Solar The Solar Panel Thread

Boots in Action

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Have seen them for about $10 from China with free postage,,, :o......., the local warehouses for these chinese mobs are pretty quick , the fella puts down his noodles, walks along a rack picks out the box and bungs it into a jiffy post bag or slaps his pre paid label on and courier picks it up, of course if it breaks don't bother going thru the, email supplier BS they won't answer just hit up Ebay for a refund/return it's way quicker........................

Hi @Drover , I too have seen solar controllers down that cheap and these are usually the PWM type with few if any settings. Suitable only for the back of some solar panels, I have also seen supposed MPPT controllers around the $50.00 mark and even cheaper, but these are DEFINITELY not genuine MPPT controllers in operation. I am sure you have seen many of the tests on Utube and that sorts out most of them as a waste of money. The MPPT controller that @Crusty181 has seems pretty good and looks very much like the LD Tracer Dream Series that I bought earlier. I paid a little more (at the time) because the specs suited what I wanted and the thought of a 2 year Australian warranty was comforting. At their going price of $200.00 now, I would not buy it, so I think @Crusty181 has a good deal as there are lots of "user " settings to adjust to your own requirements. @Bellbirdweb bought the Epever and seems to be satisfied, so I hope @Axl has the same satisfaction whatever unit he eventually buys. Go MPPT owners!!
 

Boots in Action

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Only thanks to your guys. In fact, all you tech heads should take some comfort in the knowledge that you have learn up at least one numb skull who is doing a valiant effort at following the mutterings and trying keeping up. 6 months ago I would have just bought any old panels I could find at the church car boot sale, plug them and expect all to be good. Im assuming that you all know what your talking about, my brain has too many Tabs open, and I cant afford BS to be taking up space ;)

Hello @Crusty181 , you must have been following all this solar tech stuff pretty closely as your response to my post covered ALL the aspects of deciding what to buy to cover any future changes and/or upgrades like you have done. As for talking about deciding on series or parallel connections, I for one of the "Tech Heads" was happily surprised that you seem to know enough of what you are talking about to advise others. Well done and move to the top of the class in solar technology.
Hopefully, we "Tech heads" can continue to provide technical advice that will help those that want to improve their understanding of solar generation and batteries. Good luck with your MPPT system. Cheers
 

Crusty181

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Hello @Crusty181 , you must have been following all this solar tech stuff pretty closely as your response to my post covered ALL the aspects of deciding what to buy to cover any future changes and/or upgrades like you have done. As for talking about deciding on series or parallel connections, I for one of the "Tech Heads" was happily surprised that you seem to know enough of what you are talking about to advise others. Well done and move to the top of the class in solar technology.
Hopefully, we "Tech heads" can continue to provide technical advice that will help those that want to improve their understanding of solar generation and batteries. Good luck with your MPPT system. Cheers
There is a lot of banter, railroading of threads and generally shenanigans here; but amongst all that is good company, some clever people, and great minds all too willing to provide their skills, time and patience. Its a rare bird indeed that such a welcoming group of people, mostly strangers, can come together and provide such a melting pot of fun, fact and genuine support, generally in the absence of ego or expectation. I tip my hat to you guys.
Along with you guys and the other experts who offer there time, Ill throw a grateful personal thanks to @SkinnyBuddah for going to extraordinary lengths with his time and knowledge.

This is the only forum Ive ever been on, but Im led to believe forums can be quiet precious and often hostile. I'll promise to keep up the light entertainment, if you guys promise to keep the knowledge flowing. We need the likes of you guys much more than we need the likes of me ;)
 

Bellbirdweb

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Out of curiosity what mppt reg are you using. If I stick with the 160ah panels I will probably run the redarc 20amp reg which is just the old school style reg. There are so many phoney mppt regs on eBay that im too scared to take the risk. On the other hand im not too keen to fork out $400+ on a top of the line one. And living in a remote W.A I don't have a local store so unfortunately I depend on online stores for nearly all of my purchases
If you are going for 2x160w panels id suggest setting them up in Series with the appropriate diode protection.

You’ll need 30A for that setup not 20A.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com.au/ulk/itm/122445182638
 

mikerezny

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If you are going for 2x160w panels id suggest setting them up in Series with the appropriate diode protection.

You’ll need 30A for that setup not 20A.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com.au/ulk/itm/122445182638
Hi @Bellbirdweb,
if I am not mistaken, if two panels are connected in SERIES, the voltage seen at the input to the solar controller will be doubled, but the current will be the same as one panel.

My understanding is a 160W panel would have an Isc of about 10A (assuming a panel voltage of around 20V). So an MPPT solar controller capable of 20A and a max input voltage of 60V would be suitable.

