's thing.  The turbines will spool up and start kicking out a combined output of 500w for about 20 seconds.  By the time the inverter is kicking anything out, the turbines are already coming down...and output from the inverter will peak about 185~200w...but it'll hold that output for nearly a minute.  So less output, but for a longer duration.  Makes the immediate reaction a disappointment, but in the long run I feel like it balances out.  Logged kwh on the watt meters is about 10% higher than whats shown on the appliance analyzer.

What's in the future?

I have one more turbine on hand to tie in, ans I'm going to buy another to play with.  Trying to decide if I'm going to gwet another one of the "700w" ebay mills that I'm pretty pleased with, or picking up something like the ista-breeze i1500...no one seems to like them so it's perfect for what I'm doing (though since they don't publish any specs getting compensated if it fails to perform is way riskier).

I'm also considering buying more batteries.  I'm pondering if removing the two larger batteries and adding five more of the lawn and garden batteries might be helpful in any way.  seems like the way I'm using the system the only benefit I'd have with more batteries is way more cushion during an outage.

Just thought I would share.

[noneyabussiness]

Good job, easy and cost effective way to get into this fun...

[TomT]

Solar controllers will not follow well and first big gust will fry the solar inverter.
I tried it before. The inverter will shut down on a gust and free wheel the wind turbine.
Then fry it.
 You need a dump controller.controller to dump power if it gets close to max voltage.
Which alot of them is just 28 volts.

[makenzie71]

Solar controllers will not follow well and first big gust will fry the solar inverter.
I tried it before. The inverter will shut down on a gust and free wheel the wind turbine.
Then fry it.
 You need a dump controller.controller to dump power if it gets close to max voltage.
Which alot of them is just 28 volts.

This one just goes into fault mode if power exceeds 45v.  I actually explained in deatil what happens:

I tried running the system without batteries...just turbines and the inverter.  The problem is that the inverter changes it's rate of draw really violently while the turbines spool up and down.  So long as the turbines are kicking out about 38~40v it's works awesome and I get a lot of power out of them.  The problem is that when they get a little faster, the inverter asks for more juice, and it chokes the turbines...or the breeze goes away and they slow down...but as current from the turbines goes down, the less stress the inverter puts on them.  And then a gust comes along, voltage spikes a little above 60v, and the inverter locks out.

I'm convinced that if i could f8nd an inverter that could handle upwards of 60v it'd work, but probably not the best arrangement.

These things have been in 50+ mile per hour days so far without a dump load and not damaged anything.  So long as the inverter is on they can't produce more power than it consumes, and if it's off the battery capacity is high enough that it would take a very, very long time for these things to overload them.

[SparWeb]

Great to see how much fun this can be - I agree in full!

It might be easier or cheaper to hunt a few more batteries (golf course?) and then mix and match until you're happy.
Putting in a diversion controller will be on your to-do list eventually, otherwise you'll be killing these batteries.
Not an easy choice, however, because I don't know of a diversion controller that can manage 36V, so you'll have to switch to either 24V or 48V.
Even if you don't want to do it now, I hope you can just file the thought away for later, so that you can adjust these turbines in a certain way to make the battery switch easier in the future.

In another thread, we were talking about adding resistors on the WT power lines to help match the turbine speed.  Same type of resistors can be used as diversion load.

[makenzie71]

Right now I don't think it's needed, but I'm strongly considering adding two more of the 700w models...it'll be an issue then.  I'll be adding another inverter but even that won't keep up if I have all three peaking at 800w, not to mention a couple more making 250-ish.  I've come across a programmable voltage switch that'll let me select my own on/off points.  I've been trading emails with the vendor to find out if I can use it as a dump load and recovery switch to operate a high amperage relay.  I've already got a couple of water heater elements laying around that could be used as dump load resistors.

So, plan in place at least

[margusten]

I ordered this inverter:
https://www.ebay.com/itm/1000W-Wind-Power-Generator-Grid-Tie-Inverter-Wechselrichter-AC-110V-220V-MPPT/233181350351?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
It is accepting 60V max. input and has dump load.
Batteries not needed.
Did not know before that Solar inverter can be used.
I can see makenzie71, Your Solar inverter accepting 24V input.
You can change to 24V battery, this is safer but You can harvester less energy, I think.

