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gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 02:36am 03 Sep 2016
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Hi,
I partially live off grid. Started off small, with a 1kw solar array and a small battery bank. I was looking for a cheap solar controller and came across this on..... where else but Ebay.
It looked good with fairly sturdy construction and had what I thought a decent heat sink. The price was right too! Rated at 60 A was well above the possible 40A output from my panels. It worked well even though it was getting hot, but with a small fan behind drawing air thru the fins soon fixed that problem and was running cool as a cucumber. So impressed I was that with another 1kw of panels decided to go back to ebay and purchase another. After hooking it up I was happy that my batteries were being looked after.
With yet another 1kw of solar it was time to go shopping again. Same place. The item arrived 3 days later from their Sydney depot and proceeded to wire it to my latest array. This is where it all went pear shaped. The moment I hooked it up and came on line I realised that it was not regulating. Even if I took away the B+ sense wire the controller just kept on going... like it was shorted out. On to ebay to try and sort thing out with the supplier. To cut a long story really short and after many many emails and promised replacements I gave up. By then it was too late to open a dispute in the resolution centre.
So I decided to pull it apart and check inside.. this is what I found
I noticed the connections on Q13 had been hot just a little. Hard to tell from the pic but had that slightly melted look on the connections. So I unsoldered it and with a multimeter checked the culprit. Sure enough it was shorted out. I'm hoping that if I can replace the FETs then there is a good chance that the thing might work. Can any one tell me if there is something that can replace the burnt out item?
Marcusif it aint broke dont fix it!!
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 11:02am 03 Sep 2016
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I use lots of irfb4110 which are 120a 100v .004-.006R
That one is is 75v 80a .009R
The solar controller I built uses 9x4110, and comfortable runs 110amps at 50v.. runs dead cold, but is inside an inspire box and uses the main heat sink so not surprised either.
Cold you possibly show us the innards of that unit to get an idea of how it might work?
The 4110 are a about a dollar each.. I buy them by the hundred.
..........oztules
Village idiot...or... just another hack out of his depth
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 07:26pm 03 Sep 2016
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Thanks again Oz.
So I guess that the irfb4110 are a direct substitute for the STP75NF75. I can get either from ebay for a similar price. So would it matter if some were different or are they happy to live side by side?
Here are a few pics of the internals of the controller for you to gander at. Marcus
The substantial heat sink
The flip side
Note there are 3 fets missing from the board. I removed them as I believe they were for the auxiliary load section of the controller and weren't being used so transferred them with the burnt ones to see if that would fix the problem...but it didn't. So maybe I have more issues or maybe I should just replace all of them and see what happens. Cant hurt and the parts are cheap.
@oztules
would you mind elaborating a little on your diy solar controller for the rest of us?
Thanks
Jason
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 08:31pm 03 Sep 2016
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Thanks Marcus.
Thats a tiny coil to store power in, unless the frequency is crazy high... but I have little ( no) experience with buck converters.
Have you measured the input amps and the output amps to see if you do any better than unity?
Jason, it is a simple pwm unit. It is not mppt.
In my systems, by choosing the panels as 60 cell instead of 72 cell, you can't get much if any improvement with mppt.... but you can use the extra money to buy kilowatts of extra power.... so I do that.
I will do a story on them very soon, as I need to build few for some folks nearby.
I did have mppt by GSL.... but for one of them you can get a kw or more of panels instead... which works very very much better.
..........oztulesVillage idiot...or... just another hack out of his depth
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 09:17pm 03 Sep 2016
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There are quite a few of those cheap charge controllers flogged off as MPPT but there really PWM.There are only 10 types of people in the world: those who understand binary, and those who don't.
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 12:10am 04 Sep 2016
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I'll second that.
Especially when I spotted the name "wellsee" above.
I bought one of the "Wellsee" MPPT controllers for my boat. When testing it, current in always equaled current out, so mine did not MPPT despite it saying so on the case.
And yes, I did use a solar panel with >21V open circuit voltage (12V battery).Klaus
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 01:27am 04 Sep 2016
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Thanks for that Tinker, as thats what the board says to me as well.