Or am I missing something?

cheers
Mike
 

Bellbirdweb

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Hi @Bellbirdweb,
if I am not mistaken, if two panels are connected in SERIES, the voltage seen at the input to the solar controller will be doubled, but the current will be the same as one panel.

My understanding is a 160W panel would have an Isc of about 10A (assuming a panel voltage of around 20V). So an MPPT solar controller capable of 20A and a max input voltage of 60V would be suitable.

Or am I missing something?

cheers
Mike
Hi Mike,

That would be correct, I was forgetting the higher the voltage the lower the current.

With 38v @ 320w it’s only 8A.

I was taking the current value at the 12v output side, which with the MPPT could potentially still exceed the 20A.

I’d still be inclined to have a 30A controller for a safety margin.
 
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Boots in Action

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Hi @Bellbirdweb,
if I am not mistaken, if two panels are connected in SERIES, the voltage seen at the input to the solar controller will be doubled, but the current will be the same as one panel.

My understanding is a 160W panel would have an Isc of about 10A (assuming a panel voltage of around 20V). So an MPPT solar controller capable of 20A and a max input voltage of 60V would be suitable.

Or am I missing something?

cheers
Mike

Hi @mikerezny and @Bellbirdweb , normally a 160w panel has an OCV of 22.0V, so using that a base data, 160 divided by 22 equals 7.27A ISC. So at best generation would be no more than 7A from single panel output. Being in series, that would be the current going to controller at a voltage of somewhere around 35 to 40V - let's say 35V for this exercise. 7A @ at say 35V equals approx 245 watts. If MPPT controller senses battery voltage at say 12.5V, the differential voltage between input voltage (at controller) and voltage (at battery) is 35 divided by 12.5 equals 2.8. Therefore according to my reckless calculation, output current from MPPT controller to battery is 7A X 2.8 equals 19.6A which is very close to max of 20A rating. Would be pushing the controller to limit and maybe over if battery voltage was as low as 12V , but if the charging voltage from panels under load is only 30V, even that would amount to 17.5A disregarding losses. Unless I have missed something or made another error in calculation, then a 30A controller would be the way to go to give some reserve capacity.
 
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Boots in Action

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Hi @Bellbirdweb,
if I am not mistaken, if two panels are connected in SERIES, the voltage seen at the input to the solar controller will be doubled, but the current will be the same as one panel.

My understanding is a 160W panel would have an Isc of about 10A (assuming a panel voltage of around 20V). So an MPPT solar controller capable of 20A and a max input voltage of 60V would be suitable.

Or am I missing something?

cheers
Mike

Hi @mikerezny , if the total rated output of a panel was rated at 160W and 0CV was 20V , then ISC is 8A not 10A. Volts by current equals watts. 20V X 8A equals 160W. Or where have I gone wrong?????!!!
 

mikerezny

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Hi Mike,

That would be correct, I was forgetting the higher the voltage the lower the current.

With 38v @ 320w it’s only 8A.

I was taking the current value at the 12v output side, which with the MPPT could potentially still exceed the 20A.

I’d still be inclined to have a 30A controller for a safety margin.
Hi @Bellbirdweb,
ok, I had forgotten about the current generated at the output side of the MPPT controller. Indeed, it could potentially exceed 20A, and I agree a 30A controller would be needed.

So, if I understand this correctly. There are two main issues with respect to specifying a controller for a given panel setup:
1: Maximum input voltage from the array must be less than the Maximum rated input voltage for the controller.
2: Maximum output current must be less than the Maximum rated output current for the controller.

Is that correct?

cheers
Mike
 
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Boots in Action

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Hi @Bellbirdweb,
ok, I had forgotten about the current generated at the output side of the MPPT controller. Indeed, it could potentially exceed 20A, and I agree a 30A controller would be needed.

So, if I understand this correctly. There are two main issues with respect to specifying a controller for a given panel setup:
1: Maximum input voltage from the array must be less than the Maximum rated input voltage for the controller.
2: Maximum output current must be less than the Maximum rated output current for the controller.

Is that correct?

cheers
Mike

Hi @mikerezny , that is how I understand it. As one TECH HEAD to another, the max input voltage must take into account the OCV too as this can be higher in cooler conditions. So one must allow about 10% for this too in calculating max voltage into MPPT controller. However most of the good MPPT controllers have safety cutoffs to protect system if parameters are exceeded.
 

Bellbirdweb

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Hi @Bellbirdweb,
ok, I had forgotten about the current generated at the output side of the MPPT controller. Indeed, it could potentially exceed 20A, and I agree a 30A controller would be needed.