[makenzie71]

That was why I went this route...$350+ for a three phase inverter per turbine.  I have less than half that invested in my inverter and batteries and can connect multiple turbines to it.

That said, I do want to, at some point, have a rather large high output turbine set up and that will be the way I go with it.  It's just toys and tinkering for now.

[kitestrings]

Hi Mak,

Looks like your having quite a bit of fun with these things (described in multiple posts), but it begs a question...  Why not combine the $100, $200, $350 purchases for lower quality eBay hardware into one, more robust system, or build one?  Most times you get what you pay for.  I'm not discounting the value of tinkering and deconstructing some of these gadgets, just wonder if you wouldn't be further ahead in the end.

Be safe.  ~ks

[makenzie71]

Hi Mak,

Looks like your having quite a bit of fun with these things (described in multiple posts), but it begs a question...  Why not combine the $100, $200, $350 purchases for lower quality eBay hardware into one, more robust system, or build one?  Most times you get what you pay for.  I'm not discounting the value of tinkering and deconstructing some of these gadgets, just wonder if you wouldn't be further ahead in the end.

Be safe.  ~ks

It helps to first understand that I haven't paid that much for any of them.  I have three turbines on hand right now...the 500 watt, the 700 watt, and the 400 watt.  Allegedly I have one more coming from China...a 600 watt model that looks just like the ebay 500 watt one I've already done.

The 500 watt model for $115 on eBay...but it delivered half the described performance.  With the help of this forum and a couple of facebook groups the highest output I've seen from it was 270 watts.  Also one of the blades was buggered (admittedly I may have done it while trying to stand the pole up).  In the end, the seller gave me $80 back.

The 700 watt turbine the seller accepted best offer, which was $285.  The listing said it came with a charge controller, which it didn't, and it arrived with a bent tail...the seller ended up giving me $125 back...and the turbine has so far peaked at 827 watts.  This is the one I kind of feel bad about pushing for a compensation because I wasn't going to use their controller anyway and the tail was mostly back to right with a couple of hammer blows...and then it peaked higher than stated performance.  Oh well.

The 400 watt model was $90 on eBay.  And then when it arrived the shaft hadn't been pressed into the rotor properly and the hey fell out.  After sorting that one out, there was a gigantic lock washer floating around under the rotor.  The seller ended up issuing a full refund.  I haven't gotten this one in the air yet to see what it'll really do.

So, basically, I'm floating around the $200 mark for the turbines themselves.  The inverter was $90, the batteries for I got for $60.  The wire I had on hand but real world cost is probably about $100 for all of it, and $100 for poles and hardware.  I've got about $100 tied up in meters and rectifiers, too.  All told, under $700 invested (and generating about 2kwh/day so far which makes my ROI about 19 years lmao).

My biggest drive to use these little turbines is just how crappy the reviews for them are.  Even the John Daniel fellow on youtube, who easily posts the most comprehensive reviews on the things, would only say "it doesn't work" and then spend ten minutes explaining how it's awful because it doesn't work...but not really tell you why.  I want to know why.  I want to go at it from the perspective that if it doesn't work, people should know why it doesn't work...and then I want to know what has to be done to make it work.  I will see 500 watts from that first turbine even if I have to mount it to my car and drive hit 88mph to pull it off.  And then I'm going to post the results.

Also, usually I would blow this money on building another AR15 but my safe is a tad on the stuffed side .  At some point I will either build or buy a large turbine and the appropriate hardware to tie it in...we have the wind for it here in the Texas panhandle and I'm on three acres I'm not using for much else...but for now it's just toys.

[SparWeb]

...mount it to my car and drive hit 88mph to pull it off

Ummm... what kind of car do you have?

[makenzie71]

Between the i1500 breaking stuff and having to find room to make the Heli 2.0 work...I had to upsize my board a bit.  I'm probably still going to struggle with chord management a bit.  I'm also probably going to have to start using two rectifiers on the bigger turbines so I'll need more room for those...always a work in progress.

https://youtu.be/2eABx0EluJ0

I meant to take some straight pictures...I know you guys like pictures more than videos...I'll try not to let that happen again :/