..........oztulesVillage idiot...or... just another hack out of his depth
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 01:41pm 04 Sep 2016
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I must admit that when I saw MMPT stamped on the side I was a bit jubious whether it was true or not. Especially for $65. But I thought it was worth the punt anyway. In saying that the first 2 have been going great every day for the past year or so. If I can get this one resurrected then I'll be happy.
Checked the input A vs output A this morning. Exactly the same going in as out.
Ps.. I'll be looking forward to see your DIY controller Oz as we all will.
Marcus if it aint broke dont fix it!!
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 02:54pm 04 Sep 2016
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Marcus, if you have 60 cellpanels, then your not going to do much if any better if it was mppt or not.
72 cell panels in the 200 watt range seem to be only 5-6amps and use the 5x5 cells, 60 cell panels use the 6x6 cells so more current ( 8-9a) at a lower voltage for the same amps.... it sort of has taken the place of mppt. There is still a differential that could be taken advantage of.... but it is slight, and only when the batteries are very low.
So if the units you have keep the batts up, then happy you... and if you have 6x6 cells, chances are you will do no better with mppt most of the time.
The oztules controller is stupid simple, (as you would expect), and is really only a fan controller type comparator on steroids..... so simple simple.... but sometimes simple works too.
Like this ozinverter I finished yesterday having it's burn in.
Sometimes it just works.....
That one has the clockman boards in it... seems to hold 32C @ 2.6kw for hours on end with 17C environment.... will be interested how it performs under all conditions.
Solar controller to come next.
............oztules
Edited by oztules 2016-09-06Village idiot...or... just another hack out of his depth
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 10:02pm 04 Sep 2016
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Oz,
All my panels are 72 cell. I've talked to a guy from where I purchased the panels from and he swears by MPPT, but for me I really cant see how it will make any real difference. If the sun is out and my batteries are at 27.2 then im happy. Im more for some extra panels anyway. Always said you cant have too much and there cheap as chip these days. Just a few kw s more..Thats all I need.
Stupid simple is right up my alley. Less things to wrong the better. A lot of stuff is over engineered these days ....so bring on the Oz controller... Hell, I might just make one my self as the next project.
I purchased 20 of the irfb4110 today from ebay. Should be here in a few weeks or so, so that will be the immediate project. Hopefully I can get it up and running before the summer sun comes. As at present I have 1kw east and 1kw west feeding into the same controller. Not sure if its the right thing to do but seems to work. Ill be happier with the 3 controllers on the 3 individual arrays.
Marcus if it aint broke dont fix it!!
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 01:31am 05 Sep 2016
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Yeah, 72 cells can benefit from mppt where 60 is moot...... however for 1kw you have at best 200w in good conditions to gain... but another panel for the same price and no mppt will probably win in the end.... all comes down to surface area eventually, and poor light is when you need it most.
If you series them and get up in the 400v mark, there are good gains to be made, so grid ties reverse running into the inverter will do well
Forgot to answer another query from you.
Technically, yes it makes a difference if you mix fets. The capacitance may be different and a host of other things like oxide thickness, channel size and surface area etc..... so an EE will have a fit.
In practice at the low speeds we are probably using in that thing, I doubt it will make any real difference..... and the 4110 can take 300 amp surge ... so if it triggers nano seconds earlier, I doubt you will know .... particularly with it hanging on the end of solar panels without large cap banks to store energy... ie it will only see 60 amps at best if it does trigger first.
Big cap banks and batteries would stress things a lot more, .... I have never experienced a problem with a bit of mix and match if you keep them in the same ball park but I expect some folks have.
.............oztulesEdited by oztules 2016-09-06Village idiot...or... just another hack out of his depth
mason Regular Member Joined: 07/11/2015 Location: CanadaPosts: 86
Posted: 01:49am 05 Sep 2016
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Oztules,
I was going to buy the Magnum PT-100 , but can't justify paying 800.00US for it.
I'm tired of paying these ridiculous prices for this hardware.
I think your going to save people alot of cash here.
way to go Oz thanks
BTW- how many volts/amps can the OZ controller handle?
