 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Electronics : 8 KW Inverter Build
  Page 18 of 22   |
|||||
| Author | Message | ||||
oztules Guru  Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Ok.... done and dusted  And I used tape for the cover up  Your right, easy to do, easy to wind, and looks pretty neat too. At least with the twin stack I only needed 14-15 turns. So 15t of 19 in hand works fine... have not tested it yet. I had to unwind the transformer as it had 2x25mmsq windings already... but I had to try it  Yes the GTI is the way to go. It is the most efficient, and you don't even have to have any redox reactions in the mix ......oztules Only took an hour from start to finish. The time stamps will show about 2-3 hours, but that includes a 3km walk as well...as procrastination and brekky  Edit... and sell the midnights to some other poor slob... and use more GTI, and buy more panels with the monies left over... run the air con much better too. Village idiot...or... just another hack out of his depth |
||||
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Good job. Yes not hard at all, how many square mm you got on there? Plenty of room left and a big slice off the build cost. The plan is to sell the Midnites after getting inverters sorted out then the next step is to work on charge controllers, a thought I have had to regulate the charge is to PWM the solar coming into the GTI's. I have not looked but the IGBT's from the scrapped Aero-sharps might be a good candidate. Items I will be selling are 2 Midnite Classic 150 Charge Controllers with shunt hardware, 2 Trace SW4845 Inverter Chargers and a Lister 8KVA Generator. There are only 10 types of people in the world: those who understand binary, and those who don't. |
||||
| oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Yes, that transformer has dropped from 50mmsq down to 38mmsq.... but it will be plenty for normal use... I only try for about 4kw continuous, with easy runs up to 6-7kw for 20 mins or so, and 25kw surges... that will do that just fine. Next one I will probably make about 46mmsq or 23x1.6mm wires. Yes to the pwm for the GTI I amp pondering that route also. The solar control board I build alreay does all I need, just need to add fet driver and fets/igbt. Pretty small currents to deal with @ 300-400v... so instead of pwm the panels to the batts, it will pwm the panels ( HV) to the GTI input.... only the driver and fets need altering... may even do it today too. ............oztules Village idiot...or... just another hack out of his depth |
||||
| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Thinking about GTI and battery charging, when the Inverter back charges is it losing the normal 8 - 10%. So would it pay to keep some solar DC coupled and some AC coupled? There are only 10 types of people in the world: those who understand binary, and those who don't. |
||||
| oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
You would need to measure the DC output from the GTI system, and the midnight to battery system to get a good idea of the relative efficiencies. One suspects that the GTI during daytime usage is the very best, as it does not use the battery or the inverter to push power to end uses if they are there to drive. Once the GTI is over driving, it is a different problem, and I don't have the answers to that... as I don't run an mppt system to equate it to. I suspect a mix is the best solution. ..........oztules Village idiot...or... just another hack out of his depth |
||||
| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
One thing about efficiency. Any loss in the system is going to show up as heat. If it all runs cool no problem. Cheers, Tony. |
||||
| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
What I am considering is what is the most efficient way to use energy from the PV panels. The GTI is doing well powering loads during the day and showing better efficiency than my DC charge controllers. However losing 10% charging via the Inverter is a substantial amount of power to loose. It is not an issue when the sun is shining brightly and there is not a cloud in the sky. As Oztules has said many times it is the dark days you need to cater for. Midnite claim 98% efficiency on the Classic 150 charge controllers that I have 2 of. Yet I am seeing more watts from the Aero-sharp for the size of the array connected it to it. I am wondering if the chinese product is reporting more than it is actually producing, when I get some time I will put an external meter on the Aero-sharp and see what it tells me. The power meter I put on the input to the switch board on 22/04/2016 is now showing I have made 6.050 Megawatts of AC power in the last year. There are only 10 types of people in the world: those who understand binary, and those who don't. |
||||
Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429 |
Yes I find my GTI's backfeeding through my OzInverter very efficient, compared to my 5kW of PV with a Classic 200 & a Tristar MPPT DC controllers. Sorry no actual data yet on this, its all here, its just finding time to extrapolate. However the DC controllers are very good at finishing the batteries to float and float mode. Its my 1300ah 48v batteries I want to last as long as possible. I have a real mix Energy creation. Turbines clamped to the battery, DC diversion controllers to 8kW of heaters up in the main house, DC PV trackers to the batteries, and PV GTI,to my Mini Grid, created by the OzInverter. However DC diversion controllers are not getting any cheaper and cables need to big. So I am moving to dumping AC using this circuit from Hugh Piggott. http://scoraigwind.co.uk/tristar-follower-to-control-ac-heaters/ But should the OzInverter suddenly fail, none have yet, not even hicupped, those wind turbines still need that Dumping excess energy than the battery needs. The PV DC and GTI just switches itself off. As you know the commercial Inverter I purchased could just not cut the mustard, so the OzInverter came along at just the right time. My philosophy Keep it Simple, Make it Robust, Keep it Cost Effective. Regards murky conditions with the PV. That 10% to 20% coming in, is probably about equal with my MPPT GTI's and the DC MPPT controllers. So I believe in low light conditions I am getting max power possible from the PV panels. 300w, 150w, 400w, 280w it all adds up. Just another 15kW of PV required to give me 3KW during those grim winter days here in Normandy. Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
||||
| oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
I'm still completely agog at how well these simple inverters perform....... really totally amazed at how simple they are, and how well they perform... It shouldn't be allowed really. My second set of boards are on the way now from China... another 10 units of the control and power boards. I am trying desperately to make no more, but folks want them here..... the word is spreading unfortunately. Luckily, I am running out of grid tie inverters to use as carcasses, so I will soon be able to say NO. I don't seem to be wired to say no otherwise. .........oztules Village idiot...or... just another hack out of his depth |
