Solar The Solar Panel Thread

Boots in Action

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Having a second thought about my planned solar install. And wouldn't mind some input

Was initially thinking 2x 160-200w panels, appropriate regulator and 2x 100-130ah agm batteries. Pretty much a common system

But now thinking that 2x 160w panels, appropriate regulator and 2x 70ah gel batteries.
This setup will not only be lighter and cheaper, but I'm led to believe will actually have more "capacity" due to the 50% discharge ability of cell over agm's 20%.

Can anyone offer some pro tips to this setup.
Hello @Jared Dunne and welcome to the forum. I like your original idea and think that the lesser amp hours with Gel type is NOT the way to go. Have a good read of this site on comparison .
Gel vs AGM - BatteryStuff.com
https://www.batterystuff.com/kb/articles/battery-articles/gel-vs-agm.html

IMHO, your advice regarding GEL batteries is not correct. For some strange reason, Jayco persist in installing GEL batteries in their vans, even though they are dearer and not as readily available to replace. Not every battery shop has them, but AGMs are everywhere!! The GEL work okay, but there is better technology around with the latest AGMs. Gel batteries have been quoted as 60s technology. One of the members on this forum recently moved into the 21st century with Lead Crystal batteries. Much dearer, but apparently indestructible. Try Google LEAD CRYSTAL Battery for more info. Not necessarily my own thoughts, but the facts are laid out clearly on many sites including on this forum if you look back a bit.

The set up with 2 X smaller Gel may be slightly lighter but the cost of Gel batteries is a lot higher than good AGMs which @Drover has said are readily available. Also note that Gel batteries are nowhere near as robust as AGMs and require special charging rates. If you are going to run your battery capacity down to the MARGINAL 50% DOD, then 50% of @ 2 X 120 ah AGMs is approx 120amps. Do the same with the lower capacity Gel 2 X 70ah and you can only use 70amps. In fact with a quality MPPT solar controller and 1 X 120ah AGM , you would still be way ahead with the same wattage panels than with an ordinary PWM controller and 2 X 70ah Gel. Have one good AGM with 120 or 130ah capacity and put the extra money into an MPPT controller to keep your battery charged. @Drover (Sorry @Drover - you again!!!) has said before on this forum , that you can never have enough storage, and it is a matter of working out how much you are going to use verses what you may generate in good and bad conditions. And of course, your wallet. It is an expensive mistake if you do not achieve what you want. Choose carefully.
 

Boots in Action

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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
Again @Jared Dunne , with 2 X 160 watt panels, you would need at least a 30 amp MPPT controller. On Ebay, you can get a proper and reliable MPPT controller (Epever) for around $165.00 . There may be a few dollars more for separate remote display panel and lead and remote temp sensor. Contact @Bellbirdweb as he recently fitted one for under $200.00 and is extremely happy. I myself have a LD Tracer Dream series 30A (2 year warranty) which I bought from a company in Forster NSW on Ebay which was only $140.00 at the time. Has now gone up to nearly $200.00!! I am using 2 portable panels in series 1 X 200w and 1 X 180w. Have a good look through the posts on this forum for the proven MPPT controllers.
 
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Crusty181

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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
Im using a 40amp Epsolar MPPT controller, around $160 on Ebay delivered. There are cheaper 30amp and 20amp models, youll just need to make a parallel or series preference decision and check the specs of each unit to make sure its suitable. I went with the biggest offering, the 40amp model, not for the amps but the voltage capacity which will cope with 3 x 150w panels in series so kinda of future proofs any change of system direction down the track.
 