Mason
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 02:17am 05 Sep 2016
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Mason, it runs 100v fets, and I have seen 110 amps@57v.... or about 6kw or so.
One is attached to 10kw at another site. seems to handle it fine... I'm not there to see it's max current.
It has 10 x 4110 120amp fets ( It says 180, but I I cant see how.... nor 120 for that matter).
The silicon can do 120 amps, but the legs cant I feel sure.... so I figure 20 amps max per fet gives us 180amps or more if you can cool it... which is easy with .005r units and inspire heat sinks.. they stay cold.( combined rdson is .0005R )
My bank is only 675ah, so it won't absorb 100 amps or more for long periods, it will let the voltage rise, and so the controller backs off... seems to spend a lot more time at the 40-70 amp range... but I don't see the bank at less than 70% either... so that may also mitigate long periods of very high current.
I should take more interest.
...........oztulesVillage idiot...or... just another hack out of his depth
mason Regular Member Joined: 07/11/2015 Location: CanadaPosts: 86
Posted: 11:04am 05 Sep 2016
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Well that sounds like a pretty robust controller and I'm thinking a lot of people could use it with specs like that, me for one.
I'll wait for your write up on that one.
thanks
Mason
Edited by mason 2016-09-06
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 05:38pm 04 Jan 2017
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Well I noticed the other day that my power output was down from the usual. So upon investigation I realised that one controller had just shut down. No lights, no one home, no power! Its the one which controls 2 x 1kw arrays...One facing east and the other west.
I removed it from its mounting and took off the front cover. Everything looked ok at first glance but thur the magnifying glass showed a different story. The printed circuit board was o/c to Q15,16, & 17 one being really hot. Its no surprise as this 60A controller has been working hard being fed by the 2 arrays. In the winter and spring it wasnt an issue but now the summer sun strikes directly on to it and by midday its directly averhead. Must be pumping in 70a on good days!
So I replaced all the fets, reassembled it and hooked it back up. Lights came on. It worked. Yay!! I watched as the voltage climbed above 27.....27.1,...27.2... bla bla bla. By 28v I knew I had a problem. No regulation. Not wanting to spend any more time or parts repairing a broken controller that worth $60. And I dont want to purchase another as the regulation voltage was never stable, I was wondering if any one has a simple circuit diagram of a PWM controller, say up to 80A, 24v, that is robust that I can be built. Marcus
ps .....hope you all had a merry christmas and a saw in the new year in a joyous place.
Marcus if it aint broke dont fix it!!
mason Regular Member Joined: 07/11/2015 Location: CanadaPosts: 86
Posted: 12:14pm 06 Jan 2017
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Hey Marcus, If you google charge control circuit there are a few circuits that Swagatam designed, all you have to do is add some more mosfets to them so that the circuit can handle more amps.I'm going to be using his 48volt circuit but haven't had time to mod the circuit.
Hope this helps you.
Mason
gpalterpower Senior Member Joined: 19/07/2009 Location: AustraliaPosts: 175
Posted: 11:10pm 08 Jan 2017
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Hi Mason, I checked out Swagatams site. plenty of projects there including many solar controllers. Most are the MPPT 12v type with just a single FET.(would have prefered a PWM as I believe they are simpler) I picked this one out. How would I go about increasing the number of fets within the circuit for an 80 amp controller and what changes do I need to make for a 24v system? Or, can you suggest an alternative. Marcus
if it aint broke dont fix it!!
mason Regular Member Joined: 07/11/2015 Location: CanadaPosts: 86
Posted: 07:43am 09 Jan 2017
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Marcus,
Just replace the mosfet thats there now with 3 sets of 3 in parallel, if you check the mosfets data sheet it should show you how you parallel the fets, One other thing the two top diodes are actually 5 each in parallel, just in case you didn't see that.
And I'm pretty sure thats all you have to change with this circuit.
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.
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Im more for some extra panels anyway. Always said you cant have too much and there cheap as chip these days. Just a few kw s more..Thats all I need.
but I expect some folks have.