So, if I understand this correctly. There are two main issues with respect to specifying a controller for a given panel setup:
1: Maximum input voltage from the array must be less than the Maximum rated input voltage for the controller.
2: Maximum output current must be less than the Maximum rated output current for the controller.

Is that correct?

cheers
Mike
@mikerezny, yes as I understand it, those are the 2 considerations.

Because the MPPT controller uses the additional volts and turns them into additional amps on the charge side, it would be necessary to ensure that current is catered for on the specification of the controller.
 
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Drover

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Hi @Drover , I too have seen solar controllers down that cheap and these are usually the PWM type with few if any settings. Suitable only for the back of some solar panels, I have also seen supposed MPPT controllers around the $50.00 mark and even cheaper, but these are DEFINITELY not genuine MPPT controllers in operation. I am sure you have seen many of the tests on Utube and that sorts out most of them as a waste of money. The MPPT controller that @Crusty181 has seems pretty good and looks very much like the LD Tracer Dream Series that I bought earlier. I paid a little more (at the time) because the specs suited what I wanted and the thought of a 2 year Australian warranty was comforting. At their going price of $200.00 now, I would not buy it, so I think @Crusty181 has a good deal as there are lots of "user " settings to adjust to your own requirements. @Bellbirdweb bought the Epever and seems to be satisfied, so I hope @Axl has the same satisfaction whatever unit he eventually buys. Go MPPT owners!!


@Boots in Action , the controller I was talking about being $10 was the type and brand that was being discussed that in Australia was being sold for $160 to $170, I would be a bit suss as to whats inside though.....................................................I don't buy direct from China and prefer to get Lecko stuff from known good Ebay places like Autoelecau , especially when paying big dollars, good quality with a real return process plus you can ask them something and get an answer .
 

Drover

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This forth coming tour @Boots in Action I will try and see what my sort of figures my controller works at without the boost from the portable panel, I know the Pro Star will work better than the TPS ? controller on the portable, it may lead to a MPPT for the portable and the TPS going to the ute, just have to work out if there will be a real gain that's worth shelling out the $$$$.....
If on a normal sunny day everything is back up to speed by 1000, then I don't think its justified, with week long stops plenty of off grid time to check the upgraded system out. Mind it won't be in anyway as detailed as your efforts....
 

Crusty181

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Just thinking out loud, I have an MPPT controller in the van connected to the vans roof mounted panel, and my portable panel has a PWM controller which I only ever use for the Engel (and never connect to the van). If I did connect the portable panel via its PWM directly to the van battery which is already receiving a charge from the vans MPPT; without load on the batteries would the higher MPPT voltage across the battery terminals trick the portable panels PWM into providing a higher rate of charge to match the higher rate of charge provided by the MPPT. This is either so technical advanced and revolutionary its beyond anyones comprehension ... or just not

Should I just shut up and crawl back under my rock?
 
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Axl

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I like your rock idea.....

From what I understand if you hook two regulators up to the same battery they will fight against each other and not do very much at all, happy to be proven wrong though. One delivers the other sees this and backs out then the first one backs out and the other delivers so on and so on, it becomes quite a s$^t fight between the two.
 

Crusty181

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I like your rock idea.....

From what I understand if you hook two regulators up to the same battery they will fight against each other and not do very much at all, happy to be proven wrong though. One delivers the other sees this and backs out then the first one backs out and the other delivers so on and so on, it becomes quite a s$^t fight between the two.
From my 6min of extensive research I just did on Google "can 2 seperate solar controllers be connected to the same battery" , the Inter-Google-Web has returned resounding yes you can. A couple of manufacturers of massive commercial solar arrays spoke about doing so as a matter of necessity, with a few over-riding qualiifiers about the batteries ability to handle the current etc etc

The PWM controller charges at just above the current state of charge. The voltage across the battery without a load whilst being MPPT charged would have a higher apparent voltage. Would the PWM controller react to the apparent voltage across the terminals, as opposed to actual state of charge. I presume the PWM controller can only see what a multi meter would see, and that would be the higher voltage of the MPPT controller
 
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Boots in Action

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Just thinking out loud, I have an MPPT controller in the van connected to the vans roof mounted panel, and my portable panel has a PWM controller which I only ever use for the Engel (and never connect to the van). If I did connect the portable panel via its PWM directly to the van battery which is already receiving a charge from the vans MPPT; without load on the batteries would the higher MPPT voltage across the battery terminals trick the portable panels PWM into providing a higher rate of charge to match the higher rate of charge provided by the MPPT. This is either so technical advanced and revolutionary its beyond anyones comprehension ... or just not

Should I just shut up and crawl back under my rock?