Boots in Action

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Im using a 40amp Epsolar MPPT controller, around $160 on Ebay delivered. There are cheaper 30amp and 20amp models, youll just need to make a parallel or series preference decision and check the specs of each unit to make sure its suitable. I went with the biggest offering, the 40amp model, not for the amps but the voltage capacity which will cope with 3 x 150w panels in series so kinda of future proofs any change of system direction down the track.
Hi @Crusty181 , you seem to all over it. Whilst it is important that the controller is able to handle the greater current that your MPPT controller may generate, one of the other very important areas if connecting in SERIES, (not so important if connecting in parallel as probably only 18 to 20V) is the max voltage input. With each panel producing around 22.0V on OCV and around 18.0V working voltage, one could connect up 4 panels in series and still be under the limit of say 100V which most good MPPT controllers have. My LD Tracer Dream is rated at 30A and up to 100V.

A 72.0V input (4 panels in SERIES) even at a lowly 6.0A (the lowest output in the series!) 420 W is a lot of watts for the MPPT controller to handle and convert to battery voltage. No need to worry about voltage drop in the INPUT wiring to the controller. But a very good reason to have the connecting wire between the controller and battery/ies as short as possible and able to carry the much heavier current - more than 30 Amps!!!
 

Crusty181

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Hi @Crusty181 , you seem to all over it. Whilst it is important that the controller is able to handle the greater current that your MPPT controller may generate, one of the other very important areas if connecting in SERIES, (not so important if connecting in parallel as probably only 18 to 20V) is the max voltage input. With each panel producing around 22.0V on OCV and around 18.0V working voltage, one could connect up 4 panels in series and still be under the limit of say 100V which most good MPPT controllers have. My LD Tracer Dream is rated at 30A and up to 100V.

A 72.0V input (4 panels in SERIES) even at a lowly 6.0A (the lowest output in the series!) 420 W is a lot of watts for the MPPT controller to handle and convert to battery voltage. No need to worry about voltage drop in the INPUT wiring to the controller. But a very good reason to have the connecting wire between the controller and battery/ies as short as possible and able to carry the much heavier current - more than 30 Amps!!!
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 ;)
 

Axl

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Im using a 40amp Epsolar MPPT controller, around $160 on Ebay delivered. There are cheaper 30amp and 20amp models, youll just need to make a parallel or series preference decision and check the specs of each unit to make sure its suitable. I went with the biggest offering, the 40amp model, not for the amps but the voltage capacity which will cope with 3 x 150w panels in series so kinda of future proofs any change of system direction down the track.
Can I ask where on ebay you brought this from @Crusty181? I've done a search as I want to purchase one soon and there's a guy on there selling a 40A controller and the remote display for $170. That's around $480 worth of gear something just doesn't ring true here to me.....
 

Crusty181

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Can I ask where on ebay you brought this from @Crusty181? I've done a search as I want to purchase one soon and there's a guy on there selling a 40A controller and the remote display for $170. That's around $480 worth of gear something just doesn't ring true here to me.....
Seller : trustinchina
Current offering : https://www.ebay.com.au/itm/EPsolar...654043?hash=item3f68878edb:g:KCoAAOSw9NdXqwCz

trustinchina states local stock, and mine arrived pretty quickly so I suspect it is local. trustchina has a 40A controller advertised with remote for $182, so $170 not so outrageously cheap although there isnt any others that cheap for both. Seems to work ok, good luck with it
 
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Axl

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Seller : trustinchina
Current offering : https://www.ebay.com.au/itm/EPsolar...654043?hash=item3f68878edb:g:KCoAAOSw9NdXqwCz

trustinchina states local stock, and mine arrived pretty quickly so I suspect it is local. trustchina has a 40A controller advertised with remote for $182, so $170 not so outrageously cheap although there isnt any others that cheap for both. Seems to work ok, good luck with it
Thanks @Crusty181 that was the seller I was looking at I was just shocked at their prices. I was just about to hit go on a 20A unit from a reputable online seller for $180 when I read your post.
 

Drover

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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........................
 

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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Feb 7, 2010
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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 @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?????!!!
Hi @Boots in Action,
you haven't gone wrong. I don't have the actual panel specifications, so I just rounded up to allow for a margin of error.

cheers
Mike
 

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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