||||
| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Maybe the Chinese will start making them for you. There are only 10 types of people in the world: those who understand binary, and those who don't. |
||||
mason Regular Member  Joined: 07/11/2015 Location: CanadaPosts: 86 |
Oztules, do you think there would be a problem with a split phase unit using your circuits? Thanks |
||||
| oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
No difference except for the center tapped transformer secondary. Loads will need to be balanced as you reasonably would do anyway. At least the torroid should allow for easy load sharing and still be pretty stable I would expect... sense the 240v not the 120v perhaps will be best. ...........oztules Village idiot...or... just another hack out of his depth |
||||
| mason Regular Member Joined: 07/11/2015 Location: CanadaPosts: 86 |
Oztules, I'll give it try when this pj quits. Thanks |
||||
| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
I had a Tristar controller also, they are a good product but I found the Midnites to be much easier to setup and have much more built in as standard. If you are using multiple controllers and want them to talk to each other most companies that make the controllers charge a fortune for the hardware to get them to talk to each other and connect your computer to them. The Midnites (except there cut down versions) have all the communication hardware built in as standard. It would be very doable to get the same level of control with your GTI's and back charging. By using an IGBT to control the DC from the PV panels going into the GTI. I know Oztules like to keep it as simple as possible however I will be working on getting the same level of control you get with a commercial charge controller using an Arduino. This can done with the GTI and direct DC to DC from PV panels. As per Oztules method of using panels that have maximum power at 30V then connecting them in strings of 2 so you have maximum power at 60V. With this arrangement controlled by a simple PWM inexpensive DIY controller, you can buy a lot more panels with the money you save on the charge controller. I can buy around 5KW of 2 year old secondhand panels for about the same price as one PWM controller. Once I get my Inverters finished I will start working on this. There are only 10 types of people in the world: those who understand binary, and those who don't. |
||||
| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
I just connected the Aero-sharp GTI to the new smaller Inverter I am building with nothing else running off of it. I have not measured the actual output of the GTI yet versus what it says it is producing. I was able to get actual power going back into the batteries, the GTI said it was making 728W at the shunt to the batteries I measured 633W. That is around 15% less, I need to check the GTI's actual output yet. There are only 10 types of people in the world: those who understand binary, and those who don't. |
||||
| Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429 |
 Just adding 4.5kW of the latest PV on my Old Barn roof, 1.7m by 1m by 40mm thick 60 cell Monos, 280w at 40v VOC. What I find with the Midnite and the Tristar MPPT DC controllers, is that they give way to the AC GTI's that are backfeeding into the battery. At Full/bulk charge, ie the batts are down, then all controllers are putting in. And the DC MPPT controllers soon back off when they think the battery is pushing back. The Midnite is a sensitive woossie, and soon goes hides under a bush, while the Tristar MPPT gently trickle charges at float, even when the GTI's have shut down as the battery is full. Computers, and monitoring, and comms talking to each other, well my lot just don't need it, and the system runs smooth as intended, with out the complicated add ons. The midnite is good at squeezing that last drop of power out of the panels in small systems, or in low light conditions, but personally I much prefer the simplicity of the Tristar MPPT. The only problem with the Tristar is it does not operate above 150 volts input. While with the expensive Classic Midnite there are more models that are available with higher voltage inputs. The latest PV 60 cells Monos I have just obtained are 280w each at 40v VOC, so matching panels to controllers is very important. Yes, I like Oztules 60v string concepts for DC charging, and I might try it. But to be honest, with so many second hand Good quality MPPT GTI's for sale on fleebay here in Europe, and some old stock new, at a fraction of the original price, about $50 per 1kW, the price is very right for me. I will follow your progress with interest. Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
||||
| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
I suspect the Tristar is still charging due to it's settings, if the batteries are full then should it still charge? With some tweaking I am sure the Midnite would charge under the same conditions. The voltage of panels you need to consider most for direct charging is VMP (maximum power), VOC (open circuit) only effects the maximum voltage your charge controller can handle first thing in the morning in the coldest weather. At this time the panels will put out the highest voltage before the charge controller starts to actually charge. I don't know about where you live but I discovered and Oztules confirmed it but in cloudy weather you get the most power with panels lying flat. There are only 10 types of people in the world: those who understand binary, and those who don't. |
||||
| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I can also confirm the flat panel hypothesis. Next time the sky goes a totally dull evil grey, you can look due south and the sky looks exactly the same as in any other direction. So panel orientation makes no real difference. What you need then is large panel area, no substitute for that. But the optimum in total cloud cover would be pointing straight up, with the horizon visible all the way around. And that also works amazingly well in mid summer with the sun almost directly overhead at mid day. Only thing you need to watch is the long term buildup of dirt, and bird crap. If you can duct some collected rain water to run across your flat panels, they will get a pretty good wash during each rainstorm. Cheers, Tony. |
||||
| Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429 |
. Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
||||
| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yes Europe is a very strange place. They have Christmas right in the middle of winter, and the sun is mainly in the South. They also have this strange meteorological phenomena called "snow". Cheers, Tony. |
||||
| Page 18 of 22 |
|||||
 Print this page |