Hello @Crusty181 , not a silly question at all!! Connecting two solar controllers to the same battery is like having two cooks in the kitchen . One likes his steak rare and eggs sunny side up and the other one wants his steak burnt black and eggs flattened and dried out. One wants his meal in a hurry and the other is a connoisseur and wants to take his time!! Remember the movie "The Odd Couple"?? Well that is the best example of how to explain what can happen. The greater the difference in solar controllers and settings (made either at the factory and fixed, or user adjustable and different brands), the greater task the controllers have in sorting out charge and voltage requirements and meeting changing load conditions. It may not be particularly evident, but that is what would be happening. I would NOT recommend it under normal circumstances even if it "looks" okay.

DEFINITELY NOT not a good idea to try that with two different types of controllers ie PWM and MPPT. The PWM type drags down the panel voltage to just above battery voltage to charge at what ever the input current is. Any excess voltage from panels above battery voltage is just wasted. In fact, with a Pulse Width Modulation Type, it is really just a switch between the panel and battery, turning on and off as necessary. Whilst charging, it is basically "ON" all the time until charge voltage setting is reached and then it switches "ON " and "OFF" keeping the battery at the set float voltage. But this changes all the time according to load factors which drops the voltage and makes it start charging again to make up what has been taken out and caused voltage to drop. It is a lot more complicated than that too if you want to take in temperature of components and battery. There is a different (best) charge voltage for batteries in all conditions - the hotter the battery and or ambient temp, batteries require a slightly lower charging voltage and in colder times, a slightly higher voltage is optimum. But I digress - sorry!!

An MPPT charger is constantly changing the input current to the battery by converting any excess voltage from the solar panels into extra current (amps). This is IN ADDITION to the current being produced directly by the solar panels. Let's say that the solar panels are producing 10A on their own, but there is 6 volts from panels above the battery voltage which is SENSED by the MPPT controller.( Panel charging voltage to controller is 19V but battery voltage (sensed by controller ) is 13 volts.) The MPPT controller DOES NOT WASTE THIS EXTRA VOLTAGE (like the PWM type does), but converts this excess voltage into additional amps to add to the 10 amps already available from the panels. And this is happening all the time, constantly adjusting current available to charge or carry the load placed on electrical system. The greater the differential between the panel voltage and the battery voltage, the more spare volts are available to be converted to extra amps. So the lower the battery voltage (say only 11.8V (near battery disconnect?) and the higher the input voltage from panels, the more amps you get and the faster your battery/ies are recovered by charging. MPPT stands for MAXIMUM POWER POINT TRACKING and that is exactly what it does!
@Crusty181 , in an earlier post which even @Drover thought was a good idea was to bypass the controller on portable panel with a separate lead and Anderson plug and connect this lead from portable panel in parallel with the existing input line to your MPPT controller. So you end up with two leads hanging off the back of your portable panel - one that goes through the existing panel controller which is still suitable for charging other things, and the new cable from the portable panel (bypassing the controller on the back) which you can easily join into existing system and not lose any of the original properties/uses.

God this has been an epistle!! I hope this covers all the bases and I have not lost too many. Some "Tech Heads" cannot help themselves. Sorry!!
 
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Boots in Action

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This forth coming tour @Boots in Action I will try and see what my sort of figures my controller works at without the boost from the portable panel, I know the Pro Star will work better than the TPS ? controller on the portable, it may lead to a MPPT for the portable and the TPS going to the ute, just have to work out if there will be a real gain that's worth shelling out the $$$$.....
If on a normal sunny day everything is back up to speed by 1000, then I don't think its justified, with week long stops plenty of off grid time to check the upgraded system out. Mind it won't be in anyway as detailed as your efforts....

Hello again @Drover , I am looking forward to YOUR report on what is happening with the van charger/batteries in varying conditions. There is no great difference in output efficiency between various PWM controllers. The better ones have lots more user friendly settings and displays etc to supply info to user, but not much different in output - component quality notwithstanding. However with an MPPT controller, you are talking about an entirely different technology. Like comparing carburettor power with fuel injection. Both will give you power, one just does it better and more efficiently. Your recordings are handy to have, but you are not trying to prove anything. I WAS with my detailed MPPT reports, and that is why I did so much field testing for myself, so I could put it to the other Tech Heads on this forum who are pretty switched on, and mostly have more electrical technical experience than me. But I learn fast and do a lot of research, pester expert electrical engineers with many years' experience in solar and am able to glean a lot from their own situations faced. Only then do I have the temerity to offer my ideas which have worked for me and MAY work/be useful to others who want to see what they can do. There is nothing as good as passing on tested and proven information which will help others, just like you have done on this forum!!